Biology Life on Earth, 10E Gerald Audesirk Solution Manual

Type:

Solution Manual

Resource:

Biology Life on Earth

Edition:

10th Edition

Author(s):

Gerald Audesirk Teresa Audesirk Bruce E. Byers

Instructor Guide for

Biology Life on Earth Tenth Edition

Biology Life on Earth with Physiology Tenth Edition

Teresa Audesirk Gerald Audesirk Professors Emeriti, University of Colorado, Denver

Bruce E. Byers University of Massachusetts, Amherst

CHAPTER 1 AN INTRODUCTION TO LIFE ON EARTH LECTURE OUTLINE Case Study: The Boundaries of Life?

1.1

What Is Life?

A. The Word Biology Means “the Study of Life” 1. Living things contain certain characteristics that define life 2. In the early 1800s, scientists concluded that the cell is the basic unit of life (Figure 1-1) a. Due to the small size of cells, the characteristics of life are more easily visualized in multicellular organisms (Figure 1-2) B. Organisms Acquire and Use Materials and Energy 1. Organisms need materials and energy for survival a. Organisms are continuously exchanging materials and energy with their nonliving surroundings (Figure 1-3) 2. Certain organisms conduct photosynthesis to produce food for themselves, which can also be used by other organisms such as fungi and animals â Links to Everyday Life: A Solar-Powered Big Mac? C. Organisms Actively Maintain Organized Complexity 1. Organisms must use energy to continuously to maintain themselves a. An example of this is the maintenance of body temperature (Figure 1-4) D. Organisms Perceive and Respond to Stimuli (Figure 1-5) E. Organisms Grow F. Organisms Reproduce (Figure 1-6) 1. Reproducing involves giving rise to offspring of the same type 2. Offspring inherit the instructions for maintaining life from their parents a. These instructions are carried in the hereditary molecule, deoxyribonucleic acid, or DNA (Figure 1-7) G. Organisms, Collectively, Have the Capacity to Evolve 1. Evolution is the process by which modern organisms have descended from earlier and different forms of life 2. Over the course of generations, changes in DNA in a population occur and result in evolution â Case Study Continued: The Boundaries of Life â Lecture Activity 1.1: Viruses: Alive or Not?

1.2

What Is Evolution?

A. Evolution Explains Why Earth Has Such a Huge Diversity of Life 1. Organisms typically descend from a common ancestor (Figure 1-8) B. Three Natural Processes Underlie Evolution 1. Differences in DNA among members of a population, inheritance of these differences, and natural selection 2. Mutations are the original source of differences in DNA a. Genes are the basic units of heredity and are made up of DNA b. Mutations cause changes in the DNA, and therefore genes 3. Some mutations are inherited 4. Some inherited mutations help individuals survive and reproduce a. Natural selection is the process by which organisms with certain inherited traits survive and reproduce better than others in a given environment b. Inherited traits that help organisms produce more healthy offspring become increasingly common .

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Instructor Guide Biology: Life on Earth in the population over many generations are called adaptations c. If mutations that help an organism to adapt do not occur, a changing environment may doom a species to extinction (Figure 1-9) â Case Study Continued: The Boundaries of Life â Lecture Activity 1.2: How the Theories of Evolution Relate to Modern-Day Issues

1.3

How Do Scientists Study Life? (Figure 1-10) A. Life Can Be Studied at Different Levels (Figure 1-10) 1. All matter consists of elements a. Atoms are the smallest particles of elements 2. Atoms combine to make molecules 3. Molecules form the building blocks of cells 4. Cells of similar types may combine to form tissues 5. Tissues make up organs, which make up organ systems, which are found in multicellular organisms 6. Levels of organization extend to groups of organisms and higher B. Biologists Classify Organisms Based on Their Evolutionary Relationships 1. Members of the domains Bacteria and Archaea consist of a single, simple cell; the domain Eukarya is composed of organisms with more complex cells (Figure 1-11) a. The domain Eukarya includes a diverse group or organisms called protists, and three kingdoms: fungi, plants, and animals b. The classification of an organism into a domain and kingdom is based on three characteristics: the cell type, if it is unicellular or multicellular, and how it acquires energy (Table 1-1) 2. Cell type distinguishes the Bacteria and Archaea from the Eukarya a. All cells have a plasma membrane and DNA b. Eukaryotic cells contain a nucleus that houses genetic material; contain organelles c. Prokaryotic cells do not contain a nucleus; genetic material in cytoplasm 3. Multicellularity occurs only among the Eukarya 4. The Eukarya acquire energy in different ways a. Autotrophs are organisms that are able to produce their own energy b. Heterotrophs are organisms that must acquire energy by consuming other organisms 5. Biologists use the binomial system to name organisms a. The genus and species are used to name organisms â Case Study Continued: The Boundaries of Life

1.4

What Is Science?

A. Science Is Based on the Principle That All Events Have Natural Causes 1. Science is a process of inquiry 2. Scientific inquiry is based on the assumption that people perceive natural events in similar ways (Figure 1-3) B. The Scientific Method Is an Important Tool of Scientific Inquiry 1. The scientific method consists of six interrelated elements a. Observation—observe a phenomenon b. Question—form a question about the phenomenon c. Hypothesis—a proposed explanation based on limited evidence d. Prediction—the expected outcome of testing a hypothesis e. Experiment—designed to support or refute the hypotheses f. Conclusion—states whether the hypotheis is valid or not â Links to Everyday Life: When Your Car Won’t Start C. Biologists Test Hypotheses Using Controlled Experiments 1. Controls are control variables so that they remain constant 2. Variables are factors that may affect the outcome of an experiment â Science in Action: Controlled Experiments, Then and Now (Figures E1-1 and E1-2) â Lecture Activity 1.3: Teaching the Concepts of the Scientific Method with M&M’s â Lecture Activity 1.4: The Scientific Method at Work D. Scientific Theories Have Been Thoroughly Tested 1. A scientific theory is an explanation of natural phenomena developed through extensive and reproducible observations .

Chapter 1 An Introduction to Life on Earth

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2. Scientific theories involve both inductive and deductive reasoning a. Inductive reasoning—process of creating a generalization as a result of making many observations that support it and none that contradict it b. Deductive reasoning—generating a hypothesis based on well-accepted scientific theory 3. Scientific theories are formulated in ways that can potentially be disproved E. Science Is a Human Endeavor (Figure 1-12) 1. Knowledge of biology illuminates life

Case Study Revisited: The Boundaries of Life

KEY TERMS adaptation atom autotroph binomial system biology biosphere cell cell theory community conclusion control deductive reasoning deoxyribonucleic acid (DNA) domain ecosystem element eukaryotic evolution

experiment gene heterotroph hypothesis inductive reasoning kingdom molecule multicellular mutation natural law natural selection nucleus observation organ organ system organelle organic molecule organism

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photosynthesis plasma membrane population prediction prokaryotic question science scientific method scientific theory species spontaneous generation tissue unicellular variable

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Instructor Guide Biology: Life on Earth

LECTURE ACTIVITIES Lecture Activity 1.1: Viruses: Alive or Not? Estimated Time to Complete: 40–45 minutes Section Reference 1.1 What Is Life?

Introduction This class activity introduces the students to one of the ongoing debates in the field of biology: whether a virus should be classified as a living thing or as a nonliving thing. Before beginning this activity, the students should be introduced to the characteristics of living things described in Chapter 1 of the textbook.

Chapter Concepts Addressed 1. Students become familiar with the characteristics of living things by applying their knowledge to this question 2. Students are introduced to the categories of life in biology and the basic anatomy of viruses Materials Needed • The students must have their textbooks with them.

• Alternatively, this can be carried out in a computer lab where the class can use the Internet to gather information.

Procedures 1. Instruct the students that their task will be to determine if a virus is a living thing.

2. In order to complete their task, they must list (on a separate sheet of paper) each of the characteristics of living things described in Chapter 1 of the textbook. Next, the students must determine if a virus fulfills each of the seven criteria.

3. The students should first work individually for 5 minutes, and then they should consult with other students to help complete the task.

4. After approximately 10 minutes, the students should have completed this part of the activity. Divide the class into two groups. One side must argue that viruses are alive, and the other must argue that viruses are NOT alive. Give the two groups approximately 5 minutes to organize their respective arguments.

5. Allow each side to take turns giving their reasons. The instructor should keep track of all arguments on the board. At the end of the debate, the students should be sure to copy down all of the items on the board.

6. Optional: You may wish to assign the first part of this activity as homework. You can then begin the class with the virus debate. Additionally, if you have a class Web page, you can post a survey for the students to take part in. Your class survey question may read something like this: “Following our debate, ‘Viruses: Alive or Not?’ do you feel that viruses are living things?”

Assessment Suggestions You may collect the sheets from each student for grading. Alternatively, you may assign a class participation grade for students during the debate.

Lecture Activity 1.2: How the Theories of Evolution Relate to Modern-Day Issues Estimated Time to Complete: 25–45 minutes Section Reference 1.2 What Is Evolution?

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Chapter 1 An Introduction to Life on Earth

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Introduction This activity introduces students to the concept of evolution as it relates to a serious modern-day issue: antibiotic resistance. Prior to beginning this activity, students should have already been introduced to the vocabulary terms related to evolution, including natural selection, mutations, and survival of the fittest. The students will watch the short online video clip and answer questions related to it. Next, the class will take part in a discussion of how evolution relates to this topic and how the terms just noted can be applied to this example of modern-day evolution.

Chapter Concepts Addressed 1. Students learn about the theory of evolution as it relates to a topic they have heard about in everyday life 2. Students apply evolution terminology to a new concept 3. Students learn why an understanding of evolution continues to be important in modern biology and medicine Materials Needed • Computer with projector capabilities to show video to the entire class at the same time OR computer lab with access for student groups to watch the video clip at their own stations; worksheet to accompany video clip (Please note: This video clip is available at no charge on the Internet and can also be purchased as a set of videos related to the topic of evolution. Visit the link below for more details.)

Procedures 1. Hand out the worksheet with questions that the students will be answering.

2. Go to www.pbs.org and search for “Evolution: Library: Evolving Ideas: Why Does Evolution Matter Now?” Select the first search result and play the video in QuickTime or RealPlayer.

3. Allow the students to answer questions on the worksheet as they watch the video.

4. Allow the students to break into groups to answer the final two questions. You may want to replay the part about how strains of bacteria evolve to be resistant.

5. Discuss the answers to each question as a class and relate your previous discussions of evolution to what was described here. Examples of topics to be discussed: A. Where does survival of the fittest fit in here?

B. How does natural selection occur with antibiotic-resistant bacteria?

C. Why do doctors need to understand the concept of evolution?

Assessment Suggestions You may collect the students’ question sheets to grade. Alternatively, you may pose the following question as a homework assignment: “Why does evolution matter now?” Ask them to write a paragraph answering this question using what they just learned during this session.

Lecture Activity 1.3: Teaching the Concepts of the Scientific Method with M&M’s Estimated Time to Complete: 20 minutes Section Reference 1.4 What Is Science?

Introduction Use this demonstration on the first day of class or lab or when you introduce the scientific method. This activity demonstrates how people use the scientific method every day to solve problems. You will provide several small containers full of M&M’s. Tell the students that this is like the contests they often encounter, where they have to guess the number of objects in a container to win a prize. During this short session, though, they have to use the scientific method to come up with their answer. Additionally, the students are not allowed to simply open the container to count the number of M&M’s. They must design an experiment that will give them an accurate number without opening the jar. .

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Instructor Guide Biology: Life on Earth

Chapter Concepts Addressed 1. Students learn the scientific method hands-on by actually conducting a “scientific investigation” 2. Students learn the appropriate steps of the scientific method by applying them to a particular problem 3. Students connect the concept of the scientific method to a real-world setting Materials Needed Per student group: • One plastic jar full of one bag of M&M’s • Paper and pen to record observations and results • Optional: foam block for center of jar—see below Additional materials available for student experiments • Scale for students to weigh jar if they choose • Empty jar • Rulers • Tape measures Procedures 1. Walk into class and distribute the jars of M&M’s. Instruct the students not to eat them! Instead, they need to determine the exact number of M&M’s in the jar.

2. But, because they really want to be accurate, they cannot just make a random guess. Instead, they must use the logic of the scientific method.

3. At this point, place a slide or overhead at the front of the class that outlines each of the steps of the scientific method. They should use this logic when solving this problem.

4. First, they must make observations. Have the students raise their hands to share their observations.

(Include: How big is the jar? How big is each M&M? What shape is the jar? What shape are the M&M’s?)

5. Now, they must work together in groups of two or three to come up with a hypothesis and then sketch out their experimental design to test their hypothesis. They should determine what tools they need to carry out their experimentation. The instructor may need to guide the students with their experimental design. They may use a scale to weigh one M&M, to measure the full jar, and to measure an empty jar. Using that information, for example, they could make a prediction about the total number in the jar without opening it.

They may also measure an individual M&M and determine how many would fill the jar, given its size.

6. Next, they must collect the results of their experiment and draw a conclusion about how many M&M’s are present on the basis of those results.

7. Optional endings: A. Do not allow the students to simply open the jar and count them. Remind the class that scientists often are limited by the tools they have to test a hypothesis. Additionally, they never know for sure if their conclusions are correct. Therefore, do not ever allow them to count the M&M’s by hand. (You may provide a separate bag for them to snack on during the rest of the class!) This illustrates how each of the concepts that we discuss in the class is based on simply coming up with a hypothesis and testing it. There is no surefire way in biology, however, to ever determine if your conclusion is 100% correct. The best you can do is come up with different experiments to test the same hypothesis. You may have the students come up with a different experimental approach and see if they get the same results. If not, which results should they believe?

B. As you set up this experiment, place a large piece of foam in the middle of the container before adding the M&M’s. Add the M&M’s so that the foam cannot be seen while the students do their experiment. When they have all finished, allow them to open the jars to see if they were correct. They will all be surprised to find out that they were operating on the hypothesis that the jar was completely full of M&M’s. Explain that this is often what happens in science. Scientists often make hypotheses that end up being wrong!

Assessment Suggestions Have the students record all of their observations, hypotheses, experimental design, results, and conclusions on a separate piece of paper that will be collected for grading. Be sure the students include all of the steps of the scientific method in their reports.

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Chapter 1 An Introduction to Life on Earth

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Lecture Activity 1.4: The Scientific Method at Work Estimated Time to Complete: 10–30 minutes (depending on which approach you choose to follow) Section Reference 1.4 What Is Science?

Introduction This class activity introduces students to jobs that use the scientific method. Be sure to have discussed the steps of the scientific method before beginning this exercise.

Chapter Concepts Addressed 1. Students become familiar with the steps of the scientific method 2. Connects the concept of the scientific method to a real-world setting Materials Needed • Guest speakers • Clips from TV shows (depending on which approach you choose to follow) • Paper for students to take notes Procedures (Each of the following suggestions can be used individually or together.)

1. Invite into your classroom several members of the community who use the scientific method in their work and have them explain to the students how they do so. Examples might include a meteorologist, a computer help desk worker at school, or a police investigator.

2. Alternatively, ask the students to work in groups to identify careers (besides laboratory scientists) in which workers use the scientific method every day. Give extra credit points for the most creative and well-thought-out answers!

3. Bring in a video clip from a TV show that illustrates the characters using the scientific method (e.g., a show about crime scene investigation). Instruct the students to outline how the characters are using the steps of the scientific method.

Assessment Suggestions You may collect the sheets from each student for grading. Alternatively, you may assign a class participation grade for students who ask questions, if a guest visits.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 1.2 Handout—Why Does Evolution Matter Now? Questions to accompany video 1.

What are microbes?

2.

Tuberculosis (TB) is caused by ___________________________ and is spread _________________________. The symptoms of TB are __________________________.

3.

What is multidrug-resistant TB?

4.

What does an antibiotic do?

5.

Take notes below on how a strain evolves to become antibiotic resistant:

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After the video, break into small groups of two to four students.

Use what each of you wrote down to answer the following questions: • Describe the steps involved in a strain of bacteria becoming resistant to antibiotics. (Your teacher may replay that part of the video for you.)

• Look at your answer above and identify where the terms natural selection and survival of the fittest come into play.

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CHAPTER 2 ATOMS, MOLECULES, AND LIFE LECTURE OUTLINE Case Study: Unstable Atoms Unleashed 2.1

What Are Atoms?

A. Atoms Are the Basic Structural Units of Elements (Figures 2-1 and 2-2, and Table 2-1) 1. An element is a substance that cannot be separated into simpler substances 2. An atom is the smallest unit of an element (Table 2-1) B. Atoms Are Composed of Still Smaller Particles (Table 2-1 and Figure 2-1) 1. Atoms are composed of subatomic particles: protons, neutrons, and electrons 2. The mass number is equal to the mass of the protons and neutrons 3. Protons and neutrons cluster in the atomic nucleus 4. Negatively charged electrons orbit the atomic nucleus C. Elements Are Defined by Their Atomic Numbers 1. Atomic number is the number of protons in an atom D. Isotopes Are Atoms of the Same Element with Different Numbers of Neutrons 1. Some isotopes are radioactive â Science in Action: Radioactive Medicine (Figures E2-1 and E2-2) 2. Some radioactive isotopes damage cells E. Nuclei and Electrons Play Complementary Roles in Atoms 1. Electrons occupy complex regions around the nucleus a. These regions are called electron shells and correspond to different energy levels (Figure 2-2) b. Electron shells allow interactions, or bonds, with other atoms 2. Electrons can capture and release energy (Figure 2-3) 3. As atomic number increases, electrons fill shells increasingly distant from the nucleus â Case Study Continued: Unstable Atoms Unleashed

2.2

How Do Atoms Interact to Form Molecules?

A. Atoms Form Molecules to Fill Vacancies in Their Outer Electron Shells 1. A molecule consists of two or more atoms of the same or different elements held together by interactions between their outer-shell electrons 2. Atoms with full outer electron shells do not react with other atoms and are inert 3. Atoms that do not have full outer shells are considered reactive B. Chemical Bonds Hold Atoms Together in Molecules (Table 2-3) 1. Chemical bonding involves the gain, loss, or sharing of electrons a. Ionic bonds b. Covalent bonds c. Hydrogen bonds C. Ionic Bonds Form Among Ions (Figure 2-4) 1. The outermost electron shell is almost empty or almost full 2. Ions are atoms that become stable by gaining or losing electrons 3. Ionic bonds are electrical attractions between positive and negative ions D. Covalent Bonds Form by Sharing Electrons (Figure 2-5 and Table 2-4) 1. If the outermost electron shell is partially full, an atom may form a covalent bond 2. Covalent bonds form when atoms become stable by sharing electrons 3. Most biological molecules utilize covalent bonding

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Chapter 2 Atoms, Molecules, and Life E. Covalent Bonds May Produce Nonpolar or Polar Molecules (Figure 2-6) 1. Nonpolar covalent bonds involve the equal sharing of electrons 2. Polar covalent bonds involve the unequal sharing of electrons (H2O) 3. Free radicals are unstable molecules with an unfilled outermost electron shell a. They can tear other molecules apart â Health Watch: Watch Out for Free Radicals (Figures E2-3 and E2-4) F. Hydrogen Bonds Are Attractive Forces Between Certain Polar Molecules 1. Hydrogen bonds are bonds between parts of polar molecules (Figure 2-6) 2. Hydrogen bonds are responsible for the unique properties of water â Lecture Activity 2.1: Exercise in Chemical Bonding â Lecture Activity 2.2: Atomic Love Connection â Lecture Activity 2.3: Atoms, Molecules, and Compounds

2.3

Why Is Water So Important to Life?

A. Water Molecules Attract One Another (Figure 2-7) 1. Cohesion occurs when water molecules stick together 2. Surface tension results when the surface of water is resistant to being broken â Have You Ever Wondered…Why It Hurts So Much to Do a Belly Flop?

B. Water Interacts with Many Other Molecules (Figures 2-8 and 2-9) 1. Water, a type of solvent, is capable of dissolving a wide range of substances 2. Hydrophilic molecules exhibit attraction to water (as well as ions and polar molecules) 3. Hydrophobic molecules exhibit no attraction to water (do not dissolve) C. Water Moderates the Effects of Temperature Changes (Figure 2-10) 1. It Takes a Lot of Energy to Heat Water a. Specific heat is the amount of energy required to heat 1 gram by 1°C b. Water has a high specific heat c. It takes more energy to heat water than most substances 2. It Takes a Lot of Energy to Evaporate Water a. Heat of vaporization is the amount of heat required to vaporize a substance b. Water has a high heat of vaporization â Case Study Continued: Unstable Atoms Unleashed â Lecture Activity 2.4: Specific Heat of Water and Body Temperature D. Water Forms an Unusual Solid: Ice (Figures 2-11 and 2-12) 1. Most liquids become more dense when they are solid 2. A unique property of ice is that it is less dense than liquid water E. Water-Based Solutions Can Be Acidic, Basic, or Neutral (Figures 2-13 and 2-14) 1. Pure water contains equal amounts of hydrogen and hydroxide ions 2. Acidic solutions contain more hydrogen ions (H+) than hydroxide ions (OH–) 3. Basic solutions contain more hydroxide ions (OH–) than hydrogen ions (H+) 4. The pH scale expresses the degree of acidity of a solution and ranges from 1–14 a. Acids have a pH below 7 (more H+ than OH–) b. Bases have a pH above 7 (more OH– than H+) c. Water has a pH of 7 (equal amounts of H+ and OH–) 5. A buffer helps maintain a solution at a relatively constant pH

Case Study Revisited: Unstable Atoms Unleashed

KEY TERMS acid acidic antioxidant atom atomic nucleus atomic number

electron shell element free radical heat of vaporization hydrogen bond hydrophilic .

nonpolar covalent bond pH scale polar covalent bond proton radioactive solution

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Instructor Guide Biology: Life on Earth

base basic buffer chemical bond cohesion covalent bond dissolve electron

hydrophobic hydrophobic interaction ion ionic bond isotope mass number molecule neutron

solvent specific heat surface tension

LECTURE ACTIVITIES Lecture Activity 2.1: Exercise in Chemical Bonding Estimated Time to Complete: 10–25 minutes Section Reference 2.2 How Do Atoms Interact to Form Molecules?

Introduction This activity is a basic introduction to the concept of chemical bonding. This is a short, in-class exercise that can follow an introductory discussion of atomic structure and bonding. Students will take the number of their birth month as their atomic number. Given this information, they will be able to determine the configuration of electrons. They will then be able to determine how this atom will interact with other atoms, if at all. Students will form groups with other students to form ions or molecules and will present their bond formation to the class.

Chapter Concepts Addressed 1. Students learn about atomic structure and electron configurations 2. Students apply their knowledge of electron configuration to atomic bonding 3. Students interact with classmates to form ionic or covalent bonds Materials Needed No specific materials are needed.

Procedures 1. Instruct the students to identify their birth month on a piece of paper. They will consider the number of their birth month to be their atomic number.

2. Next, instruct them to draw their appearance as an atom. Specifically, they must determine their electron configuration and how many electrons are in their outermost shell.

3. Using this information, they should determine what type of bond they might like to form to become stable and fill the outermost shell.

4. Students must then form a bond with another classmate so that both “atoms” become stable.

5. These student groups of bonded atoms can then present their bond to the class and explain why they are both now stable. Alternatively, to save class time, they could write this information on a sheet of paper to be handed in.

Assessment Suggestions Evaluate the student bonds that are formed and assign a grade for class participation.

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Chapter 2 Atoms, Molecules, and Life

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Lecture Activity 2.2: Atomic Love Connection Estimated Time to Complete: 25–30 minutes Section Reference 2.2 How Do Atoms Interact to Form Molecules?

Introduction This activity reinforces students’ understanding of atomic structure, as well as ionic and covalent bonds. These topics should be covered in class prior to beginning this activity. In this activity, the students will either choose or be assigned a particular element and will write a “personal ad” for that atom. This ad should describe the properties of the atom and also describe what type of bond the atom would “like” to form. Following completion of the handout, students should share their ads with each other to find a good bonding match between atoms.

Chapter Concepts Addressed 1. Students learn about the structure of atoms 2. Students apply their understanding of atomic structure to determine whether an atom is inert or reactive 3. Students learn how to determine whether an atom will form covalent or ionic bonds Materials Needed • Handout included in this activity • Periodic table for the entire class or for each student Procedures 1. Hand out worksheet with background information.

2. Students should work individually to write their own personal ad for their atom. The instructor may choose to assign an element, or students may choose from the elements listed on the worksheet. In larger classes, more than one student can be assigned the same element.

3. The students should first determine the atomic number of their element and how many electrons are in the outer shell. This information can then be used to determine if the atom is most likely to form a covalent or ionic bond.

4. Students can then interact with each other in groups to find matches to their ads. For example, a carbon ad would match up well with a hydrogen ad to form covalent bonds.

Assessment Suggestions You may collect the students’ sheets for grading or assign an in-class participation grade if students read their ads to the class.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 2.2 Handout—Atomic Love Connection Choose one of the following elements: carbon nitrogen oxygen sulfur

magnesium chlorine sodium potassium

hydrogen calcium phosphorus bromine

1.

Determine the atomic symbol: ___________

2.

Use the periodic table to determine the atomic number: ___________

3.

Describe how you will determine if the atoms of your element are inert or reactive.

4.

Use the characteristics of your atom to write a “personal ad” for it. Be creative! Your ad should include information regarding how your element might form bonds with other elements.

See the example below as a guide.

Example: Fluorine (F); atomic number = 9 Personal ad: Single fluorine atom seeking another kind atom willing to donate one electron to add stability to my life. I currently have seven electrons in my outer shell and am willing to form an ionic bond with any atom who answers this ad.

5.

When you are done, see if you can find another personal ad that is a good match for yours (your atomic love connection). Write your match below. What kind of bond will you form?

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Chapter 2 Atoms, Molecules, and Life

Lecture Activity 2.3: Atoms, Molecules, and Compounds Estimated Time to Complete: 15–25 minutes Section References 2.1 What Are Atoms?

2.2 How Do Atoms Interact to Form Molecules?

Introduction This activity is designed to help students understand the differences among atoms, molecules, and compounds.

The activity should be done prior to the topics being covered in class to help the students construct their own understanding of atoms, molecules, and compounds. This is a compare-and-contrast activity that will help reinforce the students’ understanding of atomic structure, molecules, and compounds.

Chapter Concepts Addressed 1. Students apply their knowledge of atoms 2. Students gain an understanding of the role of atoms in forming molecules and compounds Materials Needed • Worksheet • Access to computers for Internet searching Procedures 1. Assemble the students into pairs.

2. Hand out the worksheet with questions that the students will be answering.

3. Have the students perform an Internet search using the following search terms: atoms, molecules, compounds.

4. Allow the students to answer the questions on the worksheet while they are searching the Internet.

5. You may discuss the answers in class or collect the sheets to grade them.

Assessment Suggestions You may collect the students’ question sheets to grade. Alternatively, you may ask similar questions on a quiz or exam.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 2.3 Handout—Atoms, Molecules, and Compounds 1.

Describe two differences between molecules and compounds.

2.

Describe two similarities between molecules and compounds.

3.

Why are O2 and H2 not considered compounds?

4.

The element helium (He) is said to be inert. What does this mean? What types of molecules is this element likely to form? (HINT: You may want to do a separate Internet search for this question.)

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Chapter 2 Atoms, Molecules, and Life

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Answer Key Questions 1 and 2 will have multiple answers. Reference the textbook or the Web sites found in the search for possible answers.

3.

They contain only one type of element. Compounds contain more than one different type of element.

4.

Inert means that the element has a full outer shell of electrons. This element will not form any molecules.

Because its outer shell of electrons is full, it is unlikely to bond with other atoms.

Lecture Activity 2.4: Specific Heat of Water and Body Temperature Estimated Time to Complete: 20–25 minutes Section Reference 2.3 Why Is Water So Important to Life?

Introduction This activity helps students apply their understanding of the specific heat of water to a biological concept. The ability to maintain body temperature is an important feature of the human body that is, in part, attributable to this important property of water.

Chapter Concepts Addressed 1. Students define the term specific heat 2. Students apply the specific heat of water to the human body’s ability to maintain body temperature 3. Students examine how liquids of different specific heat could affect body temperature regulation Materials Needed • Handout included with this activity • Pens/pencils Procedures 1. This activity should be completed following a class discussion of the meaning of the term specific heat.

2. Give a copy of the handout to each student. Allow them to form groups of two or three students to work together to complete the worksheet. Alternatively, this could be a homework assignment.

3. You may either collect the sheets for grading or discuss the answers in class.

4. Important points to address are: A. The specific heat of a substance is defined as the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C. B. Because the body is composed mainly of water with a high specific heat, the human body is able to resist changes in body temperature. Therefore, it takes a long time for the human body to overheat. It will take less time for all of the “space” organisms to overheat because their specific heats are lower.

Assessment Suggestions You may collect the students’ handouts to grade. Alternatively, you may assess the students’ involvement in the class discussion that follows completion of the worksheet.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 2.4 Handout—Specific Heat and Regulating Body Temperature Background Information Our bodies are 80% water. Imagine that you work for NASA and have recently discovered many new life-forms on distant planets. Space probes have gathered some preliminary data about these living creatures. Specifically, you have learned that each life-form is composed primarily of another liquid rather than water. Work in small groups to answer the following questions.

Preliminary data Organism A: body composition is 77% ethyl alcohol (specific heat = 0.60 cal/g °C) Organism B: body composition is 81% kerosene (specific heat = 0.47 cal/g °C) Organism C: body composition is 83% seawater (specific heat = 0.94 cal/g °C) Organism D: body composition is 81% sulfuric acid (specific heat = 0.35 cal/g °C) Human body: body composition is 80% water (specific heat = 1.00 cal/g °C) Questions 1.

Define the term specific heat.

2.

It takes ___________ cal of heat to raise the temperature of 1 g of ethyl alcohol by 1°C.

3.

You place one beaker of water on one hot plate and a beaker of sulfuric acid next to it on the same hot plate.

Which one will heat up faster? Explain why.

4.

If you were to place each organism in direct sunlight on a warm day, which organism’s body temperature will increase more rapidly than the human body? Which organism’s body temperature will increase less rapidly than the human body? Explain why. (Use the term specific heat in your answer.)

5.

Put the four organisms in order starting with the one whose body temperature will increase the fastest and proceeding to the one whose body temperature will increase the slowest.

.

CHAPTER 3 BIOLOGICAL MOLECULES LECTURE OUTLINE Case Study: Puzzling Proteins 3.1

Why Is Carbon So Important in Biological Molecules?

A. Organic Molecules Contain Carbon and Hydrogen, Whereas Inorganic Molecules Do Not Contain Carbon B. The Unique Bonding Properties of Carbon Are Key to the Complexity of Organic Molecules 1. Carbon has four electrons in its outer shell and can bond with up to four different atoms (Figure 3-1) 2. Functional groups are groups of atoms attached to carbon backbones that determine the characteristics of different molecules (Table 3-1)

3.2

How Are Organic Molecules Synthesized?

A. Monomers Are Individual Subunits of Biological Molecules 1. Polymers are long chains of monomers B. Biological Polymers Are Formed by Removing Water and Are Split Apart by Adding Water 1. Dehydration synthesis is a chemical reaction that links monomers (Figure 3-2) a. Water is removed during the reaction 2. Hydrolysis is a chemical reaction splitting molecules into subunits (Figure 3-3) b. Water is needed to complete the reaction 3. Most biological molecules fall into one of four general categories (Table 3-2)

3.3

What Are Carbohydrates? (Figure 3-4) A. There Are Several Monosaccharides with Slightly Different Structures 1. Monosaccharides have one sugar molecule a. Glucose is a subunit of most polysaccharides (Figure 3-5) b. Fructose is found in corn syrup (Figure 3-6) c. Galactose is milk sugar (Figure 3-6) d. Ribose and deoxyribose sugars are found in DNA and RNA (Figure 3-7) B. Disaccharides Consist of Two Monosaccharides Linked by Dehydration Synthesis (Figure 3-8) 1. Disaccharides contain two monosaccharides linked by dehydration synthesis 2. Disaccharides are broken into monosaccharides by hydrolysis 3. Three common disaccharides are sucrose, lactose, and maltose a. Sucrose is made up of glucose and fructose b. Lactose is made up of glucose and galactose c. Maltose is made up of two glucose molecules â Links to Everyday Life: Fake Foods (Figure E3-1) C. Polysaccharides Are Chains of Monosaccharides 1. Polysaccharides are polymers of many monosaccharides a. Starch is a chain of glucose monomers used for energy storage in plants (Figure 3-9) b. Glycogen is a chain of glucose monomers used for energy storage in animals c. Cellulose is a structural polysaccharide found in plants (Figure 3-10) d. Chitin is found in the exoskeletons of insects, crabs, and spiders (Figure 3-11)

3.4

What Are Lipids?

A. Oils, Fats, and Waxes Are Lipids Containing Only Carbon, Hydrogen, and Oxygen (Figure 3-12) 1. Fats are formed by dehydration synthesis a. They contain three fatty acids and a glycerol molecule b. They are also known as triglycerides

.

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Instructor Guide Biology: Life on Earth 2. Fats and oils are used primarily as energy-storage molecules (Figure 3-13a) a. Fats and oils store the same energy with less weight than carbohydrates 3. Saturated and unsaturated fats are different forms of fats and oils a. Saturated fats contain no double bonds and are solid at room temperature (Figure 3-14a) b. Unsaturated fats contain double bonds and are liquid at room temperature (Figure 3-14b) â Health Watch: Cholesterol, Trans Fats, and Your Heart (Figure E3-2) 4. Waxes are similar to fats and are highly saturated (Figure 3-13b) â Lecture Activity 3.1: Fake Fats: To Eat or Not to Eat? B. Phospholipids Have Water-Soluble “Heads” and Water-Insoluble “Tails” 1. Phospholipids contain two fatty acids, one glycerol, and one phosphate group (Figure 3-15) 2. Fatty acid “tails” are hydrophobic (water insoluble) 3. The phosphate group “head” is polar and hydrophilic (water soluble) 4. They are a central component of cell membranes C. Steroids Contain Four Fused Carbon Rings (Figure 3-16) 1. Cholesterol is an important component of animal cell membranes a. It is also an important component of hormones b. Cholesterol is used to synthesize bile â Health Watch: Cholesterol, Trans Fats, and Your Heart (Figure E3-2)

3.5

What Are Proteins? (Figure 3-17 and Table 3-3) A. Proteins Are Formed from Chains of Amino Acids 1. Amino acids contain a central carbon and four functional groups (Figure 3-18) a. Nitrogen-containing amino group (–NH2) b. Carboxyl group (–COOH) c. Hydrogen (–H) d. The R-group is a variable group and gives each amino acid its distinctive properties (Figure 3-19) B. Amino Acids Are Joined by Dehydration Synthesis (Figure 3-20) 1. A peptide bond forms when an amino group of one amino acid is joined to a carboxyl group of another amino acid 2. A polypeptide chain or protein consists of a long chain of amino acids C. A Protein Can Have As Many As Four Levels of Structure (Figure 3-21) 1. Primary structure is the sequence of amino acids that make up the protein a. Different proteins have different sequences of amino acids 2. Secondary structure is due to interactions between hydrogen bonds of amino acids a. Helix arrangement is a coiled structure b. Pleated sheet arrangement happens when chains fold back upon themselves (Figure 3-22) â Case Study Continued: Puzzling Proteins 3. Tertiary structure is the three-dimensional configuration of the amino acid chain (Figure 3-23) a. This level of structure is influenced by surrounding environment 4. Quaternary structure occurs in certain proteins when individual polypeptides are linked together by hydrogen bonds a. Example—hemoglobin composed of four peptides D. The Functions of Proteins Are Related to Their Three-Dimensional Structures 1. Denatured proteins have their secondary and tertiary structures altered 2. Denatured proteins cannot perform their designated functions â Links to Everyday Life: What Makes Hair Curl? (Figures E3-3 and E3-4) â Lecture Activity 3.2: Protein Structure and Function

3.6

What Are Nucleotides and Nucleic Acids?

A. Nucleotides Act as Energy Carriers and Intracellular Messengers 1. Nucleotides consist of a phosphate, a sugar, and a base (Figure 3-23) 2. Adenosine triphosphate carries energy from place to place within a cell (Figure 3-24) 3. “Electron carriers” transport energy B. DNA and RNA, the Molecules of Heredity, Are Nucleic Acids 1. Nucleic acids are long chains of subunits known as nucleotides (Figure 3-25) a. The components are a 5-C sugar, a phosphate group, and a nucleotide base 2. DNA, deoxyribonucleic acid, contains deoxyribose nucleotides (AGTC) 3. RNA, ribonucleic acid, contains ribose nucleotides .

Chapter 3 Biological Molecules

21

â Case Study Continued: Puzzling Proteins â Lecture Activity 3.3: Molecular 20 Questions â Lecture Activity 3.4: Biological Molecules Review

Case Study Revisited: Puzzling Proteins

KEY TERMS adenosine triphosphate (ATP) amino acid base carbohydrate cellulose chitin dehydration synthesis denatured deoxyribonucleic acid (DNA) disaccharide disulfide bridge enzyme fat fatty acid functional group glucose glycogen

helix hydrolysis inorganic lipid monomer monosaccharide nucleic acid nucleotide oil organic peptide peptide bond phospholipid pleated sheet polymer polysaccharide primary structure

protein quaternary structure ribonucleic acid (RNA) saturated secondary structure starch steroid sugar tertiary structure trans fat triglyceride unsaturated wax

LECTURE ACTIVITIES Lecture Activity 3.1: Fake Fats: To Eat or Not to Eat? Estimated Time to Complete: 30 minutes Section Reference 3.4 What Are Lipids?

Introduction This activity allows students to engage in a debate related to the real-life issues surrounding the use of the fat substitute Olestra.

Students are assigned to two opposing groups: one in favor of the use of fake fats and the other against the use of fake fats. They are given Web links to three different sources. The Discovery Magazine reference gives a solid background about the basis for the debate. The other two links present the opposing viewpoints. This debate announcement can be posted on the course Web page on the day the details of the debate are introduced to the class. Alternatively, the debate announcement and details can be distributed as a handout to the students. (A sample debate announcement is included with this activity.) At the end of the debate, students will take part in a “taste test” to sample chips made with “real fat” versus those made with “fake fat.”

Chapter Concepts Addressed 1. Students learn about the structure of fats and fat substitutes 2. Students apply their knowledge of fats to develop arguments to support their assigned viewpoint Materials Needed • Debate announcement .

22

Instructor Guide Biology: Life on Earth

• Regular and Olestra-containing potato chips for taste test Procedures 1. The students are given this assignment in the class before the start of the debate. Before the debate, the students must gather information to support their argument for the debate. Part of this preparation involves understanding the structural differences between fake fats and real fats.

2. On the day of the debate, they are given approximately 10 minutes to meet with others on their “side” to come up with their game plan for the debate.

3. When the debate begins, the two groups take turns presenting their arguments either for or against the use of fat substitutes. The debate lasts about 15 minutes. The instructor keeps track of each side’s arguments on the board and, at the end, the students are given time to copy down what is on the board.

4. After the debate, the students take part in a taste test of potato chips made with “real fat” and “fake fat.”

During the taste test, the instructor reiterates the important points of the topic and revisits the structural comparison between the fake fat molecule and the real fat molecule. The students should offer their opinions about the taste differences and on how they relate to the structural differences between the two molecules.

Assessment Suggestions A. One option for assessment is to assign the following: 1. To hand in: (no more than one page) a. State which side of the debate you were on. b. List two reliable resources that you used to prepare for this debate. c. List at least two arguments on your side of the debate.

B. Another option involves either assigning the following questions for homework or including them as essay questions on an exam: 1. Your aunt calls you because she has heard a report about Olestra on the news. The news report has raised her concern about using products containing Olestra. She knows you are taking a biology class and hopes you can provide some facts. Write a short note to your aunt filling her in on the pros and cons of using Olestra, based on the info you learned in class. Let her know what your conclusions are and what scientific facts you have based these conclusions on.

2. Explain how the structure of a fake fat is different from that of real fat. Why does this make a difference in the digestive system? Additionally, explain how this structure is related to the debate over the use of fake fats in foods.

.

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 3.1 Handout—Class Debate For this debate: • You must research the scientific and medical arguments on your side.

• You should also research what the arguments will be on the other side, so that you are prepared to argue against their points.

• Start your debate prep by finding information through an Internet search: Go to http://www.discovermagazine.com. Once you are on the site, type in “fat chemistry” in the search box and click “search.” Look for the article “The Chemistry of Fat Substitutes” and use it for information for your debate.

Go to http://www.cspinet.org, the Center for Science in the Public Interest Web site. In the search box, enter “Olestra.” Search the links for information on Olestra. This group is against the use of fake fats.

Go to the Proctor and Gamble Web site (http://www.olean.com). It is the maker of Olean and is in favor of fake fats.

.

24

Instructor Guide Biology: Life on Earth

Lecture Activity 3.2: Protein Structure and Function Estimated Time to Complete: 15–30 minutes Section Reference 3.5 What Are Proteins?

Introduction This activity allows students to learn more about the science of protein structure analysis. A great deal of biological research is now focused on determining the structure of different proteins. Scientists then use that information to generate hypotheses about the function of that protein. In this exercise, you will display three different 3-D protein structures and ask the students to describe the structure and then make predictions about possible functions of that protein on the basis of its structural characteristics. The students may work individually or as part of a team to complete the exercise.

Chapter Concepts Addressed 1. Students learn about the 3-D configuration of proteins.

2. Students apply their knowledge of protein structure to real-life scientific discovery.

3. Students make predictions about protein function on the basis of the structures they observe.

Materials Needed Computer with projector capabilities (or the pictures can be copied onto overhead transparencies) Procedures 1. Advise the students that you will be presenting them with three pictures of proteins for which scientists have determined the structure.

2. For each of the three proteins, the students should first write down their observations of the protein’s structure. Ask the students: How would you describe what you see in your own words?

3. Now, working in small groups, the students should try to determine the function of each protein. They should state their hypothesis AND the reasoning behind their hypothesis. Explain that they will not be graded on the basis of a right or wrong answer. Instead, they should put themselves in the place of scientists who are currently working on these same problems. Encourage them to be creative!

You can use images from the text (Figures 3-20 and 3-21) or images available to instructors on the Instructor Resource DVD and on the Internet in the Instructor Resource Center.

Here are Internet search terms that can be used to find images of various protein structures: #1 Search the Internet for “barrel proteins.” #2 Search the Internet for “helicase.” #3 Search the Internet for “porin.”

Instructor’s guide for protein structures from Internet searches: #1 These proteins are “tunnels” used to transport items in and out of bacterial cells.

Varying views of these proteins show that they form circular channels for moving molecules. #2 Helicase is a protein that interacts with DNA. Scientists determined that the opening of this ring-shaped protein could accommodate the DNA molecule. This protein plays a role in unraveling a DNA molecule during DNA replication. #3 The porin protein has three domains, all of which form channels for transporting different molecules. The first view is obtained by looking down from the top of the molecule. The second view is from the side of the molecule.

Assessment Suggestions You may collect the sheets containing the students’ observations and hypotheses. Alternatively, you may assign the students to go online to find a recent study that identified the structure of a protein. They can then write a short paragraph about the significance of the study. .

Chapter 3 Biological Molecules

25

Lecture Activity 3.3: Molecular 20 Questions Estimated Time to Complete: 15–30 minutes Section Reference Chapter 3: Biological Molecules Introduction In this activity, the students will get an opportunity to test their knowledge of biological molecules. The students will form groups of three or four. Each student will draw the name of a biological molecule from a hat. The other students in the group will then take turns asking yes-or-no questions until one of them is able to correctly guess the identity of the molecule in question.

Chapter Concepts Addressed 1. Students review their knowledge of biological molecules 2. Students apply their knowledge of biological molecules 3. Students evaluate their own understanding of biological molecules in a nonexam format Materials Needed • Names of different molecules on pieces of paper in a hat or box for each student to draw from The sheet included with this activity contains the names of a few molecules that can be used in this exercise. You can cut out the names from this sheet to use in class. For a larger class, you may repeat the same molecules.

Procedures 1. Instruct the students to form groups of three or four. Explain how the game will work and have the students determine who will go first in each group.

2. Allow one member from each team to draw the name of a biological molecule from the hat.

3. The other members of each group must then take turns asking a yes-or-no question about the molecule.

4. If a student in a group guesses correctly, he or she must wait until his or her turn to answer.

5. Each member of the group must take a turn drawing the name of a molecule for the others to guess.

6. This is a useful means of reviewing for an exam and is not time consuming.

Assessment Suggestions You may have the students keep track of how many they guess correctly and give out a grade or extra credit for those who get above a certain score.

.

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 3.3 Handout—Molecular 20 Questions

DNA

Glucose

Cholesterol

RNA

Phospholipid

Starch

Lactose

Sucrose

Protein

Amino acid

Nucleotide

Lipid

.

Chapter 3 Biological Molecules

27

Lecture Activity 3.4: Biological Molecules Review Estimated Time to Complete: 15–20 minutes Section Reference Chapter 3: Biological Molecules Introduction In this simple activity, the students will review their knowledge of biological molecules. They must fill in the chart that is included without looking at their textbooks. This activity gives the students a chance to test their knowledge. It also gives instructors the chance to work one on one with students who may need some additional help. If there is something the student doesn’t know, he or she should leave it blank. The class can form groups of two or three students to fill in any blank spaces. A short review session with the teacher should reinforce what is on the chart.

Chapter Concepts Addressed 1. Students review their knowledge of biological molecules 2. Students pool their knowledge with others in the class Materials Needed • Handout included with this activity Procedures 1. Instruct the students to fill in the chart to the best of their ability. You may choose to let them use their notebooks if they need to. This may give them a chance to determine whether they have taken good notes or not.

2. They should leave blanks where they do not know the answer.

3. After 5 minutes, they may form groups of two or three students to help fill in any blank spaces.

4. After 10 minutes of group work, a short elaboration session with the entire class and the instructor should clear up any unclear concepts.

5. This activity may allow the instructor to determine if there was a portion of the lecture that was unclear to a majority of the students. It also gives the students a chance to determine if they truly understand the concepts they have just learned.

Assessment Suggestions You may include a portion of the chart on an upcoming quiz or exam.

.

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 3.4 Handout—Biological Molecules Review Class

Basic subunit(s)

Carbohydrates

Lipids

Nucleic acids

Proteins

.

Complex molecule

Functions

Examples

CHAPTER 4 CELL STRUCTURE AND FUNCTION LECTURE OUTLINE Case Study: Spare Parts for Human Bodies 4.1

What Is the Cell Theory?

A. Three Principles Comprise the Cell Theory 1. Every living organism is made up of one or more cells 2. The smallest living organisms are single cells 3. All cells come from preexisting cells â Science in Action: The Search for the Cell (Figures E4-1 and E4-2)

4.2

What Are the Basic Attributes of Cells?

A. Cell Function Limits Cell Size 1. Most cells range in size from 1 to 100 micrometers (Figure 4-1) 2. Cell parts cannot be too far away from the cell membrane; nutrients and wastes can enter and exit only at the surface of the cell B. All Cells Share Common Features 1. The plasma membrane encloses the cell and allows interactions between the cell and its environment a. The plasma membrane has three functions (Figure 4-2) i. Isolates the cell’s internal contents from the external environment ii. Regulates the flow of materials into and out of the cell iii. Allows communication with other cells 2. All cells contain cytoplasm (Figures 4-3 and 4-4) a. The cytoplasm consists of all the material and structures that lie inside the plasma membrane â Case Study Continued: Spare Parts for Human Bodies 3. All cells use DNA as a hereditary blueprint and RNA to copy the blueprint and guide construction of cell parts a. During cell division, parent cells pass exact copies of their DNA to daughter cells C. There Are Two Basic Types of Cells: Prokaryotic and Eukaryotic (Table 4-1) 1. Prokaryotic cells include bacteria and archaea; they have no nucleus or membrane-bound organelles 2. Eukaryotic cells include protists, plants, fungi, and animals; they have a nucleus that is membrane bound and other membrane-bound organelles â Lecture Activity 4.1: Surface-Area-to-Volume Considerations in Phenolphthalein Agar “Cells”: â Why Aren’t We One Big Blob? â Lecture Activity 4.2: Cell Shapes and Sizes

4.3

What Are the Major Features of Eukaryotic Cells?

A. Eukaryotic Cells Contain Organelles (Figures 4-3 and 4-4) 1. Organelles are membrane-enclosed structures that perform specific functions in the cell a. The cytoskeleton is a network of protein fibers that gives shape and organization to the cell 2. Eukaryotic cells are not all alike a. Plant and animal cells each have unique organelles that are not found in the other i. Chloroplasts, plastids, and a central vacuole are found in plant cells and not in animal cells ii. Cilia are found in animal cells and not in plant cells B. Some Eukaryotic Cells Are Supported by Cell Walls 1. The outer surfaces of plants, fungi, and some protists are covered with cell walls a. Cell walls are composed of cellulose and other polysaccharides and are produced by the cells they surround .

29

30

Instructor Guide Biology: Life on Earth b. Cell walls support and protect otherwise fragile cells but allow flow of materials C. The Cytoskeleton Provides Shape, Support, and Movement (Figure 4-5) 1. The cytoskeleton is a network of protein fibers called microfilaments (thin), intermediate filaments, and microtubules (thick) (Table 4-2) 2. The cytoskeleton functions in: a. Cell shape b. Cell movement c. Organelle movement d. Cell division D. Cilia and Flagella Move the Cell Through Fluid or Move Fluid Past the Cell (Figure 4-6) 1. Cilia and flagella are slender extensions of the plasma membrane 2. Cilia are very abundant, short projections located on the surface of some cells; provide a force parallel to the plasma membrane of the cell (Figure 4-7a) 3. Flagella are longer than cilia, fewer in number, and provide a force perpendicular to the plasma membrane (Figure 4-7b) E. The Nucleus, Containing DNA, Is the Control Center of the Eukaryotic Cell (Figure 4-8) 1. The nuclear envelope allows selective exchange of materials a. It is a double membrane, studded on the cytoplasm side with ribosomes b. It is perforated with pores that permit easy passage of small molecules and regulate passage of larger molecules such as RNA and protein 2. Chromatin consists of strands of DNA associated with proteins a. Chromosomes (“colored bodies”) contain DNA molecules and associated proteins b. Chromatin is visible just before cell division, at which time it condenses into coils of chromosomes (Figure 4-9) c. Genetic information is copied from DNA into molecules of mRNA (Figure 4-10) 3. The nucleolus is the site of ribosome assembly a. It appears as one (or more) darkly staining regions in the nucleus b. Ribosomes are small, dense particles, composed of protein and RNA, that function in protein synthesis (Figure 4-11) â Case Study Continued: Spare Parts for Human Bodies F. Eukaryotic Cytoplasm Contains Membranes That Form the Endomembrane System 1. Eukaryotic cells have an elaborate system of membranes that are fundamentally similar in composition 2. Pieces of the cell membrane system can exchange membrane material with one another 3. The plasma membrane both isolates the cell and allows selective interactions between the cell and its environment 4. The cell’s membrane system includes the plasma membrane, nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and vacuoles 5. The endoplasmic reticulum (ER) forms membrane-enclosed channels within the cytoplasm a. The ER is a large system of interconnected membrane-enclosed channels, continuous with nuclear envelope (Figure 4-11) b. Rough endoplasmic reticulum has attached ribosomes and functions in synthesizing proteins c. Smooth endoplasmic reticulum has no attached ribosomes and synthesizes lipids 6. The Golgi apparatus modifies, sorts, and packages important molecules a. The Golgi resembles flattened sacs and is derived from the ER (Figure 4-12) b. Modifies some molecules by adding carbohydrates to some proteins to make glycoprotein c. Separates proteins and lipids received from the ER according to their destination d. Packages materials into vesicles and sends them to other parts of the cell or the plasma membrane for export 7. Secreted proteins are modified as they move through the cell a. Molecules destined for export synthesized on the rough ER are modified in the Golgi, and packaged into vesicles that fuse with the plasma membrane where the contents of the vesicle are released (Figure 4-13)

.

Chapter 4 Cell Structure and Function

31

8. Lysosomes serve as the cell’s digestive system (Figure 4-14) a. Membrane-bound vesicles that contain enzymes break down molecules, cell debris, foreign particles, and defective organelles b. Recognize food vacuoles that result from endocytosis 9. Membrane is exchanged throughout the cell G. Vacuoles Serve Many Functions, Including Water Regulation, Storage, and Support 1. Freshwater protists have contractile vacuoles a. These organelles store water that enters the cell due to osmosis, and pump it out to keep the cell from bursting (Figure 4-15) 2. Plant cells have central vacuoles a. This organelle stores hazardous waste b. This organelle helps to maintain the cell’s water balance i. Water enters vacuole by osmosis, causes turgor pressure, and pushes cytoplasm against cell wall H. Mitochondria Extract Energy from Food Molecules, and Chloroplasts Capture Solar Energy 1. The endosymbiont hypothesis of mitochondrial and chloroplast evolution states that both mitochondria and chloroplasts evolved from prokaryotic bacteria. Similarities between mitochondria and chloroplasts include: a. Similar in size: 1–5 micrometers b. Both are surrounded by a double membrane c. Both make ATP d. Both have their own DNA and ribosomes 2. Mitochondria use energy stored in food molecules to produce ATP a. Found in all organisms, including plants, but not bacteria b. Enable cells to carry out metabolic processes to break down food molecules and generate ATP c. Surrounded by a double membrane with highly folded inner membrane (folds are called cristae) (Figure 4-16) d. Internal fluid part of a mitochondria is the matrix 3. Chloroplasts are the sites of photosynthesis (Figure 4-17) a. All eukaryotic life is dependent on photosynthesis b. Chloroplasts are surrounded by a double membrane with internal stacks of hollow membranous sacs (thylakoids) arranged in stacks (grana) c. Thylakoid membranes contain chlorophyll, a green pigment molecule that captures light d. Fluid portion of chloroplast is the stroma I. Plants Use Some Plastids for Storage (Figure 4-18) 1. Chloroplasts are highly specialized plastids, organelles found only in plants and some photosynthetic protists 2. These organelles store pigment molecules and sugars â Lecture Activity 4.3: Cell Structure and Function Case Studies â Lecture Activity 4.4: The Effect of Smoking on Cilia

4.4

What Are the Major Features of Prokaryotic Cells?

A. Prokaryotic Cells Are Relatively Small (Figure 4-19) B. Prokaryotic Cells Possess Specialized Surface Features 1. Most prokaryotic cells are surrounded by a cell wall 2. Most prokaryotes are rod-shaped, spiral-shaped, or spherical a. Flagella help bacteria to move 3. Some have an outermost capsule or slime layer that helps them attach to surfaces â Links to Everyday Life: Unwanted Guests 4. Some bacteria have projections on surface a. Pili aid in attachment to host C. Prokaryotic Cells Have Fewer Specialized Cytoplasmic Structures Than Do Eukaryotic Cells 1. A single, circular, coiled chromosome is found in the nucleoid region and is not enclosed by a membrane 2. Most prokaryotic cells contain small rings of DNA called plasmids 3. The cytoplasm contains ribosomes, small particles composed of RNA and protein and involved in protein synthesis 4. Some bacteria use membranes to perform biochemical reactions (Figure 4-19e) .

32

Instructor Guide Biology: Life on Earth

Case Study Revisited: Spare Parts for Human Bodies (Figure 4-20)

KEY TERMS archaea bacteria basal body cell theory central vacuole centriole chlorophyll chloroplast chromatin chromosome cilium (plural, cilia) contractile vacuole cytoplasm cytoskeleton cytosol

deoxyribonucleic acid (DNA) diffusion endomembrane system endoplasmic reticulum (ER) endosymbiont hypothesis eukaryotic flagellum (plural, flagella) food vacuole Golgi apparatus intermediate filament lysosome microfilament microtubule mitochondrion (plural, mitochondria) nuclear envelope

nuclear pore complex nucleoid nucleolus (plural, nucleoli) nucleus organelle pilus (plural, pili) plasma membrane plasmid plastid prokaryotic ribonucleic acid (RNA) ribosome vesicle

LECTURE ACTIVITIES Lecture Activity 4.1: Surface-Area-to-Volume Considerations in Phenolphthalein Agar “Cells”: Why Aren’t We One Big Blob?

Estimated Time to Complete: 30 minutes for activity and discussion. This is best suited to small classes, or may be done as a demonstration in a larger class. Alternatively, the diffusion part of the activity could be done in the lab, and the calculations and discussion could occur in the lecture.

Section Reference 4.2 What Are the Basic Attributes of Cells?

Introduction This activity helps to make the concept of limitations of cell size more concrete for students. It has been adapted for use as a lecture demonstration from ThinkQuest: http://library.thinkquest.org/27819/diffusion_lab.html. The students will determine the surface area and volumes of three cubes of agar impregnated with phenolphthalein. The cubes will then be allowed to soak in 4% NaOH. The phenolphthalein in the agar reacts with the NaOH, changing the color of the cube to pink. Students will observe the relationship between diffusion distance and surface area and volumes of the cubes.

Materials Needed • Three cubes of 3% agar phenolphthalein 1 cm, 2 cm, and 3 cm on a side (note: these can be made from regular agar with a small amount of the indicator added so that the agar does not turn pink) • 4% NaOH solution • Ruler • Razor • Plastic spoon • Paper towels • Beaker

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Chapter 4 Cell Structure and Function

33

Procedures 1. Fill the beaker with 4% NaOH so that the cubes will be completely submerged in the beaker.

2. Place the three agar cubes in the beaker.

3. While the cubes are incubating, have the students calculate the surface area and volume of each agar cube.

(Note that if s = dimension of one side of the cube, surface area = 6s2, and volume = s3). Enter the calculations into Table 1.

4. Divide the surface area (SA) by volume to get the SA/volume ratio.

5. After 15 minutes, remove the agar cubes, place them on a paper towel, and blot dry.

6. Carefully cut the cubes in half with a razor blade. Note the relative diffusion distances in each case (1 = greatest amount of diffusion).

Assessment Suggestions Use the handout on the next page for individual or group assessment.

.

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 4.1 Handout—Surface-Area-to-Volume Considerations in Phenolphthalein Agar “Cells”: Why Aren’t We One Big Blob?

Table 1 Cube Size

Volume (s3)

Surface Area (6s2)

Surface Area Volume

Relative Diffusion Distance (1 = greatest)

1 cm 2 cm 3 cm

1.

Anything that enters or exits the cell must pass through the plasma membrane. Which measurement best represents the cell membrane: surface area or volume?

2.

Determine the surface-area-to-volume ratio of each cube. What happens to this ratio as the cube (“cell”) increases in size?

3.

Imagine that the cubes are actually cells. Which cell would be able to communicate with the exterior most efficiently?

.

4.

Which cell has the greatest possibility of surviving?

5.

Think of some of the structures inside the cell. Explain why the ER membranes and the cristae of the mitochondria are so highly folded.

6.

Suppose you repeat the experiment, beginning with two cubes, each 2 cm2. Predict how each of the following changes will affect the rate of diffusion:

a. One cube is placed in NaOH at 20°C, and the other is placed in NaOH at 37°C.

b. One has smooth sides, and the other has serrated sides.

.

36

Instructor Guide Biology: Life on Earth

Lecture Activity 4.2: Cell Shapes and Sizes Estimated Time to Complete: 10 minutes Section Reference 4.2 What Are the Basic Attributes of Cells?

Introduction In this activity, students study modifications in intestinal epithelial cells and erythrocytes for maximizing the surfacearea-to-volume ratio. The structures in these cells are linked to their functions. Search the Internet for information on surface-area-to-volume ratio in cells using the following search phrase: “surface area to volume ratio in cells.” Review the first few links for relevant information. This is a good activity to follow Lecture Demonstration 4.1, in which students determine the effect of surface area and volume on diffusion.

Materials Needed 1. Prepare transparencies or pictures of various types of cells that have adaptations to increase their surface area. Some suggestions: a. intestinal cell Search the Internet for information on surface-area-to-volume ratio in cells using the following search phrase: “intestinal.” Review the first few links for relevant information. b. red blood cell (RBC) Search the Internet for information on red blood cells using the phrase: “red blood cells.” Review the first few links for relevant information.

The site http://www.cellsalive.com/gallery.htm also provides a variety of information.

Procedures 1. Show pictures of the two types of cells, and ask the following questions to guide conversation: a. Intestinal cells • These cells line the lumen of the intestine, as part of what is known as the “brush border.” What is the main function of these cells? (To absorb nutrients) • Look carefully at the surface of these cells. What do you notice? (A “frilly” appearance that results from a highly folded plasma membrane, called microvilli) • Why is this modification necessary? (To increase surface-area-to-volume ratio) • The brush border is an example of specialization for absorption of materials across the plasma membrane, found in many sites. b. Erythrocytes • What is the main function of red blood cells? (To carry oxygen to the tissues; RBCs contain the oxygenbinding protein hemoglobin) • Look carefully at the size and shape. How would you classify it? (It is small for a eukaryotic cell, and has the shape of a biconcave disc, fairly flattened in the center.)

• How does the size and shape of a cell relate to surface area and volume considerations? (Smaller, flatter cells have a greater surface-area-to-volume ratio than large, wide cells) • Erythrocytes lose their mitochondria, nucleus, ribosomes, and many cytoplasmic enzymes during maturation. How does this affect the shape of the cell? (This is one of the reasons why the cell has a flattened center—there is no nucleus; the cell is also flexible for travel through small capillaries.)

• How does its structure relate to its function? (Because of their good surface-area-to-volume ratio, diffusion of oxygen is efficient. They are small and flexible to move through the circulatory system. In addition, the cells do not have any mitochondria to consume the oxygen that is being carried.)

Assessment Suggestions Include similar questions on an essay exam, such as: 1. Can you think of other cells that may have adapted methods of increasing surface-area-to-volume ratios?

(Some of the cells in the kidney also have microvilli and are adapted for absorption; protists are generally small and flattened.) .

Chapter 4 Cell Structure and Function 2.

Show the students pictures of other types of cells, without identifying the cell or its location. Ask the students to determine the function of the cell from its structure. A couple of suggestions are: a. Perform an Internet search using “simple squamous epithelial cell” as the keywords. b. Perform an Internet search using “protists” as the keyword.

Lecture Activity 4.3: Cell Structure and Function Case Studies Estimated Time to Complete: 10 minutes for group discussion, 20 minutes to report back to the class. This can be used to teach some of the major features of eukaryotic cells.

Section Reference 4.3 What Are the Major Features of Eukaryotic Cells?

Introduction In this activity, students are asked to apply their knowledge regarding the function of cell structures. Metabolic disorders and unique characteristics of some cells are used to illustrate the importance of individual structures.

Materials Needed Use the case studies on the next two pages. You may want to assign one case study per group.

Procedures 1. Divide the class into seven groups.

2. Assign a case study to each group (there are seven choices, see following pages).

3. For each cell component, ask the students to consider the following questions: a. What is the structure of the cell component referred to in your case study? Be as specific as possible. b. Where is it located in the cell? c. Is it found in plants/animals/bacterial cells? d. What is its normal function in the cell?

4. Have the students use the Internet to search for information on each case study. Search terms are listed in the student handout.

Assessment Suggestions Include similar scenarios on an essay exam.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 4.3 Handout—Cell Structure and Function Case Studies Case 1 Erythrocytes (red blood cells) have no nucleus, mitochondria, or other organelles at maturity. These organelles are ejected when the RBC enters the bloodstream, or shortly thereafter. Should this still be considered a cell? What will be the effect of having no nucleus? In these cells, the lack of mitochondria is an advantage. Why?

Hints for students: Search the Internet for “red blood cells” to find information to help with this case study.

Case 2 Pompe’s disease is one of a class of lysosomal storage diseases in which one or more enzymes that are normally found in the lysosomes are defective or absent. In Pompe’s disease, the enzyme that normally breaks down glycogen is absent. Describe what you would see in an electron micrograph of a liver cell from an individual with Pompe’s disease. What are some possible consequences of having such a disease? Can you think of an effective way to treat it?

Search the Internet for “Pompe’s disease” to find information to help with this case study.

Case 3 You are studying a biopsy of the liver of an alcoholic. What cellular organelle might you expect to see in larger-than-normal quantities? Explain why.

Search the Internet for information to help with this case study.

Case 4 Many anticancer drugs are directed at either stabilizing or destabilizing the tubulin protein that makes up microtubules.

Although these drugs are often effective in treating cancer, treatment can lead to hair loss and nausea. Explain.

Search the Internet for “microtubule structure” for information to help with this case study.

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Case 5 In cystic fibrosis, an important protein destined for the plasma membrane never makes it beyond the Golgi complex.

This protein is necessary for Na+ and Cl– transport and is critical for maintaining mucous secretions of the appropriate consistency. Devise an explanation for why this may occur.

Search the Internet for “cystic fibrosis” for information to help with this case study.

Case 6 “Imagine a major city with half its power plants shut down. At best, such conditions would produce a ‘brown out’ with large sections of the city working far below optimum efficiency. Now imagine your body with one-half of its energy-producing facilities shut down. The brain would be impaired, vision would be dim, muscles would twitch spastically or would be too weak to allow your body to walk or write, your heart would be weakened, and you would not be able to eat and digest your food.” Which organelle is being referred to in this description? What is its normal function in the cell?

Search the Internet for “mitochondrial disease” for information to help with this case study.

Case 7 Cells with mutations in their chloroplasts are often studied in order to understand the process of photosynthesis in more detail. Suppose you have a plant with no chlorophyll (it is an albino plant). Describe its appearance and the effect this would have on the plant.

Search the Internet for “albino plants” for information to help with this case study.

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Assessment Suggestions Case Study Answer Key Case 1 Erythrocytes (red blood cells) have no nucleus, mitochondria, or other organelles at maturity. These organelles are ejected when the RBC enters the bloodstream, or shortly thereafter. Should this still be considered a cell? What will be the effect of having no nucleus? In these cells, the lack of mitochondria is an advantage. Why?

Because the cells have no nucleus, they cannot divide, or replace a worn-out plasma membrane. The plasma membrane becomes fragile and the cell eventually dies after 80–120 days, usually by rupturing in the spleen. The RBC is still considered to be a eukaryotic cell (although a dying one), because it had a nucleus and other organelles at one time in its life. The Google searches listed in the student handout provide a variety of sites with reliable information.

This is true for all of the case studies.

Case 2 Pompe’s disease is one of a class of lysosomal storage diseases in which one or more enzymes that are normally found in the lysosomes are defective or absent. In Pompe’s disease, the enzyme that normally breaks down glycogen is absent. Describe what you would see in an electron micrograph of a liver cell from an individual with Pompe’s disease. What are some possible consequences of having such a disease? Can you think of an effective way to treat it?

An electron micrograph would show large lysosomes, engorged with undigested glycogen. Eventually, the large lysosomes would disrupt other functions of the cell. In a person with Pompe’s disease, this leads to muscle weakness and an enlarged heart. Cardiac and skeletal muscle cells are most greatly affected.

Case 3 You are studying a biopsy of the liver of an alcoholic. What cellular organelle might you expect to see in larger-than-normal quantities? Explain why.

Students should recall that the SER has enzymes that aid in detoxification. Chronic alcoholics generally have more SER, which in turn can lead to a greater tolerance for alcohol.

Case 4 Many anticancer drugs are directed at either stabilizing or destabilizing the tubulin protein that makes up microtubules.

Although these drugs are often effective in treating cancer, treatment can lead to hair loss and nausea. Explain.

Students should recall that microtubules are important for maintaining cell shape, movement of organelles, movement of cells, and cell division. In this case, microtubules will halt cell division. This is particularly effective in treating cancer because cancerous cells divide quickly. However, so do cells responsible for hair growth and cells that line the digestive tract, leading to loss of hair and nausea.

Case 5 In cystic fibrosis, an important protein destined for the plasma membrane never makes it beyond the Golgi complex.

This protein is necessary for Na+ and Cl– transport and is critical for maintaining mucous secretions of the appropriate consistency. Devise an explanation for why this may occur.

Any hypothesis that can explain a disruption in membrane traffic would be acceptable. In their response, students should explain that in the Golgi complex, proteins are sorted, modified, and tagged for their appropriate destination. Students may propose that the “tag” for this particular membrane protein is deficient, so it actually never gets the signal to travel to the plasma membrane. They may also propose that the membrane protein itself is defective, and unable to accept the tag. The actual role of glycosylation of the transmembrane protein that is defective in cystic fibrosis is being investigated by researchers.

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Case 6 “Imagine a major city with half its power plants shut down. At best, such conditions would produce a ‘brown out’ with large sections of the city working far below optimum efficiency. Now imagine your body with one-half of its energy-producing facilities shut down. The brain would be impaired, vision would be dim, muscles would twitch spastically or would be too weak to allow your body to walk or write, your heart would be weakened, and you would not be able to eat and digest your food.” Which organelle is being referred to in this description? What is its normal function in the cell?

This quote is taken from http://www.umdf.org/ and describes diseases that affect mitochondria. Mitochondria are called “powerhouses of the cell” because they convert carbohydrate energy to ATP.

Case 7 Cells with mutations in their chloroplasts are often studied in order to understand the process of photosynthesis in more detail. Suppose you have a plant with no chlorophyll (it is an albino plant). Describe its appearance and the effect this would have on the plant.

Chloroplasts are responsible for capturing light energy and converting it to carbohydrate. This plant would be unable to capture light and convert it to carbohydrate, which is necessary for its survival. The plant would produce a white shoot. When all the starch supplies in the seed get exhausted, the plant will die.

(From http://www.gi.alaska.edu/ScienceForum/ASF4/433.html.)

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Instructor Guide Biology: Life on Earth

Lecture Activity 4.4: The Effect of Smoking on Cilia Estimated Time to Complete: 15 minutes for discussion Section Reference 4.3 What Are the Major Features of Eukaryotic Cells?

Introduction This class discussion helps to review and expand upon the importance of cilia. It also links the material in this chapter to a relevant health concern. Be careful not to alienate smokers with a “preachy” discussion.

Materials Needed Transparency, picture, or PowerPoint slide of a ciliated pseudostratified columnar epithelial cell with cilia Procedures 1. Ask the students what they already know regarding cilia (fine extensions of the plasma membrane made from microtubules; provide a force parallel to the plasma membrane to move fluids across the cell).

2. Explain that cells with cilia line much of the respiratory tract. Show a picture or diagram of ciliated pseudostratified columnar epithelial cells.

3. Discuss what happens to cilia as a result of cigarette smoke exposure: “Cigarette smoke causes a decrease in the action of the cilia, and even temporary paralysis of these fine hairs on the mucous linings, which help protect the deeper tissues by pushing out microorganisms and other foreign materials. Smoke also decreases phagocyte activity by diminishing macrophage function. The thinning and drying of the mucus itself cause the bronchial tubes to become dry and irritated. This not only decreases defenses, but leads to much of the inflammation, hoarseness, and chronic cough associated with smoking.” For more information, go to HealthWorld Online (http://www.healthy.net) and search for “nicotine detoxification.”

4. Ask the students to consider the results of the lack of cilia and decreased phagocytic activity in the respiratory tract. (Decreased action of cilia will lead to stationary mucus, which must be cleared by coughing; decreased phagocytic activity could result in more infectious particles reaching the lungs.)

5. Consider the following question: If a person stops smoking, is the damage to the cilia permanent? This should lead to a discussion about how cilia are formed (by the movement of a centriole to the plasma membrane and the formation of the cilia from a basal body).

Assessment Suggestions Include essay items on a written exam, such as: Primary cilia dyskinesia is an inherited disorder in which children are born with malfunctioning cilia. What would be some of the symptoms of this disorder? Males also are infertile. Can you explain why? (The main symptoms would be severe respiratory infections; males are infertile because flagella that propel sperm are also affected.) Instructor note: You may want to refer to the following Web site for more information: The Baylor College of Medicine (http://www.bcm.tmc.edu) and search for “primary cilia dyskinesia.”

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CHAPTER 5 CELL MEMBRANE STRUCTURE AND FUNCTION LECTURE OUTLINE Case Study: Vicious Venoms â Lecture Activity 5.1: The Role of the Plasma Membrane

5.1

How Is the Structure of a Membrane Related to Its Function?

A. Cell Membranes Isolate the Cell Contents While Allowing Communication with the Environment (Figure 5-1) 1. Cell membranes perform several crucial functions a. Selectively isolate the cell’s contents from the external environment b. Regulate the exchange of essential substances between the cell and the extracellular environment c. Communicate with other cells d. Create attachments within and between cells e. Regulate many biochemical reactions 2. Membrane function is dependent on membrane structure B. Membranes Are “Fluid Mosaics” in Which Proteins Move Within Layers of Lipids 1. The fluid mosaic model was developed in 1972 by S. J. Singer and G. L. Nicolson 2. The membrane consists of a mosaic of proteins within the double layer of phospholipids C. The Fluid Phospholipid Bilayer Helps to Isolate the Cell’s Contents 1. Phospholipids have a polar “head” and two nonpolar “tails” (Figure 5-2) 2. The plasma membrane is a phospholipid bilayer (Figure 5-3) a. In a bilayer, the tails point inward and the heads point toward the exterior watery environment (the extracellular fluid), or the internal watery environment (cytoplasm) b. The polar heads form hydrogen bonds with water; hydrophobic interactions keep tails facing each other c. Membrane is fluid because phospholipid molecules are not bonded to each other â In Greater Depth: Membrane Fluidity, Function, and Phospholipids (Figures E5-1 and E5-2) d. Cholesterol in animal cell membranes makes the bilayer stable, less fluid, and less permeable to water-soluble substances e. The phospholipid bilayer selectively isolates the internal environment from the external environment i. Most biological molecules are hydrophilic and cannot easily pass through the membrane ii. Some very small molecules or uncharged, lipid-soluble molecules can freely pass through membrane â Case Study Continued: Vicious Venoms â Lecture Activity 5.2: Interaction of Hydrophilic and Hydrophobic Substances D. A Variety of Proteins Form a Mosaic Within the Membrane 1. Thousands of proteins are embedded within or attached to the surface of the membrane’s phospholipid bilayer 2. Many membrane proteins are glycoproteins that have an attached carbohydrate group 3. Five major categories of proteins are found in the membrane 4. Enzymes a. Enzymes are proteins that promote chemical reactions 5. Receptor proteins a. These proteins bind molecules in the environment, triggering changes in the metabolism of the cell (Figure 5-4) 6. Recognition proteins a. These proteins serve as identification tags .

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Instructor Guide Biology: Life on Earth 7. Connection proteins a. These proteins anchor the cell membrane in various ways 8. Transport proteins a. These proteins regulate the movement of hydrophilic molecules through the plasma membrane

5.2

How Do Substances Move Across Membranes? â Lecture Activity 5.3: Concentration Gradients and Diffusion A. Background on Membrane Transport 1. Solutes are substances that can be dissolved and solvents are fluids capable of dissolving a solute 2. The concentration of a substance is the number of molecules in a given unit of volume 3. A gradient is a physical difference in properties such as temperature, pressure, electrical charge, or concentration of a particular substance between two adjoining regions a. Cells use energy and membrane proteins to create concentration gradients of various molecules B. Molecules in Fluids Diffuse in Response to Gradients 1. Diffusion is the movement of molecules from regions of high concentration to regions of low concentration, “down” a concentration gradient a. Molecules move continuously and randomly b. The greater the concentration gradient and temperature, the faster the rate of diffusion c. An example of diffusion: a drop of food coloring in a glass of water (Figure 5-5) d. Diffusion will continue until the concentrations of solutes become equal throughout a solution C. Movement Through Membranes Occurs by Passive Transport and Energy-Requiring Transport 1. There are significant concentration gradients of ions and molecules across the plasma membrane because the cytoplasm of a cell is very different from the extracellular fluid 2. Plasma membranes are described as selectively permeable a. They allow only certain molecules to pass through freely 3. Movement across the plasma membrane occurs in two ways (Table 5-1) a. Passive transport i. Substances move “down” concentration gradients b. Energy-requiring transport i. Cells expend energy to move substances across the membrane D. Passive Transport Includes Simple Diffusion, Facilitated Diffusion, and Osmosis â Lecture Activity 5.4: Demonstration of Diffusion Through a Selectively Permeable Membrane 1. Some molecules move across membranes by simple diffusion (Figure 5-6a) a. Lipid-soluble molecules and very small molecules can easily diffuse across the plasma membrane b. Rate of simple diffusion is a function of the concentration gradient, the size of the molecule, and its lipid solubility â Lecture Activity 5.5: Diffusion of Molecules Through a Selectively Permeable Membrane 2. Some molecules cross membranes by facilitated diffusion using membrane transport proteins a. Most polar molecules can diffuse only with the aid of channel proteins or carrier proteins i. This is called facilitated diffusion b. Carrier proteins bind specific molecules on one side of the membrane and move them across (Figure 5-7d) i. These proteins require no energy and can only move molecules “down” their concentration gradient c. Channel proteins form pores or channels in the lipid bilayer that are specific for certain ions or molecules (Figure 5-7b) i. Aquaporin is a channel protein that allows water to flow through the membrane (Figure 5-7c) ii. The simple diffusion of water is called osmosis â Science in Action: The Discovery of Aquaporins (Figures E5-3 and E5-4) 3. Osmosis is the diffusion of water across selectively permeable membranes a. Water moves down its concentration gradient across a selectively permeable membrane b. Dissolved substances reduce the concentration of water molecules in a solution â Lecture Activity 5.6: Demonstration of Osmosis c. The concentration of solute in a solution determines its osmotic strength, or the ability to attract water across a membrane i. In an isotonic environment, the water concentration around the cell is the same as the water concentration inside the cell and no net movement of water occurs (Figure 5-7a) .

Chapter 5 Cell Membrane Structure and Function

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ii. In a hypertonic environment, the solution outside the cell has a higher concentration of solutes (lower concentration of water) than the interior of the cell and water will flow out of the cell by osmosis (Figure 5-7b) iii. In a hypotonic environment, the solution outside the cell has a lower solute concentration (higher water concentration) than the solution inside the cell and water will flow into the cell by osmosis (Figure 5-7c) 4. Osmosis across the plasma membrane plays an important role in the lives of cells a. Plant cells have a large central vacuole, which affects water uptake and release i. When water is plentiful, plant cells have turgor pressure, which provides support for nonwoody plants (Figure 5-8a) ii. When water is not plentiful, plant cells lose turgor pressure (Figure 5-8b) b. The extracellular fluid of animal cells is usually isotonic (Figure 5-9a) i. The sizes of cells remain constant ii. In a hypertonic solution, animal cells release water and shrivel (Figure 5-9b) iii. In a hypotonic solution, animal cells take in water and swell (Figure 5-9c) â Lecture Activity 5.7: Diffusion and Osmosis in the Human Body D. Energy-Requiring Transport Includes Active Transport, Endocytosis, and Exocytosis 1. Cells maintain concentration gradients using active transport a. Membrane proteins use energy to move molecules against their concentration gradient (Figure 5-10) b. Active transport proteins span the width of the membrane and have two active sites i. One site binds the substance to be transported ii. The other site binds an energy carrier molecule, usually ATP c. Active transport proteins are sometimes called “pumps” because they move substances “uphill” against the concentration gradient 2. Endocytosis allows cells to engulf particles or fluids a. Endocytosis requires energy b. Pinocytosis moves liquids into the cell (Figure 5-11) i. This is also called “cell drinking” ii. A small patch of membrane dimples inward to form a vesicle surrounding a droplet of fluid iii. The cell is acquiring materials in the same concentration as extracellular fluid c. Receptor-mediated endocytosis moves specific molecules into the cell (Figure 5-12) i. Receptor proteins that have bound particles move through the plasma membrane and accumulate in depressions called coated pits ii. The coated pit deepens and pinches off into the cytoplasm as a coated vesicle d. Phagocytosis moves large particles into the cell (Figure 5-13) i. This can also be called “cell eating” ii. Extensions of the membrane fuse around the large particle and carry it to the interior of the cell in a vacuole for intracellular digestion 3. Exocytosis moves material out of the cell (Figure 5-14) a. A membrane-enclosed vesicle carrying material to be expelled moves to the cell surface b. The vesicle then fuses with the plasma membrane and releases its contents E. Exchange of Materials Across Membranes Influences Cell Size and Shape 1. Exchange of nutrients and wastes in cells occurs by diffusion 2. As a cell enlarges, its volume increases, causing it to require more nutrients and produce more wastes (Figure 5-15) 3. Some cells have specialized structures that increase their membrane surface area

5.3

How Do Specialized Junctions Allow Cells to Connect and Communicate?

A. Desmosomes Attach Cells Together (Figure 5-16a) 1. Protein filaments strengthen the attachment B. Tight Junctions Make Cell Attachments Leakproof (Figure 5-16b) C. Gap Junctions and Plasmodesmata Allow Direct Communication Between Cells 1. Gap junctions are cell-to-cell channels (Figure 5-16c) 2. Plasmodesmata link the insides of adjacent plant cells (Figure 5-16c)

Case Study Revisited: Vicious Venoms (Figure 5-17) .

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Instructor Guide Biology: Life on Earth

KEY TERMS active transport aquaporin carrier protein channel protein concentration concentration gradient connection protein desmosome diffusion endocytosis energy-requiring transport enzyme exocytosis facilitated diffusion

fluid fluid mosaic model food vacuole gap junction glycoprotein gradient hypertonic hypotonic isotonic osmosis passive transport phagocytosis phospholipid bilayer pinocytosis

plasmodesmata receptor protein receptor-mediated endocytosis recognition protein selectively permeable simple diffusion solute solvent tight junction transport protein turgor pressure

LECTURE ACTIVITIES Lecture Activity 5.1: The Role of the Plasma Membrane Estimated Time to Complete: 20 minutes Section Reference 5.1 How Is the Structure of a Membrane Related to Its Function?

Introduction The concepts in this chapter are easily connected to many phenomena that most students should have an interest in. The chapter case study on venomous snakebites easily demonstrates the importance of cell membranes. Other introductory scenarios can include a discussion of the importance of membrane proteins to human health. Health issues that can be used include: infectious disease, allergies, drug addiction, a variety of nervous system disorders involving neurotransmitters, genetic disorders involving membrane receptor proteins and the molecules that bind to them, the functioning and malfunctioning of the endocrine system, and even appetite signaling. Most of these ideas would work well as introductory small-group discussions.

Materials Needed None Procedures Choose one of the topics suggested in the Introduction, and develop questions for discussion. For example: 1. Present the class with the basic information about viral recognition of cells. How does a virus such as HIV infect certain cells of the immune system? How might we prevent HIV from recognizing or binding to our cells? How are different strains of HIV overcoming our treatments? The following resources may help you to prepare: • Go to the ThinkQuest Web site (http://www.thinkquest.org/library/) and search using the following terms: “viral infection and replication.” This site provides information on how viruses function and how our bodies respond to them.

• Perform an Internet search using the terms “HIV life cycle” to find information on how this virus reproduces.

2. Discuss the problem of moisture stress in plants as a result of soil salinization, especially due to poor irrigation practices.

How do halophyte plants successfully live in high-salt environments?

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Chapter 5 Cell Membrane Structure and Function

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• Perform an Internet search using the following terms: “halophyte plants.” Find information to answer these questions: (1) How does too much salt affect land plants? (2) How does too much water affect land plants? (3) How do some plants—such as mangroves—manage to grow when other plants can’t?

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Instructor Guide Biology: Life on Earth

Assessment Suggestions Use questions similar to those you opened with as essay questions on an exam.

Lecture Activity 5.2: Interaction of Hydrophilic and Hydrophobic Substances Estimated Time to Complete: 5 minutes for demonstration, 10 minutes for discussion Section Reference 5.1 How Is the Structure of a Membrane Related to Its Function?

Introduction To begin to understand the structure and function of plasma membranes, students will need to recall some basic characteristics of biological molecules from Chapter 3. This demonstration will reinforce the concept that hydrophilic and hydrophobic solutions create two distinct layers when mixed. When a hydrophilic solute is added, it will be more soluble in the water layer. A hydrophobic solute will be more soluble in the lipid layer. This could then lead to a discussion regarding the phospholipid bilayer and the cytoplasmic and extracellular fluids.

Predictions can be made about the solubility or permeability of solutes in these layers.

Materials Needed • 100-ml graduated cylinder • 30 ml of water • 30 ml of vegetable oil • Lipid-soluble dye such as Sudan red (in powder form) • Methylene blue, or food coloring dye • Parafilm or plastic wrap to cover top of graduated cylinder when shaking Procedures 1. Place 30 ml of water in the graduated cylinder.

2. Add food coloring (blue or green).

3. Carefully pour 30 ml of vegetable oil on top so that two layers exist.

4. Add Sudan red dye.

5. Now, shake the container, and place it on a desk to settle during the class period. At the end of the period, discuss what is observed, using the assessment questions on the next page.

Assessment Suggestions Use the handout on the next page for class discussion or individual assessment.

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Chapter 5 Cell Membrane Structure and Function Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

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Lecture Activity 5.2 Handout—Interaction of Hydrophilic and Hydrophobic Substances Questions 1.

Describe what occurs when the oil and water are mixed together.

2.

After the solution has been mixed and allowed to settle, describe what you observed.

3.

Relate this demonstration to what you know about membranes. What does the oil represent? What does the water represent?

4.

Predict what would happen if a polar solvent such as alcohol were added. In which layer would you expect the alcohol to dissolve? What about a nonpolar solvent?

5.

If a membrane was composed of 100% phospholipids and no protein, what types of molecules would be able to enter or exit the cell?

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Instructor Guide Biology: Life on Earth

Lecture Activity 5.3: Concentration Gradients and Diffusion Estimated Time to Complete: 20 minutes (or, if time is short, the activity can be divided into several parts) Section Reference 5.2 How Do Substances Move Across Membranes?

Introduction In this activity, random movement of molecules will be illustrated by placing beads of different colors in a box. This will lead to a discussion of concentration gradients and the molecular movement of dye molecules when placed in water. The effect of temperature on the rate of diffusion will also be demonstrated by using water at different temperatures.

Materials Needed • Beads of different colors to represent different types of molecules • Large shallow box • Large glass beakers of warm water, cold water, and water at room temperature • 3 dropper bottles of India ink or food coloring Procedures 1. You may want to begin this activity with a couple of illustrations that may help to make the concept of concentration gradients more concrete: a. Think of what happens when you are on a four-lane highway that suddenly merges into one lane because of an accident. Cars pile up behind the merger point, creating a “high” concentration on one side, and a low concentration on the other side. As the accident site is cleared up and the highway reopens, the traffic flows more evenly and the gradient disperses. b. It is only 6:30 p.m., but people have flocked to the theater to see the 7:00 p.m. showing of the new release.

Before the doors are opened, there is a “high” concentration of people outside the movie theater. After the doors are opened, the flow is steadier and the gradient disperses.

2. Start the activity by placing a handful of beads of each color in a corner of the box to represent a concentrated drop of substance. Discuss the “concentration gradient” that exists at the beginning of the experiment. Demonstrate random molecular movement by gently shaking. Point out the “molecular collisions” that occur and note the distribution of the beads at the end of the activity.

This can be done as a group activity if you have enough beads and boxes.

3. Set the large beaker of room-temperature water on a table in the front of the room where it will be undisturbed. Repeat with the beakers of cold water and warm water.

4. Let the molecular race begin! Have three students come up and simultaneously release one drop of dye from dropper bottles into the water. Allow these to remain undisturbed. Note the length of time it takes for the ink to become evenly distributed in each beaker in Table 1.

5. Discuss the results at the end of the experiment.

Assessment Suggestions Use the handout on the next page for class discussion or individual assessment.

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Chapter 5 Cell Membrane Structure and Function Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 5.3 Handout—Concentration Gradients and Diffusion Table 1 Beaker

Length of Time to Reach Equilibrium

Room temperature Hot Cold Questions 1.

Define the following: a. Concentration gradient

b. Diffusion

c. Dynamic equilibrium

2.

During diffusion, particles move from an area of _________________ concentration to an area of ______________ concentration.

3.

For diffusion to occur, is it necessary to have a membrane separating two solutions?

4.

Is energy required for diffusion?

5.

How does temperature affect the rate of diffusion? Explain.

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Lecture Activity 5.4: Demonstration of Diffusion Through a Selectively Permeable Membrane Estimated Time to Complete: 15 minutes Section Reference 5.2 How Do Substances Move Across Membranes?

Introduction This is a rather simple group activity that reinforces the concept that membranes are selectively permeable—only some molecules are able to pass through. You may want to use this activity to introduce the idea that size is not the only factor in determining what type of molecule can cross the plasma membrane.

Materials Needed • Sieves, screen, and filter paper with different mesh sizes • Substances of a variety of sizes, mixed up and placed in beakers for students (suggestions: sand, marbles, dried peas, glass beads, salt, water, super balls, charcoal, etc.)

• Beakers to catch waste • Funnels, if appropriate for the screen that you use Procedures 1. To each group, pass out a sieve or screen, a beaker of mixed substances, and a beaker to catch the filtrate.

2. Have each group filter the mix using the mesh.

3. Have the students discuss the results in their group and predict what type of molecules will cross the plasma membrane.

Assessment Suggestions 1. Have the students determine the relative permeability of the membrane to specific molecules differing only in size: O2, CO2, glucose, starch.

2. Size is not the only factor that determines molecular movement across membranes. Ask the students to consider the relative permeability of the membrane to substances of various sizes and polarities: O 2, CO2, glucose, starch, ethanol, Na+ ions.

3. A number of antibiotics work by producing ionophores, which make the plasma membrane of bacterial cells more permeable to ions. Perform an Internet search using “ionophore” as a search term. Have the students consider what ionophores do and describe what will result from exposure to antibiotics. Which type of transport will be affected: active or passive?

Lecture Activity 5.5: Diffusion of Molecules Through a Selectively Permeable Membrane Estimated Time to Complete: 10 minutes at start of lecture, 10 minutes at end of lecture Section Reference 5.2 How Do Substances Move Across Membranes?

Introduction In this experiment, you will be using dialysis tubing to represent the plasma membrane. Dialysis tubing is selectively permeable. It is made of cellulose fibers and has small pores in it, so small molecules can pass through it. You will test the permeability of the dialysis membrane to three molecules: a. glucose, a relatively small monosaccharide b. starch, the large polymer of glucose c. I2KI (iodine–potassium–iodide), a substance that reacts with starch to produce a blue-black color

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Chapter 5 Cell Membrane Structure and Function

53

A solution of glucose and starch will be placed inside a bag of dialysis tubing. Distilled water will be placed in a beaker, outside the dialysis bag. After 30 minutes, the solution inside the dialysis tubing and the solution in the beaker will be tested for glucose and starch. The presence of glucose will be tested with a glucose test strip. The presence of starch will be tested with I2KI. Materials Needed • 15% glucose solution • 1% starch solution • 50-ml beaker • I2KI solution in a dropper bottle • Glucose test strip • 2 test tubes • 1 250-ml beaker • 20-cm strip of moistened dialysis tubing • String • Plastic transfer pipettes Procedures 1. Pour equal amounts of glucose and starch (approximately 10–15 ml of each) into a small beaker.

2. Demonstrate the tests for glucose and starch, using the beaker solution: A. Glucose test: Dip the glucose test strip into the solution, wait 10 seconds ONLY, and look for any change in color as indicated on the container. Record the results in Table 1.

B. Starch test: With a plastic transfer pipette, place 1 ml of the solution from the beaker into a test tube.

Add a few drops of I2KI solution from the dropper bottle. The presence of a blue-black color indicates the presence of starch.

3. Obtain a 20-cm piece of 2.5-cm dialysis tubing that has been soaking in water. Tie off one end of the tubing to form a bag. To open the other end of the bag, rub the end between your fingers until the edges separate.

Add the starch/glucose solution that you mixed in Step 1 to the bag. Tie off the other end of the bag, leaving sufficient space for the expansion of the bag’s contents.

4. Rinse the outside of the bag thoroughly with distilled water.

5. Fill a 250-ml beaker two-thirds full with distilled water.

6. Test the beaker solution for glucose and starch, as above, and record in Table 1.

7. Add approximately 4 ml of I2KI solution to the distilled water.

8. Immerse the bag in the beaker of solution.

9. Allow your setup to stand for approximately 30 minutes or until you see a distinct color change in the bag or the beaker.

10. Test the liquid in the beaker and in the bag for the presence of glucose. Record the results in Table 1.

Assessment Suggestions Use the handout on the next page for class discussion or individual assessment.

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Instructor Guide Biology: Life on Earth

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 5.5 Handout—Diffusion of Molecules Through a Selectively Permeable Membrane Table 1 Initial Contents Bag

Beaker

End of Experiment Bag

Beaker

Glucose present?

Starch present?

Questions 1.

Which substance(s) are entering the bag and which are leaving the bag? What experimental evidence supports your answer?

2.

Do your results support your hypothesis and prediction? Explain.

3.

Quantitative data uses numbers to measure observed changes. How could this experiment be modified so that quantitative data could be collected to show that water diffused into the dialysis bag?

4.

On the basis of your observations, rank the following by relative size, beginning with the smallest: glucose molecules, water molecules, starch molecules.

5.

What results would you expect if the experiment started with glucose and I 2KI solution inside the bag and only starch and water outside? Why?

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Lecture Activity 5.6: Demonstration of Osmosis Estimated Time to Complete: 10 minutes at the beginning of lecture; 10 minutes at the end of lecture. (Begin soaking the eggs 3 days in advance.) This can be done as an introduction to the topic of tonicity in class. If you choose to do this, the discussion may require extra time.

Section Reference 5.2 How Do Substances Move Across Membranes?

Introduction This is an excellent demonstration of osmosis. Although some students may have seen this activity in an earlier biology class, it is well worth repeating for those who may not have observed it. In this experiment, you will use chicken eggs that have been soaked in vinegar for several days to remove the shell. The chicken egg is actually a large cell. The membrane, with the shell removed, can serve as a model of a cell membrane. Osmosis can be measured by changes that occur in the weight of the egg after soaking in Karo syrup.

Materials Needed • Gloves • Two 9-oz plastic cups • 2 eggs with the shell removed • Karo syrup (clear type) • Water • Digital scale and weighing boat • Plastic spoons Procedures 1. Three days before the demonstration, completely immerse medium or large eggs in vinegar to dissolve the shell. Change the vinegar each day to ensure complete removal of the shell. On the day of the demonstration, rinse the de-shelled eggs gently and transfer them to water.

2. Obtain two chicken eggs from which the shell has been dissolved.

3. Weigh each egg, making sure to carefully blot it off on a paper towel before weighing.

4. Add one egg to a plastic cup that contains water; add the other egg to a cup of Karo syrup. Karo syrup is a very thick, sugary solution.

5. Remove and weigh the eggs at 30 minutes and at 60 minutes (if you have time, weigh them again at 90 minutes). A plastic spoon will help you to lift each egg out of the cup without breaking it.

6. Record your results in Table 1.

Assessment Suggestions Use the handout on the next page for class discussion or individual assessment.

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Instructor Guide Biology: Life on Earth

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 5.6 Handout—Demonstration of Osmosis Table 1 Initial Weight of Egg

Weight of Egg at 30 Minutes

Weight of Egg at 60 Minutes

Weight of Egg at 90 Minutes

Egg in cup 1 (water) Egg in cup 2 (Karo syrup) Questions 1.

Did either egg show a change in weight? Explain.

2.

In this experiment, the Karo syrup was hypertonic to the egg. On the basis of your observations, explain what this means.

3.

Water is slightly hypotonic to the egg. Define hypotonic, on the basis of the results of your experiment.

4.

If the egg were soaking in an isotonic solution, what would occur?

5.

After severe blood loss or dehydration, patients are often treated with normal saline to help restore body fluids. Normal saline is 0.9% NaCl. Why is the salt concentration important? What would happen to the red blood cells of a patient who was treated with 0% saline? What about 10% saline?

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Lecture Activity 5.7: Diffusion and Osmosis in the Human Body Estimated Time to Complete: 20 minutes Section Reference 5.2 How Do Substances Move Across Membranes?

Introduction In this activity, students will apply their knowledge of diffusion and osmosis to real-life situations.

Materials Needed None Procedures Work in groups of three or four to discuss the following situations that cells may encounter: 1. As a person becomes very dehydrated, the concentration of water in her blood decreases. In which direction will water move across the plasma membranes of her blood cells? What will happen to the volume of the cells as a consequence? Why is proper hydration important for multicellular organisms?

2. Oops! You were cleaning out the aquariums in the biology lab and you accidentally placed the freshwater fish in the saltwater tank. What will happen to the cells of these fish?

3. In some countries, human waste is used as a fertilizer. If produce is grown in this type of fertilizer, it is possible that it will be contaminated with the protozoan that causes amoebic dysentery. One method of removing the protist without ruining the food is to place the produce in a 5% salt solution. Explain how this would kill the protist. If you cleaned your lettuce this way, what would happen to the lettuce cells? How could you return them to normal?

Assessment Suggestions Use similar questions as essay questions on an exam.

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CHAPTER 6 ENERGY FLOW IN THE LIFE OF A CELL LECTURE OUTLINE Case Study: Energy Unleashed 6.1

What Is Energy? ➢ Lecture Activity 6.1: Potential and Kinetic Energy A. Energy Is the Capacity to Do Work 1. Potential energy is stored energy (Figure 6-1) 2. Kinetic energy is the energy of movement B. The Laws of Thermodynamics Describe the Basic Properties of Energy 1. The first law of thermodynamics states that energy can neither be created nor destroyed a. The total energy in a closed system remains constant b. Energy can change form c. The first law is often called the law of conservation of energy 2. The second law of thermodynamics states that when energy is converted from one form to another, the amount of useful energy decreases (Figure 6-2) a. Entropy is the tendency toward an increase in randomness, disorder, and low-level energy ➢ Earth Watch: Step on the Brakes and Recharge Your Battery ➢ Case Study Continued: Energy Unleashed C. Living Things Use the Energy of Sunlight to Create the Low-Entropy Conditions of Life 1. Living things use a continuous input of solar energy to synthesize complex molecules and maintain orderly structures

6.2

How Is Energy Transformed During Chemical Reactions?

A. A Chemical Reaction Is a Process That Breaks or Forms Chemical Bonds 1. These reactions convert reactants to products 2. A reaction is exergonic if it releases energy (Figure 6-3) 3. A reaction is endergonic if it requires a net input of energy (Figure 6-4) B. Exergonic Reactions Release Energy 1. In an exergonic reaction, the reactants have more energy than the products and energy is released (Figure 6-5) C. Endergonic Reactions Require a Net Input of Energy 1. In this reaction, the products of a chemical reaction contain more energy than the reactants (Figure 6-6) 2. An input of energy is required for the reaction to proceed 3. All chemical reactions require activation energy to begin (Figure 6-7) a. Chemical reactions require some input of energy i. The energy of activation provides the “push” to get chemical reactions started ➢ Lecture Activity 6.2: Endergonic and Exergonic Reactions ➢ Case Study Continued: Energy Unleashed

6.3

How Is Energy Transported Within Cells?

A. Energy-Carrier Molecules Are High-Energy Molecules That Move Energy Within Cells B. ATP and Electron Carriers Transport Energy Within Cells 1. Adenosine triphosphate (ATP) is the “energy currency” of living cells because it provides energy for a wide variety of endergonic reactions 2. ATP is composed of a nitrogen-containing base, adenine, the sugar ribose, and three phosphate groups 3. ATP can be synthesized from adenosine diphosphate (ADP) and phosphate, using the energy released by exergonic reactions such as glucose breakdown (Figure 6-8a) .

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Instructor Guide Biology: Life on Earth 4. ATP can be broken down to ADP and phosphate to provide energy for endergonic reactions (Figure 6-8b) 5. ATP is not a long-term energy-storage molecule 6. Electron carriers transport energy in the form of electrons a. Common electron carriers are nicotinamide adenine dinucleotide (NAD +) and flavin adenine dinucleotide (FAD) C. Coupled Reactions Link Exergonic with Endergonic Reactions 1. Living organisms use the energy from exergonic reactions to drive endergonic reactions (Figure 6-9) 2. Exergonic and endergonic reactions may occur in different locations 3. Energy is transferred from place to place by energy-carrier molecules such as ATP

6.4

How Do Enzymes Promote Biochemical Reactions?

A. Catalysts Reduce the Energy Required to Start a Reaction (Figure 6-10) 1. Catalysts work by reducing the amount of activation energy required by a reaction 2. Three principles apply to all catalysts a. Catalysts speed up chemical reactions by lowering the activation energy b. Catalysts can speed up only exergonic reactions that would occur spontaneously if the activation energy is overcome c. Catalysts are not consumed or permanently changed by the reactions they promote B. Enzymes Are Biological Catalysts 1. In living organisms, enzymes are usually proteins a. Enzymes are usually very specific for a particular chemical reaction 2. The structure of enzymes allows them to catalyze specific reactions a. Because of its three-dimensional shape, an enzyme has a “pocket,” or active site into which a specific reactant molecule, or substrate, can enter i. Only certain molecules called substrates can enter the active site b. There are three steps in the cycle of enzyme–substrate interactions (Figure 6-11) i. Substrate(s) enter the active site in a specific orientation ii. Substrate(s) and active site change shape, promoting the reaction iii. Product is released; enzyme is ready for new substrate(s) ➢ Lecture Activity 6.3: Lactaid Action 3. Enzymes, Like All Catalysts, Lower Activation Energy

6.5

How Are Enzymes Regulated?

A. The Metabolism of a Cell Is the Sum of Its Chemical Reactions 1. These reactions are linked in sequences called metabolic pathways (Figure 6-12) B. Cells Regulate Metabolic Pathways by Controlling Enzyme Synthesis and Activity 1. The rate of enzyme-catalyzed reactions depends on the concentration of enzymes and substrates 2. Genes that code for enzymes may be turned on or off a. Cells can regulate enzymes by regulating the genes that dictate the production of the enzyme ➢ Health Watch: A Lost Enzyme Leads to Lactose Intolerance (Figure E6-1) 3. Some enzymes are synthesized in inactive forms a. Cells activate them only when needed 4. Enzyme activity may be controlled by competitive or noncompetitive inhibition a. Cells must regulate enzyme function i. Remember that substrates must bind to the active site (Figure 6-13a) b. In competitive inhibition, a substance competes with the substrate for the active site of the enzyme (Figure 6-13b) c. In noncompetitive inhibition, a molecule binds to a site on the enzyme distinct from the active site (Figure 6-13c) i. When this binding occurs, the active site is distorted and the substrate can no longer bind 5. Some enzymes are controlled by allosteric regulation a. In allosteric regulation, certain enzymes have their activity enhanced or inhibited by regulator molecules i. Feedback inhibition is a type of allosteric regulation where the enzyme is inhibited by a regulator molecule that is the end product of a metabolic pathway (Figure 6-14) C. Poisons, Drugs, and Environmental Conditions Influence Enzyme Activity 1. Some poisons and drugs are competitive or noncompetitive inhibitors of enzymes .

Chapter 6 Energy Flow in the Life of a Cell a. Some inhibitors bind permanently to the enzyme 2. The activity of enzymes is influenced by their environment a. When conditions fall outside a particular range, the enzyme is denatured b. Environmental factors that can influence enzyme activity include: i. pH (Figure 6-15a) ii. Temperature (Figure 6-15b) iii. Salt concentration

Case Study Revisited: Energy Unleashed

KEY TERMS activation energy active site adenosine diphosphate (ADP) adenosine triphosphate (ATP) allosteric regulation catalyst chemical energy chemical reaction closed system competitive inhibition coupled reaction denature

electron carrier endergonic energy energy-carrier molecule entropy enzyme exergonic feedback inhibition first law of thermodynamics kinetic energy law of conservation of energy metabolic pathway

metabolism noncompetitive inhibition potential energy product reactant second law of thermodynamics substrate work

LECTURE ACTIVITIES Lecture Activity 6.1: Potential and Kinetic Energy Estimated Time to Complete: 10 minutes Section Reference 6.1 What Is Energy?

Introduction In this demonstration, students will observe the potential and kinetic energy of different sizes of marbles (or balls) and will measure the work done to move a paper cup.

Materials Needed • 3 different-sized balls or marbles • Ramp • A meter stick • A paper cup Procedures 1. Set up the ramp with the open end of the paper cup facing the bottom of the ramp.

2. Place the meter stick at the bottom of the ramp directly beside the cup.

3. Release the small marble from the top of the ramp, and measure the distance that the marble was able to push the paper cup.

4. Repeat with the medium and large marbles, or balls.

5. Record data in Table 1. .

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Instructor Guide Biology: Life on Earth

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

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Chapter 6 Energy Flow in the Life of a Cell

61

Handout Answer Key 1. Potential energy is stored energy. The marbles had the greatest potential energy when they were poised at the top of the ramp.

2. Kinetic energy is energy of motion. The marbles had kinetic energy when they were rolling down the ramp.

3. Potential energy was converted to kinetic energy.

4. Work was done when the paper cup was moved by the rolling marble.

5. The heaviest marble had the greatest capacity to do work, as was evidenced by the fact that it moved the cup the longest distance.

6. Work that is done in the body includes active transport, muscle contraction, and the powering of endergonic reactions. The energy comes from potential energy stored in molecules; students will learn later in the chapter that the main energy carrier is ATP.

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Instructor Guide Biology: Life on Earth

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 6.1 Handout—Potential and Kinetic Energy Table 1 Trial

Size of marble or ball (small, medium, large)

Distance traveled by paper cup

1 2 3 Questions 1.

What is potential energy? When did each marble have the greatest potential energy?

2.

What is kinetic energy? When did the marbles have kinetic energy?

3.

Where did the kinetic energy come from?

4.

Energy is the ability to do work. What work was done by the marbles?

5.

Which marble had the greatest capacity to do work? How do you know?

6.

What kind of work needs to be done in the human body? Where does the energy come from to do this work?

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Instructor Guide Biology: Life on Earth

Lecture Activity 6.2: Endergonic and Exergonic Reactions Estimated Time to Complete: The demonstration requires about 15 minutes to complete.

Section Reference 6.2 How Is Energy Transformed During Chemical Reactions?

Introduction Students observe the change in temperature of two reactions and determine whether the reactions are endothermic or exothermic. You may want to introduce this experiment by bringing in a hot pack and a cold pack and discussing how these work.

Materials Needed • Two 250-ml beakers • Thermometer • Water • CaCl2, 25 g • NH4NO3, 25 g Procedure Endergonic reaction 1. Place 100 ml of room-temperature water in a 250-ml beaker.

2. Take the temperature of the solution.

3. Add 25 g of NH4NO3.

4. Keep the thermometer in the solution to monitor temperature.

5. Record results in Table 1.

Exergonic reaction 1. Place 100 ml of room-temperature water in a 250-ml beaker.

2. Take the temperature of the solution.

3. Add 25 g of CaCl2.

4. Keep the thermometer in the solution to monitor temperature.

5. Record results in Table 1.

Assessment Suggestions Use the handout on the next page for individual or group assessment.

Handout Answer Key 1. The reaction between the water and the CaCl2 was exergonic, and the reaction between the water and NH4NO3 was endergonic. This could be determined by observing an increase or decrease in temperature, respectively.

2. Some of the energy that is produced in exergonic reactions is converted to ATP; the remainder is lost as heat energy. This heat helps living organisms maintain normal or, in the case of exercise, slightly elevated body temperatures.

3. Living organisms couple exergonic and endergonic reactions, so that the energy from exergonic reactions is used to power endergonic reactions.

4. ATP is the most common energy “currency” of the cell, although sometimes electron carriers also transfer energy from one location of the cell to another.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 6.2 Handout—Endergonic and Exergonic Reactions Table 1 Initial temperature, Ti, of the water

Final Temperature, Tf

Addition

Change in temperature, (Tf – Ti)

Exothermic or Endothermic?

NH4NO3 CaCl2 Questions 1.

Identify which reaction was exergonic and which reaction was endergonic. How did you determine this?

2.

In a living organism, what happens to the energy that is produced during exergonic reactions?

3.

Where does the energy come from that is necessary to power endergonic reactions in living organisms?

4.

What is the most common energy carrier in the cell?

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Lecture Activity 6.3: Lactaid Action Estimated Time to Complete: If all the solutions are prepared and dispensed ahead of time, this demonstration can be completed in about 10 minutes. The time spent on analysis and discussion is variable.

Section Reference 6.4 How Do Enzymes Promote Biochemical Reactions?

Introduction This activity also helps to extend the information that is discussed at the end of the chapter, Health Watch: Lacking an Enzyme Can Lead to Lactose Intolerance or Phenylketonuria.

Students test milk with glucose test paper to establish that there is no glucose in milk. Students mix Lactaid and milk, use the glucose test paper, and determine the presence of glucose. The specificity of Lactaid is also explored.

Materials Needed • Milk • 1% glucose solution • 1% sucrose • 1% maltose • Water • Lactaid in liquid form (commercially available) • Spot plate or test tubes • Glucose test strips Procedures 1. Discuss lactose intolerance and the use of Lactaid. To understand the demonstration, students will need to know that Lactaid is a commercially available enzyme that breaks down lactose into its component monosaccharides, glucose and galactose.

2. Set up a spot plate or test tubes, using a few drops of each test solution.

Test tube 1 2 3 4 5 6

Solution Milk Water Glucose Sucrose Maltose Milk with no subsequent addition of Lactaid

a. Test each solution with a glucose test strip. Record results in Table 1. b. Add 3 drops of Lactaid to each solution except #6.

Assessment Suggestions Use the handout on the third page for individual or group assessment.

Handout Answer Key 1. The test tube with milk and Lactaid yielded the greatest change in glucose production. Tube 3, glucose alone, is included so that students can visualize a positive glucose reaction.

2. Enzymes are specific. Lactaid is able to catalyze only the breakdown of lactose. Maltase would be specific for maltose, and sucrase would be specific for sucrose.

3. This reaction is too slow to observe any production of glucose without an enzyme. This is characteristic of most enzymatic reactions. If allowed to stand overnight, you would still not have glucose produced—just sour milk!

.

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 6.3 Handout—Lactaid Action Table 1 Presence of glucose before Lactaid (+ or –)

Test # 1

Milk

2

Water

3

Glucose

4

Sucrose

5

Maltose

6

Milk with no addition of Lactaid

Presence of glucose after Lactaid (+ or –)

Comments

Questions 1.

Which conditions yielded the greatest change in the amount of glucose production? Why?

2.

Explain your observations for the effect of Lactaid on sucrose and maltose.

3.

In Test #6, when milk was allowed to stand with no addition of Lactaid, was glucose produced? If you left it overnight and came back tomorrow, would glucose be present?

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Lecture Activity 6.4: Effect of Global Warming on Cold-Water Fish Estimated Time to Complete: 10 minutes for discussion Section Reference 6.5 How Are Enzymes Regulated?

Introduction There are many broad-reaching consequences of global warming. This discussion is regarding one possible aspect—the effect of temperature on enzymatic reactions in organisms that cannot regulate their internal temperatures. This class discussion helps apply the information in this chapter to a relevant environmental concern.

Materials Needed Perform an Internet search using the terms “global warming and cold water fish” to find up-to-date information on this issue.

Procedures 1. Introduce the topic: Salmon and trout are cold-water fish that may be very susceptible to the consequences of global warming.

They thrive in cold streams, with temperatures of 50–65°F. In many areas, the fish are already living at the upper end of their thermal range, so that even modest warming could render streams uninhabitable.

2. Questions for discussion: a. What is the optimal temperature for most enzymes in warm-blooded animals?

(The optimal temperature for enzyme activity is about 37°C.) b. What are the impacts on cold-water fish from living in a temperature that is a few degrees warmer than it should be?

(Because some of these fish are living at the upper end of their thermal range, a few degrees could make a big difference. They are unable to regulate their temperature; their internal temperature may rise high enough to cause some denaturation and loss of activity of their enzymes.) c. In humans, a slightly elevated temperature, such as a low fever, can be beneficial. Why? What happens if the fever is too high?

(A low fever may cause an increase in the rate of immune response and enzymatic reactions that promote healing. If the temperature is too high, denaturation of enzymes and loss of activity will occur. This could lead to death.)

For more information, perform an Internet search using the term “fever.” d. An additional consequence of global warming could be the migration of warm-water fish into northern streams and rivers. How might this change predator–prey relationships?

(This migration may cause a situation in which there is no natural predator for the migrating fish, which could lead to overpopulation. Migration may also result in an alteration of the food web of an ecosystem.)

Assessment Suggestions None

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CHAPTER 7 CAPTURING SOLAR ENERGY: PHOTOSYNTHESIS LECTURE OUTLINE Case Study: Did the Dinosaurs Die from Lack of Sunlight?

7.1

What Is Photosynthesis?

A. Photosynthesis Is the Process by Which Solar Energy Is Trapped and Stored as Chemical Energy in the Bonds of Organic Molecules 1. Photosynthesis occurs in algae, certain types of bacteria, and land plants B. Leaves and Chloroplasts Are Adaptations for Photosynthesis 1. The structure and shape of a leaf are adapted for photosynthesis (Figure 7-1) a. Leaves are flat, only a few cells thick, and expose a large surface area to the sun b. The upper and lower surfaces of leaf are composed of transparent epidermal cells c. The epidermis is covered by the waxy, waterproof cuticle that reduces evaporation d. CO2 from the air enters the leaf via adjustable pores, stomata, in the epidermis (Figure 7-2) e. The mesophyll (“middle of the leaf”) contains cells where most chloroplasts are located f. Vascular bundles supply water and minerals to mesophyll cells (Figure 7-1b) 2. Photosynthesis in plants takes place in chloroplasts a. A single mesophyll cell contains numerous chloroplasts (Figure 7-1c) 3. Chloroplasts are organelles surrounded by a double membrane a. The light reactions occur within the membranous thylakoids (Figure 7-1d) b. The Calvin cycle of photosynthesis takes place in the stroma, the semifluid medium inside chloroplasts C. Photosynthesis Consists of the Light Reactions and the Calvin Cycle (Figure 7-3) 1. During the light reactions, chlorophyll in thylakoids captures light energy and converts it into the energy-carrier molecules ATP and NADPH a. Oxygen is released as a by-product 2. In the Calvin cycle, enzymes in the stroma synthesize sugars a. This process uses CO2 from the air and ATP and NADPH from the light reactions as an energy source â Case Study Continued: Did the Dinosaurs Die from Lack of Sunlight?

7.2

The Light Reactions: How Is Light Energy Converted to Chemical Energy?

A. Light Is Captured by Pigments in Chloroplasts 1. The sun emits energy in a broad spectrum of electromagnetic radiation (Figure 7-4) a. This energy ranges from short-wavelength gamma rays to very-long-wavelength radio waves b. Light is composed of individual packets of energy called photons c. Short-wavelength photons have high energy; long-wavelength photons have low energy d. Visible light is composed of wavelengths of light that are energetic enough to power reactions but not damage cells 2. When light strikes an object, it is either absorbed, reflected, or transmitted a. Absorbed light produces heat or drives reactions b. Reflected or transmitted light that reaches our eyes produces color 3. Chloroplasts contain pigment molecules that absorb different wavelengths of light a. There are several pigments in chloroplasts b. The primary pigment is chlorophyll a, which absorbs violet, blue, and red light, and reflects green c. Accessory pigments include chlorophyll b and carotenoids, which absorb additional wavelengths of light energy

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Instructor Guide Biology: Life on Earth d. Carotenoids are usually masked by chlorophyll and become apparent as chlorophyll breaks down in the fall (Figure 7-5) â Lecture Activity 7.1: Fluorescence of Chlorophyll â Lecture Activity 7.2: Chromatography of Pigments from Spinach Leaves B. The Light Reactions Occur in Association with the Thylakoid Membranes 1. Thylakoids contain many copies of two photosystems, photosystem I (PS I) and photosystem II (PS II) a. Each photosystem consists of a cluster of chlorophyll and accessory pigment molecules b. Each photosystem has a unique electron transport chain located adjacent to it i. Energized electrons pass through these chains, which ultimately produce ATP and NADPH 2. Photosystem II uses light energy to create a hydrogen ion gradient and to split water (Figure 7-6) a. Light-dependent reactions are initiated when photons of light are absorbed by PS II, energizing electrons i. Pigments absorb light and pass energy to a reaction center, a specialized region of the photosystem ii. These electrons are then passed to an electron transport chain (ETC) iii. Splitting water maintains the flow of electrons through photosystems b. As electrons are passed down the ETC, energy is used to pump H+ ions across the thylakoid membrane c. Energy stored in the H+ ion concentration gradient is harnessed to make ATP by chemiosmosis 3. Photosystem I generates NADPH (Figure 7-6) a. Light also energizes electrons in photosystem I i. These electrons are passed to another ETC that produces NADPH 4. The hydrogen ion gradient generates ATP by chemiosmosis (Figure 7-7) a. The gradient produced by the ETC associated with photosystem II is used to drive the synthesis of ATP i. The movement of H+ ions through ATP synthase is similar to a turbine (Figure 7-8) ii. The movement of H+ generates energy for ATP synthase to use to produce ATP 5. Oxygen is a by-product of photosynthesis â Case Study Continued: Did the Dinosaurs Die from Lack of Sunlight?

7.3

The Calvin Cycle: How Is Chemical Energy Stored in Sugar Molecules?

A. The Calvin Cycle Captures Carbon Dioxide 1. The Calvin cycle uses the energy in the ATP and NADPH from the light-dependent reactions to make glucose from CO2 2. This cycle occurs in three stages (Figure 7-9) a. Carbon fixation i. Carbon from CO2 is “fixed” into a larger organic molecule a) RuBP is combined with the CO2 to form an unstable 6-C molecule ii. This unstable molecule quickly splits to form molecules of 3-C PGA (phosphoglyceric acid) b. Synthesis of G3P i. ATP and NADPH energy is used to convert 6 PGA to 6 G3P c. Regeneration of RuBP i. 5 of the 6 G3P are used to regenerate RuBP ii. The remaining G3P exits the cycle 3. The Calvin cycle can be sabotaged a. Photorespiration occurs when O2 rather than CO2 is combined with RuBP b. No useful energy is generated 4. Some plants living in hot, dry environments have evolved the C 4 pathway or the CAM pathway of carbon fixation â In Greater Depth: Alternate Pathways Increase the Efficiency of Carbon Fixation (Figure E7-1) â Lecture Activity 7.5: Global Warming and Photosynthesis B. Carbon Fixed During the Calvin Cycle Is Used to Synthesize Glucose 1. Two G3P molecules can be used to produce glucose (Figure 7-10) 2. Glucose can then be used to produce other types of sugars â Earth Watch: Biofuels—Are Their Benefits Bogus? (Figure E7-2) â Lecture Activity 7.3: The Role of Carbon Dioxide in Photosynthesis .

Chapter 7 Capturing Solar Energy: Photosynthesis

69

â Lecture Activity 7.4: Modeling Photosynthesis

Case Study Revisited: Did the Dinosaurs Die from Lack of Sunlight?

KEY TERMS accessory pigment ATP synthase bundle sheath cells C3 pathway C4 pathway Calvin cycle carbon fixation carotenoid chemiosmosis

chlorophyll a chloroplast crassulacean acid metabolism (CAM) cuticle electromagnetic spectrum electron transport chain epidermis light reactions mesophyll

photon photorespiration photosynthesis photosystem reaction center rubisco stoma (plural, stomata) stroma thylakoid

LECTURE ACTIVITIES Lecture Activity 7.1: Fluorescence of Chlorophyll Estimated Time to Complete The chlorophyll extract should be prepared ahead of time and will take about 30 minutes.

The in-class demonstration of chlorophyll fluorescence and related discussion will take about 10 minutes.

Section Reference 7.2 Light Reactions: How Is Light Energy Converted to Chemical Energy?

Introduction This is a good activity for introducing the properties of light and chlorophyll as a light-capturing molecule. In this activity, chlorophyll that has been extracted from green leaves is exposed to UV light. Photons of light will cause electrons in the chlorophyll molecules to be boosted to higher energy levels. If an electron acceptor molecule is not present, the excited electrons will immediately drop back to ground state, giving off energy as light (fluorescence) and heat.

For student and/or instructor background, perform an Internet search using the terms “chlorophyll fluorescence.”

Materials Needed • Mortar and pestle • Centrifuge • Test tubes • Laboratory balance

• • • •

Pasteur pipettes 3–5 spinach leaves Ethyl acetate (or ethanol) UV light

Procedures You may begin with dry spinach leaves and extract chlorophyll with ethanol (Procedure A), or use fresh spinach leaves and extract the chlorophyll with ethyl acetate (Procedure B).

Procedure A for dry spinach leaves: 1.

2.

3.

4.

Dry 3–5 spinach leaves until brittle, overnight in a dry location at room temperature or in an oven at 45–50°C for 2–3 hours.

Grind leaves with mortar and pestle in approximately 5–10 ml of solvent (enough to cover the leaves).

Either ethyl acetate or ethanol can be used as a solvent.

Add the leaf mixture to a centrifuge tube. Rinse the contents from the mortar and pestle into the tube.

Centrifuge for about 5 minutes, or until there is a solid pellet at the bottom and a green liquid fraction. .

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Instructor Guide Biology: Life on Earth Using a Pasteur pipette, extract the green liquid fraction containing chlorophyll dissolved in ethyl acetate and transfer to a clean, dry test tube. Cap the test tube to prevent evaporation.

Procedure B for fresh spinach leaves: 1.

2.

3.

4.

5.

6.

7.

8.

Use 3–5 fresh spinach leaves. (Do not dry.)

Grind the leaves with a mortar and pestle in 5–10 ml of ethyl acetate. (Ethanol is not an appropriate solvent for the extraction of pure chlorophyll because water is soluble in ethanol.)

Add the leaf mixture to a centrifuge tube. Use additional solvent to rinse the contents from the mortar and pestle into the tube.

Centrifuge for about 5 minutes.

Using a pipette, remove the green liquid fraction containing the ethyl acetate and chlorophyll and transfer to a clean, dry centrifuge tube. Discard any solids and the aqueous layer.

Add 2–3 ml of water to the tube containing the chlorophyll solution, shake, and re-centrifuge.

Remove the lower aqueous layer by pipette and discard.

Cap the remaining green liquid that contains the chlorophyll.

Fluorescence under ultraviolet light: To observe fluorescence in the UV range, use a black light that emits in the 365-nm range. Bring the test tube containing chlorophyll to within a few centimeters of the black light, and note the color of the chlorophyll extract.

For discussion purposes, you may want to try to shine other types of light (e.g., blue, green, or red light) on the chlorophyll, and note whether any fluorescence occurs.

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

Handout Answer Key 1. red 2. The electron that was boosted to a higher energy level by the incoming light has fallen back to its ground state, releasing energy that corresponds to the red region of the visible spectrum.

3. The energy represented by the red fluorescence is normally passed on to other molecules in the photosynthetic pathway before it can be emitted as red light.

4. light chlorophyll reaction center in PSII ETC reaction center in PSI ETC NADPH 5. NADP+ picks up two energized electrons and one hydrogen ion to become NADPH. 6. The splitting of water provides replacement electrons for chlorophyll molecules.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 7.1 Handout—Fluorescence of Chlorophyll Questions 1.

What color is produced during the fluorescence of chlorophyll?

2.

What has happened to the excited electrons in the chlorophyll molecule when fluorescence occurs?

3.

Why don’t we see fluorescent red leaves?

4.

Trace the pathway of the light energy from the excitation of chlorophyll to the completion of the lightdependent reactions.

5.

During the light-dependent reactions of photosynthesis, what molecule is the final electron acceptor?

6.

Where do electrons come from to replace the energized electrons that are constantly leaving chlorophyll molecules?

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Instructor Guide Biology: Life on Earth

Lecture Activity 7.2: Chromatography of Pigments from Spinach Leaves Estimated Time to Complete This should be done as a demonstration. The preparation of the chromatogram takes about 5 minutes at the start of the period. The finished chromatogram can be viewed after about 20 to 30 minutes. If you have a document camera available, the finished chromatogram can be displayed directly on the document camera.

Section Reference 7.2 Light Reactions: How Is Light Energy Converted to Chemical Energy?

Introduction Paper chromatography is a method of separating substances in a mixture based on their physical properties. Leaves appear green, but actually contain a combination of several different pigments that have different solubility characteristics. As the solvent moves up the paper, the pigment components of the leaf will be separated.

Materials Needed • Chromatography paper • Chromatography chamber (2-qt canning jar) • Petroleum ether acetone solvent: about 20 ml of a 90% (v/v) petroleum ether: 10% acetone solvent; keep in covered chromatography chamber. (Note that this solvent should be prepared fresh; if too much evaporation of petroleum ether occurs, separation will not be good.)

• One large spinach leaf • Penny Procedures 1. On a piece of chromatography paper, make a pencil (not ink!) line 2 cm from the bottom of the paper.

2. Place a large spinach leaf over the pencil line. Using a penny, rub the spinach leaf in one long straight line to cover the pencil mark.

3. Place it in a chamber with acetone–petroleum ether solvent. Note: petroleum ether and acetone are extremely flammable! The spot should NOT be immersed in the solvent.

4. Allow the solvent to move to within 2 cm of the top of the strip and then remove and air-dry the paper.

5. When the chromatogram is dry, record the results as a sketch, showing the position of the spots on the paper. Four spots should be visible: from the bottom, working upward, the pigments are chlorophyll b, chlorophyll a, xanthophyll (this may be one or two spots), and carotene. Xanthophyll and carotene are yellow-orange pigments that belong to the class of pigments called carotenoids.

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

Handout Answer Key 1. chlorophyll a, chlorophyll b, xanthophylls, and carotenes 2. Pigment molecules capture light energy from the sun.

3. If yellow-orange leaves were used, no chlorophyll would be visible. Only the xanthophylls and carotenes would be present on the chromatogram.

4. carrot, sweet potato

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 7.2 Handout—Chromatography of Pigments from Spinach Leaves Questions 1.

What pigments are present in spinach leaves?

2.

What role do pigments play in photosynthesis?

3.

If the experiment were repeated with colorful fall leaves (yellows and oranges), how would the results differ?

4.

What common vegetable is particularly high in carotenes?

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Instructor Guide Biology: Life on Earth

Lecture Activity 7.3: The Role of Carbon Dioxide in Photosynthesis Estimated Time to Complete This activity will take about 10 minutes to set up at the beginning of class. The flasks need to stand in the light for about 20 to 30 minutes until observations can be made.

Section Reference 7.3 The Calvin Cycle: How Is Chemical Energy Stored in Sugar Molecules?

Introduction The activity assumes that students know that CO2 is exhaled during breathing.

Materials Needed • Two 125-ml flasks with airtight stoppers • Fresh Elodea • Bright light source (this can be a shop light) • Bromothymol blue (1% solution) Procedures 1. Have all solutions at room temperature.

2. Fill two 125-ml flasks (Flask A and Flask B) with water and a few drops of bromothymol blue.

3. Using a straw, blow gently into the water in both flasks until the solution turns a pale green.

4. Place a 6- to 8-cm sprig of Elodea into Flask B. Make a fresh, angled cut in the stem of the Elodea. It should be placed with the stem side up, immersed in the water.

5. Place an airtight stopper on each flask. This activity works best when there is not a lot of air left in the flask.

6. Place the flasks about 1.5 to 2 feet from a bright source of light.

7. At the end of the class period, note any color changes in the flask.

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

Handout Answer Key 1. Exhalation produces carbon dioxide, which causes the solution to become slightly acidic. The carbon dioxide will become carbonic acid, H2CO3, when it combines with water. Carbonic acid will quickly dissociate into the bicarbonate ion, HCO3–, and H+. Bromothymol blue will change from blue to greenish-yellow as a result.

2. The beaker with the Elodea in it should return more quickly to the blue color, as the Elodea uses the carbon dioxide for photosynthesis. This should be visible within the class period. The beaker without the Elodea will not be blue.

3. After the carbon dioxide is taken into the Elodea plant, it will pass into the stroma of the chloroplast, where it will be fixed (attached to an organic molecule, RuBP) and go through the reactions of the Calvin–Benson cycle.

The carbon dioxide will ultimately be used to make glucose.

4. The reactions of the Calvin–Benson cycle are dependent on ATP and NADPH from the light-dependent reactions. Because the flasks are in the dark, photosynthesis and carbon dioxide utilization will not occur. Both flasks will remain a greenish color. In fact, as the cells of the Elodea plant continue to undergo cell respiration, more carbon dioxide may build up in flask B, causing the solution to become more yellow-green.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 7.3 Handout—The Role of Carbon Dioxide in Photosynthesis Table 1 Color after addition of bromothymol blue

Color after blowing through straw (addition of CO2)

Color after exposure to light

Flask A (Elodea)

(– Elodea)

Flask B (+ Elodea)

(+ Elodea)

Questions 1.

Why did the solutions change color after your instructor exhaled into them?

2.

At the end of the class period, was there any change in the color of the beakers? Explain.

3.

Trace the path of the carbon dioxide after it is taken up by the Elodea plant.

4.

If the experiment were repeated with both flasks in the dark, what would you expect to happen?

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Instructor Guide Biology: Life on Earth

Lecture Activity 7.4: Modeling Photosynthesis Estimated Time to Complete This activity is best suited for small classes, and requires about 15 minutes to complete.

Section References 7.2 Light Reactions: How Is Light Energy Converted to Chemical Energy?

7.3 The Calvin Cycle: How Is Chemical Energy Stored in Sugar Molecules?

Introduction In this activity, students will build the reactants of photosynthesis, and trace a “radioactive” atom in the formation of products.

Materials Needed • Molecular modeling kits • Tape Procedures 1. Provide the students with molecular modeling kits. Instruct them to build a molecule of carbon dioxide and a molecule of water.

2. Mark either the O in the water molecule or the C in carbon dioxide with a piece of tape to represent a radioactive atom.

3. Now build the products (glucose and oxygen), making the appropriate product “radioactive.”

4. If you would like to “balance” the equation, have a group of students work together to provide six molecules of carbon dioxide and six molecules of water.

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

Handout Answer Key 1. 6CO2 + 6H2O + light energy → C6H12O6 + 6O2 2. oxygen 3. glucose 4. sunlight and chlorophyll

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 7.4 Handout—Modeling Photosynthesis Questions 1.

Write out the balanced equation for photosynthesis.

2.

Which product would be radioactive if you began the reaction with radioactive oxygen in the water?

3.

Which product would be radioactive if you began the reaction with radioactive carbon in the carbon dioxide?

4.

What else is required for photosynthesis, other than oxygen and carbon dioxide?

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Instructor Guide Biology: Life on Earth

Lecture Activity 7.5: Global Warming and Photosynthesis Estimated Time to Complete: 10 minutes for discussion Section Reference This activity may be used to open the chapter, or used as an extension at the end of the chapter.

Introduction There are many broad-reaching consequences of global warming. This class discussion helps apply the information in this chapter to a relevant environmental concern.

Materials Needed Computers with Internet access Procedures 1. Introduce the topic: Most likely, students are already familiar with the problem of global warming. You may want to open the discussion by determining what the class already knows about global warming. Additionally, you could have the students perform an Internet search using “global warming” as the search terms and have them take notes on what global warming is, what causes it, and what some of the environmental impacts might be. After students have gained some background knowledge, the discussion may proceed.

2. Questions for discussion: a. What is global warming?

(Global warming is an increase in the average global temperature as a result of the buildup of greenhouse gases.

One of the primary greenhouse gases is carbon dioxide.) b. What is the relationship between photosynthesis and global warming?

(Plants are carbon dioxide “sinks.” They utilize carbon dioxide from the atmosphere for photosynthesis, thereby decreasing the amount of atmospheric carbon dioxide.) c. As carbon dioxide levels rise, what will happen to the rate of photosynthesis?

(Some studies have demonstrated an increased rate of photosynthesis as a result of increased carbon dioxide levels.) d. What are the potential benefits of an increased rate of photosynthesis? What are the concerns?

(If rates of photosynthesis increase, the amount of carbon dioxide utilization will also increase. A concern is that an increased growth rate may lead to a decreased nutrient value per pound of vegetation.) e. Will photosynthesis occur at a rapid rate indefinitely? Why or why not?

(No, most likely some other nutrient will become limiting.)

Assessment Suggestions None

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CHAPTER 8 HARVESTING ENERGY: GLYCOLYSIS AND CELLULAR RESPIRATION LECTURE OUTLINE Case Study: When Athletes Boost Their Blood Counts: Do Cheaters Prosper?

8.1

How Do Cells Obtain Energy?

A. Cells Require a Constant Flow of Energy 1. Most cellular energy is stored in adenosine triphosphate (ATP) B. Photosynthesis Is the Ultimate Source of Cellular Energy (Figure 8-1) 1. Photosynthetic organisms capture and store the energy of sunlight in sugar and other organic molecules 2. The chemical equation for glucose formation during photosynthesis is essentially the reverse of the equation of glucose breakdown by glycolysis and cellular respiration C. Glucose Is a Key Energy-Storage Molecule 1. All cells metabolize glucose for energy 2. Glucose breakdown occurs in stages (Figure 8-2) a. Glycolysis in the cytoplasm begins the process b. If oxygen is present, cellular respiration occurs c. If oxygen is absent, fermentation occurs â Lecture Activity 8.1: Modeling Cell Respiration

8.2

What Happens During Glycolysis?

A. Glycolysis Breaks Down Glucose to Pyruvate, Releasing Chemical Energy (Figure 8-3) 1. Glycolysis has two stages, energy investment and energy harvesting 2. The energy investment steps of glycolysis are energy requiring a. Glucose is converted to fructose bisphosphate, a 6-C glucose with two phosphate groups b. Fructose bisphosphate is unstable and high in energy c. Glucose activation “costs” two ATP 3. The energy harvesting steps yield ATP and NADH a. Fructose bisphosphate splits into two 3-C molecules of G3P b. Each G3P molecule undergoes a series of steps to be converted to pyruvate c. Energy-harvesting steps produce two NADH and four ATP 4. Glycolysis produces a net two ATP and two high-energy electron carriers, NADH, for each molecule of glucose converted to two pyruvate â In Greater Depth: Glycolysis (Figure E8-1)

8.3

What Happens During Cellular Respiration?

A. In Most Organisms, If Oxygen Is Present, Cellular Respiration Occurs 1. Cellular respiration in eukaryotic cells occurs in mitochondria in three stages 2. A mitochondrion has two membranes that produce two compartments: the matrix and the intermembrane space (Figure 8-4) B. During the First Stage of Cellular Respiration, Pyruvate Is Broken Down 1. First, pyruvate is broken down in the mitochondrial matrix, releasing energy and CO 2 (Figure 8-5) a. In the mitochondrial matrix, pyruvate reacts with a molecule of coenzyme A to produce acetyl-CoA and one CO2 and one NADH b. Each acetyl-CoA combines with a 4-C molecule to produce 6-C citrate, releasing coenzyme A .

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Instructor Guide Biology: Life on Earth c. Citrate goes through a series of rearrangements in a cycle of reactions called the Krebs cycle d. The end products of the Krebs cycle per molecule of pyruvate are two CO2, one ATP, one FADH2, and three NADH; the 4-C molecule is regenerated â In Greater Depth: The Mitochondrial Matrix Reactions (Figure E8-2) C. During the Second Stage of Cellular Respiration, High-Energy Electrons Travel Through the Electron Transport Chain (Figure 8-6) 1. From glycolysis and the mitochondrial matrix reactions, the cell has accumulated 4 ATP, 10 NADH, and 2 FADH2 2. The electron carriers NADH and FADH2 release their electrons to the electron transport chains located in the inner mitochondrial membrane a. Energy released by these electrons is used to pump hydrogen ions from the matrix to the intermembrane space to produce ATP by chemiosmosis b. At the end of the electron transport chain (ETC), the energy-depleted electrons are transferred to oxygen, forming water D. During the Third Stage of Cellular Respiration, Chemiosmosis Generates ATP (Figure 8-6) 1. During chemiosmosis, the flow of hydrogen ions provides enough energy to produce 32 to 34 ATP 2. The ATP diffuses out of the mitochondria to the cytoplasm through the outer membrane, which is permeable to ATP â Case Study Continued: When Athletes Boost Their Blood Counts: Do Cheaters Prosper? â Lecture Activity 8.2: Cell Respiration Summary â Lecture Activity 8.3: Mitochondrial Disorders 3. A summary of glucose breakdown in eukaryotic cells (Figure 8-7) a. Glycolysis occurs in the cytoplasmic fluid b. This process produces two pyruvate molecules, two ATP molecules, and two NADH molecules c. Cellular respiration breaks down the two pyruvates during the Krebs cycle i. This process produces NADH and FADH2 and a small amount of ATP ii. Electrons from NADH and FADH2 are donated to the electron transport chain, producing 32 or 34 ATP through chemiosmosis E. Cellular Respiration Can Extract Energy from a Variety of Molecules 1. Cellular respiration can extract energy from sugars, fats, and amino acides â Health Watch: Why Can You Get Fat by Eating Sugar? (Figure E8-3)

8.4

What Happens During Fermentation?

A. Fermentation Allows NAD+ to Be Recycled When Oxygen Is Absent 1. Under aerobic conditions, most organisms use cellular respiration, regenerating NAD + from the ETC 2. Under anaerobic conditions, cellular respiration does not occur, so NAD+ must be regenerated another way to allow glycolysis to occur B. Some Cells Ferment Pyruvate to Form Lactate 1. Muscle cells undergo lactate fermentation during vigorous exercise when not enough oxygen is available (Figure 8-8) 2. As soon as oxygen is available, lactate will be converted back to pyruvate in the liver, and cellular respiration will resume (Figure 8-9a) â Case Study Continued: When Athletes Boost Their Blood Counts: Do Cheaters Prosper?

C. Some Cells Ferment Pyruvate to Form Alcohol and Carbon Dioxide 1. Many microorganisms, including yeast, convert pyruvate to ethanol and carbon dioxide (Figure 8-10) 2. Alcoholic fermentation can be used to produce alcoholic beverages and bread (Figure 8-9b) â Links to Everyday Life: A Jug of Wine, a Loaf of Bread, and a Nice Bowl of Sauerkraut â Lecture Activity 8.4: Demonstration of Fermentation

Case Study Revisited: When Athletes Boost Their Blood Counts: Do Cheaters Prosper?

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Chapter 8 Harvesting Energy: Glycolysis and Cellular Respiration

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KEY TERMS aerobic alcoholic fermentation anaerobic cellular respiration chemiosmosis electron transport chain (ETC)

fermentation flavin adenine dinucleotide (FAD or FADH2) glycolysis intermembrane space Krebs cycle lactic acid fermentation

matrix mitochondrion (plural, mitochondria) nicotinamide adenine dinucleotide (NAD+ or NADH)

LECTURE ACTIVITIES Lecture Activity 8.1: Modeling Cell Respiration Estimated Time to Complete: 20 minutes Section Reference 8.1 How Do Cells Obtain Energy?

Introduction Using molecular modeling kits, students will build the reactants of cell respiration and trace a “radioactive” atom in the formation of products.

Materials Needed • Molecular modeling kits • Tape Procedures 1. Provide the students with molecular modeling kits. Instruct them to build a molecule of carbon dioxide and a molecule of water.

2. Mark either the oxygen molecule or the carbon in glucose with a piece of tape to represent a radioactive atom.

3. Now build the products (carbon dioxide and water), making the appropriate product “radioactive.”

4. If you would like to “balance” the equation, have a group of students work together to provide six molecules of oxygen and one molecule of glucose for the reactants and six molecules of carbon dioxide and six molecules of water for the products.

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

Handout Answer Key 1. C6H12O6 + 6O2 + ADP + Pi → 6CO2 + 6H2O + ATP 2. carbon dioxide 3. water 4. intact mitochondria 5. These cells would undergo lactic acid fermentation, so the lactic acid would be radioactive.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 8.1 Handout—Modeling Cell Respiration Questions: 1.

Write out the balanced equation for photosynthesis.

2.

Which product would be radioactive if you began the reaction with radioactive carbon atoms in the glucose molecule?

3.

Which product would be radioactive if you began the reaction with radioactive oxygen?

4.

What else is required for cell respiration, other than oxygen and glucose?

5.

Suppose you are carrying out the reaction anaerobically in human cells. What radioactive product(s) would be formed if you began with radioactive glucose?

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Chapter 8 Harvesting Energy: Glycolysis and Cellular Respiration

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Lecture Activity 8.2: Cell Respiration Summary Estimated Time to Complete: 20 minutes Section Reference 8.3 What Happens During Cellular Respiration?

Introduction This is a good review of cell respiration to do in small groups in class, at the end of the lecture(s) on cell respiration.

The entire process is summarized on a one-page handout.

Materials Needed The keywords may be provided on a separate handout.

Keywords 2 ATP (used twice) 2 lactate or 2 ethanol and 2 CO2 32–34 ATP 4 CO2 Acetyl CoA Fermentation Glucose Glycolysis H2O Krebs cycle O2 Pyruvate Procedures Hand out the worksheets to students in small groups. After allowing them to work on it together for about 10 minutes, review the worksheet as a class.

Assessment Suggestions Portions of the handout or the entire worksheet can be given as a quiz. Alternatively, students can use the worksheets in conjunction with Lecture Activity 8.3, which deals with metabolic defects in the pathway.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 8.2 Handout—Cell Respiration Summary

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Instructor Guide Biology: Life on Earth

Lecture Activity 8.3: Mitochondrial Disorders Estimated Time to Complete: 10 minutes for group work, followed by 10 minutes for class discussion Section Reference 8.3 What Happens During Cellular Respiration?

Introduction In this activity, students are asked to apply their knowledge of cell respiration to predict the symptoms of genetic diseases and exposure to mitochondrial poisons.

The sequence of the metabolic pathways involved in cell respiration has been elucidated in part from the study of inherited metabolic disorders. These mostly rare disorders affect the functioning of one enzyme. The location and the function of the enzyme can be determined from studying the buildup of intermediates that occur ahead of the deficiency in the pathway. Some mitochondrial disorders are due to genetic defects in the cell’s nuclear DNA. However, other defects are due to genetic defects in mitochondrial DNA. For a good review of disorders affecting mitochondria, perform an Internet search using “mitochondrial disorders” as search terms.

Materials Needed Use the case studies on the following pages. You may want to assign one case study per group.

Procedures 1. Divide the class into groups.

2. Assign a case study to each group.

3. For each condition, ask students to consider: a. How will cell respiration be affected? Be as specific as possible. b. What symptoms will be observed?

Assessment Suggestions Include similar scenarios on an essay exam.

.

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 8.3 Handout—Mitochondrial Disorders Case 1 Pyruvate dehydrogenase complex (PDHC) deficiency This is a fairly rare genetic disorder. The enzyme that converts pyruvate to acetyl CoA is deficient. How will cell respiration be affected? What symptoms will be observed?

For more information, perform an Internet search using “pyruvate dehydrogenase complex (PDHC) deficiency” as the search terms.

Case 2 Mitochondrial cytochrome b deficiency Cytochrome b is part of the electron transport chain in mitochondria. In this rare genetic disorder, only the mitochondria in the muscle are affected. Very early in their embryonic development, a mutation occurred in the cytochrome b gene in a cell destined to produce their muscles. How will cell respiration be affected? What symptoms will be observed? What will be observed during mild exercise? For more information, perform an Internet search using “mitochondrial cytochrome b deficiency” as the search terms.

Case 3 Thiamine deficiency Thiamine (vitamin B1) is an important cofactor in one of the reactions in the Krebs cycle, and also the reaction that converts pyruvate to acetyl CoA. It is normally found in the diet in yeast, pork, legumes, cereal grains, and rice. It may become deficient during malnutrition or conditions that cause malnutrition, such as alcoholism, HIV, and anorexia nervosa. How will cell respiration be affected? What symptoms will be observed? For more information, perform an Internet search using “thiamine deficiency” as the search terms.

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Case 4 Electron transport chain inhibitors such as rotenone, antimycin, cyanide These inhibitors block one of the steps in the electron transport system. How will cell respiration be affected?

What symptoms will be observed? For more information, perform an Internet search using “rotenone, antimycin, and cyanide” as search terms.

Case 5 Uncouplers such as 2, 4 Dinitrophenol An uncoupler allows hydrogen ions to leak back across the membrane. It uncouples the process of proton pumping with ATP production. How will cell respiration be affected?

What symptoms will be observed? This drug was used in the 1930s as a weight-loss drug, but was banned in 1938 because of incidences of death. Why would weight loss occur? Why did some patients die? For more information, perform an Internet search using “uncouplers” as the search term.

Case 6 Oligomycin This drug is a direct inhibitor of ATP synthase in the electron transport system. How will cell respiration be affected? What symptoms will be observed?

For more information, perform an Internet search using “oligomycin” as the search term.

.

Case Study Answer Key For background information, perform the same Internet searches as listed in the student handout.

Case 1 Pyruvate dehydrogenase complex (PDHC) deficiency This is a fairly rare genetic disorder. The enzyme that converts pyruvate to acetyl CoA is deficient. How will cell respiration be affected? What symptoms will be observed?

Case 2 Mitochondrial cytochrome b deficiency Cytochrome b is part of the electron transport chain in mitochondria. In this rare genetic disorder, only the mitochondria in the muscle are affected. Very early in their embryonic development, a mutation occurred in the cytochrome b gene in a cell destined to produce their muscles. How will cell respiration be affected? What symptoms will be observed? What will be observed during mild exercise?

Case 3 Thiamine deficiency Thiamine (vitamin B1) is an important cofactor in one of the reactions in the Krebs cycle, and also the reaction that converts pyruvate to acetyl CoA. It is normally found in the diet in yeast, pork, legumes, cereal grains, and rice. It may become deficient during malnutrition or conditions that cause malnutrition, such as alcoholism, HIV, and anorexia nervosa. How will cell respiration be affected?

What symptoms will be observed?

Case 4 Electron transport chain inhibitors such as rotenone, antimycin, cyanide These inhibitors block one of the steps in the electron transport system. How will cell respiration be affected?

What symptoms will be observed?

.

This will cause an increase in levels of pyruvate, and a decrease in ATP levels because the Krebs cycle will not be supplied with acetyl CoA. Lack of ATP will lead to many problems, especially in tissues that require a large amount of ATP (nerve and muscle tissue). Cells will use fermentation to replenish ATP supplies, leading to a buildup of lactic acid (metabolic acidosis).

If there is a genetic defect in the electron transport system of these cells, they will not be able to produce ATP. During mild exercise, lactic acid buildup is observed, as well as extreme exercise intolerance— these patients are unable to exercise without becoming exhausted. Because only the muscle mitochondrial DNA are affected, these patients do not have other symptoms.

If thiamine is deficient, the reactions beyond glycolysis will not be efficient. This will lead to muscle weakness, disorders of the nervous system (which requires a good supply of ATP), and possibly metabolic acidosis as lactate levels increase.

In high enough concentrations, these inhibitors can prevent the formation of ATP, thus leading to almost immediate death.

Case 5 Uncouplers such as 2, 4 Dinitrophenol An uncoupler allows hydrogen ions to leak back across the membrane. It uncouples the process of proton pumping with ATP production. How will cell respiration be affected?

What symptoms will be observed? This drug was used in the 1930s as a weight-loss drug, but was banned in 1938 because of incidences of death. Why would weight loss occur? Why did some patients die?

Case 6 Oligomycin This drug is a direct inhibitor of ATP synthase in the electron transport system. How will cell respiration be affected? What symptoms will be observed?

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The electron transport chain and chemiosmosis will be affected. Weight loss occurs because of an increase in metabolic rate. More calories will be consumed trying to form adequate ATP for body function.

However, if too much DNP is taken, ATP formation will be inhibited and death will result.

The proton gradient becomes greater than normal, but no ATP can be made. In high enough concentrations, this will lead to death.

Chapter 8 Harvesting Energy: Glycolysis and Cellular Respiration

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Lecture Activity 8.4: Demonstration of Fermentation Estimated Time to Complete: This activity will require about 10 minutes of setup at the beginning of lecture, and about 10 minutes at the end of lecture for observation and discussion.

Section Reference 8.4 What Happens During Fermentation?

Introduction This is a demonstration of fermentation in yeast. The oxygen supply to the yeast is cut off in the tail of the fermentation tube. As carbon dioxide gas is produced, it will collect in the tail. The ability of the yeast to ferment glucose is compared to its ability to ferment the disaccharide, lactose.

Materials Needed • 4 fermentation tubes • 4 small beakers • Stirring rod • 10% glucose solution • 10% lactose solution • Yeast solution: add one packet of baker’s yeast to 500 ml of warm, distilled water • Water • Metric ruler Procedures 1. Set up four small beakers as follows (you may need to adjust the volumes to fit your fermentation tubes): Beaker # 1 2 3 4 2.

3.

4.

15 ml of 10% glucose + yeast 15 ml of 10% lactose + yeast 15 ml of water + yeast 15 ml of water

Stir gently.

Pour into fermentation tubes. When filling the fermentation tube, cover the opening and invert so that the tail of the tube is filled with the liquid.

At the end of the lab period, measure the distance from the tip of the tail to the top of the liquid. Record data in Table 1.

Assessment Suggestions Use the questions on the following page for individual assessment or group discussion.

Handout Answer Key 1. C6H12O6 → 2C2H5OH + 2CO2 + 2ATP 2. CO2 gas 3. ethanol 4. Fermentation occurs only in the tube with glucose. Lactose cannot be utilized by yeast because it does not have the lactase enzyme.

5. Tube 3 was a control tube that had no sugar; tube 4 was a control tube that had no yeast.

6. Cellular respiration produces 36 to 38 ATP per molecule of glucose, whereas fermentation produces only 2 ATP per molecule of glucose.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 8.4 Handout—Demonstration of Fermentation Fermentation tube #

Contents

1

15 ml of 10% glucose + yeast

2

15 ml of 10% lactose + yeast

3

15 ml of water + yeast

4

15 ml of water

Distance from tip of tail to level of liquid (mm)

Questions 1.

Write out the equation for fermentation.

2.

What gas is collecting in the fermentation tube?

3.

What other product of fermentation should be present in solution?

4.

Did you observe a difference in the tubes? Can you explain?

5.

Which tube(s) was (were) your control(s)?

6.

Compare and contrast fermentation and cell respiration. Which process produces more ATP per molecule of glucose?

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CHAPTER 9 THE CONTINUITY OF LIFE: CELLULAR REPRODUCTION LECTURE OUTLINE Case Study: Body, Heal Thyself 9.1

Why Do Cells Divide?

A. Cells Reproduce by Cell Division, Giving Rise to Daughter Cells B. Cell Division Transmits Hereditary Information to Each Daughter Cell 1. DNA is the hereditary information of all living cells a. DNA is made up of four nucleotides: adenine (A), thymine (T), guanine (G), and cytosine (C) (Figure 9-1) b. DNA is replicated into two identical copies before cell division C. Cell Division Is Required for Growth and Development 1. After cell division, daughter cells may differentiate, becoming specialized a. The cell cycle is the process by which cells divide, grow, and possibly differentiate 2. Most multicellular organisms have three categories of cells a. Stem cells can self-renew and differentiate into a variety of cell types b. Cells in the bodies of embryos, juveniles, and adults can divide, but only differentiate into one or two cell types c. Some cells differentiate and never divide again D. Cell Division Is Required for Sexual and Asexual Reproduction 1. Sexual reproduction in eukaryotic organisms occurs when offspring are produced by the fusion of gametes, sperm and egg, from two adults 2. Asexual reproduction is when offspring are produced from a single adult (Figure 9-2) a. It produces offspring called clones that are genetically identical to the parent 3. Both prokaryotic and eukaryotic cells have cell cycles

9.2

What Occurs During the Prokaryotic Cell Cycle? (Figure 9-3) A. The DNA of a Prokaryotic Cell Is Contained in a Circular Chromosome 1. The prokaryotic cell cycle consists of growth during which the DNA replicates, and is followed by a type of cell division called prokaryotic fission a. The DNA is attached at one point to the plasma membrane b. DNA is replicated during the growth phase c. Points of attachment move apart after DNA is replicated d. The cell becomes constricted, eventually dividing e. The plasma membrane fuses, forming two identical cells 2. Prokaryotic cells can divide as often as every 20 minutes

9.3

How Is the DNA in Eukaryotic Chromosomes Organized? â Lecture Activity 9.1: Chromosome Kit for Mitosis/Meiosis A. Eukaryotic Chromosomes Are Separated from the Cytoplasm in a Membrane-Bound Nucleus 1. Eukaryotic cells always have multiple chromosomes B. The Eukaryotic Chromosome Consists of a Linear DNA Double Helix Bound to Proteins 1. DNA is very long and totals about 6 feet in each human cell 2. The linear DNA molecule is bound to packaging proteins called histones (Figure 9-4) a. Proteins are required to package it efficiently b. DNA becomes folded into a dense structure during cell division

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Instructor Guide Biology: Life on Earth C. Genes Are Segments of the DNA of a Chromosome 1. Genes are sequences of DNA hundreds to thousands of nucleotides long a. Each gene occupies a specific place on a chromosome called a locus (Figure 9-5a) 2. Telomeres are long stretches of repeated nucleotide sequences at the tips of chromosomes a. These structures protect the ends of chromosomes from damage 3. Centromeres are another specialized region of the chromosome a. These structures have two functions i. They hold the DNA double helices together after replication ii. They are the attachment sites for microtubules that move the chromosomes during cell division D. Duplicated Chromosomes Separate During Cell Division 1. Two duplicated DNA helices remain attached after replication a. Sister chromatids are the two copies of DNA that remain attached (Figure 9-5b) b. Sister chromatids will separate during division (Figure 9-5c) E. Eukaryotic Chromosomes Usually Occur in Pairs Containing Similar Genetic Information 1. A karyotype is an entire set of stained chromosomes from a cell (Figure 9-6) 2. Members of a given pair share certain characteristics a. Size, shape, and staining pattern b. Members of a pair carry the same genes in the same order i. These are called homologous chromosomes c. Cells with pairs of homologous chromosomes are called diploid 3. There are 23 pairs of chromosomes in humans a. The 22 autosomes are similar in appearance b. One pair of sex chromosomes, X and Y, are quite different in appearance i. They differ in size and genetic composition ii. They behave as a pair during division 4. Homologous chromosomes are usually not identical a. Cells may make mistakes when the DNA is copied b. Mutations, changes in the sequence of nucleotides in DNA, may occur also i. Mutations that are inherited generation after generation are called alleles, and are alternate forms of a gene (Figure 9-7) 5. Not all cells have paired chromosomes a. Most cells in our bodies are diploid and contain the same complement of paired chromosomes b. Gametes (sperm and eggs) have half the number of chromosomes i. They are considered haploid ii. When a sperm fertilizes an egg, the chromosomes combine to form a diploid cell c. In biological shorthand, the number of chromosomes in a species is called the haploid number i. It is designated by the letter n ii. This number is characteristic of a given species iii. Some species are not diploid: n, 4n, 6n, or more

9.4

What Occurs During the Eukaryotic Cell Cycle?

A. The Eukaryotic Cell Cycle Consists of Interphase and Mitotic Cell Division (Figure 9-8) 1. During interphase, a cell grows in size, replicates its DNA, and often differentiates a. Interphase contains three subphases i. During G1, a cell grows, it may specialize, and may divide in response to external signals ii. During the S phase, the cell duplicates its DNA iii. During G2, the cell may continue growing and synthesize materials needed for division 2. Mitotic cell division consists of nuclear division and cytoplasmic division a. Mitosis, the division of the nucleus, gives rise to two genetically identical daughter cells b. Cytokinesis is the division of the cytoplasm c. Meiotic cell division is a prerequisite for sexual reproduction i. Meiosis gives rise to four genetically unique daughter cells that can become gametes â Case Study Continued: Body, Heal Thyself

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Chapter 9 The Continuity of Life: Cellular Reproduction

9.5

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How Does Mitotic Cell Division Produce Genetically Identical Daughter Cells? (Figure 9-8) A. After Interphase, Mitotic Cell Division Can Occur 1. The four phases of mitosis occur on a continuum, with each phase merging into the next (Figure 9-9) B. During Prophase, the Chromosomes Condense, the Spindle Microtubules Form, the Nuclear Envelope Breaks Down, and the Chromosomes Are Captured by the Spindle Microtubules (Figures 9-9b, c) 1. The duplicated chromosomes condense 2. The spindle microtubules form from the centrioles a. The centrioles migrate to opposite poles of the cell 3. The nuclear envelope disintegrates 4. The chromosomes become attached to the spindle at the kinetochore, near the centromere a. The kinetochore on each sister chromatid attaches to the microtubule originating from the opposite pole of the cell C. During Metaphase, the Chromosomes Line Up Along the Equator of the Cell (Figure 9-9d) 1. The two kinetochores of each pair are connected to spindle microtubules that lead to opposite poles of the cell D. During Anaphase, Sister Chromatids Separate and Are Pulled to Opposite Poles of the Cell (Figure 9-9e) 1. Sister chromatids separate and travel toward opposite poles of the cell a. Polar microtubules lengthen to elongate the cell E. During Telophase, a Nuclear Envelope Forms Around Each Group of Chromosomes (Figures 9-9f, g) 1. The following events occur during telophase a. Spindle disappears b. Nuclear envelopes re-form c. Chromosomes expand again d. Nucleolus reappears e. Usually, cytokinesis occurs F. During Cytokinesis, the Cytoplasm Is Divided Between Two Daughter Cells (Figure 9-9h) 1. During telophase in animal cells, the following events occur a. Microfilaments around equator contract b. This constricts the cell’s equator c. Eventually, they pinch the cell in two 2. Cytokinesis in plant cells is quite different (Figure 9-10) a. A stiff cell wall means a different mechanism is required b. Carbohydrate-filled vesicles accumulate at equator and fuse to form a cell plate c. The cell plate grows at the edges, eventually partitioning cell â Case Study Continued: Body, Heal Thyself â Lecture Activity 9.2: Stages of Mitosis Time Crunching

9.6

How Is the Cell Cycle Controlled?

A. The Activities of Specific Proteins Drive the Cell Cycle 1. In most cases, a cell will divide only if it receives signals from growth factors 2. The cell cycle is controlled by a family of proteins called cyclin-dependent kinases (Cdks) 3. If a person cuts his or her skin, a series of events will occur to replace the damaged cells (Figure 9-11) a. latelets in the blood release growth factors that bind to nearby cells b. The binding stimulates the cells to produce cyclin proteins c. The cyclins bind to Cdks, which send the cell into the cell cycle B. Checkpoints Regulate Progress Through the Cell Cycle 1. There are three major checkpoints in the eukaryotic cell cycle (Figure 9-12) a. G1 to S b. G2 to mitosis c. Metaphase to anaphase â Health Watch: Cancer—Running Through the Stop Signs at the Cell Cycle Checkpoints (Figure E9-1)

9.7

Why Do So Many Organisms Reproduce Sexually?

A. Asexual Reproduction Seems to Work Well—Why Bother with Sex? 1. Sexual reproduction produces genetically unique offspring

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Instructor Guide Biology: Life on Earth B. Sexual Reproduction May Combine Different Parental Alleles in a Single Offspring 1. Some combinations are better than others 2. Consider two individuals, each with a desirable trait a. Through sexual reproduction, some offspring may carry both traits b. Although mutations create new alleles, combining alleles through sexual reproduction allows for more rapid evolution

9.8

How Does Meiotic Cell Division Produce Haploid Cells? â Lecture Activity 9.3: Meiosis Walk A. The Key to Sexual Reproduction in Eukaryotes Is Meiotic Cell Division 1. This process consists of meiosis and cytokinesis 2. Meiosis is similar to mitosis, but there are some important differences a. DNA replication in meiosis is followed by two nuclear divisions (Figure 9-13) i. The DNA is not replicated before the second division (Figure 9-13a) b. The first division separates the homologous chromosomes, but each chromosome still consists of two sister chromatids (Figure 9-13b) c. The second division separates the sister chromatids d. At the end of meiosis there are four haploid daughter cells (Figure 9-13c) i. his is important so that when haploid sperm and egg fuse, the resulting offspring are diploid again (Figure 9-14) B. Meiosis I Separates Homologous Chromosomes into Two Haploid Daughter Nuclei 1. The phases of meiosis have the same names as those in mitosis (Figure 9-15) 2. During prophase I, homologous chromosomes pair up and exchange DNA (Figures 9-15a and 9-16) a. Homologous chromosomes pair up i. Maternal and paternal homologues exchange DNA ii. Chiasmata form at sites of crossing over, where the exchange occurred, sometimes leading to recombination, the formation of new combinations of alleles on chromosomes b. Other events are similar to those of mitosis i. Nuclear envelope dissolves ii. Chromosomes condense iii. Spindle forms 3. During metaphase I, paired homologous chromosomes line up at the equator of the cell (Figure 9-15b) a. One member of the pair is attached to the microtubules from one pole i. The other member is attached to the other pole b. The arrangement of paternal and maternal homologues is random 4. During anaphase I, homologous chromosomes separate (Figure 9-15c) a. Sister chromatids remain attached and move together b. Homologues separate from each other 5. During telophase I, two haploid clusters of duplicated chromosomes form (Figure 9-15d) a. Chromosomes cluster at each pole i. Each pole contains a haploid complement of chromosomes ii. Each still consists of sister chromatids attached at the centromere b. Cytokinesis usually occurs at this time c. There is no replication of DNA between meiosis I and meiosis II C. Meiosis II separates sister chromatids into four daughter nuclei 1. The stages of meiosis II are almost identical to those of mitosis a. Prophase II i. Spindle re-forms (Figure 9-15e) ii. Chromosomes attach as in mitosis b. Metaphase II: individual chromosomes line up at equator (Figure 9-15f) c. Anaphase II (Figure 9-15g) i. Centromeres split ii. Daughter chromosomes move to opposite poles d. Telophase II: nuclear envelopes re-form; cytokinesis occurs (Figure 9-15h) e. Four haploid daughter cells are produced (Figure 9-15i) 2. A comparison between mitosis and meiosis shows similarities and differences (Table 9-1) .

Chapter 9 The Continuity of Life: Cellular Reproduction

9.9

When Do Mitotic and Meiotic Cell Division Occur in the Life Cycles of Eukaryotes?

A. The Life Cycles of Almost All Eukaryotic Organisms Have a Common Overall Pattern 1. The fertilization of haploid gametes brings together genes from different parental organisms 2. At some point, meiotic cell division produces haploid cells 3. At some point in the life cycle, mitotic cell division produces a multicellular organism 4. The differences between life cycles are caused by variations in three aspects: a. The interval between meiotic cell division and the fusion of haploid cells b. At what point in the life cycle mitotic and meiotic cell division occur c. The relative proportions of the life cycle spent in the diploid and haploid states B. In Diploid Life Cycles, the Majority of the Cycle Is Spent as Diploid Cells (Figure 9-17) C. In Haploid Life Cycles, the Majority of the Cycle Is Spent as Haploid Cells (Figure 9-18) D. In Alternation-of-Generations Life Cycles, There Are Both Diploid and Haploid Multicellular Stages (Figure 9-19)

9.10 How Do Meiosis and Sexual Reproduction Produce Genetic Variability?

A. Shuffling of Homologues Creates Novel Combinations of Chromosomes 1. This happens during metaphase I of meiosis (Figure 9-20) â Lecture Activity 9.4: Random Assortment Card Trick B. Crossing Over Creates Chromosomes with Novel Combinations of Genes C. Fusion of Gametes Adds Further Genetic Variability to the Offspring

Case Study Revisited: Body, Heal Thyself

KEY TERMS allele anaphase asexual reproduction autosome cell cycle cell division cell plate centriole centromere checkpoint chiasma (plural, chiasmata) chromatid chromosome clone crossing over cytokinesis

daughter cell deoxyribonucleic acid (DNA) differentiate diploid duplicated chromosome gamete gene growth factor haploid homologous chromosome homologue interphase karyotype kinetochore locus (plural, loci) meiosis

LECTURE ACTIVITIES Lecture Activity 9.1: Chromosome Kit for Mitosis/Meiosis Estimated Time to Complete: Variable; 5–20 minutes Section References 9.5 How Does Mitotic Cell Division Produce Genetically Identical Daughter Cells?

9.8 How Does Meiotic Cell Division Produce Haploid Cells?

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meiotic cell division metaphase mitosis mitotic cell division mutation nucleotide prokaryotic fission prophase recombination sex chromosome sexual reproduction spindle microtubule stem cell telomere telophase

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Instructor Guide Biology: Life on Earth

Introduction Students often have difficulty following the events of mitosis and meiosis, particularly if the only way these topics are presented involve text and static figures. Although video presentations help to convey the dynamic nature of these processes, watching videos is still a passive learning method. In this activity, you will have your students construct a set of model chromosomes that they can manipulate to demonstrate the behavior of chromosomes during cell division. They can use these models at home, or you can have them follow along in class.

Materials Needed • Pipe cleaners (two different colors) Procedures 1. Distribute pipe cleaners to the students. Each student should receive four pipe cleaners of each of the two colors, for a total of eight pipe cleaners per student.

2. Instruct the students to create two sets of homologues. They need two long and two short pipe cleaners of each color. Provide wire cutters for the students to use for shortening the pipe cleaners. Alternatively, provide the pipe cleaners already cut to appropriate lengths.

3. To create a chromosome consisting of two sister chromatids, lightly twist two chromosomes of the same color and length together to represent the centromere. The twist should be at any one point along the length of the chromosome; the position of the twist should be the same for the two homologues. Avoid twisting the pipe cleaners too tightly, so that they will last for several demonstrations without breaking. Alternatively, you could use beads with holes of the appropriate size to represent the centromeres. In either case, it helps if you use a marker such as a Sharpie to color the positions of the centromeres.

4. There are many ways to use the chromosome kit. Here are some suggestions: • The students can use the kit at home when they are studying, re-creating the arrangements of chromosomes during the various stages of mitosis and meiosis.

• The instructor can demonstrate in front of the class, while the students follow along with their own kits.

This is best done by manipulating the chromosomes on the glass of an overhead projector, or using a document camera. The document camera would show the colors of the homologues better.

• To demonstrate the large number of configurations of homologues possible with even a few chromosomes, have students work in groups of four, pooling their chromosomes to simulate meiosis in an organism with a haploid number of 8. For each homologous pair, have them determine the arrangement of paternal and maternal homologues by flipping a coin. Two or three runs of this should convince the students that the number of possible arrangements is large (256 in this example).

• It is possible to simulate crossing over with the kit, but each kit could then be used only once. Have the students simulate making chiasmata by twisting the chromosomes at the points of crossing over. Then, use wire cutters to clip the pipe cleaners at the chiasmata; twist the swapped pieces together to represent the recombined chromosomes.

Assessment Suggestions During an exam, the instructor could include a “practical” component. The students would individually come to the instructor with their kits and demonstrate specific chromosomal arrangements of either meiosis or mitosis.

The instructor could assign homework problems that would use the chromosome kits. For example, a classic question involves asking the students to identify the number of chromosomes present during each stage of mitosis or meiosis.

This is the sort of question for which the chromosome kit would be useful.

Lecture Activity 9.2: Stages of Mitosis Time Crunching Estimated Time to Complete: 10 minutes Section Reference 9.5 How Does Mitotic Cell Division Produce Genetically Identical Daughter Cells?

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Introduction Students often find learning the phases of mitosis tedious, as they often see no use for the information. In this activity, students will calculate how long the various stages of the cell cycle last in a rapidly dividing cell. To determine this, they will need to identify the stage of the cell cycle for a large number of cells. By determining the proportion of cells in each stage, they can estimate the amount of time spent in each of those stages. This exercise reinforces the stages of mitosis and demonstrates one way of knowing how these stages can be applied.

Materials Needed The instructor will need images of tissues undergoing mitosis to provide about 200 cells to evaluate. If 35-mm slides of onion root tip are available, they can be projected for the class to see. Ideally, each slide will show only about 25 or 30 cells, so that the individual cells are large enough when projected to be seen and evaluated clearly.

Alternatively, handouts could be prepared of a high-quality micrograph showing at least 100 cells. These could be provided to students, who would work off the sheets at their desks.

Finally, if using an image is not practical, the exercise can be done using data provided by the instructor. This is less desirable, as learning to recognize the stages in actual cells is one of the more valuable learning goals of this activity.

Procedures 1. Explain the concept underlying this activity to the students: that a micrograph represents a frozen moment in time, and the proportion of cells in any given stage will be roughly equivalent to the proportion of time that a cell will spend in that stage of the cell cycle.

2. Draw a table on the board as follows, and instruct the students to do the same in their notebooks. Be sure that the table cells are big enough that you can enter several numbers into each one.

Number of cells

Total number of cells examined in this stage

Percentage of cells in this stage

Interphase Prophase Metaphase Anaphase Telophase 3.

4.

5.

6.

7.

Project the first image. Point to several cells, one at a time, and ask the students to identify the stage of the cell cycle they are in. Most cells will be in interphase, so you should be sure to select examples of all five stages. With practice, the students should become fairly good at identifying the stage.

Once the students are proficient at identifying the stages, have them count the numbers of cells in each stage.

Hint: Because most of the cells will be in interphase, it is usually easiest to count all the other stages, then count the total number of cells in the view, and determine the number of interphase cells by subtraction.

Record the numbers in the cells of the table. There should be enough room to accumulate counts from more than one image within one table cell.

Continue as previously with the rest of the images. When you have counted at least 100 cells, preferably more (200 to 300 is a good number), complete the table by adding all the counts for individual images together. Note: each cell in the third column, labeled “total number of cells examined in this stage,” should have the same number—this redundancy merely makes the calculation of the percentage (column 4) more convenient.

Have the students calculate the percentage of cells in each stage (column 4). This is just the number in the second column divided by the number in the third column, multiplied by 100. Wrap up by asking students to interpret these results in terms of the amount of time spent in each stage. One possibility is to provide an average generation time for dividing cells, such as 120 minutes.

Assessment Suggestions An exam question could be constructed using either a good-quality (one that will survive photocopying) micrograph, or one projected on a screen in the exam room. Alternatively, the instructor could prepare a drawing of a section of tissue, with the stages drawn by hand. The students could be asked to construct an appropriate table for compiling the results, and to calculate the percentage of time spent in each stage of the cell cycle.

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Instructor Guide Biology: Life on Earth

Lecture Activity 9.3: Meiosis Walk Estimated Time to Complete: 15–20 minutes Section Reference 9.8 How Does Meiotic Cell Division Produce Haploid Cells?

Introduction This activity will engage students in acting out the events of meiosis. Each student will play the role of a sister chromatid. The students will act out the motions of the chromosomes during both meiotic divisions, with the ultimate production of four daughter cells with unique collections of chromosomes. This activity reinforces the mechanics of meiotic division.

Materials Needed • Armbands or bandanas. You will need 16 total, four each of four different colors.

Procedures 1. You need 16 students to simulate meiosis in a cell having four pairs of chromosomes. If you wish (and you have the space), you can modify this for larger numbers of students, but it doesn’t work well with a smaller number of students. Students who are watching should be able to see the process (they can encircle the area in which the “chromosomes” will be moving), and they typically enjoy the simulation.

2. Give each student an armband; those having the same color should find each other and pair up. Members of a pair will link arms to represent sister chromatids linked by a centromere (the linked arms). Ideally, each foursome will have two men and two women; the two men would link arms to represent a paternal chromosome, the two women to represent the maternal chromosome.

3. Once you have eight chromosomes (four pairs of homologues), begin the simulation as follows: • Have the students cluster in the middle of the room, representing the nucleus. They can wander around, with homologous pairs not spending any more time near each other than near other chromosomes.

Designate a line to serve as the equator of the cell, and two points to serve as poles.

• Announce that the cell is entering prophase I. The students should find their homologues (the other chromosome with the same color armband), and remain near each other.

• Announce that the cell is at metaphase I. The students should line up at the equator (an imaginary line), with homologues paired and oriented at random with respect to maternal and paternal homologues.

• Announce that the cell is entering anaphase I. The homologues should move away from each other, toward the poles. Be sure that arms are still linked!

• Announce that the cell is entering telophase I. The chromosomes should be at their respective poles. You should now designate new equators and poles for the second division.

• Announce that the cells are entering prophase II. The students can just wander about, and you may want to point out that there is no homologue to pair up with.

• Announce that the cells are at metaphase II. The chromosomes will line up at the equators of their respective cells.

• Announce that the cells are entering anaphase II. Finally, arms will be unlinked, and sister chromatids will separate and move to opposite poles.

• As soon as the students reach the poles, announce that the cells are at telophase II. The students should now be in four clusters, representing the nuclei of four daughter cells.

4. Once the process is complete, have the students examine the armbands of the cells in each nucleus. There should be one of each color. If you were able to specify maternal and paternal homologues, make notice of their random assortment.

If time permits, you can run this one or two more times, perhaps with different students. If you do this with the same students, it should reinforce the random assortment of homologues during meiosis.

Assessment Suggestions Standard questions on an exam relating to the behavior of chromosomes during meiosis should be adequate for assessing this activity.

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Lecture Activity 9.4: Random Assortment Card Trick Estimated Time to Complete: 10 minutes Section Reference 9.10 How Do Meiosis and Sexual Reproduction Produce Genetic Variability?

Introduction Students often have a hard time realizing the vast number of possible arrangements of paternal and maternal homologues for a relatively small number of chromosomes. This exercise reinforces the concept of independent assortment during meiosis, with particular emphasis on the large number of possible outcomes. Although the procedure describes this exercise as a demonstration, it can easily be adapted as an in-class exercise done by the students themselves.

Materials Needed • Two decks of playing cards, with backs of two contrasting colors or patterns. If you do this as a student exercise rather than a demonstration, you will need more decks—two pairs of decks for every four students or groups.

Procedures 1. Introduce this topic to the students by explaining that a relatively small number of chromosome pairs can produce a huge number of possible configurations at metaphase I of meiosis. The instructor should review the math behind this, which is a simple exponential relationship. Perhaps begin by relating the story of the peasant who was offered either 1000 shillings per day for one month’s work, or one shilling on the first day, two on the second, four on the third, and so on. The peasant, should he choose this second option, would demonstrate his wisdom, as he would become a very wealthy man long before the end of the month.

2. Create a deck representing the chromosome set of an organism having 13 pairs of chromosomes by removing all the cards of one suit from both decks and combining them. There are enough cards in two decks of cards to create four such sets. (If you wish, you can create sets of 46 cards to represent the chromosome complements of humans.) This preparation should be done before class. The deck of 26 cards represents 13 pairs of chromosomes. The maternal and paternal versions of each chromosome are represented by the different colors or patterns of the backs.

3. When you have shuffled the deck, turn it so the cards are face up. Deal the cards from the top. You will create two rows of 13 cards, one above the other. There is no need to place the cards in numerical order. Alternatively, create several such decks, and have the students perform this exercise in groups of two to four.

4. Because there are two of each card in this deck (with the only difference being the color or pattern on the back of the cards), you will eventually turn up a second card of each pip value. When the first such duplicate (homologue) card is reached, start the second row by placing the card above its match in the first row.

5. Continue in this manner, placing the first homologue to turn up in the first row, and the second one in the second row, until the deck is depleted.

6. Once the cards are dealt, turn them over. The random arrangement of the maternal and paternal homologues should be evident.

You can do this several times. If you do so, it may be useful to record the results on the board, so that students can see that the combinations of homologues obtained with each shuffling are strikingly different.

Assessment Suggestions Standard questions on an exam relating to the behavior of chromosomes during meiosis should be adequate for assessing this activity.

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CHAPTER 10 PATTERNS OF INHERITANCE LECTURE OUTLINE Case Study: Sudden Death on the Court 10.1 What Is the Physical Basis of Inheritance?

A. Inheritance Is the Process by Which Characteristics of Individuals Are Passed to Their Offspring B. Genes Are Sequences of Nucleotides at Specific Locations on Chromosomes 1. Genes are the units of inheritance (Figure 10-1) 2. A gene’s location on a chromosome is called its locus 3. Genes occur as pairs of alleles C. Mutations Are the Source of Alleles 1. Mutations are changes in the DNA sequence of a gene D. An Organism’s Two Alleles May Be the Same or Different 1. If both homologous chromosomes have the same allele, the organism is homozygous at that locus 2. If both homologous chromosomes have different alleles, the organism is heterozygous at that locus

10.2 How Were the Principles of Inheritance Discovered?

A. Gregor Mendel Deduced the Common Patterns of Inheritance (Figure 10-2) B. Doing It Right: The Secrets of Mendel’s Success 1. Mendel chose pea plants as the subjects for his experiments (Figure 10-3) a. Reproductive structures are enclosed within petals i. This normally prevents cross-pollination ii. Pea plants, however, often get self-fertilized, where a flower on one plant pollinates itself b. Mendel artificially caused cross-pollination i. Self-pollination is normal, simplifying self crosses ii. True-breeding varieties were already available 2. Mendel chose to examine single traits individually 3. Mendel followed traits through several generations

10.3 How Are Single Traits Inherited?

A. Mendel’s Early Experiments Involved Flower Color: Purple and White True-Breeding Plants 1. In the parental generation (P), one parent was true-breeding for purple and the other true-breeding for white a. True-breeding parent plants always produce the same color flower each time they reproduce 2. The first filial generation (F1) was the offspring (Figure 10-4) a. All were purple 3. Mendel self-fertilized the F1 generation to produce the F2 generation (Figure 10-5) a. White flowers reappeared among the F2 b. About ¾ were purple and ¼ white i. The white trait had “receded” into the background ii. The purple trait had “dominated” white B. The Inheritance of Dominant and Recessive Alleles on Homologous Chromosomes Can Explain the Results of Mendel’s Crosses 1. Each trait is determined by discrete pairs of physical units called genes 2. When two different alleles are present in an organism, the dominant allele may mask the expression of the recessive allele 3. Pairs of alleles on homologous chromosomes segregate from each other during meiosis a. This is Mendel’s law of segregation 4. The distribution of alleles into gametes is random

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5. True-breeding plants have two copies of the same allele for a given gene and are homozygous (Figure 10-6a) a. Hybrid organisms have two different alleles for a given gene and are heterozygous (Figure 10-6b) 6. Mendel’s experiments with flower color provided the evidence for his conclusions a. Parents that were true-breeding and homozygous for each flower color produced heterozygous offspring, the F1 generation (Figures 10-7a, b) b. Mating the F1 individuals together produced an F2 generation with a 3:1 ratio of purple to white flowers (Figure 10-7c) 7. The genotype is the combination of alleles carried by an individual 8. The phenotype is the physical appearance of the individual C. Simple “Genetic Bookkeeping” Can Predict Genotypes and Phenotypes of Offspring 1. The Punnett square method is a convenient way for following alleles during crosses (Figure 10-8) D. Mendel’s Hypothesis Can Be Used to Predict the Outcome of New Types of Single-Trait Crosses 1. A test cross is a cross between a dominant phenotype and a recessive phenotype (Figure 10-9) a. It can determine the genotype of the dominant individual â Case Study Continued: Sudden Death on the Court

10.4 How Are Multiple Traits Inherited? â Lecture Activity 10.1: Group-Worked Genetics Problems A. After Figuring Out the Inheritance of Single Traits, Mendel Turned His Attention to the Inheritance of Multiple Traits in Peas (Figure 10-10) 1. Mendel crossed plants differing in two traits: seed color and seed shape 2. F1 individuals all showed the dominant trait for each gene 3. He saw a 9:3:3:1 phenotype ratio among F2 offspring B. Mendel Hypothesized That Traits Are Inherited Independently 1. Mendel realized that his results could be explained if the traits for seed color and seed shape were inherited independently from each other a. His results supported this idea (Figure 10-11) b. This is the law of independent assortment i. Multiple traits are inherited independently because the alleles of one gene are distributed to gametes independently of the alleles for other genes 2. The events of meiosis explain independent assortment (Figure 10-12) C. In an Unprepared World, Genius May Go Unrecognized 1. Mendel presented his findings in 1865, but they were largely misunderstood 2. It was not until 1900 that Mendel’s work was “rediscovered” and he got the credit he deserved

10.5 Do the Mendelian Rules of Inheritance Apply to All Traits? â Lecture Activity 10.2: What If Mendel Chose Different Genes: Class Discussion A. A Review of Mendel’s Assumptions Indicates That: 1. Traits are controlled by a single gene 2. There are two alleles for each trait 3. One allele is completely dominant over the other 4. There are other possibilities, however B. In Incomplete Dominance, the Phenotype of Heterozygotes Is Intermediate Between the Phenotypes of the Homozygotes 1. Curly hair in humans is an example of incomplete dominance (Figure 10-13) C. A Single Gene May Have Multiple Alleles 1. Examples in humans include Marfan syndrome, Duchenne muscular dystrophy, and cystic fibrosis â Health Watch: Muscular Dystrophy (Figure E10-2) 2. Another example is human ABO blood groups (Table 10-1) a. There are six possible genotypes b. Both A and B are dominant to O i. This is known as codominance c. The biochemical explanation involves antibodies to cell-surface antigens D. Many Traits Are Influenced by Several Genes 1. This is an example of polygenic inheritance 2. Human skin color is an example of this type of inheritance (Figure 10-14) .

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Instructor Guide Biology: Life on Earth E. Single Genes Typically Have Multiple Effects on Phenotype 1. This is called pleiotropy, where single genes affect more than one phenotypic trait 2. An example is the nude mice mutation (Figure 10-15) F. The Environment Influences the Expression of Genes 1. In Siamese cats, temperature affects the expression of fur color (Figure 10-16) 2. Many traits are probably influenced by the environment

10.6 How Are Genes Located on the Same Chromosome Inherited?

A. Genes on the Same Chromosome Tend to Be Inherited Together 1. Such genes are said to exhibit gene linkage 2. An example of flower color and pollen shape in sweet peas shows linkage (Figure 10-17) B. Crossing Over Creates New Combinations of Linked Alleles 1. Crossing over during meiosis explains genetic recombination a. This is the appearance of new combinations of alleles that were previously linked b. This process occurs during prophase I of meiosis (Figure 10-18) 2. The distance between genes on a chromosome determines the likelihood of crossing over

10.7 How Are Sex and Sex-Linked Traits Inherited?

â Lecture Activity 10.3: XY Females: Class Discussion A. Sex Chromosomes Determine Sex in Many Different Types of Animals 1. Females have two X chromosomes, males one X and one Y (Figure 10-19) a. The Y is much smaller than the X b. These pair up during prophase; act as homologues B. In Mammals, the Sex of an Offspring Is Determined by the Sex Chromosome in the Sperm 1. The sex chromosome carried by sperm determines sex in organisms in which males are XY (Figure 10-20) C. Sex-Linked Genes Are Found Only on the X or Only on the Y Chromosome 1. Genes located only on sex chromosomes are referred to as sex-linked genes a. There are few genes on Y, mostly for sex determination b. The X chromosome has many genes that determine traits in both sexes 2. Males carry only one copy of genes on the X chromosome a. They will always express a recessive sex-linked trait b. Red-green color blindness is a common sex-linked trait (Figure 10-21) c. Males inherit sex-linked traits from their mothers (Figure 10-21c)

10.8 How Are Human Genetic Disorders Inherited?

A. It Is Unethical to Perform Experimental Crosses on Humans B. Some Human Genetic Disorders Are Controlled by Single Genes 1. Some human genetic disorders are caused by recessive alleles a. An individual usually must be homozygous to have the condition b. Heterozygotes are called carriers c. Albinism results from a defect in melanin production (Figure 10-23) d. Sickle-cell anemia is caused by a defective allele for hemoglobin synthesis i. The red blood cells can become misshapen and do not function properly (Figure 10-24) ii. Sometimes heterozygotes have a mild form of disease â Links to Everyday Life: The Sickle-Cell Allele and Athletics (Figure E10-1) 2. Some human genetic disorders are caused by dominant alleles a. Huntington disease is caused by a defective protein that kills cells in specific brain regions 3. Some human genetic disorders are sex-linked a. These will be expressed in males more often than in females b. These traits frequently skip generations c. Examples include red-green color blindness, muscular dystrophy, and hemophilia (Figure 10-25) â Health Watch: Muscular Dystrophy (Figure E10-2) â Lecture Activity 10.4: Human Genetic Disorders and Genetic Counseling C. Some Human Genetic Disorders Are Caused by Abnormal Numbers of Chromosomes 1. Occasionally, errors in meiosis produce gametes with too many or too few chromosomes a. These disorders are caused by nondisjunction of chromosomes (Figure 10-26) .

Chapter 10 Patterns of Inheritance 2. Some genetic disorders are caused by abnormal numbers of autosomes a. Nondisjunction of sex chromosomes may result in gametes with different combinations of sex chromosomes (Table 10-2) i. Sperm: XX, XY, YY, or O ii. Eggs: XX, O b. Turner syndrome (XO) i. Individuals with this disorder are phenotypically female, but fail to go through puberty ii. They are usually sterile and have other traits c. Trisomy X (XXX) i. These individuals are female, and are usually fertile d. Klinefelter syndrome (XXY) i. These individuals are phenotypically male and are usually sterile e. Jacob syndrome (XYY) i. These individuals are male and have a variety of traits 3. Some genetic disorders are caused by abnormal numbers of autosomes a. The loss of one autosome is usually fatal b. The gain of one autosome often causes abortion, but some survive c. Trisomy 21 (Down syndrome) (Figure 10-27) i. These individuals have three copies of chromosome 21 ii. The probability of this increases with the age of the parents

Case Study Revisited: Sudden Death on the Court

KEY TERMS albinism allele autosome carrier codominance cross-fertilization dominant Down syndrome gene gene linkage genetic recombination genotype hemophilia heterozygous homozygous

Huntington disease incomplete dominance inheritance Jacob syndrome Klinefelter syndrome law of independent assortment law of segregation locus (plural, loci) muscular dystrophy mutation nondisjunction pedigree phenotype

LECTURE ACTIVITIES Lecture Activity 10.1: Group-Worked Genetics Problems Estimated Time to Complete: 15–20 minutes Section Reference 10.4 How Are Multiple Traits Inherited?

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pleiotropy polygenic inheritance Punnett square method recessive self-fertilization sex chromosome sex-linked sickle-cell anemia test cross trisomy 21 trisomy X true-breeding Turner syndrome X chromosome Y chromosome

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Introduction One of the better ways for students to master Mendelian inheritance is to have them work out problems. Genetics problems lend themselves to both individual homework and group work. This exercise combines individual and group work into a single exercise, which can be graded or ungraded. The exercise works through a dihybrid cross example in a logical sequence; the students first work out the possible gametes formed, and then figure out the genotypes and phenotypes of the offspring.

This exercise can be modified for use in teaching monohybrid crosses (Section 10.3).

Materials Needed You will need to prepare a handout with the genetics questions to be worked through, using either your own problem set or the following suggested genetics problems.

Procedures 1. Provide the students with the homework assignment. One possibility is to provide a dihybrid cross problem in which the students have to figure out the genotypes of the parents from information about their phenotypes, then the gametes, and then the offspring. A sample problem is appended.

2. At the next class session, have the students turn in their homework. Divide the class into groups of about four students each. Then hand out blank copies of the homework assignment, or one similar to it, for the students to work on in their groups. Give them 10 minutes to complete the problems. This is sufficient for the same problems; if the second problem set you have provided differs significantly from the homework problem set, you may need to provide 15 minutes.

3. Collect the problems to be graded. Students should receive the average of their individual and group scores.

If a student’s individual score is higher than the group score, you should give the individual grade, without averaging. This avoids the valid complaint that a student who did well individually should not suffer if the group as a whole did poorly.

Assessment Suggestions This exercise is self-assessing. However, including dihybrid cross problems on exams provides further assessment of the topic.

Handout Answer Key: 1. S = spotted, s = solid B = black, b = brown 2. Ssbb 3. ssBB 4. Sb and sb 5. sB 6.

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0% spotted brown, 50% solid black

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Name: ________________________

Date:_________________________

Instructor: _____________________

Course Section: _________________

Lecture 10.1 Activity Handout—Dihybrid Cross Assignment Complete the following multipart genetics problem.

Rabbits can have solid or spotted coats, and the base color can be either brown or black. Spotted coat color is dominant to solid, and black is dominant to brown. Complete the following problem by answering the following questions.

1.

Write down letter designations for the alleles. Be sure to distinguish between the two traits, and be sure to consider which alleles are dominant and recessive. For example, Mendel used P to designate the purple allele, and p to designate the white allele for pea flower color.

2.

What would be the genotype of a female spotted brown rabbit whose mother was solid black?

3.

What would be the genotype of a male solid black rabbit whose parents were homozygous for the black allele?

4.

If you cross these two rabbits, what kinds of gametes would be produced by the spotted brown rabbit?

5.

What kinds of gametes would be produced by the solid black rabbit?

6.

Draw a Punnett square showing the mating of this pair of rabbits.

7.

What proportion of the offspring of this cross would you expect to be spotted brown? Solid black?

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Lecture Activity 10.2: What If Mendel Chose Different Genes?: Class Discussion Estimated Time to Complete: 10 minutes Section Reference 10.5 Do the Mendelian Rules of Inheritance Apply to All Traits?

Introduction Mendel was in some senses very lucky in the choice of genes he chose for his studies with pea plants. For example, his early experiments on monohybrid crosses refuted the concept of blending inheritance. This was partly because the traits he chose to study exhibited complete dominance. In this group-discussion exercise, the students will consider what would have happened had Mendel chosen a trait for his first crosses that exhibited incomplete dominance.

Materials Needed None Procedures 1. Once the topic of incomplete dominance has been introduced, ask the students to break up into discussion groups. Alternatively, this could be conducted as a class discussion.

2. Ask the students to consider how Mendel’s interpretations of the F1 results would have differed had he studied flower color in snapdragons, which exhibit incomplete dominance. Considering only the F1 generation, would Mendel have been so quick to reject blending inheritance?

3. Ask the class what evidence Mendel would have obtained from his experiments that would have been inconsistent with blending inheritance. Could Mendel have deduced his law of segregation if he had studied flower color in snapdragons?

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Explain how incomplete dominance, in spite of its initial, superficial resemblance to blending inheritance, still obeys Mendel’s law of segregation.

Lecture Activity 10.3: XY Females: Class Discussion Estimated Time to Complete: 10 minutes Section Reference 10.7 How Are Sex and Sex-Linked Traits Inherited?

Introduction Section 10.7 introduces the X-Y system for sex determination. Some students may wish to know how the complement of sex chromosomes determines sex; this exercise introduces the concept with an applied example.

The SRY region of the Y chromosome contains a gene that encodes a testis-determining factor (TDF), which must be present for male sexual development in the embryo to begin. One possible way for an XY individual to develop as a female is if there is a mutation in this gene that results in no functional TDF being produced. Such individuals will become XY females. Other causes of XY females involve defective receptors for TDF. This exercise can be performed as either a class discussion, group work, or both.

Materials Needed None Procedures 1. Introduce the details of sex determination to students, explaining the role of the SRY region and TDF. 2. Have the students discuss the consequences of an XY female mating with an XY male. What are the possible phenotypes and genotypes? Would all the offspring survive? .

Chapter 10 Patterns of Inheritance 3.

This can be either a class discussion or you can break the class into small discussion groups.

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Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Describe how two XY individuals can mate, and describe the genetic consequences for their potential children.

(If an XY female is produced as described earlier, she can have children with a male (XY). A Punnett square of this mating shows that one quarter of the fertilizations will result in the YY chromosomal complement, which is lethal. For each child born, the chances of having a son are two-thirds; the chances of having a daughter are one-third.)

Lecture Activity 10.4: Human Genetic Disorders and Genetic Counseling Estimated Time to Complete: 10–15 minutes Section Reference 10.8 How Are Human Genetic Disorders Inherited?

Introduction Students usually find the topic of human genetics and human genetic disorders interesting. Genetic counseling is a field that has been growing with our increased knowledge of the human genome. Individuals and prospective parents can now get competent advice about genetic disorders so that they can make informed decisions. This counseling is nondirective. In other words, counselors provide information and discuss the consequences of various decision scenarios, but they do not tell their clients what to do.

Materials Needed None Procedures 1. Introduce a case study of a human genetic disorder to your students. The chapter case study on Marfan syndrome is one possibility, but others include Huntington disease or one of the chromosomal disorders such as trisomy 21.

2. Have the students discuss in groups how they would advise a couple who were at risk for having a child with the disorder in the case study.

Follow with a class discussion in which the different groups compare and contrast their decisions.

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Describe the consequences of a couple having children if both are carriers for a genetic disorder such as Marfan syndrome.

How would your advice differ if the disorder were more severe, such as cystic fibrosis?

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CHAPTER 11 DNA: THE MOLECULE OF HEREDITY LECTURE OUTLINE Case Study: Muscles, Mutations, and Myostatin â Lecture Activity 11.1: DNA Is Relevant

11.1 How Did Scientists Discover That Genes Are Made of DNA? A. Hereditary Information Is Found in Discrete Units Called Genes 1. Genes are segments of DNA located on chromosomes 2. Chromosomes are composed of DNA and proteins B. Transformed Bacteria Revealed the Link Between Genes and DNA 1. In the 1920s, Griffith worked with bacteria that caused pneumonia (Figure 11-1) a. He worked with two strains: R and S i. R did not cause pneumonia in mice ii. S did cause pneumonia in mice b. He mixed heat-killed S-strain and living R-strain i. He tested to see if the mixture could cause pneumonia ii. He isolated living S-strain bacteria from infected mice iii. Some substance from dead S-strain transformed R-strain 2. The transforming molecule is DNA a. Avery, MacLeod, and McCarty showed DNA was the transforming material (Figure 11-2) 3. DNA, not protein, is the molecule of heredity â Science in Action: DNA Is the Hereditary Molecule of Bacteriophages (Figures E11-1 and E11-2)

11.2 What Is the Structure of DNA? A. DNA Is Composed of Four Nucleotides 1. There are four kinds of nucleotides that differ depending on the nitrogen-containing base (Figure 11-3) 2. Each nucleotide is composed of three parts a. Phosphate b. Deoxyribose sugar c. Nitrogen-containing base 3. The four bases are adenine (A), guanine (G), cytosine (C), and thymine (T) 4. Chargaff’s rule states that equal amounts of adenine and thymine, and guanine and cytosine are found in DNA B. DNA Is a Double Helix of Two Nucleotide Strands 1. In 1952, Maurice Wilkins and Rosalind Franklin used X-ray diffraction in an attempt to determine the structure of DNA (Figure 11-4) 2. James Watson and Francis Crick used Franklin’s data to suggest that DNA was a double helix a. The helix has two sugar–phosphate backbones (Figure 11-5) b. All of the nucleotides of one strand are oriented in the same direction â Science in Action: The Discovery of the Double Helix (Figure E11-3) C. Hydrogen Bonds Between Complementary Bases Hold Two DNA Strands Together in a Double Helix (Figure 11-5b) 1. The sugar–phosphate backbone forms the double helix a. The backbones are antiparallel i. Each strand is directional: free sugar on one end, phosphate on other ii. The directions of the two strands are opposite iii. Car headlight–taillight analogy; traffic on two-lane road 110

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b. Nitrogen-containing bases from each backbone bond in the middle and are like rungs in a ladder c. Pairing rules: A always pairs with T; G always pairs with C i. This is called complementary base pairing ii. This pairing explains Chargaff’s rules

11.3 How Does DNA Encode Genetic Information?

A. The Small Number of Nucleotides (4) Made Many Scientists Skeptical That DNA Was the Hereditary Molecule B. Genetic Information Is Encoded in the Sequence of Nucleotides â Lecture Activity 11.2: Human DNA Model â Case Study Continued: Muscles, Mutations, and Myostatin

11.4 How Does DNA Replication Ensure Genetic Constancy During Cell Division?

A. Replication of DNA Is a Critical Event in the Cell Cycle 1. DNA replication produces identical DNA double helices that are passed on to cells during cell division B. DNA Replication Produces Two DNA Double Helices, Each with One Original Strand and One New Strand 1. DNA replication is quite simple and needs the following (Figure 11-6) a. Parental DNA strands b. Free nucleotides c. A variety of enzymes i. DNA helicases ii. DNA polymerases 2. DNA replication is semiconservative (Figure 11-7) â In Greater Depth: DNA Structure and Replication (Figures E11-4 through E11-7) â Lecture Activity 11.3: DNA Replication on Paper â Lecture Activity 11.4: DNA Replication Done Large! â Case Study Continued: Muscles, Mutations, and Myostatin

11.5 What Are Mutations, and How Do They Occur?

A. Mutations Are Changes in the Base Sequence of DNA B. Accurate Replication, Proofreading, and DNA Repair Produce Almost Error-Free DNA 1. DNA replication is highly accurate due to complementary base pairing 2. DNA repair enzymes proofread each daughter strand of DNA after its synthesis and fix mistakes C. Toxic Chemicals, Radiation, and Occasional Errors During DNA Replication Cause Mutations 1. Certain chemicals and some types of radiation can cause mutations a. Some of these mutations are fixed by repair enzymes, but some remain D. Mutations Range from Changes in Single Nucleotide Pairs to Movements of Large Pieces of Chromosomes (Figure 11-8) 1. Nucleotide substitutions are called point mutations because individual nucleotides in the DNA sequence are changed a. Insertion mutations occur when one or more nucleotide pairs are inserted into the DNA double helix b. Deletion mutations occur when one or more nucleotide pairs are removed from the DNA double helix 2. Pieces of chromosomes ranging in size from a single nucleotide pair to massive pieces of DNA are occasionally rearranged a. These include inversions and translocations

Case Study Revisited: Muscles, Mutations, and Myostatin (Figure 11-10)

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Instructor Guide Biology: Life on Earth

KEY TERMS adenine (A) bacteriophage base complementary base pair cytosine (C) deletion mutation deoxyribonucleic acid (DNA) DNA helicase DNA ligase

DNA polymerase DNA replication double helix free nucleotide guanine (G) insertion mutation inversion mutation nucleotide

nucleotide substitution point mutation semiconservative replication strand sugar–phosphate backbone thymine (T) translocation

LECTURE ACTIVITIES Lecture Activity 11.1: DNA Is Relevant Estimated Time to Complete: 10 minutes Section Reference Chapter 11 DNA: The Molecule of Heredity Introduction The discovery of the structure and function of DNA, and of the central role that it plays in biology, is one of the profound scientific achievements of the past 50 years. Most students have probably already heard about DNA, and many will have some interest in it. However, few will probably realize how far-ranging the impact of DNA has been. This discussion activity can be used to reinforce the idea that DNA is important to everyone, and can be an effective way to introduce the topic to students.

Materials Needed None Procedures 1. Collect news articles that describe the use of DNA in biology and other areas: forensics, anthropology, paternity, genetic screening and counseling, environmental issues, pathology, biotechnology, genetically modified organisms, or any other subject that is recent and relevant to DNA. You could also clip help-wanted ads from the local newspaper (or a national paper such as The New York Times), especially, in a nonmajors course, those recruiting nonscientists into a biotechnology, pharmaceutical, or other company involved with DNA technology.

2. Create a one-page handout that is a collage of headlines or short excerpts from these articles. Design it so that the diversity of areas in which DNA has an impact is readily apparent.

3. Distribute the handout to the class, and then lead a discussion about the diversity of areas in which DNA has had an impact. If you have included jobs in the handout, point out how a knowledge of DNA might be useful to people with degrees in both science and nonscience disciplines.

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Name three significant topics in the news that involve DNA. 2. Describe at least two career opportunities involving DNA technology that are available to nonscience majors.

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Lecture Activity 11.2: Human DNA Model Estimated Time to Complete: 10 minutes Section Reference 11.2 What Is the Structure of DNA? Introduction The structure of DNA is critical to its function. In this exercise, the students themselves act as the nucleotides, forming two long antiparallel strands. The activity reinforces the concepts of complementary base pairing, the sugar–phosphate backbone, and the antiparallel orientation of the two strands in DNA. Materials Needed Optional: Small index cards with the letters of the four nitrogen-containing bases written on them, one base per card Procedures 1. Divide the class into halves. The first half should line up single file, one behind the other. Have these students hold the shoulder of the person in front of them with the left hand. Tell them that they are a human nucleotide: their bodies represent the deoxyribose sugar, their left arms are the phosphate group, and their right arms are the nitrogenous base.

2. Now have the second half of the class line up alongside the first line of students. They should also hold the shoulder of the person in front of them with the left hand.

3. Now have the students extend their right arms and touch fingertips with their “complementary base” on the other strand. Point out to the students that the two lines must be facing in opposite directions for this to work out. Point out that the relatively stronger grip they have on the person in front of them represents the relatively strong covalent bond that holds the backbone together. Then, point out the relatively weak interaction represented by touching fingertips, the analogy to the weak hydrogen bonds holding the base pair together.

4. Variation: You can distribute index cards with letters representing the four bases to the first half of the class, thereby designating which nitrogen-containing base they represent. Then, instead of having the second half of the class simply line up, they will have to be sure to find a complementary base to pair with. Be sure to have the correct number of each complementary base in the second half of the class to ensure that no students are left out of the line. This activity can also be modified to represent DNA replication, if there are enough students in the class.

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Explain why the two strands in a DNA double helix are said to be antiparallel. Describe the main difference between the way the nucleotides of DNA’s sugar–phosphate backbone are bonded together and the way the complementary base pairs are joined.

Lecture Activity 11.3: DNA Replication on Paper Estimated Time to Complete: 10 minutes Section Reference 11.4 How Does DNA Replication Ensure Genetic Constancy During Cell Division?

Introduction The process of DNA replication depends on complementary base pairing, the separation of parent strands that is allowed by the relatively weak hydrogen bonding between complementary base pairs, and the antiparallel nature of the DNA strands. In this exercise, students will first construct a DNA strand complementary to one that is provided. They will then separate these two parent strands, and using them as templates, construct new complementary strands to form two identical DNA molecules. .

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Materials Needed One handout for each student (see appended handout master) Procedures 1. Photocopy enough of the handout masters so that each student has one.

2. Have the students fold the handout along its center line, so that the printing is inside. Then, have them fold along the two other lines to form a pleated fan (M in cross section) with the printed first column exposed on the outside. It may be easiest if the instructor demonstrates this for the students.

3. Have the students place the sheet so that the two center columns are folded together, and the first and fourth columns (the outer ones) are lying adjacent to each other. They can now write the appropriate letters for the complementary strand in the empty fourth column. Be sure that they indicate the phosphate and sugar ends of this strand.

4. Now point out to the students that replication cannot proceed until the two strands are separated, which they can now do by unfolding the paper, exposing the two empty middle columns. This represents the unwinding and separation of the two parental strands.

5. The students can now “replicate” the DNA by writing the complementary bases in the middle columns, thereby generating identical copies of the original DNA. Point out the semiconservative nature of replication: their daughter strands each contain one of the original parental strands.

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Explain the antiparallel nature of the sugar–phosphate backbone of DNA. 2. Explain why we say that DNA replication is semiconservative.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 11.3 Handout—DNA Replication on Paper

SUGAR A T C G A A T A C C G A T PHOS .

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Lecture Activity 11.4: DNA Replication Done Large!

Estimated Time to Complete: 15–20 minutes Section Reference 11.4 How Does DNA Replication Ensure Genetic Constancy During Cell Division?

Introduction In this exercise, students will collaborate to construct a DNA strand that is as large as your classroom is wide.

They will then act out the replication of this DNA, with students taking on the role of the various enzymes that participate in the process.

Materials Needed You will need two lengths of flagging tape (3-inch barricade tape works well), as long as you have room for them in your classroom. The two lengths of tape should have a letter representing a base every 4 inches, and they should be constructed to be complementary to each other. Be sure to label the sugar and phosphate ends of the two strands. You will also need two rolls of masking or label tape, and a collection of “nucleotides” made out of 4-inch strips of the flagging tape, with the letters of the needed bases written on them. The best way to make these is to construct a second pair of strands exactly like the ones above, and then cut up the duplicate.

On each nucleotide, label the sugar and the phosphate ends with a small “s” and “p.”

Procedures 1. Have one student hold one end of the two long pieces of flagging tape, making sure that the strips are aligned in an antiparallel, complementary fashion. (It is sometimes easiest if the two strips are attached at this end.) Have a second student hold the other ends, pulling them taut. These students should now twist the strands until there is one twist for every 10 bases. Point out to the students that this is the same degree of twisting as exists in a DNA double helix.

2. Now assign two students to serve as DNA polymerase molecules. Give each of them a stack of nucleotides and a roll of masking or label tape. Designate one other student to be a DNA ligase molecule; give this student a roll of tape. Finally, designate one other student to be a DNA helicase molecule.

3. Have the helicase molecule begin to separate the two strands, so that the DNA polymerases can get to work.

Be sure that the student holding the opposite end does not let the DNA untwist at first. This way, students will see how untwisting the molecule is not a simple process, as kinks develop. You may want to explain that helicase has a more complex task than the textbook describes. You should also point out the replication fork.

4. When 4 feet or so of the helix are unwound, put the polymerases to work taping together new strands from their pool of nucleotides. Be sure that they add nucleotides ONLY to the sugar end of an existing strand, and that their new strand is both antiparallel and complementary to the parent strand. One polymerase will be able to start at the free end of one of the parent strands, and will be able to continuously follow the replication fork. The other will have to synthesize away from the replication fork, and synthesize the new strand in short pieces. You may need to orchestrate this closely at first. The student serving as DNA ligase will join these short strands together.

5. Variation: If you have a very large room, you can try to start replication in the middle, forming two replication forks and a replication bubble. You will need to have four DNA polymerases, two DNA ligases, and two helicases.

Assessment Suggestions Include a short-answer question on a written exam such as: 1. Explain the role of DNA helicases in DNA replication.

2. Describe the process of DNA replication, including the functions of all the enzymes involved.

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CHAPTER 12 GENE EXPRESSION AND REGULATION LECTURE OUTLINE Case Study: Cystic Fibrosis â Lecture Activity 12.1: Human Genome, Mutations, and Genetic Information

12.1 How Is the Information in DNA Used in a Cell?

A. Most Genes Contain the Information Needed to Synthesize a Protein 1. Genes provide information to make proteins 2. Proteins are the cell’s “molecular workers” â Science in Action: One Gene, One Protein (Figure E12-1) B. DNA Provides Instructions for Protein Synthesis via RNA Intermediaries 1. Ribonucleic acid (RNA) carries the information in DNA necessary for making proteins a. There are structural differences between DNA and RNA (Table 12-1) i. RNA is single-stranded ii. RNA has the sugar ribose instead of deoxyribose iii. RNA has the base uracil (U) instead of thymine (T) 2. DNA codes for the synthesis of the three kinds of RNA (Figure 12-1) a. mRNA b. rRNA c. tRNA 3. Messenger RNA carries the code for protein synthesis from DNA to ribosomes (Figure 12-1a) a. mRNA takes genetic information from the nucleus to the cytoplasm 4. Ribosomal RNA and proteins form ribosomes (Figure 12-1b) a. The small subunit of the ribosome has binding sites for mRNA b. The large subunit of the ribosome has binding sites for tRNA 5. Transfer RNA carries amino acids to the ribosomes (Figure 12-1c) a. Every cell synthesizes at least one tRNA for each amino acid b. Complementary base pairs between the tRNA anticodon and the mRNA codon ensure that the correct amino acid is used to synthesize a protein C. Overview: Genetic Information Is Transcribed into RNA and Then Translated into Protein (Figure 12-2 and Table 12-2) 1. In transcription, the information contained in the DNA of a specific gene is copied into RNA (Figure 12-2a) a. This process occurs in the nucleus 2. During translation, the mRNA base sequence is decoded into an amino acid sequence a. tRNA molecules bring amino acids to the ribosome for assembly into proteins (Figure 12-2b) 3. Transcription is the process of copying DNA to RNA using the nucleotide “language” a. Translation is the process of translating the nucleotide “language” into the “language” of amino acids D. The Genetic Code Uses Three Bases to Specify an Amino Acid 1. The genetic code translates the sequence of bases in nucleotides into a sequence of amino acids in a protein 2. Codons are sequences of three bases that code for specific amino acids (Table 12-3) 3. Stop and start codons act as the “punctuation” for an mRNA sequence a. The start codon (AUG) signifies the start of the mRNA message b. The three stop codons (UAG, UAA, and UGA) signify the end of the mRNA message 4. The genetic code is redundant a. There is more than one codon for many amino acids .

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Instructor Guide Biology: Life on Earth 5. Anticodons in the tRNA are complementary to the codons in mRNA a. The anticodons ensure that the correct amino acid is placed in the proper sequence in the protein

12.2 How Is the Information in a Gene Transcribed into RNA? (Figure 12-3) â Lecture Activity 12.2: Transcription A. Transcription Has Three Steps: Initiation, Elongation, and Termination B. Transcription Begins When RNA Polymerase Binds to the Promoter of a Gene 1. RNA polymerase binds at the promoter region (TATAAA sequence) 2. The DNA begins to unwind C. Elongation Generates a Growing Strand of RNA (Figure 12-4) 1. RNA polymerase synthesizes RNA that is complementary to template strand of DNA D. Transcription Stops When RNA Polymerase Reaches the Termination Signal 1. RNA polymerase continues down the template strand of DNA until it reaches a sequence of bases called the termination signal a. RNA polymerase then releases the completed RNA and detaches from the DNA

12.3 How Is the Base Sequence of mRNA Translated into Protein?

A. Messenger RNA Synthesis Differs Between Prokaryotes and Eukaryotes 1. Messenger RNA synthesis in prokaryotes a. Prokaryotes commonly transcribe a single, very long mRNA from a series of adjacent genes (Figure 12-5a) b. Transcription and translation typically occur together (Figure 12-5b) B. In Eukaryotes, a Precursor RNA Is Processed to Form mRNA That Is Translated into Protein 1. In eukaryotes, the genes that encode proteins are not clustered together as they are in prokaryotes a. The coding segments are called exons, and the noncoding segments are called introns (Figure 12-6a) b. Transcription of a eukaryotic gene produces a very long RNA strand i.More nucleotides are added to the beginning and end of the RNA, forming a “cap” and a “tail” (Figure 12-6b) ii. The introns are removed from the RNA and the exons are spliced together, forming mRNA (Figure 12-6b) 2. Functions of intron–exon gene structure a. This structure appears to allow a cell to produce multiple proteins from a single gene b. This structure may allow eukaryotes to evolve new proteins with new functions C. During Translation, mRNA, tRNA, and Ribosomes Cooperate to Synthesize Proteins (Figure 12-7) 1. Like transcription, translation has three steps 2. Initiation: translation begins when tRNA and mRNA bind to a ribosome a. The preinitiation complex scans the mRNA for an initiation codon, AUG, which codes for methionine b. The initiation complex forms c. The large ribosomal subunit joins the complex 3. Elongation: amino acids are added one at a time to the growing protein chain a. The ribosome holds two mRNA codons in both binding sites i. A peptide bond forms between the two amino acids b. The complex moves one codon along mRNA i. This process repeats one codon at a time 4. Termination: a stop codon signals the end of translation a. Translation stops when the stop codon is reached b. Ribosome releases the complete protein c. Ribosome and mRNA dissociate D. Summing Up: Decoding the Sequence of Bases in DNA into the Sequence of Amino Acids in Protein (Figure 12-8) 1. With some exceptions, each gene codes for the amino acid sequence of a protein 2. Transcription of a protein-coding gene produces an mRNA that is complementary to DNA, and starting with AUG, each codon in mRNA is a sequence of three bases that specifies an amino acid or a “stop” 3. Enzymes in the cytoplasm attach the appropriate amino acid to tRNA .

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4. During translation, tRNAs carry their attached amino acid to the ribosome based on the tRNA anticodon a. The amino acids are linked together to form a protein â Lecture Activity 12.3: Transcription and Translation

12.4 How Do Mutations Affect Protein Structure and Function?

A. A Mutation Is a Change in the DNA Sequence of a Gene â Case Study Continued: Cystic Fibrosis B. The Effects of Mutations Depend on How They Alter the Codons of mRNA 1. Inversions and Translocations a. Inversions are mutations that occur when a piece of DNA is cut out of a chromosome, flipped around, and reinserted b. Translocations are mutations that occur when a piece of DNA is removed from one chromosome and attached to another c. These mutations can be benign or very serious 2. Deletions and insertions a. The effects of deletions and insertions usually depend on how many nucleotides are removed or added 3. Substitutions a. This type of mutation may cause four different effects (Table 12-4) i. The amino acid sequence of a protein may be unchanged ii. Protein function may be unchanged iii. Protein function may be changed by an altered amino acid sequence iv. Protein function may be destroyed by a premature stop codon â Case Study Continued: Cystic Fibrosis â Lecture Activity 12.4: Point Mutation Group Activity

12.5 How Is Gene Expression Regulated?

A. Some Genes Are Expressed in All Cells 1. Other genes are expressed exclusively in certain cell types 2. Regulation may occur at the level of transcription, translation, or protein activity B. In Prokaryotes, Gene Expression Is Primarily Regulated at the Level of Transcription 1. Prokaryotic DNA is organized into packages called operons, which contain various components (Figure 12-9) a. A regulatory gene b. A promoter c. An operator d. Structural genes 2. The lactose operon is an example of gene regulation in prokaryotes C. In Eukaryotes, Gene Expression Is Regulated at Many Levels (Figure 12-10) 1. Regulation of gene expression in eukaryotic cells can be controlled at any of a number of steps a. Cells can control the frequency at which an individual gene is transcribed b. The same gene may be used to produce different mRNAs and protein products c. Cells can control the stability and translation of mRNAs d. Proteins may require modification before they can carry out their functions e. Cells can control the rate at which proteins are degraded 2. Regulatory proteins binding to a gene’s promoter alter its rate of transcription a. Many transcription factors require activation before they can affect gene transcription â Health Watch: A Case of Mistaken Gender (Figure E12-2) 3. Epigenetic controls alter gene transcription and translation a. Epigenetics is the study of gene expression â Health Watch: The Strange World of Epigenetics (Figure E12-2) b. Epigenetic control works in three ways i. Epigenetic modification of DNA may suppress transcription ii. Epigenetic modification of histones may enhance transcription iii. Changing transcription and translation through the actions of several types of RNA 4. Noncoding RNA may alter transcription or translation a. MicroRNA and RNA Interferences .

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Instructor Guide Biology: Life on Earth i. MicroRNA binds mRNA and interferes with translation

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b. Altering transcription with noncoding RNA i. Some noncoding RNAs bind to RNA polymerase, blocking transcription ii. Other noncoding RNAs alter DNA or histones on specific parts of a chromosome iii. The X chromosome may be condensed into a Barr body, and inactivated, preventing transcription and altering gene expression (Figures 12-11 and 12-12)

Case Study Revisited: Cystic Fibrosis (Figure 12-13)

KEY TERMS anticodon Barr body codon deletion mutation epigenetics exon genetic code insertion mutation intron inversion lactose operon messenger RNA (mRNA)

microRNA mutation neutral mutation nucleotide substitution operator operon point mutation promoter regulatory gene repressor protein ribonucleic acid (RNA) ribosomal RNA (rRNA)

ribosome RNA polymerase start codon stop codon structural gene template strand transcription transfer RNA (tRNA) translation translocation

LECTURE ACTIVITIES Lecture Activity 12.1: Human Genome, Mutations, and Genetic Information Estimated Time to Complete: 10–15 minutes Section Reference Chapter 12: Gene Expression and Regulation Introduction This chapter completes the textbook’s primary treatment of the gene, including gene regulation and mutation.

Your students can now begin to consider some of the more complex implications of our expanding knowledge of the human genome. This topic could be done either at the beginning of Chapter 12 or at the end. The advantage of presenting it at the beginning is that it may generate greater interest in the material as it is covered in class; the advantage at the end is that students better understand the nature of both the gene and of mutations.

Materials Needed None Procedures 1. Introduce the topic of the Human Genome Project (HGP) to your students by briefly describing the nature and scope of the HGP. Point out that several genes were well understood before the HGP was completed, and that for some of these genes our knowledge now includes an understanding of specific mutations that cause (or may cause) specific diseases.

2. Create a set of questions to be discussed. Possible topics include: • Would you want your own genome to be sequenced?

• Would you wish to be screened for specific disease-causing mutations?

• Would you want to be screened for mutations that you know exist in your family?

• Would you want to be screened for specific mutations even if there was no cure for the disease? .

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Instructor Guide Biology: Life on Earth • Who should have the right to information about your genetic makeup?

• Who should control access to your genetic information?

• Should insurance companies be allowed to deny you coverage for specific conditions based upon your genetic makeup?

• What other ethical or moral consequences are there with respect to genetic information?

• If you carry a gene for an incurable condition, should you have children?

This can be either a class discussion, or you can break the class into small discussion groups.

If you break the class into separate groups, you could assign different questions to each group and have each summarize their discussion to the class as a whole. This would require more class time.

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Describe three areas of concern regarding the ethics of the use of genetic information about individuals.

Lecture Activity 12.2: Transcription Estimated Time to Complete: 5 minutes Section Reference 12.2 How Is the Information in a Gene Transcribed into RNA? Introduction This exercise has a single purpose: to reinforce the point that T is replaced by U in RNA. Some students still have trouble with this difference even after covering transcription and translation in the textbook and in lecture.

Taking 5 minutes when transcription is introduced can reinforce this important difference between DNA and RNA for these students Materials Needed None Procedures 1. Ask the students to take out a sheet of paper. A half-sheet of notebook paper should be sufficient.

2. On the board, create a DNA sequence several nucleotides long, labeled “TEMPLATE DNA:”. Immediately below and to the left of it, place the label “COMPLEMENTARY DNA STRAND:”. Immediately below that, place the label “RNA STRAND:”. The board would look like this: TEMPLATE DNA: AGCTGTTACACGGATTACT COMPLEMENTARY DNA STRAND: RNA STRAND: Alternatively, you could prepare small sheets of paper with the sequence and labels printed out. If you do this, be sure to print the letters large enough so that the complementary strand and the RNA strand can be handwritten below them, with the bases lined up. A template for a handout having five copies of the above sequence can be found on the next page.

3. Instruct the students to fill in the complementary DNA strand immediately under the template strand. Then have them write down the RNA strand that is complementary to the TEMPLATE strand. (Some will try to transcribe the complementary strand instead.)

4. While the students are doing this, you may want to write a message on the board reminding them that there is no T in RNA—replace it with “U.” 5. When the students are finished, have them inspect the strands. Point out that the RNA and the complementary DNA are identical, except the RNA strand has a U nucleotide where the DNA strand has a T. 6. You may either have the students retain these sheets as a reminder of this simple yet important concept, or you can collect them for a grade. An alternative to assigning a grade is to enter all correctly done sheets into a random drawing for a simple item of your choice—candy bars and sodas often seem welcome.

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Chapter 12 Gene Expression and Regulation Assessment Suggestions The exercise itself can be used as an assessment. Alternatively, ask the students to construct an RNA sequence complementary to a DNA template strand on a quiz or an exam.

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Name: ________________________

Date:_________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 12.2: Transcription Handout—Transcription TEMPLATE DNA: COMPLEMENTARY DNA STRAND: RNA STRAND:

AGCTGTTACACGGATTACT

TEMPLATE DNA: COMPLEMENTARY DNA STRAND: RNA STRAND:

AGCTGTTACACGGATTACT

TEMPLATE DNA: COMPLEMENTARY DNA STRAND: RNA STRAND:

AGCTGTTACACGGATTACT

TEMPLATE DNA: COMPLEMENTARY DNA STRAND: RNA STRAND:

AGCTGTTACACGGATTACT

TEMPLATE DNA: COMPLEMENTARY DNA STRAND: RNA STRAND:

AGCTGTTACACGGATTACT

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Lecture Activity 12.3: Transcription and Translation Estimated Time to Complete: 15–20 minutes Section Reference 12.2 How Is the Information in a Gene Transcribed into RNA? 12.3 How Is the Base Sequence of Messenger RNA Translated into Protein?

Introduction This exercise reinforces both the process and the compartmentalization of gene expression. Students will work in groups to simulate transcription within one compartment, the nucleus, and translation in another, the cytoplasm.

Although the description of this exercise is long, once the groups get started, their tasks usually are completed quickly.

Materials Needed There are several ways to do this exercise. At minimum, the groups should have the following: 1. Nucleus group: • A pool of RNA nucleotides—1-inch squares of paper with one letter representing a nucleotide written on each: A, C, G, and U. For durability, a permanent set of these could be printed and then laminated in plastic. A template for photocopying is on the last page of this activity.

• Adhesive tape • A strip of paper on which you have provided a DNA message long enough to code for about 15–20 amino acids. This should be double-stranded, with one strand labeled “coding” and the other “non-coding.”

Ideally, the strand should begin with TAC and end with a triplet that will create a STOP codon: ATT, ATC, or ACT. Check to make sure that no premature stop codons will be created.

2. Cytoplasm group: • A pool of RNA nucleotides as above • A pool of amino acids written on 1-inch squares of paper. As for the RNA nucleotide pool, these could be printed and laminated for durability.

• A stack of index cards large enough to tape three of the above RNA nucleotides along one edge (to form a tRNA anticodon) • Adhesive tape • A copy of the genetic code; Table 12-3 from the textbook is sufficient.

Procedures 1. Divide the class into two groups; in larger classes, you may have to set up more than one pair of groups.

Ideal group size is three or four students per group, but you could have several more if you subdivide the functions of the group members more finely. Ideally, have the “nucleus” groups in one room and the “cytoplasm” groups in another, to represent the two separate compartments where these processes occur.

Alternatively, have the groups meet in discrete, separate parts of the classroom.

2. Have the group of students simulating transcription (the “nucleus” group) begin to generate an mRNA molecule. One student will read the “coding” sequence. As he or she reads the nucleotides, another student will announce the correct RNA base to insert. For example, if the student reading the coding strand says “A,” the second student will say “U.” 3. Have one or two students “synthesize” the mRNA strand by selecting the correct RNA base from the RNA nucleotide pool and taping them together in sequence.

4. When the mRNA is complete, the members of the “nucleus” group carry it to the “cytoplasm” group. This represents the mRNA leaving the nucleus through the nuclear pores.

5. The “cytoplasm“ group now translates the sequence. They should lay the sequence out on a flat surface. One student should read the sequence, but this time, read the nucleotides in groups of three, starting from the beginning. A second student will immediately create a tRNA by taping the anticodon nucleotides to an index card. Meanwhile, a third student will determine the correct amino acid to go with the codon announced by the first student. This third student, or a partner, will select the correct amino acid from the pool and tape it lightly to the index card, opposite the anticodon. The completed tRNA, with anticodon and amino acid attached, should be placed along the mRNA with the anticodon next to its corresponding codon.

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Instructor Guide Biology: Life on Earth Do the same for the second codon. When its corresponding tRNA is assembled, place it next to the first tRNA along the mRNA strand. Continue like this until the last codon is reached. (Note: Although it may be tempting to simulate the tRNA binding sites on the ribosome, this lends a degree of detail and confusion that you will probably find counterproductive at this point.)

When the last codon has been translated, the students should tape the amino acids together in sequence, and remove them from the tRNAs. This is the finished protein.

Assessment Suggestions There are several questions in the test bank that cover these two sections of the textbook. Alternatively, provide students with a sample DNA sequence on an exam, and have them write down the sequence of the mRNA that would be produced, as well as the amino acid sequence. As part of their answer, have them indicate which processes would occur in which subcellular compartment.

A A C C G G U U

A A C C G G U U

A A C C G G U U

A A C C G G U U

A A C C G G U U

A A C C G G U U

Lecture Activity 12.4: Point Mutation Group Activity Estimated Time to Complete: 10–15 minutes Section Reference 12.4 How Do Mutations Affect Protein Structure and Function?

Introduction Students often assume that all mutations cause a change in proteins. This exercise will demonstrate that nucleotide substitutions often result in no change at all in the protein, whereas others can have a profound change. Furthermore, it should demonstrate that the third codon position is usually the least important in specifying the amino acid. Finally, it also demonstrates the basic connection between mutation of the DNA and possible changes in the resulting protein. If class time is short, the instructor could do this exercise on the board as part of a lecture, enlisting the students’ aid in translating the sequences.

Materials Needed No special materials are needed. However, if the students do not have their books in class, the instructor may wish to either photocopy Table 12-3 from the textbook or project it as an overhead or PowerPoint slide during the exercise.

Procedures 1. Before beginning the exercise, it may be productive to have a brief class discussion of the question: Will a change in a single DNA nucleotide always result in a changed protein?

2. Divide the class into groups of about four students. Have each group generate a random 15-nucleotide DNA sequence, starting with TAC, and write it on a piece of paper.

3. The students should now transcribe (write down the mRNA sequence) and translate (write down the corresponding amino acid sequence) the DNA, referring to Table 12-3 in the text as needed.

4. The students should then mutate the original sequence by changing the first nucleotide, and then translating again. They should note any changes in the resulting amino acid sequence. (Note: This mutation should result in no resulting protein, as the start codon is lost.)

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Continue in this fashion, mutating the second nucleotide (third, fourth, fifth, etc.) in the original strand until the end is reached, translating the mutated strand each time. The mutations are not cumulative; that is, each mutated strand should differ from the original strand by no more than one nucleotide.

The students should record which mutations caused a change in the resulting protein. For most randomly generated sequences, there should be one or two mutated strands that produce proteins that are identical to the original strand. Furthermore, these will almost always result from mutations of the third nucleotide in the codons.

Variation: You can demonstrate frameshift mutations nicely using a similar exercise. A randomly generated sequence of at least 30 nucleotides or longer will almost always produce a premature stop codon if the frameshift occurs close to its beginning.

Assessment Suggestions There are several questions in the test bank that cover this section of the textbook. Alternatively, provide DNA sequences on an exam, and have the students translate them using Table 12-3. Then ask them to create specific mutated strands; for example, have them change one nucleotide that you know will create no change to the resulting protein. Have them translate again. Do this with three or four mutations; be sure to craft “mutations” that will provide a variety of results.

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CHAPTER 13 BIOTECHNOLOGY LECTURE OUTLINE Case Study: Guilty or Innocent?

13.1 What Is Biotechnology?

A. Biotechnology Is Any Use or Alteration of Organisms, Cells, or Biological Molecules to Achieve Specific Goals 1. Traditional biotechnology includes selective breeding, domestication, brewing, winemaking, etc.

2. Modern biotechnology includes a variety of techniques a. Cloning is the process that makes copies of genes or entire organisms b. Genetic engineering is the modification of genetic material toward a specific end â Science in Action: Carbon Copies—Cloning in Nature and the Lab (Figure E13-1) c. Recombinant DNA is DNA that has been altered to contain genes or portions of genes from different organisms i. Organisms that express DNA that has been modified are called genetically modified organisms (GMOs) 3. This chapter will address five themes a. Recombinant DNA mechanisms found in nature b. Biotechnology in criminal forensics c. Biotechnology in agriculture d. Analyzing the entire genomes of organisms e. Biotechnology in medicine â Lecture Activity 13.1: Biotechnology in the News

13.2 How Does DNA Recombine in Nature?

A. Sexual Reproduction Recombines DNA B. Transformation May Combine DNA from Different Bacterial Species (Figure 13-1) 1. Bacteria can pick up different types of DNA from the environment a. DNA from another bacterium b. Plasmids are circular molecules of DNA i. These molecules are 1,000 to 100,000 nucleotides in length ii. There can be several in a single bacterium iii. They can carry genes for novel metabolic activities iv. They can carry genes for antibiotic resistance C. Viruses May Transfer DNA Among Species (Figure 13-2) 1. Viruses are made up of protein and nucleic acid 2. Infection occurs when viral genes are reproduced in an infected cell a. Infected cells are used to make new viruses b. New copies of genes become packaged in viruses and are released c. Sometimes host genes become packaged as well d. These genes can be transferred to the next host e. Next host may be an unrelated species

13.3 How Is Biotechnology Used in Forensic Science?

A. Forensic Science Uses DNA Biotechnology to Identify Victims and Criminals 1. Many techniques are used in other areas of biotechnology B. The Polymerase Chain Reaction Amplifies DNA (Figure 13-3) 1. PCR amplifies small amounts of DNA into virtually unlimited quantities and occurs in two steps a. The DNA segment to be copied is marked b. Repetitive reactions make multiple copies 2. This process can target specific sequences of DNA 126

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3. DNA polymerase requires a primer a. This is a small piece of DNA complementary to template strand b. It binds to a template with complementary base pairing c. It serves as a starting point for DNA polymerase 4. In PCR, two DNA primers are needed a. They are at the ends of the DNA segment of interest b. One is complementary to the beginning of one strand of the DNA segment c. The other is complementary to the beginning of the other strand d. These provide starting points for the DNA polymerase 6. In a test tube, mix DNA, primers, nucleotides, and DNA polymerase 7. The temperature is cycled during the process a. High (90–95°C): “melts” the DNA to make it single-stranded b. Lower (50°C): primers will bind to DNA c. Higher (70–72°C): DNA polymerase synthesizes new strands i. A special DNA polymerase is used that was isolated from microbes that live in hot springs (Figure 13-4) ii. This polymerase is active only at high temperature d. Repeat e. The process doubles the number of copies of DNA each time: 1, 2, 4, 8, 16, 32 copies, and so on C. Differences in Short Tandem Repeats Are Used to Identify Individuals by Their DNA 1. Short tandem repeats (STRs) are repeating segments of DNA (Figure 13-5) a. These can be used to identify different individuals b. They are two to five nucleotides long c. The number of repeats varies greatly among people d. In forensics, a standard set of 13 STR regions is used i. Primers that amplify only the DNA surrounding the STRs are used â Case Study Continued: Guilty or Innocent?

D. Gel Electrophoresis Separates DNA Segments (Figure 13-6) 1. DNA is placed into wells at one end of a slab of a gel (agarose) 2. The gel is placed into buffer in a special chamber 3. Electricity is passed through the gel 4. DNA is negatively charged and will move toward the positive electrode 5. Smaller pieces move more rapidly 6. DNA becomes separated by size, forming distinct bands on the gel E. DNA Probes Are Used to Label Specific Nucleotide Sequences (Figure 13-7) 1. These are short pieces of DNA that are complementary to a given STR 2. They are labeled with radioactivity or a colored molecule 3. DNA in a gel is transferred to a special nylon paper a. The paper with the DNA is bathed in solution containing DNA probes b. The STRs are immediately visible F. Unrelated People Almost Never Have Identical DNA Profiles (Figure 13-8) 1. DNA samples run on STR gels produce a pattern called a DNA profile 2. The profiles allow comparisons between DNA samples to determine if they match particular people a. This can be helpful in criminal investigations b. The chances of a random match of the 13 STRs is very rare â Lecture Activity 13.2: Paternity Testing Using STR Polymorphisms â Earth Watch: What’s Really in That Sushi? (Figures E13-2 and E13-3) â Case Study Continued: Guilty or Innocent?

13.4 How Is Biotechnology Used to Make Genetically Modified Organisms?

A. There Are Three Steps to Making a GMO 1. Obtain the desired gene 2. Clone the gene 3. Insert the gene into the cells of a the host organism B. The Desired Gene Is Isolated or Synthesized C. The Gene Is Cloned 1. Insert the gene into a plasmid .

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Instructor Guide Biology: Life on Earth a. Bacteria can take up the plasmid and produce huge quantities of it b. Plasmids can be easily separated from bacteria when needed c. Plasmids can be taken up by other bacteria or injected into other organisms d. Bacteria with the plasmid can infect plant cells and transfer the desired gene to the plant 2. Restriction enzymes cut DNA sequences at specific nucleotide sequences (Figure 13-9) a. The cuts often leave “staggered” or “sticky” ends 3. Cutting two pieces of DNA with the same restriction enzyme allows the pieces to be joined together (Figure 13-10) a. The sticky ends are the same i. Can join gene and plasmid ii. The nicks can be sealed with DNA ligase D. The Gene Is Inserted into a Host Organism 1. Transfecting the host is the process of inserting the foreign gene into it a. In some cases, vectors such as viruses or bacteria are used for this purpose b. “Gene guns” inject DNA via small pellets coated with metals c. Small pipettes can also be used to inject the genes directly into a host cell (Figure 13-11)

13.5 How Is Biotechnology Used in Agriculture?

A. Many Crops Are Genetically Modified 1. Almost all genetically modified organisms are plants 2. In 2011 in the USA: 88% of corn, 90% of cotton, 94% of soybeans were transgenic (Table 13-1) 3. Most are modified for resistance to insects and herbicides 4. Insect resistance can be enhanced with the Bt gene product (Figure 13-12) a. This substance harms insect digestive tracts, but not mammals B. Genetically Modified Plants May Be Used to Produce Medicines 1. Biotechnology can be used to insert medically useful genes into plants a. These can be used as vaccines that can be eaten C. Genetically Modified Animals May Be Useful in Agriculture and Medicine 1. Producing transgenic animals often involves using a disabled virus to inject the desired DNA 2. This can also be done by injecting modified DNA into a fertilized egg a. After a few rounds of cell division, the egg is implanted into a surrogate mother 3. Biotechnologists are also developing animals that will produce medicines and other essential proteins

13.6 How Is Biotechnology Used to Learn About the Genomes of Humans and Other Organisms?

A. Why Do Scientists Want to Sequence the Genomes of Humans and Other Organisms?

1. This would allow them to discover the functions of genes that are unknown 2. The information could assist medical practice 3. This will help us appreciate the place of humans in the evolution of life

13.7 How Is Biotechnology Used for Medical Diagnosis and Treatment? â Health Watch: Prenatal Genetic Screening (Figures E13-4 and E13-5) A. DNA Technology Can Be Used to Diagnose Inherited Disorders 1. Using PCR to obtain disease-specific alleles a. PCR can amplify and isolate specific genes for various diagnostic procedures 2. Restriction enzymes may cut different alleles of a gene at different locations a. Some alleles may have different sequences that are not cut by the same enzyme i. This results in different lengths of DNA fragments ii. These can be separated and visualized by gel electrophoresis iii. Example: sickle-cell trait 3. Different alleles bind to different DNA probes a. This is useful when there are numerous alleles for a disorder, e.g., cystic fibrosis i. Over 1,200 different alleles encode defective chloride pump ii. Inherited as recessive trait b. Companies have manufactured arrays of filter paper with many DNA probes attached i. If you cut up a person’s DNA, label it, and wash over an array, you can detect various cases with this method (Figure 13-13) .

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ii. DNA arrays containing thousands of probes for human genes are being manufactured B. DNA Technology Can Help to Treat Disease 1. There are two applications of DNA technology in treating disease a. Producing medicines using bacteria and recombinant DNA methods b. Gene therapy 2. Using biotechnology to produce medicines a. Many human proteins, such as insulin and growth hormone, are being produced by inserting the gene into bacteria b. The bacteria then express the gene and produce the protein 3. Treating AIDS by gene therapy a. The HIV virus binds to the CCR5 receptor protein i. Some people carry a mutant form of the gene which produces a CCR5 receptor that HIV doesn’t bind ii. Biotechnology may be able to treat AIDS by damaging the CCR5 gene with a specialized enzyme 4. Treating severe combined immune deficiency by gene therapy a. In SCID, a child fails to develop an immune system i. Several forms of SCID exist ii. One type is defective adenosine deaminase (ADA) b. In 1990, Ashanti DeSilva was 4 years old when treated with gene therapy i. White blood cells were removed and infected with virus containing functional ADA ii. She is reasonably healthy iii. More recent types of treatments involve removing bone marrow stem cells and inserting the gene into them c. A second type of SCID is X-linked SCID i. Many children have been treated for this with gene therapy, but some complications have arisen

13.8 What Are the Major Ethical Issues of Modern Biotechnology?

A. Should Genetically Modified Organisms Be Permitted in Agriculture?

1. There are three major differences between traditional agriculture and modern genetic engineering a. Genetic engineering can produce massive changes in a single generation b. Genetic engineering can combine genetic material from very different species c. Genetic engineering can create genes and alleles that never existed before 2. Transgenic crops have clear advantages a. Herbicide resistance: fewer weeds, so higher yields b. Insect resistance: use less insecticide c. Overall, larger harvests at lower cost to farmer â Health Watch: Golden Rice (Figure E13-6) 3. Are foods from GMOs dangerous to eat? a. There is no reason to think that GMOs are dangerous to eat b. Some people might be allergic to genetically modified plants i. Brazil nut protein in soybeans ii. Potential problem was recognized before soybeans were marketed 4. Are GMOs hazardous to the environment? a. Pollen will carry genes of transgenic crops b. Wind can carry pollen for many miles c. If there are wild relatives, could introduce new genes to wild population d. Bacteria and viruses could transfer genes to other species e. Transgenic animals do not pose the same issues as transgenic plants B. Should the Genome of Humans Be Changed by Biotechnology?

1. Some ethical issues related to biotechnology are the same as with other medical procedures â Health Watch: Prenatal Genetic Screening (Figures E13-4 and E13-5) a. Should results of diagnostics on embryos drive decisions to abort? b. Traditional methods could diagnose trisomy 21, with similar ethical concerns 2. The creation of embryos to use as tissue donors presents ethical concerns a. Girl born with Franconi anemia: normally fatal in childhood b. Parents created dozens of embryos in culture and screened them c. Selected a healthy one and implanted in the mother .

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Instructor Guide Biology: Life on Earth d. A son was born; umbilical cord blood used to treat sister e. Both children are now healthy f. Was it ethical to create dozens of embryos?

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3. What if biotechnology could change the genes of fertilized eggs? (Figure 13-14) a. May be possible to alter genes in fertilized eggs b. Could be used to “correct” genetic disorders such as SCID, cystic fibrosis c. Would this type of alteration be ethical? d. What about improving performance? Where should the line be drawn? â Lecture Activity 13.3: Ethical and Moral Implications of Biotechnology â Lecture Activity 13.4: Guilty or Innocent?

Case Study Revisited: Guilty or Innocent? (Figure 13-15)

KEY TERMS amniocentesis biotechnology chorionic villus sampling (CVS) cloning DNA cloning DNA probe DNA profile gel electrophoresis

gene therapy genetic engineering genetically modified organism (GMO) plasmid polymerase chain reaction (PCR) recombinant DNA

restriction enzyme restriction fragment length polymorphism (RFLP) short tandem repeat (STR) transformation transgenic

LECTURE ACTIVITIES Lecture Activity 13.1: Biotechnology in the News Estimated Time to Complete: 10 minutes Section Reference Chapter 13: Biotechnology Introduction The rapid advances in biotechnology have generated much attention in the press, not all of it positive. Whether the issue is genetically modified foods, forensic testing, cloning technology, or any of the other diverse topics encompassed by biotechnology, student interest can be stimulated by these stories. If you did not use Lecture Activity 9.1, DNA Is Relevant, you may wish to complete this activity now. This activity reinforces the idea that DNA technology is relevant to everyone, and that understanding the principles underlying biotechnology is important in our modern world.

Materials Needed None Procedures 1. Collect news articles that describe the use of molecular techniques in agriculture, medicine, forensics, or any other subject that is recent and relevant to biotechnology. You could also clip help-wanted ads from the local newspaper (or a national paper such as The New York Times). In particular, ads targeting nonscientists to work in the biotech industry will make an impression on your students.

2. Create a one-page handout that is a collage of headlines or short excerpts from these articles. Design it so that the diversity of areas in which biotechnology has an impact is readily apparent.

3. Distribute the handout to the class, and then lead a discussion about the diversity of areas in which biotechnology has had an impact. If you have included jobs in the handout, point out how a knowledge of biotechnology might be useful to people with degrees in both science and nonscience disciplines.

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Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Name three significant topics in the news that involve biotechnology.

2. Describe at least two career opportunities involving biotechnology that are available to nonscience majors.

Lecture Activity 13.2: Paternity Testing Using STR Polymorphisms Estimated Time to Complete: 10–15 minutes Section Reference 13.3 How Is Biotechnology Used in Forensic Science?

Introduction This exercise will provide a practical but simplified demonstration of how STR polymorphisms are used to determine paternity.

It also gives the students a chance to see what those rows of bars on an electrophoresis gel represent. The exercise uses only 3 STR loci; you should point out to your students that forensic analysis typically looks at a minimum of 10 loci, and usually more.

Materials Needed Provide the students with a copy of the example gel (appended, or create your own). You can use the sample to produce handouts, or you can make overhead transparencies or PowerPoint slides for projection to the class as a whole.

Procedures 1. Introduce the exercise by reviewing STRs (section 13.3). Point out that one half of a child’s chromosomes, and of the alleles they carry, is inherited from each of his or her parents. In the example provided, you can see that the bands are clustered into three groups; the central group shows everyone being homozygous for a single allele, except for Chris. Everyone is heterozygous for the other two groups. Point out these patterns to your students, so that they can make the connection between these bands and the alleles they learned about in Chapter 12.

2. Once the students understand the background, identify the individuals whose STRs are displayed, and the scenario leading up to the analysis.

• Alex and Barb are a separated couple.

• Chris is Barb’s new boyfriend.

• Doug and Ellen are children born to Alex and Barb when they were still together.

• Frank was born after Alex and Barb separated. Barb wants Alex to pay child support.

• Alex doesn’t believe that Frank is his child. He asked for a genetic analysis to support his case.

• Once the students understand the question, ask the following questions: o Can Alex be Frank’s father? Why or why not? o Can Chris be Frank’s father? Why or why not? o Does this test prove conclusively that either man is Frank’s father? Why or why not? o Does this test prove conclusively that either man is excluded from being Frank’s father? Why or why not?

3. Conclude by reinforcing the idea that when many more loci are considered, the confidence with which you can say a person is identified as the father increases to the point that the possibility of making an error is minimal.

Assessment Suggestions Include a similar question on a written exam. Try to create a pattern of bands that differs significantly from the example used in class.

Handout or display See following page. .

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 13.2 Handout—A Gel Showing the Results of the STR Analysis for Alex, Barb, Chris, and the Children

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Lecture Activity 13.3: Ethical and Moral Implications of Biotechnology Estimated Time to Complete: 10–15 minutes Section Reference 13.8 What Are the Major Ethical Issues of Modern Biotechnology?

Introduction This chapter introduces technologies that are rapidly advancing; in many ways, our social systems have not yet resolved the ethical and moral issues raised by these quickly evolving technologies. This exercise is designed to get your students thinking about the ethical, moral, environmental, and societal consequences of biotechnology.

Materials Needed None Procedures 1. This exercise can be done as a class discussion, or as a task for small groups. One possibility is to assign different topics to each small group, and have each group report on their discussion to the class as a whole.

If you structure the activity this way, you should at least double the estimated time.

2. Present one or more of the following questions to the class or the individual groups.

• What are the possible consequences, both positive and negative, of gene transfers across species and kingdom barriers?

• What ethical limits should we place on the application of DNA technology? Who should decide these limits?

• Should genetically modified organisms, including crops, be released into the environment?

• Who has a right to your genetic information? Should insurance companies be allowed free access to it?

Should they be allowed to deny you coverage based on a genetic predisposition toward a particular disease? Should employers have access to your genetic information? The government? Law enforcement agencies?

• Should people be allowed to screen embryos for genetic defects before having them implanted?

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Describe three ethical issues raised by our rapidly advancing biotechnologies.

Lecture Activity 13.4: Guilty or Innocent?

Estimated Time to Complete: 10–15 minutes Section Reference Case Study: Guilty or Innocent?

Introduction The Case Study introduces a legal case in which DNA analysis proved critical to solving the crime and convicting the perpetrator. Students and the general public often think of molecular evidence, because it is “scientific,” as being infallible. However, no such analysis is foolproof. Sloppy handling of evidence can render molecular evidence just as suspect as nonmolecular evidence.

This exercise is a class discussion of the strengths and weaknesses of molecular forensic evidence.

Materials Needed None

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Procedures 1. Review the story described in the Case Study. Describe in general terms that evidence must first be collected at a crime scene, from victims, suspects, and other persons involved, as well as from nonhuman organisms in the surroundings: pets, plant material, and soil, for example. All of this evidence must be carefully labeled, protected from contamination, and preserved.

2. Discuss as a class the chain of custody of forensic evidence, and the probabilistic aspects of molecular forensic analysis. Possible topics to consider include intentional contamination (“framing”), accidental contamination, and the low but nonzero probability of false positives.

3. This can be either a class discussion or you can break the class into small discussion groups.

4. If you break the class into separate groups, you could assign different questions to each group and have each summarize their discussion to the class as a whole. This would require more class time.

Assessment Suggestions Include a short-answer question on a written exam, such as: 1. Describe the strengths and potential problems associated with the use of molecular forensic evidence in criminal proceedings.

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CHAPTER 14 PRINCIPLES OF EVOLUTION LECTURE OUTLINE Case Study: What Good Are Wisdom Teeth and Ostrich Wings?

14.1 How Did Evolutionary Thought Develop?

A. Evolution Is the Change over Time in the Characteristics of Populations B. Early Biological Thought Did Not Include the Concept of Evolution 1. Pre-Darwinian science held that all organisms were created by God 2. Plato (427–347 B.C.) proposed that each object on Earth was a temporary reflection of its divinely inspired “ideal form” 3. Aristotle (384–322 B.C.) categorized all organisms into a linear hierarchy he called the “Ladder of Nature” (Figure 14-1) C. Exploration of New Lands Revealed a Staggering Diversity of Life 1. By the 1700s, naturalists had begun to realize that the variety of living organisms was much greater than anyone had suspected (Figure 14-2) D. A Few Scientists Speculated That Life Had Evolved 1. G. L. LeClerc (1707–1788) suggested that creation provided a relatively small number of founding species that evolved through natural processes E. Fossil Discoveries Showed That Life Has Changed over Time 1. Fossils are the preserved remains of organisms (Figure 14-3) 2. W. Smith (1769–1839) recognized that certain fossils were always found in the same rock layers 3. Other scientists discovered that fossil remains showed a remarkable progression (Figure 14-4) F. Some Scientists Devised Nonevolutionary Explanations for Fossils 1. G. Cuvier (1769–1832) suggested the theory of catastrophism a. He stated that successive catastrophes produced layers of rock and destroyed many species, with some being fossilized G. Geology Provided Evidence That Earth Is Exceedingly Old 1. C. Lyell (1797–1875) built on the thinking of Hutton that natural forces explained the findings of geology a. Lyell developed the idea of uniformitarianism, that the same gradual geological processes that have shaped the Earth are still occurring today H. Some Pre-Darwin Biologists Proposed Mechanisms for Evolution 1. Lamarck (1744–1829) proposed the idea of the inheritance of acquired characteristics a. Changes during an organism’s lifetime would be passed on to the offspring b. Lamarck’s ideas were refuted upon further study I. Darwin and Wallace Proposed a Mechanism of Evolution 1. C. Darwin (1809–1882) developed the theory of evolution; species evolved through natural selection and an adaptation to their ever-changing environment (Figure 14-5) 2. A. Wallace (1823–1913) supported Darwin’s theory â Science in Action: Charles Darwin—Nature Was His Laboratory (Figures E14-1 and E14-2)

14.2 How Does Natural Selection Work?

A. Darwin and Wallace’s Theory Rests on Four Postulates B. Postulate 1: Individuals in a Population Vary (Figure 14-6) 1. Variations in populations are a result of random mutation C. Postulate 2: Traits Are Passed from Parent to Offspring 1. Individuals pass their traits on to offspring D. Postulate 3: Some Individuals Fail to Survive and Reproduce 1. More organisms are born than survive long enough to reproduce E. Postulate 4: Survival and Reproduction Are Not Determined by Chance 1. Reproductive success depends on an individual’s characteristics .

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Instructor Guide Biology: Life on Earth F. Natural Selection Modifies Populations over Time 1. Natural selection acts on individuals, but populations evolve â Lecture Activity 14.1: Blended Inheritance vs. Mendelian Genetics

14.3 How Do We Know That Evolution Has Occurred? â Lecture Activity 14.2: Getting the Big Picture A. Fossils Provide Evidence of Evolutionary Change over Time 1. Intermediate forms are evidence of evolutionary change (Figure 14-7) â Lecture Activity 14.3: Your Own “Fossil Record” B. Comparative Anatomy Gives Evidence of Descent with Modification 1. Homologous structures provide evidence of common ancestry (Figure 14-8) a. These structures may be different in form but have the same evolutionary origin â Lecture Activity 14.4: Homologous Forelimb Bones 2. Functionless structures are inherited from ancestors (Figure 14-9) a. Vestigial structures serve no apparent purpose and are inherited 3. Some anatomical similarities result from evolution in similar environments (Figure 14-9) a. Organisms that live in similar environments may evolve similar structures through convergent evolution b. Analogous structures may be similar in function but are typically very different in structure (Figure 14-10) C. Embryological Similarity Suggests Common Ancestry 1. All vertebrate embryos look similar to one another in early development, with the development of a tail and gill slits (Figure 14-11) D. Modern Biochemical and Genetic Analyses Reveal Relatedness Among Diverse Organisms 1. DNA similarities show relatedness between organisms (Figure 14-12) 2. All cells have DNA, RNA, ribosomes, the same 20 amino acids, and use ATP as an energy carrier â Case Study Continued: What Good Are Wisdom Teeth and Ostrich Wings?

14.4 What Is the Evidence That Populations Evolve by Natural Selection?

A. Controlled Breeding Modifies Organisms 1. Artificial selection is the breeding of domestic plants and animals to produce desired features (Figure 14-13) B. Evolution by Natural Selection Occurs Today 1. Brighter coloration can evolve when fewer predators are present (Figure 14-14) a. Guppy populations have exhibited this phenomenon 2. Natural selection can lead to herbicide and pesticide resistance a. Repeated exposure to herbicides can lead to natural selection of resistance in plants b. Repeated exposure to pesticides can lead to natural selection of resistance in insects â Earth Watch: People Promote High-Speed Evolution (Figure E14-3) 3. Experiments can demonstrate natural selection a. Anolis lizard leg evolution is an example (Figures 14-15) 4. Selection acts on random variation to favor traits that work best in particular environments a. The variations upon which natural selection works are produced by chance mutations b. Natural selection favors organisms that are best adapted to a particular environment

Case Study Revisited: What Good Are Wisdom Teeth and Ostrich Wings? (Figure 14-16)

KEY TERMS analogous structures artificial selection convergent evolution

evolution fossil homologous structure

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natural selection population vestigial structure

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LECTURE ACTIVITIES Lecture Activity 14.1: Blended Inheritance vs. Mendelian Genetics Estimated Time to Complete: 5–10 minutes Section Reference 14.2 How Does Natural Selection Work?

Introduction The major “hole” in Charles Darwin’s proposal that evolution occurs by natural selection was his understanding of the principles of inheritance of traits from parents to offspring. This is not surprising, as Gregor Mendel’s work on determining these principles had not been done at the time of the publication of On the Origin of Species, and were not generally recognized and accepted until well after Darwin’s death. In the absence of such work, Darwin held to the concept of “blended inheritance,” in which it was assumed that offspring are a mixture of the traits of both parents. For example, a tall male and a short female might produce medium-sized offspring.

In this activity, students can compare the expected outcomes of genetic crosses, first using correct Mendelian inheritance principles, then using the incorrect concept of blended inheritance. They may conclude that blended inheritance, if true, would actually reduce the opportunity for evolution, whereas Mendelian inheritance maintains that opportunity.

Materials Needed None Procedures 1. Briefly review basic Mendelian genetic principles.

(Chapter 10, Patterns of Inheritance) 2. Introduce the concept of blended inheritance and Darwin’s belief in it to the class.

3. Write the following genetic cross on the board: AA × aa. Explain that the phenotypes of these genotypes correspond to extreme values of a trait, such as tall and short.

4. Ask the students to predict the expected offspring proportions of this cross according to Mendelian genetics.

What is (are) their phenotype(s)? (all Aa offspring; medium height, or tall if A is dominant to a) 5. Now ask them to predict the expected offspring proportions if blended inheritance were correct.

(All would be intermediate—Aa, medium height—so, there could be no dominance of alleles under blended inheritance.)

6. Repeat this for the cross Aa × Aa. (Mendelian inheritance predicts proportions of ¼ AA, ½ Aa, and ¼ aa; blended inheritance predicts all intermediate phenotypes again [Aa].)

Assessment Suggestions Discuss the results of the activity with the class using the following questions as guides: 1. What would happen to a population of AA, Aa, and aa individuals with Mendelian inheritance?

(All three genotypes will remain in the population, as various types of matings produce all three.)

2. What would happen with blended inheritance?

(Eventually, the entire population would consist of the intermediate [Aa] genotype and phenotype as extreme phenotypes are eliminated by the blending.)

3. Would natural selection be effective on a population with Mendelian inheritance?

(Yes, the variation in the phenotype is maintained, so one phenotype may be favored over others and be more represented in later generations.)

4. Would it be effective on a population with blended inheritance?

(Not for very long, because the phenotypic variation would be quickly eliminated by the genetics. There would be no way for extreme phenotypes to be favored, unless they were to mate only with an individual with the same phenotype. Thus, Darwin’s concept of inheritance, if true, would greatly restrict the possibility that a

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Instructor Guide Biology: Life on Earth population could evolve by natural selection. Mendelian genetics allows evolution by natural selection to be possible.)

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Lecture Activity 14.2: Getting the Big Picture Estimated Time to Complete: 10–15 minutes Section Reference 14.1 How Did Evolutionary Thought Develop?

14.3 How Do We Know That Evolution Has Occurred?

Introduction The study of evolution involves looking at evidence of living organisms from the past, such as fossils. This evidence, however, is limited to parts of organisms that are easily fossilized (i.e., they do not decay quickly) and happened to be in conditions suitable for fossilization soon after death. Fossilization is a very rare process, so even a fairly complete fossil record is a series of “snapshots” of only pieces of certain species at very long intervals. By observing overall patterns and comparing the observed fossil anatomy to living species, we may be able to build up a picture of biological change in a lineage over time.

In this activity, students will simulate the process of inferring the “big picture” by gradually seeing more and more information about a photograph or painting, and modifying their guess about its subject as they proceed.

Using puzzles, the picture will be revealed in pieces, a process that is analogous to the discovery of increasing numbers of fossils representing changes in a taxonomic group.

Materials Needed • Several 24-piece children’s puzzles, each with a single clear subject for the picture (the picture can be a photograph, drawing, or painting) Procedures 1. Before class, remove the puzzles from their boxes (so that students cannot see the full picture on the box).

Remove all of the edge pieces to make it more difficult to establish a pattern while putting together the puzzles.

2. Introduce the topic to the class, perhaps by expanding on the first paragraph of the Introduction above.

3. Have the class divide into smaller groups of four to six students. (Alternatively, if the puzzle can be displayed to the entire class via a document camera, this can be done as a whole-class exercise.)

4. Give each group two or three random pieces of a puzzle. Ask them to try to arrange them according to their position in the final picture and to guess at the subject of the picture. Record the guess.

5. Repeat the previous step until the students correctly identify the picture.

Assessment Suggestions After the activity, bring the class back together to discuss it. Some possible discussion questions include: 1. How many puzzle pieces were needed to get a rough idea of the picture? How many for the full picture?

(This will vary—one or two rounds to get an idea, more for an accurate conclusion.)

2. How is this activity like trying to study evolution using fossil evidence?

(Paleontologists try to put together an accurate “picture” of an extinct organism based on fossils and other preserved evidence. The more evidence that is available, the better the picture.)

3. How confident would you be in a “story” of evolution constructed from a few fossils? Many fossils? (Answers will probably vary, but confidence in the accuracy of a conclusion will increase with additional evidence.)

4. Would the fossils have to be complete skeletons, or can whole-organism anatomy be inferred from a few or single bones?

(By comparing individual fossil bones to known fossils and bones of living species, one can certainly tell a great deal about the original owner of the bone, sometimes the actual species.)

5. What can you learn from 10 well-preserved complete fossils of one species from the same time period?

From 10 similarly preserved fossils from intervals of several million years?

(In the first case, you could probably learn a lot about the species at that time, and how much anatomical variation there might be in the species, such as sexual dimorphism [differences in males and females]. In the latter case, you can get an idea of how that lineage has evolved morphologically, if it occurred quickly enough to see changes over a few million years.)

6. What is inference? How do biologists use inference to construct a picture of the past?

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Instructor Guide Biology: Life on Earth (Inference means reasoning conclusions from observed evidence. Biologists use this process to make logical speculative conclusions about the anatomy, life, and habits of species from the available evidence.)

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Lecture Activity 14.3: Your Own “Fossil Record” Estimated Time to Complete: 5–10 minutes Section Reference 14.3 How Do We Know That Evolution Has Occurred?

Introduction Biologists base their understanding of the past on fragmentary pieces of evidence—fossils, comparisons of fossil material to living species, climatic information from chemical analysis of rocks, and other geological analyses.

From this information, we can try to construct an overall description of the organism and its environment—for example, where and under what ecological conditions it lived, how it performed various activities, and what its predators and food species may have been. Sometimes, you can tell a lot from just a little evidence.

In this brief activity, each student will list the contents of their own “fossil record”—those things that may provide a picture of their lives, activities, habits, and habitats. They may see themselves as a future archaeologist or paleontologist might see them.

Materials Needed None Procedures 1. Introduce the activity to the class using the Introduction as a reference.

2. Have the students take a few minutes to jot down the specific current contents of their own living areas or bedrooms—clothes, books, DVDs, and any other objects or materials that might tell someone else about their lives.

Assessment Suggestions Use the following questions as a guide for class discussion about the activity: 1. What could an observer with no previous knowledge of you or your life tell about you? (taste in clothes, music, literature; what classes you take; general interests; eating habits; etc.)

2. What could that observer not tell about you? (past activities and other interests not represented by current observations) 3. Is this an accurate picture of you and your life? (probably yes to some extent, probably missing some things but not really false) 4. How is this activity similar to scientists reconstructing natural history?

(Biologists studying past evolution may get a partial picture of the anatomy, physiology, habits, and environment of an organism from fossils and other clues, but some details will necessarily be missing. However, in some cases the scientist can get a fairly good idea of the life of that organism.)

Lecture Activity 14.4: Homologous Forelimb Bones Estimated Time to Complete: 10 minutes Section Reference 14.3 How Do We Know That Evolution Has Occurred?

Introduction One piece of evidence that different species are related by descent from a common ancestor is that they have homologous structures. Different species may have the same anatomical structures in approximately the same positions, although their sizes, shapes, and specific functions may vary among species. Darwin proposed that this similarity reflects a common ancestry and that the differences represent specific evolutionary modifications, presumably resulting from natural selection in the lineages leading to the modern species.

This activity allows students to compare forelimb bones of vertebrate species, using the human arm as a reference, and to identify the homologous bones in each forelimb. .

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Instructor Guide Biology: Life on Earth

Materials Needed • Bones from chicken wing (cooked with meat removed) • Articulated skeletal human arm (if available) • Skeletal forelimbs of other vertebrates (if available), or Figure 14-7 Procedures 1. Display the skeletal human arm (or a labeled figure of it) to the class. Identify the radius, ulna, and humerus, and note their positions.

2. Display the articulated chicken wing bones. Point to the major bones and have the students identify them, using the names of the human homolog.

3. Do the same for displays of other skeletal vertebrate forelimbs, or use an unlabeled version of Figure 14-7.

Assessment Suggestions Discuss the question, How are homologous structures evidence of evolution?

(Similarity suggests relatedness; differences suggest biological change from a common ancestor. Natural selection is suggested because the form of the structure [if not vestigial] is suited to its function.)

Quiz the students on the human homologs of bones by having them label Figure 14-7.

Present the students with another reference set of human bones and unlabeled diagrams of the homologs in related vertebrates. Have them identify the homologs in each set. Possible examples are the hindlimb bones of terrestrial vertebrates, or the jaw/ear bones of fish, amphibians, reptiles, and mammals.

Handouts or Display None, other than those listed in Materials Needed.

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CHAPTER 15 HOW POPULATIONS EVOLVE LECTURE OUTLINE Case Study: Evolution of a Menace 15.1 How Are Populations, Genes, and Evolution Related?

A. Evolution Is the Change in the Characteristics in a Population over Time 1. A population is a group that includes all the members of a species living in a given area B. Genes and the Environment Interact to Determine Traits 1. An organism’s genotype interacts with the environment to produce the phenotype (Figure 15-1) C. The Gene Pool Comprises All of the Alleles in a Population (Figure 15-2) 1. The relative proportion of each allele of a gene is the allele frequency D. Evolution Is the Change of Allele Frequencies Within a Population E. The Equilibrium Population Is a Hypothetical Population in Which Evolution Does Not Occur 1. The Hardy–Weinberg principle is a mathematical model that can illustrate evolution â In Greater Depth: The Hardy–Weinberg Principle 2. The equilibrium population is a non-evolving one that must meet five conditions a. No mutation occurs b. There is no gene flow between populations c. The population must be very large d. All mating must be random e. There is no natural selection 3. Few natural populations are truly in equilibrium

15.2 What Causes Evolution?

A. Mutations Are the Original Source of Genetic Variability 1. Most mutations are quickly corrected after they occur a. Unrepaired mutations may be passed to offspring and enter the gene pool 2. Inherited mutations are rare but important a. Despite the rarity, the cumulative effect of mutations is essential to evolution 3. Mutations are not goal directed a. Mutations happen spontaneously (Figure 15-3) â Case Study Continued: Evolution of a Menace B. Gene Flow Between Populations Changes Allele Frequencies (Figure 15-4) 1. Gene flow is the movement of alleles between populations a. Movement of alleles tends to change the gene pools of the destination population â Lecture Activity 15.1: Gene Flow in Action C. Allele Frequencies May Change by Chance in Small Populations 1. Genetic drift is the process by which chance events change allele frequencies (Figure 15-5) 2. Population size matters a. Genetic drift occurs more rapidly and has a bigger effect on small populations (Figure 15-6) â Lecture Activity 15.2: Genetic Drift and Random Evolution 3. A population bottleneck can cause genetic drift (Figure 15-7) a. In a population bottleneck, a population is drastically reduced by a natural catastrophe b. This can lead to a loss of genetic variability â Earth Watch: The Perils of Shrinking Gene Pools (Figure E15-1) 4. Isolated founding populations may produce bottlenecks (Figure 15-8) a. The founder effect occurs when isolated colonies are founded by a small number of organisms i. The founding population may have allele frequencies that are very different from those of the parent population

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Instructor Guide Biology: Life on Earth D. Mating Within a Population Is Almost Never Random (Figure 15-9) 1. This can affect the distribution of phenotypes in a population E. All Genotypes Are Not Equally Beneficial 1. Anytime an allele gives an individual some type of advantage in a population, that individual is favored by natural selection 2. A summary of evolution (Table 15-1) â Lecture Activity 15.3: Genetic Effects of Nonrandom Mating â Case Study Continued: Evolution of a Menace

15.3 How Does Natural Selection Work?

A. Natural Selection Shapes the Evolution of Populations as They Adapt to Changing Environments B. Natural Selection Stems from Unequal Reproduction 1. Reproductive success determines the success of an individual’s alleles and is referred to as fitness C. Natural Selection Acts on Phenotypes 1. The selection of phenotypes affects the genotypes present in a population D. Some Phenotypes Reproduce More Successfully Than Others 1. Adaptations are characteristics that help an individual survive and reproduce 2. An environment has nonliving and living components a. Organisms must cope with both nonliving and living factors in an environment i. Nonliving factors include climate, water, and the soil ii. Living factors include other organisms 3. Competition acts as an agent of selection a. Competition for resources affects the survival of organisms 4. Both predator and prey act as agents of selection a. When two species interact, they exert strong selection on each other b. Coevolution is the constant feedback between these organisms c. Predation includes any situation in which one organism eats another i. Coevolution occurs between predator and prey 5. Antibiotic resistance illustrates key points about natural selection a. Natural selection does not cause genetic changes in individuals b. Natural selection acts on individuals, but populations evolve c. Evolution is not progressive E. Sexual Selection Favors Traits That Help an Organism Mate 1. Sexual selection acts on traits that help an animal acquire a mate a. Male–male competition for access to females can favor evolution of traits that provide an advantage in fights (Figure 15-10) b. Some male organisms are highly ornamented, influencing female selection of them as mates (Figure 15-11) F. Selection Can Influence Populations in Three Ways (Figure 15-12) â Lecture Activity 15.4: Three Types of Selection on Height 1. Directional selection shifts character traits in a specific direction a. This type of selection favors individuals with an extreme value of a trait 2. Stabilizing selection acts against individuals who deviate too far from the average a. This type of selection favors individuals with the average value of a trait 3. Disruptive selection adapts individuals within a population to different habitats a. This type of selection favors individuals at both extremes of a trait b. In balanced polymorphism, two or more phenotypes are maintained in a population (Figure 15-13) i. Sickle-cell anemia is a human example of this phenomenon

Case Study Revisited: Evolution of a Menace

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KEY TERMS adaptation allele frequency coevolution competition directional selection disruptive selection equilibrium population

fitness founder effect gene flow gene pool genetic drift Hardy–Weinberg principle mutation

natural selection population population bottleneck predation sexual selection stabilizing selection

LECTURE ACTIVITIES Lecture Activity 15.1: Gene Flow in Action Estimated Time to Complete: 15–20 minutes Section Reference 15.2 What Causes Evolution?

Introduction Gene flow between populations of a species can be a force aiding evolutionary change in those populations. When individuals from one population or family group leave (emigrate) and travel to another group, and then successfully mate and have offspring, they have contributed their alleles to that group. In other words, alleles have “flowed” from one group to another. If this is a one-way migration (and gene flow is the only process affecting changes in allele frequencies), over time the recipient population becomes more like the source population. If it is a two-way reciprocal migration, the two populations change to become more alike. In this way, adaptations that have evolved in one population may be spread to other populations of the same species. Students should observe that evolutionary change, represented by the changing proportions of different colored marbles, occurs in populations receiving genes carried by immigrants.

Materials Needed • Marbles with two distinct colors (for example, red and blue) Procedures This activity can be done as an instructor demonstration as long as the color and number of marbles is visible to all members of the class, such as in a small classroom or with the use of a document camera or overhead projector. If done this way, have students keep track of the number and color of marbles in each “population.”

Alternatively, students can do this themselves in smaller groups, or (ideally) in pairs, if there are enough marbles.

One student can model the gene flow while the other records the data. See the attached handout for a chart to be completed.

1. Briefly introduce the concept of gene flow between populations to the class, without yet discussing the genetic consequences of the process.

One-Way Gene Flow 2. Begin with Population 1 (P1, the “source” population) with 10 red marbles, and Population 2 (P2, the “recipient” population) with 10 blue marbles. Have an extra supply of red marbles available to replace those migrating from the source population.

Explain that the population sizes will stay the same (10 marbles) each “generation,” so every red marble removed from P1 will be replaced by another red marble, and for every red marble received by P2, a marble of either color will be removed at random.

3. Record the data for “Generation 0” as “P1 – 10 red; P2 – 10 blue.” Transfer a marble from P1 to P2, add another red marble to P1, and randomly remove a marble from P2. Record the number of marbles in each population in “Generation 1.” Repeat for up to 10 generations. .

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Two-Way Gene Flow 4. To model two-way gene flow, start again with P1 of 10 red marbles and P2 of 10 blue marbles. This time, do a reciprocal exchange between P1 and P2. Because both populations will remain at 10 marbles, there is no need for replacement or removal of marbles after the exchange. After the first generation, choose from each group randomly; do not choose only red from P1 or blue from P2, although these colors may of course be chosen at random. Again, repeat for up to 10 generations and record the data for each generation.

Assessment Suggestions Discuss the following questions with the class: 1. With one-way gene flow, what happened in the recipient population P2? (If the activity was done in groups or pairs, each group can report its final data.)

(After a few generations, P2 should have become mostly or completely red, like P1.)

2. With two-way gene flow, what happened to both populations P1 and P2? (Present final data for both.)

(In theory, both populations should eventually become alike, half red and half blue. With small sizes of 10 each, this will not happen exactly, but each should be a more alike mixture of red and blue.)

3. What effect will gene flow have on allele frequencies in real populations?

(Gene flow between groups tends to make them more genetically similar over time.)

4. What would happen if a new favorable mutation occurred in one population of a species of many populations, and there is some amount of gene flow between them?

(The mutation may be allowed to spread from one population to the next by gene flow, and eventually spread throughout the species. The spread may be more rapid than usual if it is a favored mutation, as selection will increase the frequency of that allele within populations.)

5. What would happen if there is gene flow between two bird populations, one homozygous for an allele for red color, the other homozygous for an allele for white color? (Assume that the heterozygote would be pink, and that selection will not influence color.)

(Each population would begin by having pink individuals appear. As they bred, there would be more pink heterozygotes and “foreign” homozygotes. Eventually, both populations would have a mixture of the three phenotypes.)

Handout See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 15.1 Handout—Gene Flow in Action One-way gene flow Generation

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Lecture Activity 2: Genetic Drift and Random Evolution Estimated Time to Complete: 10–15 minutes Section Reference 15.2 What Causes Evolution?

Introduction Genetic drift is a type of genetic “sampling error” that occurs in small populations. The formation of gametes is much like flipping a coin: there are two possible outcomes, one allele for a particular gene (heads) or the other allele (tails). In flipping a fair coin 10 times, there is a theoretical expectation of 50% heads and 50% tails, but you might get 7 heads and 3 tails due to chance and not question the fairness of the coin. Such chance events work in gamete formation and gamete union as well. A heterozygote has an equal probability of forming a gamete with either of the two alleles, but which one is contributed to an individual offspring is a matter of chance. In small populations, these chance events can result in random shifts in allele frequencies from generation to generation.

In a larger population, sampling error is less of a factor, and allele frequency changes resulting from genetic drift are smaller.

Students doing this activity will simulate a population’s gamete formation, fertilization, and offspring for the next generation by sampling from a “gene pool” of marbles of two different colors (alleles). The samples will be used to make up the gene pool of the next generation, and the sampling process will be repeated over several generations. Students will record the data, observe random allele frequency changes, and write answers to questions about the process of genetic drift.

Materials Needed • Marbles with two distinct colors (for example, red and blue), 40 each per group • Paper bags, 1 per group Procedures Divide the class into small groups of about four students each. Give each a supply of red and blue marbles, about 40 each, and a paper bag. Have them put 10 of each color in the bag for a total of 20 marbles. The initial proportions are 50% red, 50% blue.

1. Tell the students that the bag contains the “gene pool” of a small population of 10 individuals, each with two alleles. To simulate gamete formation and gamete union, two marbles will be taken from the bag at random; this is the genotype of a single offspring in the next generation. Record the number of red and blue marbles (2 red, 2 blue, or 1 red and 1 blue). Return the two marbles to the bag.

2. Repeat the first step 9 more times, for a total of 10 members of the next generation. Calculate the total number of red and blue marbles for all 10 offspring, and their percentages. (The total number of marbles should be 20.) Remove all the marbles from the bag and replace them with the same numbers that were just calculated. (The numbers and percentages have probably changed from the previous generation.)

3. Repeat the first two steps several times. Each generation’s numbers and percentages should be different from those of the previous generation.

Assessment Suggestions Briefly discuss the results with the class, emphasizing the randomness of the changes in allele frequency, and have them complete the handout in class or as a homework assignment. The handout includes the following questions: 1. Is there any pattern to the changing percentages (allele frequencies)? Do you expect a pattern? Why or why not?

(Some students may see a pattern of increasing or decreasing frequencies by chance, but most should see random fluctuations. A few may even end up with all red or all blue. Because the sampling error of genetic drift is random, no particular pattern is expected.)

2. What do you predict will eventually happen to the allele frequencies in this population?

(Eventually, the frequency of an allele may drift to 0 or 1, and would stay there from that point on. Genetic drift tends to result in a loss of alleles, and therefore a loss of genetic variation.)

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Chapter 15 How Populations Evolve 3.

What would you expect to see in a similar population that has 100 members instead of 20? What would eventually happen to the allele frequencies?

(The magnitude of the random frequency changes would be smaller in a larger population, so frequency changes by genetic drift will occur more slowly. The eventual outcome of loss of genetic variation is still expected, but it will take much longer.)

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members: ______________________________________________________________________

Lecture Activity 15.2: Handout—Genetic Drift and Random Evolution On the following graph, record the data from the class activity on genetic drift. Put an “R” for the percentage of red marbles for each generation and a “B” for the percentage of blue marbles. Connect the points to form two lines showing the changing percentages of red and blue marbles, then answer the questions below.

Questions 1.

Is there any pattern to the changing percentages (allele frequencies)? Do you expect a pattern? Why or why not?

2.

What do you predict will eventually happen to the allele frequencies in this population?

3.

What would you expect to see in a similar population that has 100 members instead of 20? What would eventually happen to the allele frequencies?

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Chapter 15 How Populations Evolve

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Lecture Activity 15.3: Genetic Effects of Nonrandom Mating Estimated Time to Complete: 5–10 minutes Section Reference 15.2 What Causes Evolution?

Introduction One of the conditions for a population in Hardy–Weinberg equilibrium is that mating among genotypes is random—that is, mates are not chosen on the basis of genotype. If this and the other equilibrium conditions are met, there will be no allele frequency change in the population, and no evolution. Nonrandom mating, on the other hand, means that mates are chosen on the basis of genotype. This brief lecture demonstration shows that nonrandom mating will change genotype frequencies, which may enhance or slow down evolutionary change resulting from some other force, such as natural selection.

Materials Needed None Procedures Explain to the class that you have a population of mice in which the allele B in homozygous form confers brown fur color and a homozygote for the allele b has white fur. The heterozygote Bb has a cream color. Start with a population in Hardy–Weinberg equilibrium: ¼ BB, ½ Bb, and ¼ bb.

With random mating, these frequencies will remain constant from generation to generation. What happens if mating is nonrandom?

An extreme form of nonrandom mating would be complete assortative mating, in which one genotype will mate only with another individual with the same genotype. Because in this case each phenotype corresponds to a single genotype, recognizing the same genotype is easy. Only three types of matings will take place: 1. BB × BB (brown mates with brown) Ask the students what the genotype proportions of offspring would be. (This will produce all BB [brown] offspring.) The proportions of matings of this type is based on the proportion of the genotype, ¼. So, at least ¼ of the offspring in the next generation will be brown.

2. bb × bb (white mates with white) Ask the students what the genotype proportions of offspring would be. (This produces all bb (white) offspring.)

This is ¼ of all matings in the population, so at least ¼ of the offspring in the next generation will be white.

3. Bb × Bb (cream mates with cream) Ask the students what the genotype proportions of offspring would be. (This produces ¼ BB, ½ Bb, and ¼ bb offspring.) This is ½ of the matings in the population. Multiplying these by ½, the proportion of matings, this represents a contribution of 1 8 BB, 1 8Bb, and ¼ bb to the next generation.

The total offspring proportions are: BB: ¼ + 1 8 = 3 8brown Bb: ¼ cream bb: ¼ + 1 8 = 3 8white Assessment Suggestions Ask the students the following questions: 1. What would eventually happen to the phenotype proportions in the mouse population?

(Because the proportion of heterozygotes is halved every generation, in the long run there will be no heterozygotes, unless they are favored by natural selection for some reason. The population will effectively split into two groups of brown mice and white mice, each mating among themselves.)

2. What would happen to the same population if there were complete negative assortative mating, where individuals will only mate with different genotypes?

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Instructor Guide Biology: Life on Earth (The students may correctly conclude that the proportion of heterozygotes will increase, while the homozygote proportions will decrease. But, can it eventually become a population of all heterozygotes? No, because about half of the offspring from matings among heterozygotes are homozygous.)

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Lecture Activity 15.4: Three Types of Selection on Height Estimated Time to Complete: 5–10 minutes Section Reference 15.3 How Does Natural Selection Work?

Introduction Many, if not most, organismal traits are not represented by discrete and simple genotypes and phenotypes (such as either purple or white flowers), but show continuous variation from one extreme to the other. Size traits, such as height, are a good example of a continuous trait. Natural selection may act on such a trait in one of three ways: directional selection, in which one extreme (very tall or very short) is favored; stabilizing selection, in which average height is favored; or disruptive selection, in which both very short and very tall are favored, but average height is not.

If the class is fairly large (at least 25 students), students can be arranged by height range into an approximate “bell curve,” and the instructor can move students to simulate the three types of selection and show how the distribution will change over time.

If the class is very large, separate the class into separate groups of males and females, so that the distribution is not confounded by sex differences in height.

Materials Needed • Papers with height ranges (such as “4 ft–4 ft 5 in.,” “4 ft 6 in.–4 ft 11 in.,” etc., up to whatever is needed for the class) taped in order on the wall Procedures 1. Ask the students to stand in a single-file line in front of the paper corresponding to their height. Have them note the shape of the “curve” that results. (In a large class, it will be approximately bell-shaped, but will differ if the class is small or biased, such as having a lot of basketball players.)

2. Tell the students that they will next become members of the next generation, after a type of natural selection has taken place. Their heights may change because of natural selection, so they may need to move to a different range. For directional selection, have each student move to the line on his or her right. (Those in the rightmost line should stay in it.) Repeat this for several “generations,” so that the distribution has shifted far to the right.

3. Start again with the students in their original positions. Simulate stabilizing selection by having students in the lines on the right side of the distribution move to the line on their left, and having those in the lines on the left side of the distribution move to the line on their right. If there is a center line because of an odd number of height ranges, those students should not move. Repeat for several generations.

4. Again have the students assume their original positions, and simulate disruptive selection by having students in the lines on the right of the distribution move to their right, and those in lines on the left side of the distribution move to their left. If there is a center line because of an odd number of height ranges, one student should move to the left and one to the right each generation. Repeat several times.

Assessment Suggestions Discuss the results of the activity with the class, using the following questions as guides: 1. How did the distribution change with directional selection? What would happen to a population under this type of selection?

(The distribution shifted to one end as the population average became shorter [or taller]. If there were enough genetic variation for height to allow it, the population would continue to evolve in that direction until the physical or energetic limit would stop it.)

2. As above, for stabilizing selection.

(The distribution became narrower as the extremes were eliminated. This type of selection would maintain the average height and not allow evolution to some other average.)

3. As above, for disruptive selection.

(The population “split” into a tall group and a short group. This type of selection may favor diversification of a population into groups, and may set the stage for evolution of new species.)

4. What are the effects of the three types of selection?

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Instructor Guide Biology: Life on Earth (Directional selection pushes evolution of a trait in one direction; stabilizing selection on a trait keeps it the same; and disruptive selection divides a population into one group with one extreme form of a trait and another group with the other extreme form of the trait, selecting in both directions simultaneously.)

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CHAPTER 16 THE ORIGIN OF SPECIES LECTURE OUTLINE Case Study: Lost World 16.1 What Is a Species?

A. Each Distinct Type of Organism Is Known as a Species B. Biologists Need a Clear Definition of Species 1. On a coarse scale, it is easy to use quick visual comparisons to distinguish species a. How do scientists make finer distinctions?

C. Each Species Evolves Independently 1. Biologists define a species as a group of populations that evolves independently 2. The biological species concept defines species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups a. This definition is based on reproductive isolation i. Reproductive isolation is the inability to successfully interbreed outside the group b. The biological species concept has limitations i. It does not help define species boundaries among asexually reproducing organisms ii. It is not always practical or possible to observe whether members of different groups interbreed D. Appearance Can Be Misleading 1. Biologists have found that some organisms with very similar appearances belong to different species (Figures 16-1 and 16-2) â Lecture Activity 16.1: Bicknell’s Thrush: A True Species?

16.2 How Is Reproductive Isolation Between Species Maintained?

A. Traits That Prevent Interbreeding and Maintain Reproductive Isolation Are Called Isolating Mechanisms (Table 16-1) B. Premating Isolating Mechanisms Prevent Mating Between Species 1. Members of different species may be prevented from meeting a. Geographic isolation prevents mating between species that do not come in contact with each other (Figure 16-3) i. A physical barrier may separate one population into two, allowing the evolution of distinct species 2. Different species may occupy different habitats a. Ecological isolation occurs when two populations use different resources and spend time in different habitats (Figure 16-4) 3. Different species may breed at different times a. Temporal isolation describes when species have different mating seasons (Figure 16-5) 4. Different species may have different courtship signals a. Behavioral isolation prevents mating between organisms that have different courtship behaviors (Figure 16-6) 5. Differing sexual organs may foil mating attempts a. Mechanical incompatibility makes mating physically difficult or impossible C. Postmating Isolating Mechanisms Limit Hybrid Offspring 1. One species’ sperm may fail to fertilize another species’ eggs a. Gametic incompatibility prevents fertilization because the sperm cannot bind to the egg

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Instructor Guide Biology: Life on Earth 2. Hybrid offspring may fail to survive or reproduce a. The hybrid may not survive, a situation called hybrid inviability 3. Hybrid offspring may be infertile a. Hybrid infertility prevents hybrids from passing on their genetic material to offspring (Figure 16-7)

16.3 How Do New Species Form?

A. Speciation Is the Process by Which New Species Form 1. Speciation depends on two processes a. Isolation of populations b. Genetic divergence of populations 2. Speciation is described by two broad categories a. Allopatric speciation b. Sympatric speciation â Science in Action: Seeking the Secrets of the Sea (Figure E16-1) B. Geographic Separation of a Population Can Lead to Allopatric Speciation 1. Organisms may colonize isolated habitats (Figure 16-8) a. Isolated populations may diverge and become different species â Lecture Activity 16.2: Allopatric Speciation Demonstration 2. Geological and climate changes may divide populations a. Isolation can result from landscape changes that divide a population 3. Natural selection and genetic drift may cause isolated populations to diverge C. Genetic Isolation Without Geographic Separation Can Lead to Sympatric Speciation 1. Limited gene flow is required for speciation, but populations can become isolated without it 2. Ecological isolation can reduce gene flow a. Different members of a single species may begin to specialize in one habitat or the other (Figure 16-9) 3. Mutations can lead to genetic isolation a. Mutations that change the number of chromosomes can cause speciation i. The acquisition of multiple copies of chromosomes is called polyploidy ii. This happens more often in plants D. Under Some Conditions, Many New Species May Arise 1. Discoveries about the evolutionary relationships between species are often depicted as tree diagrams (Figure 16-10a) 2. In adaptive radiation, multiple speciation events occur as an original species evolves to colonize available niches (Figures 16-10b and 16-11) â Lecture Activity 16.3: Population Genetics of Speciation â Case Study Continued: Lost World

16.4 What Causes Extinction?

A. Extinction Is the Death of the Last Members of a Species 1. The cause of extinction is probably always environmental change B. Localized Distribution Makes Species Vulnerable (Figure 16-12) 1. If a species inhabits a small area, any disturbance can result in extinction C. Overspecialization Increases the Risk of Extinction 1. In some cases, species are adapted to a limited set of environmental conditions (Figure 16-13) D. Interactions with Other Species May Drive a Species to Extinction 1. Competition between species for resources can lead to the extinction of one of the species E. Habitat Change and Destruction Are the Leading Causes of Extinction â Lecture Activity 16.4: Predicting Extinction of Bat Species â Earth Watch: Why Preserve Biodiversity? (Figure E16-2)

Case Study Revisited: Lost World

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Chapter 16 The Origin of Species

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KEY TERMS adaptive radiation

hybrid infertility

allopatric speciation behavioral isolation extinction gametic incompatibility geographic isolation hybrid

hybrid inviability isolating mechanism mechanical incompatibility polyploidy postmating isolating mechanism

premating isolating mechanism reproductive isolation speciation species sympatric speciation temporal isolation

LECTURE ACTIVITIES Lecture Activity 16.1: Bicknell’s Thrush: A True Species?

Estimated Time to Complete: 5–10 minutes Section Reference 16.1 What Is a Species?

Introduction Bicknell’s Thrush has an interesting taxonomic history. The first specimen was found by Eugene P. Bicknell in 1881 in the Catskill Mountains of New York. It was originally described by Mr. Bicknell and Dr. Robert Ridgway of the American Museum of Natural History as a subspecies of the Gray-cheeked Thrush (Catharus minimus), a species whose range is far Northern Canada. In the field, it is difficult to distinguish the two, but Bicknell’s Thrush is generally smaller and has more yellow coloring at the base of the bill. Work in the 1990s indicated that the wintering and breeding ranges of the two birds do not overlap, and that there is genetic divergence between them. As a result, in 1995 Bicknell’s Thrush was given full species status—Catharus bicknelli. There is also experimental evidence of premating isolation between the two species; Bicknell’s Thrushes do not respond to the songs and calls of Gray-cheeked Thrushes.

This lecture activity can be used as a way to illustrate the difficulty of species designation and the criteria used to make such taxonomic decisions. It works best if the students first speculate on the species status based only on pictures of the two birds. For information and pictures of this bird, perform an Internet search using the following terms: “Bicknell’s Thrush” and “Gray-cheeked Thrush.” Media files can be accessed in class directly via the Web site (if the classroom has an Internet connection) or saved and presented on the computer in class. The instructor may choose to display these during or following this activity.

Materials Needed • Pictures of the Gray-cheeked Thrush and Bicknell’s Thrush (from the Internet search) Display or distribute copies of pictures of the two birds (without the labels), and ask the students to consider whether they are members of the same or different species. (You may want to briefly review species concepts at this point.) Guided by the questions listed in the following Assessment Suggestions, choose students who would classify them together and have them explain why, then choose some who would classify them differently and have them explain why. Next, reveal the names, taxonomic designations, and taxonomic history of the two species, either in its brief form as in the Introduction here, or in a more detailed form by using information from your Web site search. (Optional: conclude the activity by presenting video and audio of Bicknell’s Thrush.)

Assessment Suggestions As they view the two unlabeled pictures, ask the students: 1. Are these two birds members of the same species? Why or why not?

(Those who say no will probably point out the difference in coloration of the feathers, or maybe the beak coloration. Some may notice a size difference, though that may be too difficult to see depending on the pictures you provide. Those who say yes might point out their similarities, and that the differences might be variations within the species. Some might choose to withhold judgment without additional information, such as whether they interbreed.) .

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Instructor Guide Biology: Life on Earth What additional information would you want in order to make a better decision?

(They will probably want to know whether they can or do interbreed [apparently not], whether one is male and one is female [we don’t know!], whether they are found in some of the same areas [no], and so on. Try to answer their questions as much as possible and have them reconsider their previous decision.)

Now what do you think?

(Most will probably now say they are different species.)

Lecture Activity 16.2: Allopatric Speciation Demonstration Estimated Time to Complete: 15–20 minutes Section Reference 16.3 How Do New Species Form?

Introduction Allopatric speciation occurs when two populations are geographically separated for a long period of time and diverge enough genetically to no longer be able to interbreed successfully. This demonstration is a simple depiction of the genetic divergence of two populations, using colored marbles to represent “genes” or “traits” of the population. Independent evolution of the two populations is shown by substituting different-colored marbles in the two populations, showing that with evolution the two populations genetically diverge but also retain similarities that can be used to reconstruct the evolutionary history of the two new species. You can also point out how sympatric speciation must work.

Materials Needed • Marbles or beads of at least five different colors Procedures Provide the accompanying handout for the students. Introduce the concept of allopatric speciation, stressing the long geographic isolation and genetic divergence necessary for the two populations to become separate species.

Arrange 12 marbles of the same color in a line to represent genes or traits in a population. (If the class is small, this can be done on a desk or table.) If it is a large class, use a document camera or computer display of images from a preselected Web site. Alternately, have groups of students do the demonstration along with the instructor.

Have a collection of marbles of mixed colors, different from that of the other 12 marbles, to pull out for “mutations.” Have the class decide what animal this will represent, and what the 12 traits will be.

1. Demonstrate evolution within a population by randomly pulling out a marble and randomly replacing one of the marbles in the line. Have the students decide what the new form of the trait will be. Repeat three times, keeping the total number of marbles at 12.

2. Split the population into two by forming a second identical line of marbles. Continue the process of evolution for each of the two new populations as in Step 1, randomly choosing a different-colored marble for each population each time. After a few rounds of “mutation,” the two populations will have diverged to some extent, but will still have some homology in the marbles shared between the two.

Assessment Suggestions After completing the Procedures, ask the students: 1. Have the two groups evolved enough to be separate species? Why or why not?

(Possibly yes. Students should point out differences that would be premating or postmating isolation mechanisms if they have evolved, and that these would be grounds for calling the two groups different species. If the differences do not significantly affect interbreeding, they should not be considered different species.)

2. What might cause the complete separation of two groups of the population? (colonization of a group on an isolated island, or gradual or sudden development of an impassable barrier, such as a mountain, gorge, or river) 3. Why are the two groups evolving differently?

(Mutations are random, so different mutations will happen in the different areas. If the populations are small, the random process of genetic drift will result in different alleles being maintained/lost. If the areas differ environmentally, selection may drive evolution differently.) .

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What types of genetic changes would be necessary for the two divergent groups to be different species?

(Any heritable change that would prevent mating or successful production of offspring would make them different species according to the biological-species concept.)

Optional: Have the students consider sympatric speciation by having them suppose that the two groups were not separated by a physical barrier, but were effectively separated into different groups in the same area by different adaptations. Ask: What are some adaptations that may result in separate groups without physical separation? (Answers might include adaptations to specific feeding/mating sites or times, or sexual selection such that females prefer specific male traits or behaviors.)

Handout or Display See the following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 16.2 Handout—Allopatric Speciation Allopatric speciation occurs when two populations are geographically separated for a long period of time and diverge enough genetically to no longer be able to interbreed successfully. This demonstration is a simple depiction of the genetic divergence of two populations, using colored marbles to represent “genes” or “traits” of the population. First, 12 marbles are arranged in a line to represent 12 traits in an animal. Choose an animal and the 12 traits the marbles represent: Animal: Trait 1: Trait 2: Trait 3: Trait 4: Trait 5: Trait 6: Trait 7: Trait 8: Trait 9: Trait 10: Trait 11: Trait 12:

___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________

One trait will now be “mutated” by randomly replacing one of the marbles. Decide what the new form of the trait is. Repeat this three more times.

Trait #: Trait #: Trait #: Trait #:

_________ _________ _________ _________

New form of trait: New form of trait: New form of trait: New form of trait:

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Now split the “population” into two identical groups that will evolve independently by forming an identical second line of marbles. Continue to “mutate” both of them independently as before.

Population 1 Trait #: Trait #: Trait #: Trait #:

_________ _________ _________ _________

New form of trait: New form of trait: New form of trait: New form of trait:

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Population 2 Trait #: Trait #: Trait #: Trait #:

_________ _________ _________ _________

New form of trait: New form of trait: New form of trait: New form of trait:

___________________________ ___________________________ ___________________________ ___________________________

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Now, answer the following questions: Have the two groups evolved enough to be separate species? Why or why not?

What might cause the complete separation of two groups of the population?

Why are the two groups evolving differently?

What types of genetic changes would be necessary for the two divergent groups to be different species?

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Lecture Activity 16.3: Population Genetics of Speciation Estimated Time to Complete: 5–10 minutes Section Reference 16.3 How Do New Species Form?

Introduction Chapter 15 of the text (How Populations Evolve) introduced a number of evolutionary forces that can influence microevolutionary change in populations. Speciation involves the accumulation of genetic differences of two groups that are either allopatric (completely physically isolated from each other) or sympatric (not physically isolated, but adapted in some way that prevents successful reproduction). In this activity, students review the five major evolutionary forces, consider what effects they have on evolving populations, and conclude with how genetic divergence may result in speciation.

Materials Needed None Procedures 1. Ask the students to recall and name the five major forces that result in evolutionary change in populations (selection, genetic drift, gene flow, mutation, and nonrandom mating). Write these in a column on the board.

For each one suggested, ask how it tends to change the gene pool of the population, and write correct answers in a second column to form a table.

2. Now, have students consider two populations separated by a physical barrier or isolated by different adaptations. Ask whether each of these forces will cause the two populations to change differently and diverge genetically. Add the answers to the table. The goal is to construct a table much like the one presented in the handout on the following page. (Alternatively, the table can be displayed or distributed and discussed as a quick review of the Chapter 15 concepts, before discussing the questions in the following Assessment Suggestions.)

Assessment Suggestions Discuss the following questions with the class: 1. How might the population “split” into two without any physical barrier?

(Disruptive selection may result in two groups with adaptations that prevent them from interbreeding.)

2. Which forces would be most important in causing two populations to diverge?

(Selection, if the habitats of the two populations are different enough that they are adapting differently; genetic drift, if the populations are small. Mutation would be important given a long enough time, and nonrandom mating may assist other forces in speeding up genetic differentiation.)

3. What types of changes would have to occur for the two groups to become different species?

(They would have to be different in some way that either prevents mating from occurring, or in some way that makes hybrid offspring less fit or less fertile. This would be a good opportunity to review premating and postmating isolating mechanisms. For sympatric groups that already have at least one premating isolating mechanism, the evolution of other mechanisms would strengthen the decision that they are different species.)

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 16.3 Handout—Population Genetics of Speciation Evolutionary force Selection Genetic drift Gene flow Mutation Nonrandom mating

Affects different populations differently?

Directional, stabilizing—only if the environments of the two populations are different.

Disruptive—may result in two separate groups.

Yes, change in each population is random; faster in small populations.

Makes populations more similar; genetic divergence requires barrier to gene flow.

Yes, change in each population is random, but happens very slowly.

Not by itself; changes genotype frequencies but not allele frequencies.

But, can enhance selection by increasing or decreasing genotype frequencies.

Handout—Isolation of Drosophila Species

Species 1

Species 2

Allopatric/ Sympatric

Genetic distance

Premating isolation

Postmating isolation

Aldrichi aldrichi aldrichi arizonensis mojavensis arizonensis lacicola lacicola montana

mulleri mojavensis arizonensis mulleri mulleri mojavensis montana texana texana

sympatric allopatric sympatric sympatric allopatric sympatric sympatric allopatric allopatric

0.123 0.326 0.289 0.232 0.324 0.212 0.210 1.450 1.510

0.928 0.817 1.000 1.000 0.972 0.732 0.954 0.992 0.985

0.25 0.00 0.75 0.50

• Allopatric/Sympatric—used here, the term “allopatric” means that the species’ ranges do not overlap, and “sympatric” means that the species’ ranges overlap in some area.

• Genetic distance—calculated from the number of codon differences between homologous proteins of the two species, this measure ranges from 0 to 2, with zero being identical and 2 being the highest level of difference measured among Drosophila species.

• Premating isolation—based on mate choice tests, this measure ranges from 0 to 1, where 0 is “no mating isolation” (all possible between-species matings occur) and 1 is “complete mating isolation” (no mating between species at all).

• Postmating isolation—for those species pairs that did successfully mate, this measure incorporates both hybrid inviability and sterility. It ranges from 0 to 1, again with 0 being “no isolation” (all viable and fertile hybrid offspring) and 1 being “complete isolation” (both sexes of hybrid offspring are inviable or sterile).

Usually, a measure of 0.5 means that one of the two sexes of hybrid offspring, usually males, is sterile or inviable.

Adapted from Table 1 of Coyne and Orr, “Patterns of Speciation in Drosophila,” Evolution 42: 362–381, March 1989.

“-” means “no measurement available.”

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Instructor Guide Biology: Life on Earth

Lecture Activity 16.4: Predicting Extinction of Bat Species Estimated Time to Complete: 10–15 minutes Section Reference 16.4 What Causes Extinction?

Introduction Extinction of a species can result from a number of different problems, including adaptations of the species that limit its potential range, the influence of other species in its habitat, and the loss of suitable habitat due to environmental change or human activity. In this activity, students will explore characteristics of three species of bats of the genus Myotis, make predictions about which species are at risk for extinction and which are not, and identify what factors might determine the eventual failure or success of the species. Myotis is a good choice for this activity, because there are three species in the United States and Canada, two of which are endangered. The remaining species, the little brown bat, is well represented throughout its range and is in no danger of extinction.

A species’ status, or risk of extinction, is ranked on a scale of 1 to 5, with 5 being the most secure. Ranks are assigned as global, national, and (if limited to a very small area) state/province. Because Myotis species are found in multiple states, only the global and national ranks are presented. These ranks are described in the following table:

Rank Critically imperiled Imperiled Vulnerable Apparently secure Secure

Global conservation status

National conservation status

G1 G2 G3 G4 G5

N1 N2 N3 N4 N5

The data in this activity were obtained from the NatureServe Explorer Web site (http://www.natureserve.org/explorer/), which has continually updated conservation information on the plants and animals of the United States and Canada, including an extensive and fully searchable database. Instructors may wish to develop other exercises using this data, or to verify the current status of Myotis species and adapt this activity accordingly.

Materials Needed None Procedures Review the major reasons for a species’ extinction, as detailed in Section 16.4 of the text.

1. Distribute the accompanying handout to the class and ask them to assess each species as to whether it is at risk for extinction or not, and why. Explain the status ranking system as described in the Introduction and on the handout.

2. After a few minutes, discuss the students’ conclusions using the questions in the following Assessment Suggestions. (These questions are also found on the handout.)

3. Reveal the status rankings of the three species. They are: M. leibii—G3, N3 (in both United States and Canada); M. sodalis—G2, N2 (United States); M. lucifugus—G5, N5 (in both United States and Canada). There is an active effort to preserve the existing populations of the Indiana bat, Myotis sodalis.

Alternatively, the handout could be distributed during the class period covering extinction, completed by the students outside of class, and discussed during the next class period.

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Assessment Suggestions Guide the discussion with the following questions.

For each of the three species, ask: Is this species at risk for extinction? Why or why not? If at risk, do you think it is likely that the species will one day no longer be at risk? (leibii—has a limited habitat and found in small populations, so probably at risk; habitat may have been fragmented by human activity; may not recover. sodalis—most of the species is found as a small number of populations, so probably at risk; vulnerable to human disturbance, so may not be likely to recover; lucifugus— large, widespread populations, so probably not at risk; adapted to presence of humans, so likely to continue to do well.)

Handouts or Display See the following pages. Include photos of individuals from each species from the suggested or other sources.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 16.4 Handout—Predicting Extinction of Bat Species Bats of the Genus Myotis Myotis leibii (Eastern small-footed bat) Habitat: Hilly or mountainous areas near forests Distribution: Widespread in southeastern Canada and eastern United States; populations are spotty and small Photos can be found by doing an Internet search using “Eastern small-footed bat” as the search terms.

Myotis sodalis (Indiana bat) Habitat: Trees or limestone caves Distribution: Northern, eastern, and midwestern United States; nine populations in Kentucky, Indiana, and Missouri have about 75% of species; vulnerable to human disturbance.

Photos can be found by doing an Internet search using “Indiana bat” as the search terms.

Myotis lucifugus (Little brown bat) Habitat: Caves, hollow trees, human-made structures Distribution: Widespread in North America from northern Canada to central Mexico Photos can be found by doing an Internet search using “Little brown bat” as the search terms.

Extinction of a species can result from a number of different problems, including adaptations of the species that limit its potential range, the influence of other species in its habitat, and the loss of suitable habitat due to environmental change or human activity.

A species’ status, or risk of extinction, is ranked on a scale of 1 to 5, with 5 being the most secure. Ranks are assigned as global, national, and (if limited to a very small area) state/province. Because Myotis species are found in multiple states, only the global and national ranks are presented. These ranks are described in the following table:

Rank Critically imperiled Imperiled Vulnerable Apparently secure Secure

Global conservation status

National conservation status

G1 G2 G3 G4 G5

N1 N2 N3 N4 N5

Try to determine the status rankings for each of the three bat species. After your assessment, the instructor will provide the actual status ranks.

.

Myotis leibii Is this species at risk for extinction? Why or why not? If at risk, do you think it is likely that the species will one day no longer be at risk?

Actual Status: Global _____

National _____

Myotis sodalis Is this species at risk for extinction? Why or why not? If at risk, do you think it is likely that the species will one day no longer be at risk?

Actual Status: Global _____

National _____

Myotis lucifugus Is this species at risk for extinction? Why or why not? If at risk, do you think it is likely that the species will one day no longer be at risk?

Actual Status: Global _____

National _____

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CHAPTER 17 THE HISTORY OF LIFE LECTURE OUTLINE Case Study: Little People, Big Story 17.1 How Did Life Begin?

A. Life Was Thought to Have Developed from Living and Nonliving Matter Through Spontaneous Generation B. Experiments Refuted Spontaneous Generation (Figure 17-1) 1. In the mid-1800s, this idea was refuted by Louis Pasteur and John Tyndall C. The First Living Things Arose from Nonliving Ones 1. Oparin and Haldane hypothesized that organic molecules could have formed through ordinary chemical reactions on the early Earth 2. Organic molecules can form spontaneously under prebiotic conditions a. In 1953, the Miller–Urey experiment showed a possible origin of organic molecules (Figure 17-2) b. In recent years, new evidence has convinced scientists that the early Earth atmosphere was probably different from what Miller and Urey predicted, but their results are still considered important â Lecture Activity 17.1: The Miller–Urey Experiment 3. Organic molecules can accumulate under prebiotic conditions a. Molecules may have accumulated in the oceans, away from the sun’s destructive UV radiation 4. Clay may have catalyzed the formation of larger organic molecules D. RNA May Have Been the First Self-Reproducing Molecule 1. RNA can act as a catalyst a. Ribozymes are RNA molecules that can catalyze a variety of reactions involving RNA (Figure 17-3) 2. Earth may once have been an RNA world a. RNA may have served as both an information-carrying molecule and an enzyme catalyst for its own replication E. Membrane-Like Vesicles May Have Enclosed Ribozymes 1. Lipids and proteins can form membrane-like vesicles a. This could explain the possible origins of cell-like structures called protocells F. But Did All This Really Happen?

1. Researchers disagree on how life arose on Earth

17.2 What Were the Earliest Organisms Like? (Figure 17-4 and Table 17-1) â Lecture Activity 17.2: Sequence of Evolutionary Events â Science in Action: How Do We Know How Old a Fossil Is? (Figure E17-1) A. The First Organisms Were Anaerobic Prokaryotes 1. These organisms probably absorbed nutrients from the environment B. Some Organisms Evolved the Ability to Capture the Sun’s Energy 1. Photosynthetic bacteria set the stage for the evolution of an oxygen-rich environment 2. Photosynthesis increased the amount of oxygen in the atmosphere C. Aerobic Metabolism Arose in Response to Dangers Posed by Oxygen D. Some Organisms Acquired Membrane-Enclosed Organelles 1. The rise of eukaryotes began about 1.7 billion years ago a. Some bacteria may have engulfed others 2. The internal membranes of eukaryotes may have arisen through infolding of the plasma membrane 3. Mitochondria and chloroplasts may have arisen from engulfed bacteria a. The endosymbiont hypothesis proposes that early eukaryotic cells acquired the precursors of mitochondria and chloroplasts by engulfing certain types of bacteria (Figure 17-5) 4. Evidence for the endosymbiont hypothesis is strong a. One species of Paramecium harbors symbiotic algae (Figure 17-6)

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17.3 What Were the Earliest Multicellular Organisms Like?

A. Some Algae Became Multicellular B. Animal Diversity Arose in the Precambrian Era 1. Marine invertebrates dominated at this time 2. Predation favored the evolution of improved mobility and senses (Figure 17-7) 3. Skeletons improved mobility and protection a. Exoskeletons are hard outer coverings that help protect animals that have them

17.4 How Did Life Invade the Land?

A. The Vast Expanses of Paleozoic Landmasses Provided Many Opportunities for Organisms to Evolve and Adapt B. Some Plants Became Adapted to Life on Dry Land 1. Primitive land plants retained swimming sperm and required water to reproduce a. Mosses and ferns were the first plants to evolve on land (Figure 17-8) b. The plants were still dependent on water for reproduction 2. Seed plants encased sperm in pollen grains a. Conifers were the earliest seed-bearing plants 3. Flowering plants enticed animals to carry pollen a. Pollination of these plants is facilitated by insects and other animals b. These are the dominant plant form today C. Some Animals Became Adapted to Life on Dry Land 1. Arthropods invaded the land first a. Their exoskeleton facilitates survival 2. Amphibians evolved from lobefin fishes (Figure 17-9) a. They have muscular fins that allow crawling b. They have an outpouching in the digestive system, which is like a primitive lung c. Amphibians were still dependent on water for survival and reproduction 3. Reptiles evolved from amphibians a. Reptiles evolved shelled eggs, water-resistant skin, and fully functional lungs b. Dinosaurs dominated the Earth for millions of years (Figure 17-10) c. Reptiles have trouble retaining body heat d. One group of reptiles evolved into birds i. Insulating feathers retain body heat ii. Feathers evolved for flight also 4. Reptiles gave rise to mammals a. Insulating hair retains body heat b. Mammals bear live young and have mammary glands to nourish them

17.5 What Role Has Extinction Played in the History of Life? â Lecture Activity 17.3: Vertebrate Diversity and Mass Extinction A. Evolutionary History Has Been Marked by Periodic Mass Extinctions 1. Climate change contributed to mass extinctions a. One cause of climate change is continental drift i. This is caused by plate tectonics, in which the Earth’s surface moves slowly and land changes place (Figure 17-11) 2. Catastrophic events may have caused the biggest mass extinctions a. The extinction that killed the dinosaurs is thought to have been caused by a meteor impact 65 million years ago

17.6 How Did Humans Evolve? â Lecture Activity 17.4: Interactive Online Human Evolution Activities A. Humans Inherited Some Early Primate Adaptations for Life in Trees (Figure 17-12) 1. Binocular vision provided early primates with accurate depth perception 2. Early primates had grasping hands 3. A large brain facilitated hand–eye coordination and complex social interactions

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Instructor Guide Biology: Life on Earth B. The Oldest Hominin Fossils Are from Africa (Figure 17-13) 1. The earliest hominins were likely represented by various groups of primates a. The earliest appeared more than 6 million years ago b. Australopithecus had the largest brain of the earliest hominins (Figure 17-14) 2. Early hominins could stand and walk upright a. Fossil evidence supports this idea b. Several species of Australopithecus emerged in Africa C. The Genus Homo Diverged from the Australopithecines 2.5 Million Years Ago D. The Evolution of Homo Was Accompanied by Advances in Tool Technology (Figure 17-15) 1. Homo habilis produced crude stone and bone tools 2. Homo ergaster produced more sophisticated stone tools that aided hunting 3. Homo neanderthalensis produced even more advanced tools 4. Neanderthals had large brains and excellent tools a. These hominins evolved 150,000 years ago b. They were similar to humans and were muscular, fully erect, dexterous, and had large brains c. DNA evidence supports the idea that they were a separate species 5. Neanderthals and Homo sapiens may have interbred a. Recent DNA studies have shown some similarities between the DNA of Neanderthals and Homo sapiens E. Modern Humans Emerged Less Than 200,000 Years Ago 1. Homo sapiens originated in Africa at least 160,000 years ago 2. Cro-Magnons appeared approximately 90,000 years ago a. Evidence supports the idea that they were a more sophisticated human (Figures 17-16 and 17-17) 3. Cro-Magnons and Neanderthals lived side by side a. There are conflicting hypotheses about what happened to the Neanderthals 4. Several waves of hominins emigrated from Africa (Figure 17-18) F. The Evolutionary Origin of Large Brains May Be Related to Meat Consumption and Cooking 1. The evolutionary origin of human behavior is speculative G. Sophisticated Culture Arose Relatively Recently 1. Biological evolution continues in humans a. Researchers have identified changes in genes in humans that have occurred recently 2. Culture also evolves a. The development of tools was influential b. The development of agriculture was important

Case Study Revisited: Little People, Big Story

KEY TERMS amphibian arthropod conifer endosymbiont hypothesis eukaryote exoskeleton

hominin lobefin mammal mass extinction plate tectonics primate

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prokaryote protocell reptile ribozyme spontaneous generation

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LECTURE ACTIVITIES Lecture Activity 17.1: The Miller–Urey Experiment Estimated Time to Complete: 10–15 minutes Section Reference 17.1 How Did Life Begin?

Introduction The experiment performed by Stanley L. Miller and Harold C. Urey, working at the University of Chicago in 1953, was an attempt to re-create conditions on the early Earth before life existed and see whether chemical reactions would lead to the formation of the more complex chemicals found in living organisms. In this experiment, Miller and Urey added methane ammonia (NH3), hydrogen (H2), and water (H2O) to a glass flask and provided energy for chemical reactions by running an electric current through the apparatus. The chemical composition of the resulting products was analyzed by chromatography. After about a week, about 10 to 15% of the carbon was in the form of organic compounds, some of which were amino acids, the components of proteins found in living organisms. Later experiments showed that different mixtures of chemicals could result in organic compounds as long as oxygen gas (O2) was absent from the mixture. For example, a combination of hydrogen cyanide (HCN) and ammonia will produce a significant amount of the amino acid adenine.

In this activity, students will experiment with mixing different combinations of chemicals found on the prebiotic Earth and analyze the results to determine the best mixture for production of amino acids.

The CalSpace Web site at http://www.ucsd.tv/miller-urey/ has an interactive animation demonstrating the Miller–Urey experiment. Go to this site and search for “Miller-Urey.” The user can choose to add any combination of N2, CO2, O2, H2, CH4, NH3, and boiling water to the flask, and then start the experiment by clicking on the sparker. Some combinations will cause the apparatus to explode; if this does not happen, then the resulting products will be injected into an HPLC chromatograph and compared with a control sample containing alanine and glycine. The correct mixture of chemicals will result in the production of these two amino acids. The chamber can be cleared by clicking on the vacuum for additional trials. The site also has two short videos of Stanley Miller describing the apparatus and talking about how the experiment came to be done. These can be used in presenting this activity, although the video appears in a very small window on the computer screen. For best results, this activity should be done before students have been instructed in the exact details of the Miller–Urey experiment, so that they can speculate on the probable composition of the prebiotic Earth’s atmosphere and test their ideas.

If the classroom has a computer with a broadband Internet connection that is suitable for display for a large group, this activity can be done as a class exercise, with the students suggesting input to the instructor, who then runs the simulation. If this cannot be presented in the class, it may be assigned as homework to the students to do on their own, and the concluding discussion may be held in the next class period.

For descriptions of the Miller–Urey experiment, the CalSpace Web site has videos of Stanley Miller describing the experiment, or perform an Internet search using the terms “Miller-Urey experiment.”

Materials Needed • A computer with a broadband Internet connection for downloading and viewing QuickTime videos and running the online simulation • Diagrams of alanine and glycine (see structure diagrams included on the handout) Procedures 1. Distribute the accompanying handout to the students and briefly introduce the Miller–Urey experiment without revealing the exact details of the chemicals used.

2. Connect to the Web site http://www.ucsd.tv/miller-urey/ and search for “Miller-Urey.”

3. Begin the simulation by having the students choose a combination of chemicals, observe the results, and record them on the handout. (Alternatively, this may be assigned for homework and discussed in the next class period.)

4. Repeat the experiment up to four more times until the correct mixture is chosen. Be sure to empty the chamber between each trial by clicking on the vacuum. If the correct mixture has not been chosen by the fifth trial, the instructor should choose it to present the successful result. (The correct mixture is H2, CH4, NH3, and boiling water.) Mention that this is believed to be an accurate representation of the prebiotic atmosphere. .

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Assessment Suggestions Discuss the results with the class using the questions on the handout: 1. Which combination of chemicals was successful in producing alanine and glycine? Why should this mixture produce amino acids?

(See Step 4 for the correct combination. Refer to the chemical diagrams of the two amino acids on the handout.

Methane and water might react to form carbon dioxide, the basis for the carboxyl group; the central carbon would come from methane; the amino group would come from ammonia; hydrogen would be provided by hydrogen gas or methane; and the methyl group of alanine would come from methane.)

2. Some combinations caused an explosion. Why? (Both oxygen and hydrogen gas are flammable in some combinations.)

3. How was the composition of the prebiotic atmosphere different from that of today? What caused it to change? (The atmosphere today consists mainly of molecular nitrogen [N 2] and oxygen [O2] as well as CO2 and other gases in low concentrations. The prebiotic atmosphere had carbon in the form of methane [CH 4], nitrogen in the form of ammonia [NH3], and oxygen in the form of water [H2O]. The biochemical activity of living organisms has had the greatest influence on changes in the atmosphere. Photosynthetic organisms process carbon to release O2 as a by-product, and aerobic respiration produces CO 2. The action of certain bacterial species chemically converts nitrogen compounds.)

Handouts or Display See the following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 17.1 Handout—The Miller–Urey Experiment In 1953, scientists speculating on the origin of life wondered whether the chemical composition of the Earth’s atmosphere before life was present (its prebiotic composition) would favor the production of the organic chemicals that are today found in living organisms. Stanley Miller, a graduate student under the direction of Harold Urey at the University of Chicago, performed an experiment in which he combined the inorganic chemicals thought to be present in the prebiotic atmosphere, and provided energy for chemical reactions with an electric current. He let the experiment run for 1 or 2 weeks, chemically analyzed the products with chromatography, and found that several amino acids were present. Amino acids are the subunits used to make proteins in living cells, and their presence in the products of the experiment suggests that prebiotic conditions could have led to the formation of at least some of the organic compounds found in cells. Use the simulation found at http://www.ucsd.tv/miller-urey/ to simulate the Miller–Urey experiment. Think about what chemicals would and would not have been present in the early Earth’s atmosphere. At the CalSpace Web site, you can add chemicals to the flask by clicking on them, add water by clicking on “Boiling Water,” and start the experiment by clicking on the sparker. If you change your mind or want to repeat the experiment, click on the vacuum to clear the chamber and start over.

For each trial, check below which chemicals were added to the flask, and record the result. If you are successful, the experiment will produce the amino acids alanine and glycine. (Remember, empty the chamber between each trial by clicking on the vacuum.)

Trial 1 ? N2 ? CO2 What happened?

? O2

? H2

? CH4

? NH3

? water

Trial 2. ? N2 ? CO2 What happened?

? O2

? H2

? CH4

? NH3

? water

Trial 3 ? N2 ? CO2 What happened?

? O2

? H2

? CH4

? NH3

? water

.

Trial 4 ? N2 ? CO2 What happened?

? O2

? H2

? CH4

? NH3

? water

Trial 5 ? N2 ? CO2 What happened?

? O2

? H2

? CH4

? NH3

? water

Questions 1.

Which combination of chemicals was successful in producing alanine and glycine?

Why should this mixture produce amino acids?

2.

Some combinations caused an explosion. Why?

3.

How was the composition of the prebiotic atmosphere different from that of today? What caused it to change?

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Lecture Activity 17.2: Sequence of Evolutionary Events Estimated Time to Complete: 10–15 minutes Section Reference 17.2 What Were the Earliest Organisms Like?

17.3 What Were the Earliest Multicellular Organisms Like?

17.4 How Did Life Invade the Land?

Introduction The subject of this chapter, The History of Life, can be difficult to present in interesting ways because the material is more factually than conceptually based. This is especially true for the sequence of evolutionary events because it is usually presented as a list of historical facts. One way to make the lecture more interactive is to have the students guess at the sequence of major events and present and defend it before the class. Usually, students can get the major events—prokaryotes before eukaryotes, reptiles before mammals, and so on, but there may be a few surprises for them, such as that terrestrial insects evolved before terrestrial plants.

In this exercise, groups of students can put the accompanying “flash cards” in what they believe to be the correct sequence of events and explain their reasoning before the class. The rest of the class can respond to one group’s presentation and refute it if they wish, before the instructor concludes the discussion.

The pictures for the flash cards can be taken from the excellent University of California Museum of Paleontology Web site, http://www.ucmp.berkeley.edu/. Go to this site and search for “geological time machine.”

The cards are presented in the correct order. Instructors are encouraged to make and add more cards for a more detailed historical sequence.

Materials Needed • Color printer • Heavy card stock paper for printing Procedures In preparation for the lecture, print the flash cards in color on heavy card stock paper and cut them out. You will be dividing the class into several groups, so prepare several sets of cards.

1. Break the class into four or five groups. Give each group a set of cards and ask them to place them in the order in which they presumably evolved, based on the order in which they appear in the fossil record.

Encourage them to discuss within the group before making a final decision. This should take a few minutes.

2. Choose one group to present their sequence (you may want to do this before they make their choices, so the group can prepare to present). Encourage discussion and feedback from the rest of the class.

3. Conclude the discussion by summarizing the consensus, correct any misinterpretations, and further discuss any conclusions that deviate from the actual sequence.

Assessment Suggestions In the concluding discussion, summarize the class consensus and compare it to the true sequence. If there are any discrepancies, point them out and further explain them. After presenting the material from Sections 17.2 through 17.4, you may want to briefly repeat this exercise to reinforce the major events represented in the fossil record.

Handouts or Display Perform Internet searches using the following terms to obtain images that can be used as templates for making flash cards by adding appropriate images.

Cyanobacteria Eukaryotes Multicellular organisms Invertebrate animals Terrestrial insects Terrestrial plants Amphibians Reptiles Mammals Primates .

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Instructor Guide Biology: Life on Earth

Lecture Activity 17.3: Vertebrate Diversity and Mass Extinction Estimated Time to Complete: 15–20 minutes Section Reference 17.5 What Role Has Extinction Played in the History of Life?

Introduction Extinction has influenced the diversity of living organisms across biological history as much as speciation has.

Extinction of species opens up ecological niches that provide opportunities for existing species to adapt, resulting in new species. Rarely, catastrophic changes in climatic conditions can result in the geologically instantaneous extinction of many species at the same time—a mass extinction event.

In this activity, students will plot data on diversity in the vertebrate family (the taxonomic level) over the last 550 million years, and identify possible mass extinction events as decreases in the numbers of families. Because extinction at the family level represents the loss of many related species, it is an appropriate measure for mass extinction; genus- and species-level extinction data are erratic, and the number of vertebrate orders (and higher levels) are too few to show a clear trend.

The students’ graphs should look approximately like this:

For more information on mass extinctions, perform an Internet search using the search terms “mass extinctions.”

Materials Needed None Procedures 1. Distribute the accompanying handout to the class and briefly introduce the activity. If necessary, review the taxonomic levels and explain why family-level diversity is appropriate for this analysis.

2. Have the students plot the data on the chart on the handout.

3. Discuss the results using the questions in Assessment Suggestions as a guide.

4. If desired, further discuss the five mass extinction events in more detail. Two of these, the end-Permian and end-Cretaceous events (at 245 and 65 million years ago, respectively), are discussed in detail in Section 17.5 of the text.

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Assessment Suggestions Discuss the plots with the class using the following questions. (These questions are included on the accompanying handout. Answers are in italics.)

1. How many times does the number of vertebrate families decrease, and approximately when did the decreases take place?

(There are five clear decreases in family number. They are dated at precisely 440, 360, 245, 208, and 65 million years ago; students’ answers should reflect these approximately.)

2. Look at Table 17-1 of the text. To what geological periods do these times correspond?

(These times represent the ends of the Ordovician, Devonian, Permian, Triassic, and Cretaceous Periods.)

3. Why is there a correspondence between mass extinctions and the ends of geological periods?

(Geological periods were established on the basis of the types of fossils found at corresponding layers of rock over widespread locations, so that a shift in the types of fossils marked the end of one period and the beginning of another. Because mass extinction events marked the loss of a number of species and the subsequent evolution of many new species to fill the available ecological niches, these events correspond to the boundaries of geological periods.)

Handouts or Display See the following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 17.3 Handout—Vertebrate Diversity and Mass Extinction Extinction has influenced the diversity of living organisms across biological history as much as speciation has.

Extinction of species opens up ecological niches that provide opportunities for existing species to adapt, resulting in new species. Rarely, catastrophic changes in climatic conditions can result in the geologically instantaneous extinction of many species at the same time—a mass extinction event.

To identify mass extinction events, paleontologists usually look at the taxonomic family level of a group of organisms over time. A decrease in the number of families at one point in geological history represents the loss of a large number of species in that family at one time, and indicates a mass extinction.

The following page lists data on the numbers of vertebrate animal families over the last 550 million years, based on fossil evidence. Plot the data on the provided chart, with the number of millions of years ago on the x axis (note that the numbers should be in reverse numerical order) and the number of families on the y axis. Connect the plot points with straight lines.

With the rest of the class, discuss the following questions: 1.

How many times does the number of vertebrate families decrease, and approximately when did the decreases take place?

2.

Look at Table 17-1 of the text. To what geological periods do these times correspond?

3.

Why is there a correspondence between mass extinctions and the ends of geological periods?

.

Data: Millions of Years Ago 550 520 490 470 450 440 400 375 365 340 320 300 250 240 230 220 210 195 175 150 120 90 75 70 65 50 40 20 5 0

Number of Vertebrate Families 75 100 150 300 410 320 415 440 350 400 415 410 405 300 195 250 270 225 300 370 430 510 560 600 520 580 660 700 725 725

.

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Instructor Guide Biology: Life on Earth

Lecture Activity 17.4: Interactive Online Human Evolution Activities Estimated Time to Complete: 15–30 minutes, possibly over more than one class period, with some time out of class Section Reference 17.6 How Did Humans Evolve?

Introduction There are a number of excellent interactive Web sites that offer resources for the presentation and investigation of the history of human evolution. A number of in-class and out-of-class activities can be designed using these sites, particularly if the classroom has a large-group computer display with a broadband Internet connection.

A list of resources is as follows: • The PBS television network Web site has many ideas and online resources for evolution teachers that were originally developed for its Evolution series, which was originally broadcast in September 2001. One page on the site, coincidentally titled How Did Humans Evolve?, has a link to an interactive timeline of human evolution titled Origins of Humankind. (This requires a Flash plug-in.) Go to http://www.pbs.org and search using the terms “how did humans evolve activity.” The first link will take you to the activity. After some introductory text with fossil skull images, users can access the timeline of human phylogeny dating back 6 million years. Clicking on a species’ name reveals additional information and a fossil image, and clicking on various icons presents more information on specific fossil finds and cultural innovations. Also, for those without a high-speed Internet connection, there is a non-Flash low-bandwidth version, with links to text-based versions of the same information, at the same site.

• Human Evolution: The Fossil Evidence in 3D (The University of California, Santa Barbara, Department of Anthropology site authored by P. L. Walker and L. H. Hagen.) To find the site, perform an Internet search using the terms “human fossil evidence in 3D.” The site includes a gallery of primate and hominid fossil skulls in three dimensions, and requires a Shockwave plug-in. Images and informational text are accessed by clicking on a phylogenetic tree diagram. Each image can be rotated 360° by clicking and dragging on it.

The skull images included in the gallery are those of a tree shrew, a ring-tailed lemur, a spider monkey, a chimpanzee, Australopithecus afarensis, Homo habilis, Homo erectus, archaic Homo sapiens from 400,000 years ago, Homo neanderthalensis, and modern Homo sapiens.

• The Early Human Phylogeny site of the Smithsonian Institution National Museum of Natural History has an image map of the human phylogenetic tree dating back to Ardipithecus ramidus from 4.4 million years ago.

Clicking on a species name takes the user to a new page with textual information and fossil images. There is also a small virtual reality gallery (which requires a QuickTime plug-in) of fossil skulls for Paranthropus boisei, Homo ergaster, and P. aethiopicus. (Note that Paranthropus is an alternate genus name for a branch of the Australopithecus line that includes the species aethiopicus, boisei, and robustus.) This gallery also allows a clickand-drag 360° rotation of fossil images. To access this resource, go to http://www.mnh.si.edu and search using the terms “early human phylogeny.” The first link will take you to the gallery.

Materials Needed • Computer(s) with a broadband Internet connection • Web browser with Flash, Shockwave, and QuickTime plug-ins (free downloads) Procedures Instructors are encouraged to use these resources for presentation of lecture material from Section 17.6 of the text, “How Did Humans Evolve?” All of the listed sites have fossil images, and the latter two allow threedimensional image presentation of skulls of some species.

These sites may also be used for in-class or homework assignments for the students, depending on the availability of suitably equipped computers in the classroom. One suggested exercise is to assign a species to an individual student or group of students and have them work individually or, if in groups, collaboratively to explore the time period and important characteristics of the species. (The accompanying handout has a suggested format for recording their research findings.) The results can be handed in and graded, presented in class by the students, or both. The list of possible species might include: Nonhominid primates: Lemur .

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Spider monkey Pongid: Chimpanzee Hominid lineage: Ardipithecus ramidus Australopithecus anamensis Australopithecus afarensis Australopithecus africanus Australopithecus garhi Australopithecus (Paranthropus) aethiopicus Australopithecus (Paranthropus) robustus Australopithecus (Paranthropus) boisei Homo habilis Homo rudolfensis Homo ergaster Homo erectus Homo heidelbergensis Homo neanderthalensis Homo sapiens (ancient) Assessment Suggestions After submission and/or presentation of student research on the various species, compile a short handout summarizing the important features of each as a study guide, and include the material in a test or quiz. Optionally, images from the sites used for the research can be included in the test/quiz material.

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 17.4 Handout—Primate/Hominid Species Research Species Name (assigned by the instructor) ____________________________ When did this species live?

What are the closest relatives of this species?

Did any other hominid species live at the same time as this species?

What are the unique features of this species’ skull?

How does the skull differ from that of modern Homo sapiens?

What are some of the known or inferred habits or cultural innovations of this species?

If this species is now extinct, why do you think it is?

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CHAPTER 18 SYSTEMATICS: SEEKING ORDER AMID DIVERSITY LECTURE OUTLINE Case Study: Origin of a Killer 18.1 How Are Organisms Named and Classified?

A. The Branch of Biology Concerned with Naming and Classifying Organisms Is Known as Taxonomy 1. The basis of modern taxonomy was developed by Carolus Linnaeus a. He introduced the two-part scientific naming of organisms B. Each Species Has a Unique, Two-Part Name 1. The scientific name of an organism designates its genus and species (Figure 18-1) C. Modern Classification Emphasizes Patterns of Evolutionary Descent 1. The process of classification focuses almost exclusively on reconstructing phylogeny, or evolutionary history 2. The science of reconstructing phylogeny is known as systematics D. Systematists Identify Features That Reveal Evolutionary Relationships 1. They must distinguish between similarities among living organisms that stem from convergent evolution or inheritance from a common ancestor 2. Systematists look carefully at similarities in both external and internal structure (Figure 18-2) E. Modern Systematics Relies on Molecular Similarities to Reconstruct Phylogeny 1. Systematists can use similarities in nucleotide sequences and chromosomes to investigate relatedness between organisms (Figure 18-3) â Lecture Activity 18.1: Molecular Systematics â In Greater Depth: Phylogenetic Trees (Figures E18-1, E18-2, and E18-3) â Links to Everyday Life: Small World F. Systematists Name Groups of Related Species 1. Systematists name groups called clades, which include species linked by descent from a common ancestor (Figure 18-4) a. When systematists name a clade, the name itself does not convey much information b. One way to reveal the inclusiveness of a clade is to use taxonomic categories that form an increasingly inclusive nested hierarchy i. The Linnaean classification came to include eight categories ii. Domain, kingdom, phylum, class, order, family, genus, and species iii. The ranking system does pose various problems for categorizing organisms â Lecture Activity 18.2: Hierarchical Categorization â Lecture Activity 18.3: Hardware Taxonomy G. Use of Taxonomic Ranks Is Declining

18.2 What Are the Domains of Life?

A. By the 1970s, Systematists Concluded from the Available Evidence That the Earliest Split in the Tree of Life Divides All Species into Five Kingdoms 1. As knowledge of life’s evolutionary history expanded, it became apparent that this was an oversimplification B. A Three-Domain System More Accurately Reflects Life’s History 1. Carl Woese and other researchers studying RNA nucleotide sequences showed that prokaryotes include two very different kinds of organisms (Figure 18-5) 2. This classification scheme divides organisms into three domains a. Bacteria, Archaea, and Eukarya (Figure 18-6)

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Instructor Guide Biology: Life on Earth b. Eukarya is divided into a variety of clades, including plants, fungi, and animals, and a separate group generically called “protists” (Figure 18-7) â Lecture Activity 18.4: Exploring the Tree of Life (Parts 1 and 2 of Procedures)

18.3 Why Do Classifications Change?

A. The Hypotheses of Evolutionary Relationships on Which Classification Is Based Are Subject to Revision as New Data Become Available B. Species Designations Change When New Information Is Discovered C. The Biological Species Definition Can Be Difficult or Impossible to Apply 1. The biological species definition fails for asexually reproducing species 2. The phylogenetic species concept offers an alternative definition a. This concept defines a species as the smallest diagnosable group that contains all the descendents of a single common ancestor

18.4 How Many Species Exist?

A. Scientists Do Not Know How Many Species Exist on Earth â Lecture Activity 18.4: Exploring the Tree of Life (Part 3 of Procedures) 1. Between 7,000 and 10,000 new species are identified annually 2. The total number of named species is approximately 1.5 million 3. Biodiversity is the number and variety of Earth’s species 4. Destruction of rain forests could endanger undiscovered species (Figure 18-8)

Case Study Revisited: Origin of a Killer

KEY TERMS Archaea Bacteria biodiversity clade domain Eukarya

genus phylogeny scientific name species systematics taxonomy

LECTURE ACTIVITIES Lecture Activity 18.1: Molecular Systematics Estimated Time to Complete: 10–15 minutes in each of two consecutive classes Section Reference 18.1 How Are Organisms Named and Classified?

Introduction Systematists today compare nucleotide sequences of homologous DNA regions of various species to try to reconstruct the evolutionary relationships of these species. Sequence comparisons are often fraught with problems such as deletions and insertions of nucleotides during the evolutionary divergence of groups, but there are computer algorithms for alignment of DNA sequences. Once aligned, nucleotide positions that are variable have information about the relationship between them; those pairs that have more matches between them are more closely related and by inference have shared a common ancestor more recently.

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In this exercise, students will compare three DNA sequences and formulate the relationships among the three of them. All are sequences of the NADH dehydrogenase subunit 3 (ND3) gene, located on the mitochondrial genome. Sequence 1 is taken from Homo sapiens (human), Sequence 2 is from Rattus norvegicus (rat), and Sequence 3 is from Mus musculus (mouse). Students will find that the rat and mouse sequences are most closely related, and the human sequence is about equally related to both of the other two.

The exercise works best if it is assigned and introduced in one class period, completed for homework, and discussed in the following period.

The three sequences were obtained from the Entrez online genetic database sponsored by the U.S. National Center for Biotechnology Information (NCBI) (http://www.ncbi.nlm.nih.gov/Database), which allows free access and search capabilities.

Materials Needed None Procedures 1. Introduce or review the use of DNA sequence information in systematics.

2. Distribute the accompanying handout and, using the provided instructions, explain the exercise. Do not reveal the species from which the sequences are taken. For each nucleotide position that has a match between two of the three sequences, students will circle the two nucleotides that match. Then, they will count the number of positions that have matches between Sequences 1 and 2, between Sequences 1 and 3, and between Sequences 2 and 3. The exercise and questions on the handout should be completed for homework. (The instructor may want to take the last 10 minutes of class to introduce the assignment and have the students begin work on it, in case there are questions.)

3. In the next class, discuss the results using the questions on the handout as a guide. After the discussion, reveal the names of the species from which the sequences are taken.

Assessment Suggestions Begin by asking the results of their analysis located at the bottom of the first page of the handout. The correct numbers of sequence matches are as follows: Only 1 and 2 match: 24 Only 1 and 3 match: 26 Only 2 and 3 match: 74 Discuss the answers to the questions on the handout: 1. Which two sequences are most closely related? How do you know?

(Sequences 2 and 3 are the most closely related, as they have the most number of pairwise matches. There are about three times more matches in the Sequences 2 and 3 comparison than in the other two pairs.)

2. Is the least related sequence about equally related to the other two? How do you know? What does this suggest about the evolutionary history of the three species?

(Yes, Sequence 1 has about the same number of matches with Sequence 2 [24] as it does with Sequence 3 [26].

This means that the ancestor of Sequence 1 diverged from a common ancestor of Sequences 2 and 3, and that 2 and 3 have evolved at about the same rate over time.)

3. Draw a phylogenetic tree diagram that shows the relationship between the three sequences.

(The tree should look something like the following picture. The identity of the three species could be revealed at this point in the discussion.)

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Instructor Guide Biology: Life on Earth Why are there some positions in which none of the three sequences match?

(These positions represent nucleotides that have evolved in at least two, and perhaps all three, of the species’ lineages since their divergence from the common ancestor.)

Handouts or Display See the following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 18.1 Handout—Molecular Systematics Three aligned DNA sequences are listed below. All three are sequences of the NADH dehydrogenase subunit 3 (ND3) gene, which is located on the mitochondrial genome, the small circular DNA molecule carried in the mitochondria of eukaryotes. Each of the three sequences is taken from a different mammalian species, and it is your job to determine the evolutionary relationship of the three species using these data.

Sequence 1 ATAAACTTCGCCTTAATTTTAATAATCAACACCCTCCTAGCCTTACTACAATAATTATT Sequence 2 ATTAACCTACCCATTATCATCACAATTAACATCACCTTATCCTTTATCCTCATTTCAATT Sequence 3 ATCAACCTGTACACTGTTATCTTCATTAATATTTTATTATCCCTAACGCTAATTCTAGTT ** *** * * * * ** ** * ** ** * * ** ** Sequence 1 ACATTTTGACTACCACAACTCAACGGCTACATAGAAAAATCCACCCCTTACGAGTGCGGC Sequence 2 GCATTCTGATTGCCTCAAATAAACTTATACTCCGAAAAAGCAAACCCATATGAATGTGGC Sequence 3 GCATTCTGACTCCCCCAAATAAATCTGTACTCAGAAAAAGCAAATCCATATGAATGCGGA **** *** * ** *** * ** *** ****** * * ** ** ** ** ** Sequence 1 TTCGACCCTATATCCCCCGCCCGCGTCCCTTTCTCCATAAAATTCTTCTTAGTAGCTATT Sequence 2 TTCGACCCAACAAGTTCTGCACGCCTTCCTTTTTCAATAAAATTTTTCTTAGTAGCCATT Sequence 3 TTCGACCCTACAAGCTCTGCACGTCTACCATTCTCAATAAAATTTTTCTTGGTAGCAATT ******** * * * ** ** * ** ** ** ******** ***** ***** *** Sequence 1 ACCTTCTTATTATTTGATCTAGAAATTGCCCTCCTTTTACCCCTACCATGAGCCCTACAA Sequence 2 ACATTTCTACTATTCGACCTAGAAATCGCCTTACTACTTCCCCTCCCATGAGCGATTCAA Sequence 3 ACATTTCTATTATTTGACCTAGAAATTGCTCTTCTACTTCCACTACCATGAGCAATTCAA ** ** ** **** ** ******** ** * ** * ** ** ******** * *** Sequence 1 ACAACTAACCTGCCACTAATAGTTATGTCATCCCTCTTATTAATCATCATCCTAGCCCTA Sequence 2 ACAACCAATACCACTACAATAATAGCAACTGCCTTTATTTTAGTCACTATTTTGTCTCTT Sequence 3 ACAATTAAAACCTCTACTATAATAATTATAGCCTTTATTCTAGTCACAATTCTATCTCTA **** ** * *** * ** * * ** *** ** * * ** Sequence 1 AGTCTGGCCTATGAGTGACTACAAAAAGGATTAGACTGAGCCGAAT— Sequence 2 GGCCTAGCCTACGAATGAACACAAAAAGGACTAGAATGAACAGAATAA Sequence 3 GGCCTAGCATATGAATGAACACAAAAAGGATTAGAATGAACAGAGTAA * ** ** ** ** *** ********** **** *** * ** * Systematists use computer programs to compare and analyze DNA sequence data, as well as to draw the tree diagrams that graphically show the relationships between the sequences. These sequences were aligned and displayed as above using one such program. There are four lines to the analysis. The first three lines have the aligned sequences; a “dash” symbol (“—”) indicates a gap in the alignment. The fourth line has matching information for the three sequences; an asterisk (*) indicates that all three sequences match at that position, and a space indicates that all three do not match.

Look at each position where all three do not match. If two of the three match, circle the two that match. Then, count the numbers of positions that show the following: Only 1 and 2 match: _____ Only 1 and 3 match: _____ Only 2 and 3 match: _____

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Now, answer the following questions: 1.

Which two sequences are most closely related? How do you know?

2.

Is the least related sequence about equally related to the other two? How do you know? What does this suggest about the evolutionary history of the three species?

3.

Draw a phylogenetic tree diagram that shows the relationship between the three sequences.

4.

Why are there some positions in which none of the three sequences match?

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Lecture Activity 18.2: Hierarchical Categorization Estimated Time to Complete: 5–10 minutes Section Reference 18.1 How Are Organisms Named and Classified?

Introduction This class exercise is a quick and easy way to illustrate the practice of hierarchical categorization and the sometimes arbitrary nature of choosing which are to be higher-level and lower-level categories. Students in groups are given a series of colored shapes to categorize. They can quickly decide the higher-level categorical criterion (color or shape) and form groups based on similarity. The discussion following the exercise can lead students into thinking about how biologists decide what criteria are more important in establishing a classification hierarchy of organisms.

Materials Needed • Several groups of differently shaped pieces of plastic, with several different colors of each. (If these are not available, colored shapes printed on paper will suffice; see the accompanying handout.)

Procedures 1. Before class, obtain plastic objects of different shapes and various colors (such as blue, red, and yellow spheres; blue, red, and yellow pyramids; etc.) and put identical collections in several bags. One bag will be given to each student group. (Alternatively, print several copies of the attached handout on a color printer, cut out each colored shape, and put each collection in a plastic baggie.)

2. In class, assemble the students into several groups, and give each group a bag. Tell the groups to decide how to categorize the shapes, and then put the shapes into groups based on their decisions.

3. Discuss their decisions using the questions in the Assessment Suggestions section.

Assessment Suggestions Following the exercise, have each group present and explain its categorization. (Some groups will have chosen “shape” as the category criterion, with all colors of the same shape in the same category; others will have chosen “color” as the category criterion, with all shapes of the same color in the same category.) Keep a tally of how many groups choose “shape” and how many choose “color.” With the entire class, discuss the results as follows: 1. Which is better to choose for categorizing these objects, shape or color?

(Neither is really better; the choice is arbitrary. It depends on whether the person doing the categorizing feels that shape or color is more important, and should be used as a higher-level category.)

2. In assigning biological species to categories, are there some characteristics that are more or less important?

If so, what are they?

(Yes, important characteristics might be cell structure [prokaryote or eukaryote], method of obtaining energy [photosynthetic or heterotrophic], and so on. Less important characteristics might be color or size.)

3. Why are the important characteristics important?

(They represent major, fundamental biological differences among organisms.)

4. Why are the less important characteristics less important?

(They represent ways in which biologically very similar organisms may vary, or change over a period of development.)

5. What should a biologist do if, as with the colored shapes, some characteristics are not any more or less important than others?

(The biologist may choose a category arbitrarily, until and unless more data make it clear that one character is “better” than another and warrants being placed at a higher level.)

Handouts or Display See the following page.

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Instructor Guide Biology: Life on Earth

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Lecture Activity 18.3: Hardware Taxonomy Estimated Time to Complete: 15–20 minutes Section Reference 18.1 How Are Organisms Named and Classified?

Introduction This exercise may be done in addition to, or instead of, Lecture Activity 18.2 (Hierarchical Categorization).

Taxonomists (biologists who categorize organisms into the hierarchical system of biological classification) have historically used the physical characteristics of organisms as the basis for assigning organisms to the same or different biological categories of various levels. Today, taxonomy is rooted in the field of systematics, the determination of evolutionary relationships between species. Although other types of data (such as behavior, geographic location, and genetic comparisons) are used to assess similarity, morphological characteristics are still important in determining similarity, and inferring relatedness.

With this activity, students will be presented with a collection of small hardware items, such as nuts and bolts, choose a hierarchical system of categorization, and assign each “species” its taxonomic place. Students get a feel for the difficulty of such work, and the sometimes arbitrary nature of deciding “higher-level” and “lowerlevel” variability.

Materials Needed • Bags of various types of hardware pieces, or pictures of the different types. For suggested pictures, perform an Internet search using the terms “brass fittings.”

Procedures The instructor should obtain a number of small inexpensive hardware pieces, available at any hardware store or department. The pieces should vary in size, shape, color, and function, so that there are many possible ways to categorize the pieces. Prepare a bag of pieces for each collaborative group of students in the class.

1. Divide the class into several groups and provide each with a bag of hardware that includes various types of nuts and bolts. Ask each group to categorize the collection into a hierarchy of major categories, minor categories within each major category, and (if possible) subcategories within each minor category.

2. After about 5 minutes, have each group present its categorization system, including the highest-level category, the next-level category, and so on. Ask the members of each group to tell why they ranked the characteristics as more or less important, and conclude with a discussion of how biological classification decisions are made. (See Assessment Suggestions for guiding discussion questions.)

Assessment Suggestions Ask each group to respond to the following questions: 1. What is the highest-level category characteristic in your system? What is the next-level characteristic? etc.

(Many will probably choose function [if known] or shape of the piece as the highest level of categorization.

Characteristics such as size or color may be lower or lowest-level categories.)

2. Why did you choose _________ (the highest-level characteristic) as most important?

(As groups respond to this question, write the responses on a blackboard or display for the discussion to follow.)

When each group has responded, consider the results.

3. Are some characteristics frequently chosen for the highest level? Is there a consensus on ranking the importance of the characteristics?

(Probably, there will be some agreement that function and shape are very important, size and color less so.)

Discuss with the class: 4. What are some higher-level or important characteristics for categorizing biological species?

(Again, write and display the responses. Students may consider such things as cell structure, method of obtaining energy, method of reproduction, or body structure as very important, whereas size and color should be considered to be less important.)

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188 5.

Instructor Guide Biology: Life on Earth It seems to be easier to decide what characteristics are very important or unimportant in categorization, but there is disagreement on the intermediate levels. What can biologists do to decide how to establish these intermediate characters?

(This may be a difficult question for the students to answer. If so, point out that species that are very different, and would be categorized in a different higher-level category, differ in a suite of characters, not just a few. Once a group showing higher-level similarity is established, variation among members of the group then becomes more important for subcategorization, and establishing the next most important set of differences is easier.)

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Lecture Activity 18.4: Exploring the Tree of Life Estimated Time to Complete: 5-minute introduction in one class, and 20 minutes for group presentations in a later class Section Reference 18.2 What Are the Domains of Life?

18.4 How Many Species Exist?

Introduction The Tree of Life Web Project (http://www.tolweb.org/tree/) is a professionally maintained, regularly updated, peer-reviewed Web site with information on evolutionary relationships and the biodiversity of taxonomic groups.

The information is arranged in the same way as the biological classification system, but presented in a way that is easy for biology students to access. For example, both scientific and common names are included in the hierarchical arrangement of taxa (e.g., Annelida [segmented worms]). The site was originally designed for use by professional taxonomists and systematists, but is also of use for biology education at the undergraduate level.

Each individual page for a group of organisms on the site has several sections: pictures of representative organisms; a phylogenetic tree of subtaxa within the group; references to journal articles on the phylogeny of the group; and links to more Internet information on the group. Each page is written by experts in the phylogeny of the group, and peer reviewed. Any tentative information is labeled as such.

In presenting material from Section 18.2 of the text (“What Are the Domains of Life?”), there is one page on the site that is very helpful. From the home page of the site (referenced above), click on Root of the Tree. This accesses a page entitled “Life on Earth” that presents current views on the relationships between the three domains: Archaea, Eubacteria (a.k.a. Bacteria), and Eukaryotes (a.k.a. Eukarya). Although current data suggest that Archaea and Eukarya are more closely related to each other than either are to Eubacteria, there is some controversy over the relationships of specific groups of Archaea to Eukarya.

If the instructor has access to a computer display system with an Internet connection, this page can be accessed and displayed during lecture, or printed for class display or distribution.

Given the variety and complexity of information on organismal phylogenies, it is advisable to assign takehome projects to students. The results of these assignments can be submitted for grading and/or presented in class. One such assignment, as detailed here, would be for each student to explore the relationships between the three domains, and to research the biodiversity of specific taxonomic groups as assigned by the instructor.

Materials Needed • Classroom computer display with Internet access (optional) • Each student should have access to the Internet for take-home assignments Procedures Introduce the material from Section 18.2 of the text (“What Are the Domains of Life?”) on the change in the biological classification system from the two-kingdom to the five-kingdom system, and the recent change to the three-domain system. At this point, access the “Life on Earth” page of the Tree of Life Web site to show the alternate phylogenies that are in dispute. The link to access this site is called “The Root of the Tree,” or the direct link to the page is http://www.tolweb.org/Life_on_Earth/1; the two phylogenies are reprinted here.

The “archaea tree”: ,=============== Eubacteria | | ,== Euryarchaeota =====| ,=Archaea=| `==| `== Crenarchaeota-Eocytes | `============ Eukaryotes The “eocyte tree”:

,======== Eubacteria | | ,===== Euryarchaeota =====| | `==| ,== Crenarchaeota-Eocytes `==| .

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Instructor Guide Biology: Life on Earth

`== Eukaryotes Assign the students to collaborative groups and give each group a copy of the accompanying handout. Explain that each group is to use the Tree of Life Web site to (1) research and report on the relationships between the three domains, and (2) research the biodiversity of a specific taxonomic group, to be assigned. (See the following list for suggestions.) Have the due date be the day that Section 18.4 of the text (“How Many Species Exist?”) will be presented and discussed. Some suggestions for taxonomic groups: Echinoderms (sea urchins, starfish, sea cucumbers, etc.)

Frogs Mammals Annelida (segmented worms) Beetles Wasps, Bees, and Ants Flies Butterflies and Moths Spiders Fungi Flowering Plants During the class covering the topic of biodiversity, have a class discussion of the results of the “three-domain” research, using the questions on the handout as a guide. Also, have each collaborative group give a brief report of the answers to the questions on the handout.

Assessment Suggestions The answers to the questions in Part 1 of the handout, which can be discussed with the class on the due date of the assignment, are as follows.

1. Why do you think these are called subsections rather than phyla?

(Prokaryotes, including Bacteria, reproduce asexually, so that “populations,” “species,” and so on are really collections of independently evolving lineages that may occasionally exchange genetic material. The taxonomic system for prokaryotes is different from those of most eukaryotes because classification is based on the similarity of anatomical characteristics of various combinations. The intermediate levels of bacterial classification have different names because the designations of “class,” “order,” and “family” would not have the same meaning as they would for animals.)

2. Which eukaryotic kingdom contains members that may not all be closely related?

(Protista has groups that are more closely related to animals [collar-flagellates], fungi [microsporidia], and plants [euglenids] than to other groups of protists.)

3. Why are Archaeans called “life’s extremists”?

(Archaeans are often found in very extreme environments—hot springs [high temperature], very acidic [low pH], or high-alkaline [high-pH] habitats.)

Make copies of Part 2 of each group’s completed handout for each member of the class, and include questions about the presented information on a quiz or exam.

Handouts or Display See the following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Student Name(s): _____________________________________________________________________

Name of Taxonomic Group (assigned by the instructor): ______________________________________

Lecture Activity 18.4 Handout—Exploring the Tree of Life Part 1: The Three Domains Access the Tree of Life Web site on the Internet (http://www.tolweb.org/tree). Click on the text Root of the Tree to access the page (entitled “Life on Earth”) with information on the three domains: Archaea, Eubacteria (called “Bacteria” in your text), and Eukaryotes (called “Eukarya” in your text).

1.

Click on Eubacteria on the phylogenetic tree. This brings up a tree showing the relationships between the “kingdoms” of this domain. Click on Cyanobacteria to bring up a list of “Subsections.” Why do you think these are called subsections rather than phyla?

(Hint: What is different about bacterial genetics and evolution as compared to most eukaryotes?)

2.

Return to the “Life on Earth” page and click on Eukaryotes. Which eukaryotic kingdom contains members that may not all be closely related?

3.

Return to the “Life on Earth” page and click on Archaea. Use the links at the bottom of the page to answer the question: Why are Archaeans called “life’s extremists”?

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Part 2: Exploring ___________________________ (name of assigned taxonomic group) Return to the main Tree of Life page, click on Popular Pages, click the name of your assigned group, and answer the following questions. (You may need to explore the provided links to answer some of them.)

1.

What is the classification “rank” of your group (kingdom, phylum, etc.)?

2.

What are the major characteristics of your group? (Include as much as you can find from this list: habitat location, definitive anatomical attributes, behavior.)

3.

List three representative species that are classified as members of your group.

4.

Click on one of the highlighted “subgroups” of your assigned group. Which one did you choose? What are some of the characteristics of the “subgroup”?

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CHAPTER 19 THE DIVERSITY OF PROKARYOTES AND VIRUSES LECTURE OUTLINE Case Study: Unwelcome Dinner Guests 19.1 Which Organisms Are Members of the Domains Archaea and Bacteria?

A. Both Bacteria and Archaea Are Very Small 1. All prokaryotes differ in size and shape a. Common shapes include rodlike, spherical, and corkscrew-shaped (Figure 19-1) B. Bacteria and Archaea Are Fundamentally Different 1. The cell walls of bacteria are unique and are made up of peptidoglycan 2. Bacteria and archaea differ in the structure and composition of their plasma membranes, ribosomes, and RNA polymerases C. Classification of Prokaryotes Within Each Domain Is Difficult 1. The Gram stain distinguishes two types of cell walls in bacteria 2. DNA and RNA sequence comparisons have helped biologists classify prokaryotes â Lecture Activity 19.1: Visualization of Bacteria That Are All Around Us â Lecture Activity 19.2: Microbe Identification

19.2 How Do Prokaryotes Survive and Reproduce?

A. Some Prokaryotes Are Motile 1. Many prokaryotes have flagella for locomotion (Figure 19-2a) 2. The structure of prokaryote flagella is different than that of eukaryotic flagella (Figure 19-2b) B. Many Bacteria Form Protective Films on Surfaces 1. Some species aggregate to form biofilms a. Dental plaque is a type of biofilm (Figure 19-3) C. Protective Endospores Allow Some Bacteria to Withstand Adverse Conditions (Figure 19-4) 1. They provide longevity until conditions improve â Case Study Continued: Unwelcome Dinner Guests D. Prokaryotes Are Specialized for Specific Habitats 1. Some can survive extreme environmental conditions (temperature, pressure, salinity) (Figure 19-5) â Health Watch: Is Your Body’s Ecosystem Healthy? (Figure E19-1) E. Prokaryotes Have Diverse Metabolisms 1. Anaerobes do not require oxygen for survival 2. Opportunists can survive in aerobic or anaerobic conditions 3. Aerobes require oxygen for survival 4. Some species of bacteria are photosynthetic (Figure 19-6) F. Prokaryotes Reproduce by Fission (Figure 19-7) 1. This is a simple form of mitotic cell division G. Prokaryotes May Exchange Genetic Material Without Reproducing 1. Conjugation is the exchange of genetic material without reproducing (Figure 19-8) 2. Plasmids are small circular pieces of DNA that are often exchanged during conjugation â Lecture Activity 19.3: Bacterial Conjugation

19.3 How Do Prokaryotes Affect Humans and Other Organisms?

A. Prokaryotes Play Important Roles in Animal Nutrition 1. Cellulose digesters live in the digestive tract of many leaf-eating organisms 2. In humans, some bacteria use food products to produce vitamins K and B12 .

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Instructor Guide Biology: Life on Earth B. Prokaryotes Capture the Nitrogen Needed by Plants 1. Nitrogen-fixing bacteria live in the soil and convert nitrogen gas to ammonium, which can be absorbed by plants (Figure 19-9) C. Prokaryotes Are Nature's Recyclers 1. Prokaryotes help decompose organic matter in the environment D. Prokaryotes Can Clean Up Pollution 1. Bioremediation is the process of using prokaryotes to clean up pollutants E. Some Bacteria Pose a Threat to Human Health 1. Some anaerobic bacteria produce dangerous poisons a. Clostridium species cause tetanus and botulism 2. Humans battle bacterial diseases old and new a. Bubonic plague and Lyme disease are examples of bacterial diseases 3. Common bacterial species can be harmful a. Examples include certain Streptococcus species â Case Study Continued: Unwelcome Dinner Guests â Links to Everyday Life: Unwelcome Dinner Guests (Figure E19-1) â Lecture Activity 19.4: Bacterial Diseases Contest â Lecture Activity 19.5: Natural Selection for Antibiotic Resistance Animation

19.4 What Are Viruses, Viroids, and Prions?

A. A Virus Consists of a Molecule of DNA or RNA Surrounded by a Protein Coat (Figures 19-10, 19-11, and 19-12) B. Viruses Require a Host to Reproduce â In Greater Depth: Virus Replication (Figure E19-2) 1. Viruses attack host cells 2. Viruses are host specific a. Bacteriophages attack bacteria (Figure 19-13) b. In plants and animals, different viruses specialize in attacking particular cell types 3. Viral infections are difficult to treat C. Some Infectious Agents Are Even Simpler Than Viruses â Case Study Continued: Unwelcome Dinner Guests 1. Viroids are infectious particles a. They consist only of strands of RNA b. They cause many crop diseases 2. Prions are infectious particles of protein (Figure 19-14) a. Various diseases are caused by prions D. No One Is Certain How These Infectious Particles Originated â Lecture Activity 19.6: Viral Diseases Contest â Lecture Activity 19.7: Treatment of Viral Diseases Discussion

Case Study Revisited: Unwelcome Dinner Guests

KEY TERMS anaerobe Archaea Bacteria bacteriophage biofilm bioremediation

conjugation endospore flagellum (plural, flagella) host nitrogen-fixing bacterium pathogenic

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plasmid prion prokaryotic fission viroid virus

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LECTURE ACTIVITIES Lecture Activity 19.1: Visualization of Bacteria That Are All Around Us Estimated Time to Complete: 15–20 minutes in a couple different class times Section Reference 19.1 Which Organisms Are Members of the Domains Archaea and Bacteria?

Introduction This activity can be introduced by asking students if they can see the bacteria that are all around them and how many they think might be present in the room or on them. This demonstration will enable students to visualize colonies of bacteria that grow after nutrient agar is simply exposed to the air or their (what may appear to be clean!) fingers.

Materials Needed • A few nutrient agar (NA) plates (petri dishes into which a basic nutrient agar has been poured) • A Sharpie or china marker to mark the plates • An incubator for incubating the plates overnight is nice but not necessary Procedures 1. Bring the petri dishes to class.

2. Leave one dish (more if you want to sample different areas in the room and especially if it's a large room) open for 10–15 minutes while covering other materials.

3. Have a few student volunteers smear their fingers around on different NA plates.

4. Be sure the bottoms of all the plates are labeled correctly with location or student name.

5. Incubate overnight in an incubator. This is not entirely necessary, as growth will occur at room temperature, albeit more slowly.

6. Bring the plates back to class once growth has occurred and bacterial colonies are visible.

Assessment Suggestions Initiate discussion about which area (if multiple are done) of the room appeared to have the most bacteria and the growth of bacteria from the samples of students' fingers.

Be sure to ask if students are alarmed by the number of bacteria that grew on the plates because it is a good way to emphasize (assuming some will indicate alarm) that most bacteria are harmless to us and amazingly important in their ecosystems (as producers or decomposers).

A fun way to ask about this on an exam is to ask students why they are never alone even when they think they are.

Lecture Activity 19.2: Microbe Identification Estimated Time to Complete: 5–10 minutes Section Reference 19.1 Which Organisms Are Members of the Domains Archaea and Bacteria?

Introduction This activity is a good way to get students to review and apply their knowledge of the characteristics of the microbes covered in this chapter. Completion of the activity in small groups encourages the development of teamwork. Its revision from the format associated with previous editions of the text allows students to be more creative about how they test for the specific characteristics of microbes. If desired, fungi could be added to the list of potential organisms, and then this activity could be done as a review of concepts from two chapters.

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Materials Needed • Copies of the handout that describes the scenario and provides the directions

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Chapter 19 The Diversity of Prokaryotes and Viruses Procedures 1. Divide the students into groups of three or four.

2. Distribute the handouts and circulate (if possible) to help the students get started and answer questions.

Assessment Suggestions Follow up with a discussion about the various characteristics that could be tested for (presence of a nuclear membrane, chloroplasts, or peptidoglycan) and what organisms are indicated by the results of each test.

For future assessment include a question related to this activity on an exam.

Handouts or Display Provide the students with the scenario and directions on the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members' Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 19.2 Handout—Microbe Identification You're working at a remote field station and you've been given a container of unidentified mostly microscopic organisms. Your job is to determine if the organisms are bacteria, unicellular algae, or protozoans. Unfortunately the electricity is out, so you can't use your microscope. However, the lab is stocked with all the chemicals you need to test for the presence of particular molecules and cellular components (for example, you might have a hypothetical chemical that would turn blue in the presence of chloroplasts, which should distinguish one of the four groups listed above). Discuss your research goals and prepare a list of at least three tests that you'll perform on the sample to allow you to determine what organisms it contains. Then indicate the test results you expect for bacteria, algae, and protozoans.

Hint: You need to think about what chemicals and/or organelles make these organisms unique and different from each other, so you might start with that type of list. Your chemicals do NOT have to be real chemicals; for example, you can use my example of the one that turns blue in the presence of chloroplasts or you might use one that glows in the presence of something else.

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Lecture Activity 19.3: Bacterial Conjugation Estimated Time to Complete: 5–10 minutes Section Reference 19.2 How Do Prokaryotes Survive and Reproduce?

Introduction Conjugation enables bacteria to acquire "new" DNA that often includes genes for resistance to antibiotics. This is one method by which bacteria can increase their genetic variability. Review of bacterial reproduction via binary fission can be covered prior to viewing the animation or included in the discussion afterward.

Materials Needed • Computer lab with Internet connection for all of the students, or for the instructor and a method of showing the sites you will access Procedures Perform individual Internet searches using the terms "bacterial conjugation" and "binary fission in bacteria."

If students will be doing the searches, ask them to note how genetic material is passed on in these two processes and what the basic differences are between the two processes.

Assessment Suggestions Discuss the difference between conjugation and binary fission, as students often seem to equate them. The importance of conjugation to bacteria in acquiring resistance to antibiotics should be emphasized, as it underscores the importance of responsible and correct use of antibiotics. This topic also provides an opportunity to review concepts about DNA replication, heredity, and evolution (because bacteria that acquire antibiotic resistance are usually fitter than those bacteria without resistance).

For future assessment, one or more questions could be asked on an exam about the difference between conjugation and binary fission and how conjugation can affect the survival of bacteria.

Lecture Activity 19.4: Bacterial Diseases Contest Estimated Time to Complete: 5–10 minutes Section Reference 19.3 How Do Prokaryotes Affect Humans and Other Organisms?

Introduction There are many diseases caused by microbes, and often people confuse them with regard to the disease-causing agent. It is imperative that students become familiar with the common disease-causing agents. If they are somewhat familiar with common disease agents, then they can assume greater responsibility for their health care needs/concerns.

Materials Needed No special materials are needed unless prizes are awarded, which makes the activity more fun. The awarding of Smarties™ candy to the winning student(s) generally elicits a chuckle from students.

Procedures Give the students around 30 seconds to write down as many bacterial diseases as they can (without help) and then give them an additional 30 seconds to consult with one or two classmates to see if they can expand their lists.

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Assessment Suggestions Follow up the contest with a discussion about students' lists. Bacterial diseases that are typically listed include strep throat, staph infections, and anthrax. If not mentioned, the following are generally of interest to students: the plague and Lyme disease (particularly because they are more often interested in their means of transmission), tetanus, TB, and the STDs that are bacterial.

For future assessment, include a question on the exam about the identification of diseases as bacterial or not.

Lecture Activity 19.5: Natural Selection for Antibiotic Resistance Animation Estimated Time to Complete: 5–10 minutes Section Reference 19.3 How Do Prokaryotes Affect Humans and Other Organisms?

Introduction Numerous disease-causing bacteria are now resistant to a number of antibiotics (details about which bacteria and the antibiotics to which they are resistant are easily found on the Web, and there are links to a couple of sites within the Issues in Biology for this chapter on the Web site). Resistance to vancomycin is especially alarming, as that was typically reserved for use as an antibiotic of last resort. Review of concepts about mutations and natural selection can be covered prior to the Internet search or included in the discussion afterward.

Materials Needed • Computer lab with Internet connection for all of the students, or for the instructor and a method of showing the sites you will access Procedures Perform individual Internet searches using the terms "antibiotic resistance." If students will be doing the searches, ask them to note how antibiotic resistance evolves in bacteria.

Assessment Suggestions Discuss antibiotic resistance and the appropriate use of antibiotics for bacterial infections versus the inappropriate use of them for viral infections. The means by which bacteria acquire resistance (starting with a mutation and followed by transmission of and selection for the mutation) can be included in the discussion. This is a nice way to make connections to concepts about heredity and evolution. This may also be an opportune time to slip in some of the concepts associated with population growth that are addressed in Chapter 26. Competition for resources ties in well with this because the antibiotic-resistant bacteria will be able to acquire more resources, as they'll have less competition from species susceptible to the antibiotic(s).

Lecture Activity 19.6: Viral Diseases Contest Estimated Time to Complete: 5–10 minutes Section Reference 19.4 What Are Viruses, Viroids, and Prions?

Introduction There are many diseases caused by microbes, and often people confuse them with regard to the disease-causing agent. It is imperative that students become familiar with the common disease-causing agents. Too often people try to self-medicate with leftover or borrowed antibiotics when they have a viral infection for which antibiotics are useless, and thus concurrently contribute to the ever-increasing occurrence of antibiotic-resistant bacteria.

Materials Needed No special materials are needed unless prizes are awarded, which makes the activity more fun. The awarding of Smarties™ candy to the winning student(s) generally elicits a chuckle from students. .

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Procedures Give the students ~30 seconds to write down as many viral diseases as they can (without help) and then give them an additional 30 seconds to consult with one or two classmates to see if they can expand their lists.

Assessment Suggestions Follow up the contest with a discussion about students' lists. Viral diseases that are typically listed include colds, flu, and AIDS. Some that have received a lot of recent media attention that might be listed include West Nile, Ebola, and SARS. Students who have pets may have rabies on their list. Inevitably, students will mention some diseases caused by bacteria. Some typically mentioned are anthrax, tetanus, and TB. This is a good time to dispel some misconceptions students have about what diseases are caused by viruses and what diseases are caused by other organisms. There are some diseases, such as pneumonia and meningitis, that can be viral or bacterial.

For future assessment, include a question on an exam about the identification of viral diseases discussed in class.

Lecture Activity 19.7: Treatment of Viral Diseases Discussion Estimated Time to Complete: 5–10 minutes Section Reference 19.4 What Are Viruses, Viroids, and Prions?

Introduction Many students STILL haven't absorbed the importance of NOT taking antibiotics to treat a viral disease. It is imperative that we educate them about the proper use of antibiotics, as a great deal of the increase in antibioticresistant bacteria is attributed to abuse of antibiotics by the general public (taking "old" prescriptions, borrowing antibiotics from someone else) and the demand for prescriptions for antibiotics when they are not needed (for sore throats and colds).

Materials Needed None Procedures Initiate a discussion about this topic while covering Section 19.4 by asking students how viral diseases can be treated. Some savvy students will reply with methods to treat the symptoms of viral diseases if they know that antibiotics should not be used to treat viruses. The variety of ways to alleviate symptoms (antihistamines, bed rest, hydration with fluids, chicken noodle soup) of viral infections can be part of this discussion. Finish with discussion of the development of viral-specific medications, such as the protease inhibitors that AIDS patients take or valacyclovir and acyclovir that are used for herpes. There are several medications for treating the flu that could be included in the discussion.

Assessment Suggestions At a later time (during review of previously covered material), ask about specific diseases covered in the course and how they could be treated (with antiviral medicines or antibiotics). Include a question on an exam that lists specific diseases covered in class and ask which can/can't be treated with antibiotics.

Handouts or Display For more information about medications for treating the flu, go to http://www.cdc.gov/ and search using the term "flu."

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CHAPTER 20 THE DIVERSITY OF PROTISTS LECTURE OUTLINE Case Study: Green Monster 20.1 What Are Protists? (Table 20-1) A. Protists Are a Diverse Group of Organisms in the Domain Eukarya 1. Most protists are single celled B. Protists Use Diverse Modes of Nutrition 1. Some are predators, ingesting food using pseudopods 2. Some absorb nutrients from the environment 3. Other protists are photosynthetic C. Protists Use Diverse Modes of Reproduction 1. Most reproduce asexually but some can reproduce sexually (Figure 20-1a) 2. Some protists can exchange genetic information (Figure 20-1b) D. Protists Affect Humans and Other Organisms 1. Algae in the ocean capture solar energy, making it available to other organisms 2. Some protists cause human diseases â Lecture Activity 20.1: Microbe Identification

20.2 What Are the Major Groups of Protists?

A. Protist Systematics Has Been in a State of Flux 1. Different protists have different key features (Table 20-1) B. Excavates Lack Mitochondria 1. Diplomonads have two nuclei (Figure 20-2) 2. Parabasalids include mutualists and parasites (Figure 20-3) C. Euglenozoans Have Distinctive Mitochondria 1. Euglenids lack a rigid covering and swim by means of flagella (Figure 20-4) 2. Some kinetoplastids cause human diseases (Figure 20-5) D. Stramenopiles Have Distinctive Flagella 1. Water molds have had important impacts on humans a. They can cause various plant diseases 2. Diatoms are encased within glassy walls (Figure 20-6) a. Diatomaceous earth has many uses b. These organisms are an important component of phytoplankton 3. Brown algae are multicellular a. These organisms are photosynthetic b. Some have air sacs to maintain buoyancy (Figure 20-7a) c. Kelp forms dense forests that are important for marine life (Figure 20-7b) E. Alveolates Include Parasites, Predators, and Phytoplankton 1. These are single-celled organisms with distinctive, small cavities beneath the surface of their cells 2. Dinoflagellates swim by means of two whip-like flagella (Figure 20-8) a. These organisms are photosynthetic b. These organisms can cause red tide (Figure 20-9) â Case Study Continued: Green Monster 3. Apicomplexans are parasitic and have no means of locomotion a. These are parasites b. They are transmitted from one host to another via spores c. A well-known example is the parasite that causes malaria (Figure 20-10)

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Instructor Guide Biology: Life on Earth 4. Ciliates are the most complex of the alveolates a. Locomotion occurs in these organisms via cilia, as in Paramecia (Figure 20-11) b. Some ciliates are predators (Figure 20-12) F. Rhizarians Have Thin Pseudopods 1. Fossil foraminiferan shells form chalk (Figure 20-13a) 2. Radiolarians have glassy shells (Figure 20-13b) G. Amoebozoans Have Pseudopods and No Shells 1. Amoebozoans move by extending finger-like pseudopods 2. Amoebas have thick pseudopods (Figure 20-14) 3. Slime molds are decomposers that inhabit the forest floor a. Acellular slime molds form a multinucleate mass of cytoplasm called a plasmodium (Figure 20-15) b. Cellular slime molds live as independent cells but aggregate into a pseudoplasmodium when food is scarce (Figure 20-16) H. Red Algae Contain Red Photosynthetic Pigments (Figure 20-17) 1. These organisms are multicellular, photosynthetic seaweeds â Links To Everyday Life: Have You Eaten Your Protists Today?

I. Green Algae Are Closely Related to Land Plants 1. Some form long chains of cells (Figure 20-18a) 2. Some are colonial (Figure 20-18b) 3. Some are being cultivated for the production of biofuels (Figure 20-18c) â Lecture Activity 20.2: Pond Water Investigation

Case Study Revisited: Green Monster

KEY TERMS acellular slime mold alga (plural, algae) alveolate amoeba amoebozoan apicomplexan cellular slime mold ciliate diatom dinoflagellate

diplomonad euglenid euglenozoan excavate foraminiferan kinetoplastid parabasalid phytoplankton plasmodium

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protist protozoan (plural, protozoa) pseudoplasmodium pseudopod radiolarian rhizarian stramenopile water mold

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LECTURE ACTIVITIES Lecture Activity 20.1: Microbe Identification Estimated Time to Complete: 5–10 minutes Section Reference 20.1 What Are Protists?

Introduction This activity is a good way to get students to review and apply their knowledge of the characteristics of the microbes covered in this chapter. Completion of the activity in small groups encourages the development of teamwork. Its revision from the format associated with previous editions of the text allows students to be more creative about how they test for the specific characteristics of microbes.

If desired, fungi could be added to the list of potential organisms, and then this activity could be done as a review of concepts from two chapters.

Materials Needed • Copies of the handout that describes the scenario and provides the directions Procedures 1. Divide the students into groups of three or four.

2. Distribute the handouts and circulate (if possible) to help the students get started and answer questions.

Assessment Suggestions Follow up with a discussion about the various characteristics that could be tested for (presence of a nuclear membrane, chloroplasts, or peptidoglycan) and what organisms are indicated by the results of each test.

For future assessment include a question related to this activity on an exam. Sample multiple-choice and essay versions are provided in the test bank and Web site's Essay Challenge and Self-Test sections.

Handouts or Display Provide the students with the scenario and directions on the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members' Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 20.1 Handout—Microbe Identification You're working at a remote field station and you've been given a container of unidentified mostly microscopic organisms. Your job is to determine if the organisms are bacteria, unicellular algae, or protozoans. Unfortunately the electricity is out, so you can't use your microscope. However, the lab is stocked with all the chemicals you need to test for the presence of particular molecules and cellular components (for example, you might have a hypothetical chemical that would turn blue in the presence of chloroplasts, which should distinguish one of the four groups listed above). Discuss your research goals and prepare a list of at least three tests that you'll perform on the sample to allow you to determine what organisms it contains. Then indicate the test results you expect for bacteria, algae, and protozoans.

Hint: You need to think about what chemicals and/or organelles make these organisms unique and different from each other, so you might start with that type of list. Your chemicals do NOT have to be real chemicals; for example, you can use my example of the one that turns blue in the presence of chloroplasts or you might use one that glows in the presence of something else.

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Lecture Activity 20.2: Pond Water Investigation Estimated Time to Complete: 30–45 minutes Section Reference 20.2 What Are the Major Groups of Protists?

Introduction This activity is more of a laboratory exercise but is a good way to get students to use a microscope and review their knowledge of the wide variety of protists in this chapter. It may be used as an integrated activity while this chapter is being addressed in a lecture class period. Completion of this activity in pairs encourages the development of teamwork and allows each student to spend significant time using the microscope and observing the various types of freshwater protists.

Materials Needed • Compound microscopes with at least 40X objective • Microscope slides (cover slips are optional) • Dropper pipets • Pond water samples (can be obtained from any freshwater pond or lake that contains algae) • Glycerol solution to slow down swimming protists (can be obtained from most biological supply companies) Procedures 1. Have students pair up with a partner.

2. Have students obtain two or three microscope slides.

3. Ask students to place 1–2 drops of pond water and 1 drop of glycerol solution on their slides.

4. Have students observe their samples under 40X total magnification until they see living protists.

5. Have the students observe their samples at 100X total magnification so they can see their samples in greater detail.

6. Have the students sketch any protists they see and ask them to attempt to identify them. An Internet search using the term "protists" should provide them with pictures of actual protists to use as a guide.

Assessment Suggestions This activity is primarily observational, but assessment opportunities might include having the students identify various structures in their protists and then asking questions related to the function of the structures on a quiz or exam.

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CHAPTER 21 THE DIVERSITY OF PLANTS LECTURE OUTLINE Case Study: Queen of the Parasites â Lecture Activity 21.1: Discussion/Make a List of the Benefits of Plants/Plant Products

21.1 What Are the Key Features of Plants?

A. Plants Exhibit Three Characteristic Traits B. Plants Are Photosynthetic C. Plants Have Multicellular, Dependent Embryos 1. Plant embryos are attached to the parent D. Plants Have Alternating Multicellular Haploid and Diploid Generations (Figure 21-1) 1. Plants exhibit a life cycle called alternation of generations a. A diploid sporophyte stage alternates with a haploid gametophyte stage b. Haploid spores are produced via meiosis in the sporophyte c. Haploid gametes are produced via mitosis in the gametophyte d. Zygotes form by the fusion of two haploid gametes â Lecture Activity 21.2: Alternation of Generations Skit

21.2 How Have Plants Evolved?

A. The Ancestors of Plants Were Photosynthetic Protists (Figure 21-2) 1. These organisms were likely similar to green algae 2. DNA comparisons reflect evolutionary relationships 3. Many characteristics are similar between green algae and plants a. Chlorophyll and photosynthetic accessory pigments b. Food storage c. Cellulose cell walls B. The Ancestors of Plants Lived in Water C. Early Plants Invaded Land 1. Plants evolved various traits for life on land a. Structures to support the body b. Conducting cells to transport water and nutrients c. Processes to disperse gametes without water D. Plant Bodies Evolved to Resist Gravity and Drying 1. Roots anchor the plant and absorb water and nutrients from the soil 2. A waxy cuticle covers the surfaces of leaves and stems and limits water evaporation 3. Pores in leaves called stomata open for gas exchange, but will close during dry times 4. Conducting cells transport water and nutrients upward into the plant 5. Lignin, a rigid polymer, helps support the plant body E. Plants Evolved Protection for Their Embryos and Sex Cells That Disperse Without Water F. More Recently Evolved Plants Have Smaller Gametophytes 1. Nonvascular plants have a small sporophyte that remains attached to a more prominent gametophyte 2. Seedless vascular plants have a dominant sporophyte and a smaller, but still independent gametophyte 3. Seed plants have microscopic gametophytes that are barely noticeable â Case Study Continued: Queen of the Parasites

21.3 What Are the Major Groups of Plants?

A. The Two Major Groups of Plants Are Nonvascular Plants and Vascular Plants (Figure 21-3 and Table 21-1) B. Nonvascular Plants Lack Conducting Structures 1. These plants possess rhizoids that bring water and nutrients to the plant 206

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2. These plants are of limited size due to the lack of vascular tissue and lignin 3. Nonvascular plants include the liverworts, hornworts, and mosses (Figure 21-4) a. Liverworts and hornworts are named for their shapes (Figure 21-4a, b) b. Mosses are the most diverse and abundant nonvascular plant (Figure 21-4c, d) 4. The reproductive structures of nonvascular plants are protected (Figure 21-5) a. Archegonia produce eggs b. Antheridia produce swimming sperm that require water to reach the egg C. Vascular Plants Have Conducting Cells That Also Provide Support 1. Lignin adds extra support, so plants grow taller than nonvascular plants 2. The sporophyte stage is larger and more conspicuous than the gametophyte D. The Seedless Vascular Plants Include the Club Mosses, Horsetails, and Ferns 1. These plants produce swimming sperm, so water is essential for reproduction 2. Club mosses and horsetails are small and inconspicuous (Figure 21-6a, b) 3. Ferns are broad-leaved and diverse (Figure 21-6c, d) a. The life cycle of ferns is similar to that of other nonvascular plants (Figure 21-7) b. Sporangia produce spores on special leaves E. The Seed Plants Are Aided by Two Important Adaptations: Pollen and Seeds 1. Pollen transports the sperm without water and can be dispersed by wind or animals 2. Seeds consist of a plant embryo, food supply, and protective coat (Figure 21-8) a. The seed coat protects the embryo and maintains dormancy b. Stored food is used by the embryo until it does its own photosynthesis F. Gymnosperms Are Nonflowering Seed Plants 1. Only one ginkgo species survives (Figure 21-9a) 2. Cycads are restricted to warm climates (Figure 21-9b) a. These plants can be toxic and many are endangered 3. Gnetophytes include the odd Welwitschia (Figure 21-9c) a. Some produce the chemical ephedra 4. Conifers are adapted to cool climates a. Thin, green needles retained year-round and “antifreeze” are adaptations to dry, cold conditions (Figure 21-9d) b. Conifer seeds develop in cones (Figure 21-10) i. Male cones produce pollen dispersed by the wind ii. Female cones produce female gametophytes that develop and produce eggs iii. Pollen tube development takes 14 months, after which fertilization of the egg with the sperm occurs iv. Embryos are enclosed in seeds dispersed when the scales of the female cone open G. Angiosperms Are Flowering Seed Plants (Figure 21-11a, b) 1. Flowers attract pollinators (Figure 21-11b–d) a. They develop on the dominant sporophyte plant (Figure 21-12) b. They produce male and female gametophytes c. Female gametophytes develop from an ovule in the ovary of a flower d. Male gametophytes (pollen) are produced by flower anthers e. Pollen lands on the stigma and tubes transport sperm from the flower stigma to the egg in the ovary f. The plant embryo enclosed in a seed is formed from the ovule 2. Fruits encourage seed dispersal â Lecture Activity 21.3: Funny Fruit Salad or Fruits List Contest a. The flower ovary becomes the fruit b. Many fruits are eaten; seeds are undigested and dispersed c. Other fruits stick to animals, or are wind or water borne â Case Study Continued: Queen of the Parasites 3. Broad Leaves Capture More Sunlight a. Seasonal leaf drop occurs depending on climate b. Adaptations to avoid predation by herbivores have evolved â Lecture Activity 21.4: Outside Tour

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21.4 How Do Plants Affect Other Organisms?

A. Plants Play a Crucial Ecological Role 1. Plants capture energy that other organisms use a. This occurs through photosynthesis 2. Plants help maintain the atmosphere a. Photosynthesis produces oxygen as a by-product 3. Plants build and protect soil (Figure 21-13) 4. Plants help keep ecosystems moist B. Plants Provide Humans with Necessities and Luxuries 1. Plants Provide Shelter, Fuel, and Medicine 2. Plants Provide Pleasure

Case Study Revisited: Queen of the Parasites

KEY TERMS alternation of generations angiosperm antheridium (plural, antheridia) archegonium (plural, archegonia) conifer cuticle flower

fruit gametophyte gymnosperm lignin nonvascular plant ovule

pollen seed sporophyte stoma (plural, stomata) vascular plant

LECTURE ACTIVITIES Lecture Activity 21.1: Discussion/Make a List of the Benefits of Plants/Plant Products Estimated Time to Complete: 10–20 minutes Section Reference 21.3 What Are the Major Groups of Plants?

Introduction This activity is a good and fun way to start learning about plants.

Materials Needed No special materials are needed unless prizes are awarded, which makes the activity more fun. Prizes could be small plants (appropriate for the subject), packets of seeds, candy, pencils, or other inexpensive items.

Procedures Give the students approximately a minute to write down as many plant products or ways they benefit from plants as they can (without help) and then give them an additional minute to consult with one or two classmates to see if they can expand their lists.

Assessment Suggestions Follow up the contest with a discussion about students’ lists. Discuss how they’re personally involved with plants either by having houseplants, growing a garden, visiting a park, or living as a vegetarian. For future assessment, include a question on an exam about the importance of angiosperms to humans.

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Lecture Activity 21.2: Alternation of Generations Skit Estimated Time to Complete: 10–20 minutes Section Reference 21.1 What Are the Key Features of Plants?

Introduction The alternation of generations of plants is such a foreign concept to most nonmajor biology students that it may be helpful to try acting it out after it’s been covered in lecture.

Materials Needed None, unless you want to make up index cards with the various “parts” students will play.

Procedures Divide the students into groups and assign them a plant group (moss, ferns, pines, flowering plants) for which they will create a skit. Or pass out the index cards on which you’ve pre-assigned the alternation of generations “parts.” After the students have sorted out their skits, have them perform them for the class. In a large lecture class, select a handful of students to participate in a single skit you’ve prepared in advance or select one or two groups to perform their skits.

Suggested parts: Sporophyte—It’s the dominant form for ferns, pines, and flowering plants; nondominant form for moss.

Students might act overbearing or meek, depending on which plant groups’ sporophyte they represent.

Sperm—Because moss and ferns make swimming sperm, it would be nice to have a student uninhibited enough to pretend to be swimming.

Pollen—Ideally the student playing the part of pine pollen would “fly,” as conifers produce windblown pollen.

The student playing the part of flowering plant pollen will need a “partner” to play the role of pollinator.

Props that might inspire students: a snorkel and mask (for swimming), wings (for flying), and a green sheet or blanket moss/fern gametophytes could use to emphasize their independence from the sporophyte.

Assessment Suggestions Follow up the skits with review of the alternation of generations. If you’ve had different groups act out the alternation of generations of different plant groups, have a vote for the best skit (which one best represented the plant group assigned).

For future assessment, include one or more questions on an exam about the alternation of generations. There are several questions in the test bank.

Handouts or Display None, unless you want to make up index cards with the various “parts” students will play.

Lecture Activity 21.3: Funny Fruit Salad or Fruits List Contest Estimated Time to Complete: 5–10 minutes Section Reference 21.3 What Are the Major Groups of Plants?

Introduction Students typically find the whole “it’s a fruit if it has seeds thing” pretty fascinating. Prior to completing this activity, it would be helpful to have covered the functions of a seed and how fruits are involved in dispersing seeds.

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Instructor Guide Biology: Life on Earth

Materials Needed Vary depending on the approach you want to take: For the list contest, no special materials are needed, unless prizes are awarded, which makes the activity more fun. Prizes could be small plants, packets of seeds, a piece of fruit (appropriate for the subject), candy, pencils, or other inexpensive items.

For instructor-provided funny fruit salad, you’ll need a variety of “atypical” fruits (ones generally described as vegetables, such as a cucumber, pole bean, snow pea, pepper, eggplant, or squash); a few “true” fruits; some other plant structures we consume, such as carrots, broccoli, or potatoes; and a bowl. A knife and cutting board, if you think you’ll want/have to cut some of the fruits open to convince students that they’re really fruits (because they contain seeds). Paper towels for cleaning, if you plan on cutting up anything.

For student-provided funny fruit salad, you’ll need a bowl or bowls.

Procedures Vary depending on the approach you want to take: For the list contest, give students approximately a minute to write down as many examples of fruits as they can (without help), and then give them an additional minute to consult with one or two classmates to see if they can expand their lists.

For the instructor-provided funny fruit salad, show students the plant structures you brought to class and begin asking them if they should be included in the (funny) fruit salad you’re going to make. Work your way through the selections.

For student-provided funny fruit salad, you’ll want to give the students an assignment to come to class with a fruit or other plant structure with which the activity will be done. To ensure you have a good selection of “true” fruits, “atypical” fruits, and other plant structures, you may want to assign specific items to specific students.

Complete in a manner similar to the instructor-provided funny fruit salad.

Assessment Suggestions Follow up the contest with a discussion about students’ lists of fruits; ask if anyone wishes to partake of the funny fruit salad.

This would be a good way to review the difference between a fruit and a seed (students sometimes think of them as equivalent things), how fruits are formed (or from what flower part), and which groups of plants produce fruits and/or seeds.

For future assessment, include a question on an exam about fruits. There are some in the test bank about fruits’ role in seed dispersal, the flower part from which a fruit forms, and examples of fruits.

Lecture Activity 21.4: Outside Tour Estimated Time to Complete: 20–30 minutes; students tend to walk really slowly!

Section Reference 21.3 What Are the Major Groups of Plants?

Introduction Students typically LOVE to have class outside, so if you have landscaping or a wooded area on campus or a nearby park at which to meet, this is a great way to generate some enthusiasm for plants and review some of the concepts of the plant diversity chapter.

Materials Needed No special materials are needed, unless you want to provide the students with a handout of questions to be answered during the tour.

You may want to tour in advance and plan what to point out and ask about.

Procedures Suggest that the students wear comfortable shoes for walking easily. Tour and ask questions (prepared in advance or as you tour) about the plants you observe. It’s a great way to emphasize the dominance of the sporophyte stage of angiosperms and gymnosperms, the location of cones if you observe any conifers, and the importance of flowers and fruits if they’re observed. .

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Assessment Suggestions Have the students complete and submit a handout with questions answered while touring. Have the students write and submit a brief summary of what they observed outside.

For future assessment, include one or more questions on an exam about some of the observations made during the tour.

Handouts or Display You could provide a list of questions that will be answered on the tour (see an example on the following pages).

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Name:

Date:

Instructor:

Course Section:

Lecture Activity 21.4 Sample Handout—Outside Tour (with questions to be answered while touring) Note that this was written for a specific campus. You will need to adjust accordingly for your campus.

1. Why won’t we have to worry about being overrun by GIANT moss?

(Asked because moss may or may not be seen.)

2.

a. What kind of leaves does the cherry tree have? (simple vs. compound, monocot vs. dicot, attachments, and margins can be covered during this tour)

b. What kind of leaves does the maple tree have?

c. What kind of leaves does the golden raintree have?

d. What kind of leaves does the redbud have?

e. What’s the difference between the hemlock’s leaves and the pine’s leaves?

3.

a. Which angiosperms did we see today that produce windblown pollen?

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b. Which angiosperms did we see today that employ a pollinator to transfer their pollen?

4.

What’s the most common division of gymnosperms, and what representatives of that division did we see today?

5.

What other gymnosperm representative did we observe today? (ginkgos on this campus)

6.

Where are the male cones (typically) located? Why?

7.

What is the difference between the very small female cones and the larger female cones?

8.

a. What role do fruits play in the success of angiosperms?

b. On what different kinds of trees did we see fruits?

9.

Without a microscope, how can you distinguish a monocot from a dicot (angiosperms)?

Monocot—

Dicot—

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List two examples of monocots that we saw.

List three examples of dicots that we saw.

10. We observed organisms from other kingdoms besides plants. What were they?

(On the campus for which this was written, there are numerous lichens to observe, many fungi that “cooperate” by producing visible fruiting bodies, geese, and lots of insects.)

Depending on the season of the tour, fall or spring, the emphasis on fruits and flowers varies. In the spring, it’s fun to point out some of the angiosperms with flowers that produce windblown pollen because most students don’t give those flowers a second thought (oaks, birches, and sweetgums are all good examples of trees that produce inconspicuous flowers that make windblown pollen).

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CHAPTER 22 THE DIVERSITY OF FUNGI LECTURE OUTLINE Case Study: Humongous Fungus 22.1 What Are the Key Features of Fungi?

A. Fungal Bodies Consist of Slender Threads 1. The body of almost all fungi is a mycelium (Figure 22-1a) a. A mycelium is a mass of filaments called hyphae (Figure 22-1b, c) 2. The cell walls of fungi are made of chitin 3. Hyphae will differentiate into a reproductive structure that is the visible part of fungi B. Fungi Obtain Their Nutrients from Other Organisms 1. Fungi obtain nutrients in different ways a. Some are decomposers b. Some are parasites c. Some develop mutualistic relationships with other organisms d. Some are predators (Figure 22-2) 2. Fungi secrete enzymes outside their bodies and then absorb the nutrients broken down by the enzymes â Lecture Activity 22.1: Unknown Organism Identification C. Fungi Can Reproduce Both Asexually and Sexually 1. Fungi develop from spores (Figure 22-3) 2. Most fungi reproduce asexually when environmental conditions are stable a. Fungi reproduce sexually under conditions of environmental change or stress (Figure 22-4) 3. Asexual reproduction produces haploid spores by mitosis a. A haploid mycelium produces asexual spores by mitosis b. The asexual spore develops into a new mycelium genetically identical to the original 4. Sexual reproduction produces haploid spores by meiosis a. Two haploid hyphae of different mating types fuse b. A diploid zygote forms after two haploid nuclei fuse c. Haploid sexual spores form after the zygote undergoes meiosis d. Sexual spores form new mycelia that are genetically different from the original hyphae â Lecture Activity 22.2: Fungi Classification Discussion

22.2 What Are the Major Groups of Fungi? â Lecture Activity 22.3: Collected Fungi Contest/Demonstration A. Fungus Species Are Classified into Six Taxonomic Groups (Figure 22-5 and Table 22-1) B. Chytrids, Blastoclades, and Rumen Fungi Produce Swimming Spores C. Chytrids Are Mostly Aquatic 1. These organisms are the ancestors of other fungi 2. They are decomposers and parasites D. Rumen Fungi Live in Animal Digestive Tracts 1. These fungi are anaerobic and reside primarily in the digestive tract of plant-eating animals a. They form a symbiotic relationship with the animal host E. Blastoclades Have a Nuclear Cap (Figure 22-6) F. Glomeromycetes Associate with Plant Roots (Figure 22-7) G. Basidiomycetes Produce Club-Shaped Reproductive Structures 1. These fungi reproduce sexually (Figure 22-8) 2. Basidia, formed from hyphae in the fruiting body, produce haploid basidiospores by meiosis 3. Basidia and basidiospores form in fruiting bodies such as mushrooms, puffballs, and shelf fungi (Figure 22-9)

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Instructor Guide Biology: Life on Earth 4. Fairy rings develop as hyphae grow outwards in a circular pattern from a basidiospore that germinated (Figure 22-10) â Case Study Continued: Humongous Fungus H. Ascomycetes Form Spores in a Saclike Case (Figure 22-11) 1. Specialized hyphae form asexual spores 2. Spores containing a saclike case called an ascus form after sexual reproduction 3. Examples of ascomycetes are quite diverse (Figure 22-12) a. Cup fungi and morels are examples b. Some are molds that destroy fruit and grain crops c. Yeasts and the mold that produces penicillin are other examples I. Bread Molds Are Among the Fungi That Can Reproduce by Forming Diploid Spores 1. Many of the species formerly called zygomycetes live in soil or on decaying plant and animal matter 2. Examples of this fungus include soft fruit rot and black bread mold caused by species in the Rhizopus genus 3. Sporangia form haploid spores during asexual reproduction (Figure 22-13) 4. Diploid zygosporangia form after sexual reproduction

22.3 How Do Fungi Interact with Other Species?

A. Lichens Are Formed by Fungi That Live with Photosynthetic Algae or Bacteria (Figures 22-14 and 22-15) 1. The fungal member provides protection for algae or bacteria 2. The algae or cyanobacteria provide sugars absorbed by the fungus 3. These organisms can colonize newly formed volcanic islands B. Mycorrhizae Are Fungi Associated with Plant Roots (Figure 22-16) 1. These fungi form symbiotic associations with plants 2. Mycorrhizae help feed plants a. The fungus increases the availability of minerals, organic nutrients, and water for the plant b. The plant produces sugars absorbed by the fungus c. Plants with mycorrhizae grow better than plants without C. Endophytes Are Fungi That Live Inside Plant Stems and Leaves D. Some Fungi Are Important Decomposers 1. Digestive activities of saprophytes release nutrients from dead plant and animal bodies 2. Soil is enriched and the nutrients are used by plants

22.4 How Do Fungi Affect Humans? â Lecture Activity 22.4: How Fungi Affect Humans Contest A. Fungi Attack Plants That Are Important to People 1. Crops are often damaged by fungi a. Corn smut damages corn (although in Mexico, corn smut is a delicacy and is known as the Mexican truffle) (Figure 22-17) 2. Trees such as American elms and chestnuts can be damaged by ascomycete fungi 3. Some fungal species cause wood rot and textile damage 4. Fungi that benefit agriculture include fungal pathogens used to control insect pests (Figure 22-18) B. Fungi Cause Human Diseases 1. Skin diseases include athlete’s foot, ringworm 2. Vaginal yeast infections are a common fungal disease (Figure 22-19) 3. Internal diseases include valley fever, histoplasmosis C. Fungi Can Produce Toxins 1. Aflatoxins are produced by molds in the genus Aspergillus 2. Ergot is a disease caused by a fungal toxin associated with infected rye D. Many Antibiotics Are Derived from Fungi 1. Penicillin was the first antibiotic discovered (Figure 22-20) 2. Cyclosporin is an immunosuppressive drug important for transplant patients E. Fungi Make Important Contributions to Gastronomy 1. Truffles are a fungus that is a delicacy (Figure 22-20) 2. Cheeses are flavored by molds â Links to Everyday Life: Collect Carefully (Figure E22-1) F. Wine and Beer Are Made Using Yeasts .

Chapter 22 The Diversity of Fungi 1. As the yeast consume the sugars in grapes and grains, they produce alcohol and carbon dioxide

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Instructor Guide Biology: Life on Earth G. Yeasts Make Bread Rise â Lecture Activity 22.5: Fungal Foods, Label or Recipe Contest

Case Study Revisited: Humongous Fungus

KEY TERMS ascomycete ascus (plural, asci) basidiomycete basidium (plural, basidia) chytrid club fungus

glomeromycete hypha (plural, hyphae) imperfect fungus lichen mycelium (plural, mycelia) mycorrhizae

sac fungus septum (plural, septa) sporangium (plural, sporangia) spore zygomycete

LECTURE ACTIVITIES Lecture Activity 22.1: Unknown Organism Identification Estimated Time to Complete: 15–20 minutes Section Reference 19.1 Which Organisms Are Members of the Domains Archaea and Bacteria?

19.4 What Are Viruses, Viroids, and Prions?

20.1 What Are Protists?

22.1 What Are the Key Features of Fungi?

Introduction This activity is a good way to get students to review and apply their knowledge of the distinguishing characteristics of the fungi covered in this chapter and the microbes covered in previous chapters.

Completion of the activity in small groups encourages the development of teamwork. Its revision from the format associated with previous editions of the text allows students to be more creative about how they test for the specific characteristics of fungi and microbes.

Note: This activity is basically the same as the Chapter 19 Lecture Activity 19.5. However, fungi have been added to the list of potential organisms. This activity could be done as a review of concepts from both chapters.

Materials Needed • Copies of the handout that describes the scenario and provides the directions Procedures 1. Divide the students into groups of three or four.

2. Distribute the handouts and circulate (if possible) to help students get started and answer questions.

Assessment Suggestions Follow up with a discussion about the various characteristics that could be tested for (presence of a nuclear membrane, chloroplasts, peptidoglycan, chitin, the number of cells) and what organisms are indicated by the results of each test.

For future assessment, include a question related to this activity on an exam. Sample multiple-choice questions are provided in the test bank.

Handouts or Display Provide the students with the scenario and directions. .

Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 22.1 Handout—Unknown Organism Identification You’re working at a remote field station and you’ve been given a container of unidentified mostly microscopic organisms. Your job is to determine if the organisms are bacteria, unicellular algae, protozoans, or fungi.

Unfortunately, the electricity is out so you can’t use your microscope. However, the lab is stocked with all the chemicals you need to test for the presence of particular molecules and cellular components (for example, you might have a hypothetical chemical that would turn blue in the presence of chloroplasts, which should distinguish one of the four groups listed above). Discuss your research goals and prepare a list of at least three tests that you’ll perform on the sample to allow you to determine what organisms it contains.

Then, indicate the test results you expect for bacteria, algae, protozoans, and fungi.

Hint: You need to think about what chemicals and/or organelles make these organisms unique and different from each other, so you might start with that type of list. Your chemicals do NOT have to be real chemicals; for example, you can use my example of the one that turns blue in the presence of chloroplasts, or you might use one that glows in the presence of something else.

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Lecture Activity 22.2: Fungi Classification Discussion Estimated Time to Complete: 5–10 minutes Section Reference 22.1 What Are the Key Features of Fungi?

Introduction Fungi and plants were once classified together in one kingdom. In small groups, discuss reasons for this historical classification and reasons why the current separation of fungi and plants into two separate kingdoms is more appropriate.

Materials Needed None Procedures Initiate a discussion about this topic while covering Sections 22.1.A and B. Brief coverage of general plant characteristics may be helpful, or suggest that the students quickly read Sections 21.1.A and B (or remember to assign that as “homework” prior to this activity if your students don’t bring their texts to class).

Assessment Suggestions After the students have a chance to discuss their ideas, regroup as a class and see if there is a general consensus about the topic.

Include a question on an exam about this issue. It makes for a good essay or short-answer question if Chapters 20 and 21 are covered on the same exam.

Lecture Activity 22.3: Collected Fungi Contest/Demonstration Estimated Time to Complete: 15–20 minutes in class; a fair amount of prep time before class if the demonstration option is used Section Reference 22.4 How Do Fungi Affect Humans?

Introduction Often the only fungi with which students are familiar are the ones on their pizzas or at the grocery store. This should be a great activity to incorporate if your course doesn’t do a lab that allows the students to observe and examine fungi. This will give the students a chance to go on a fungal scavenger hunt or observe and identify the fungal samples you provide.

Materials Needed For a contest, you may want to provide some fungus identification guides for student use during their presentation of their specimens. Divide the students into groups and have them try to identify the fungi they collected. Prizes (funny candy such as Smarties™, Dumdum lollipops™, or Nerds™; a coupon for a mushroom pizza; pencils) would make the activity more fun.

Prizes could be awarded for the biggest, most colorful, funniest looking, and/or smallest fungus collected.

IF the fungi showing is done instead of a contest, you’ll need to have several samples of different kinds of fungi. It would be nice if you could provide representatives of the four different fungal phyla. Different kinds of mushrooms, puffballs, shelf fungi, and lichens should be easily found on a walk through the woods or a park (though you might need to look for the samples at a time other than during a dry spell!). A hunt through the refrigerator may yield some moldy things that could be used also. Some fungus identification books are the only other thing you’ll need. You might find a local fungus expert to help you with identification, so you’ll know going in what you have.

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Procedures Contest—Give the students several days to locate their fungal samples. If there are rules (such as where they can do their collecting), share those with the students. If you intend to award prizes for certain fungi, you could announce that, because students seem to respond well to incentives in addition to grades.

Demo—Bring your collection of fungi to class. Divide the students into groups and give each group a fungus identification book and at least one or two samples to observe and identify.

Assessment Suggestions A student presentation to the class could complete the activity. Students should display their samples or the ones you provided and share their identifications with the class. It would be a good review if they’d share the phylum in which the fungus is classified and some characteristics of the fungi in that phylum.

Handouts or Display Perform an Internet search using “fungi” as the search term to find information that might be helpful during the identification of fungi you collect for a demonstration.

Lecture Activity 22.4: How Fungi Affect Humans Contest Estimated Time to Complete: 5–10 minutes Section Reference 22.4 How Do Fungi Affect Humans?

Introduction There are numerous ways in which fungi affect us both directly and indirectly. Students are more likely to be familiar with the direct effects of fungi: diseases caused by fungi and the effects of fungi we consume. They are less likely to be familiar with the effects of fungi on agriculture, even though they are indirectly affected (by changes in food prices or the need to replace landscaping killed by fungi) by fungal damage to plants. Some may not know that fungi are a source of antibiotics (a topic covered in Chapter 19) and other important drugs.

Materials Needed No special materials are needed unless prizes are awarded, which makes the activity more fun. Prizes for winning could be SmartiesTM candy, boxes of NerdsTM (small ones are made for holidays like Halloween and Easter), or pencils (you could add that the pencils are ones that know the exam answers!).

Procedures Give the students time to write down as many as they can (without help) and then give them an additional 30 seconds to consult with one or two classmates to see if they can expand their lists.

Assessment Suggestions Follow up the contest with a discussion about students’ lists. Fungi that affect landscaping and the notion that the fungal-infected rye may have been the cause of the witch sightings that led to the Salem witch trials (perform an Internet search using “Salem witch trials and ergot” for more details on this) are usually of interest to students and worth mentioning if they don’t appear on students’ lists.

For future assessment, include a question or questions on an exam about the number of ways fungi affect humans that were discussed in class. There are some examples of such questions in the chapter’s test bank.

Handouts or Display Perform an Internet search using the terms “fungal diseases” for more information.

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Lecture Activity 22.5: Fungal Foods, Label, or Recipe Contest Estimated Time to Complete: 10–15 minutes Section Reference 22.4 How Do Fungi Affect Humans?

Introduction Students seem to like anything that involves food, so this would be a fun way to stimulate their interest in fungi.

There are numerous fungal food products, ranging from actual mushrooms (the varieties available in stores seem to be increasing, with portabello and oyster mushrooms found in most grocery stores today) to mushroomflavored soups or prepared foods and breads made with yeast. An Internet search for mushroom-related recipes will reveal more information, so students shouldn’t have any problems locating unique recipes.

Materials Needed No special materials are needed unless prizes are awarded, which makes the activity more fun. Prizes for winning could be SmartiesTM candy, boxes of NerdsTM (small ones are made for holidays like Halloween and Easter), a coupon for a mushroom pizza, or pencils (you could add that the pencils are ones that know the exam answers!).

Procedures Assign the students their “homework,” which is to bring a food, food label, or recipe that includes some kind of fungi (though you may want to specify that examples associated with the alcohol product of yeasts’ fermentation are not appropriate to bring!).

Assessment Suggestions Students could submit a brief summary of the number of different foods or recipes associated with fungi that they were able to find. Students could vote for their favorite food made with or flavored by fungi.

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CHAPTER 23 ANIMAL DIVERSITY I: INVERTEBRATES LECTURE OUTLINE Case Study: Physicians’ Assistants â Lecture Activity 23.1: Discussion or Make a List Contest of Animal Uses and/or Animal Products

23.1 What Are the Key Features of Animals?

A. Animals Are Eukaryotes B. Animals Are Multicellular C. Animal Cells Lack a Cell Wall D. Animals Obtain Energy by Eating Other Organisms E. Animals Typically Reproduce Sexually F. Animals Are Motile During Some Stage of Their Lives G. Most Animals Are Able to Respond Rapidly to External Stimuli

23.2 Which Anatomical Features Mark Branch Points on the Animal Evolutionary Tree? (Figure 23-1) A. Lack of Tissues Separates Sponges from All Other Animals 1. Tissues are groups of similar cells integrated into a functional unit B. Animals with Tissues Exhibit Either Radial or Bilateral Symmetry (Figure 23-2) 1. The difference between radially and bilaterally symmetrical animals reflects another major branching point in the animal evolutionary tree 2. Radially symmetrical animals have two embryonic tissue layers; bilaterally symmetrical animals have three a. Endoderm gives rise to tissues that line the gut cavity b. Ectoderm gives rise to tissues that cover the body c. Mesoderm gives rise to tissues that lie between the endoderm and ectoderm 3. Bilaterally symmetrical animals have heads a. The evolution of bilateral symmetry was accompanied by cephalization, the concentration of sensory organs and a brain in a defined head region â Lecture Activity 23.2: Create a Radial Animal C. Most Bilateral Animals Have Body Cavities 1. Body cavity structure varies among phyla a. Coelomates have a true body cavity completely surrounded by mesoderm (Figure 23-3a) b. Pseudocoelomates have a body cavity that is not completely surrounded by mesoderm (Figure 23-3b) c. Acoelomates have no body cavity (Figure 23-3c) D. Bilateral Organisms Develop in One of Two Ways (Figure 23-4) 1. Protostome and deuterostome development differ in many ways E. Protostomes Include Two Distinct Evolutionary Lines 1. These lines include the ecdysozoans and the lophotrochozoans (Figure 23-5)

23.3 What Are the Major Animal Phyla?

A. Vertebrates Have Backbones and Invertebrates Do Not (Table 23-1) B. Sponges Are Simple, Sessile Animals (Figure 23-6) 1. Sponges can reproduce asexually by budding, but can also reproduce sexually a. They are often hermaphrodites, possessing both female and male sexual organs 2. Sponges lack tissues (Figure 23-7) 222

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Chapter 23 Animal Diversity I: Invertebrates 3. Sponge cells are specialized for different functions a. Three cell types are found in sponges, each with a specialized role 4. Some sponges contain chemicals useful to humans C. Cnidarians Are Well-Armed Predators 1. Cnidarians include see jellies, corals, sea anemones, and hydrozoans 2. Cnidarians have tissues and two body types a. They contain nerve and muscle cells b. Cnidarians come in two forms: polyp and medusa (Figures 23-8 and 23-9) c. Reproduction can occur sexually or asexually, as in budding 3. Cnidarians have stinging cells a. Cnidocytes inject venom into anything that touches them (Figure 23-10) b. Once prey is captured, it is forced into the gastrovascular cavity 4. Many corals secrete hard skeletons a. These form coral reefs, which are of great importance in ocean ecosystems D. Comb Jellies Use Cilia to Move (Figure 23-11) 1. All comb jellies are carnivores E. Flatworms May Be Parasitic or Free Living (Figure 23-12) 1. Flatworms are bilaterally symmetrical and can reproduce both sexually and asexually a. Many species are hermaphroditic 2. Flatworms have organs but lack respiratory and circulatory systems a. Most flatworms have sensory organs i. They have nerve cells called ganglia and nerve cords to process information b. Gas exchange occurs through diffusion between body cells and the environment c. Nutrients move directly from the digestive tract to body cells 3. Some flatworms are harmful to humans (Figure 23-13) a. Tapeworms and flukes cause a variety of ailments F. Annelids Are Segmented Worms 1. Annelids are divided into a series of similar repeating segments a. They are sexual species and some are hermaphroditic 2. Annelids are coelomates and have organ systems a. The coelom is filled with fluid, which provides a hydrostatic skeleton b. Annelids have a closed circulatory system that distributes gases and nutrients i. Fluid is pumped through the system by five “hearts” (Figure 23-14) c. Excretory organs called nephridia filter and remove wastes d. The digestive system includes a tubular gut 3. Annelids include oligochaetes, polychaetes, and leeches (Figure 23-15) a. The oligochaetes include earthworms, which serve an important role in improving soil fertility â Case Study Continued: Physicians’ Assistants G. Most Mollusks Have Shells 1. Mollusks are very diverse and typically have open circulatory systems (Figure 23-16) a. Blood bathes the internal organs 2. Gastropods are one-footed crawlers (Figure 23-17) a. Gastropods feed with a radula b. Gas exchange occurs via skin or a simple lung 3. Bivalves are filter feeders (Figure 23-18) 4. Cephalopods are marine predators (Figure 23-19) a. They have closed circulatory systems b. They have highly developed brains and sensory structures â Science in Action: The Search for a Sea Monster (Figure E23-1) H. Arthropods Are the Most Diverse and Abundant Animals 1. Arthropods have appendages and an external skeleton a. The exoskeleton and appendages provide for flexibility of movement (Figure 23-20) b. The exoskeleton is molted periodically (Figure 23-21) 2. Arthropods have specialized segments and adaptations for active lifestyles (Figure 23-22) a. Gas exchange occurs through gills, tracheae, or lungs b. Most have open circulatory systems c. Most have compound eyes (Figure 23-23) .

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Instructor Guide Biology: Life on Earth 3. Insects are the only flying invertebrates (Figure 23-24) a. Insects undergo metamorphosis during their life cycle i. A larva develops into a pupa, and then an adult b. Butterflies and moths i. These insects are probably the most conspicuous c. Bees, ants, and wasps i. These insects are highly social d. Beetles i. Some beetles have impressive adaptations â Lecture Activity 23.3: Discussion or Make a List Contest of How Insects Impact Different Ecosystems and Humans 4. Most arachnids are predatory meat eaters (Figure 23-25) a. Arachnids have simples eyes b. Many can produce silk 5. Myriapods have many legs (Figure 23-26) 6. Most crustaceans are aquatic (Figure 23-27) I. Roundworms Are Abundant and Mostly Tiny (Figure 23-28) 1. Roundworms are pseudocoelomates with a simplified body plan a. They lack circulatory and respiratory systems b. Most produce sexually 2. A few roundworm species are harmful to humans (Figure 23-29) a. Trichinella causes the disease trichinosis J. Echinoderms Have a Calcium Carbonate Skeleton (Figure 23-30) 1. Echinoderms have an endoskeleton 2. Echinoderms are bilaterally symmetrical as larvae and radially symmetrical as adults a. They exhibit deuterostome development 3. Echinoderms have a water-vascular system (Figure 23-31) a. This functions in locomotion, respiration, and food capture 4. Some echinoderm organ systems are simplified a. Many echinoderms can regenerate lost body parts K. The Chordates Include the Vertebrates â Lecture Activity 23.4: Invertebrate Success

Case Study Revisited: Physicians’ Assistants (Figure 23-32)

KEY TERMS bilateral symmetry budding cephalization closed circulatory system coelom compound eye deuterostome ectoderm endoderm endoskeleton

exoskeleton ganglion (plural, ganglia) hemocoel hermaphroditic hydrostatic skeleton invertebrate larva (plural, larvae) mesoderm metamorphosis molt

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nerve cord open circulatory system parasite protostome pseudocoelom pupa (plural, pupae) radial symmetry segmentation tissue vertebrate

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LECTURE ACTIVITIES Lecture Activity 23.1: Discussion or Make a List Contest of Animal Uses and/or Animal Products Estimated Time to Complete: 10–20 minutes Section Reference 23.1 What Are the Key Features of Animals?

Introduction The impact of animals on humans is not a specific chapter topic, but is addressed in various sections of the chapter. This would be a fun way to introduce the topic of animals and should emphasize the bias humans have for vertebrates. Students’ lists are likely to be exclusively of vertebrates or to contain only a few invertebrates, which can open up the discussion of the differences between the two groups and the importance of the invertebrates.

Materials Needed No special materials are needed, unless prizes are awarded for the most extensive lists, which makes the activity more fun. Prizes could be small bags/boxes of Animal Crackers™, candy (gummy worms are fun), pencils, or other inexpensive items.

Procedures Give the students a few minutes to make a list of animal uses and/or animal products. Then give them an additional minute or two to consult with one or two classmates to see if they can expand their lists.

Assessment Suggestions Follow up the contest with a discussion about students’ lists. Because students’ lists are likely to emphasize the uses of, and products from, vertebrates, it might make for a nice introduction to invertebrates and how, in spite of their importance, they are often overlooked. Discussion can include the ways students are directly and indirectly affected by invertebrates that spread diseases, serve as food, serve as tourist attractions (aquariums, snorkeling, and coral reef observations), and impact the production of crops (via pollination).

Future assessment could involve asking a question on an exam, based on the discussion that ensues, or assigning a short paper that requires the students to research one invertebrate and the different ways it affects humans.

Lecture Activity 23.2: Create a Radial Animal Estimated Time to Complete: 10–20 minutes Section Reference 23.2 Which Anatomical Features Mark Branch Points on the Animal Evolutionary Tree?

Introduction Students sometimes have a difficult time grasping what it means to have radial symmetry. This is a fun way to illustrate the concept of radial symmetry and the differences between radial and bilateral symmetry. An explanation of radial symmetry and the observation of Figure 23-2 should occur prior to attempting this activity.

Materials Needed Plain paper or other material on which students can draw their animals. Crayons, colored pencils, or markers will be needed for coloring. This could be very involved if you want to provide an assortment of craft-type materials (pipe cleaners, cotton, Styrofoam spheres, and so forth) with which they can make their radial animals threedimensional (3D). For 3D animals, you may want to provide glue, pins, or other means of attaching the craft products together. .

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Prizes could be awarded for the most creative or most colorful animal, which makes the activity more fun.

Prizes could be small bags/boxes of Animal Crackers™, candy, pencils, or other inexpensive items.

Procedures Divide the class into small groups (three or four students maximum) and tell them they need to design an animal that has radial symmetry and at least two different internal organs that are labeled. They can observe the examples in their text (jellyfish, anemones, and starfish), but should attempt to create a unique (never before discovered) animal (this is a nice way to “reward” creative and artistically inclined students). Encourage them to consider forms other than the typical round or spherical shapes of the examples in their text. Caution them that an attempt to make their animal cute by giving it a face (eyes, nose, etc.) may result in an animal with bilateral symmetry.

Assessment Suggestions Have the students exchange animals (3D or illustrations) and critique them. They should assess whether or not the animal has radial symmetry. If it doesn’t, the students should be able to explain why the animal isn’t radial.

For future assessment, include a question on an exam about the characteristics of animals with radial symmetry or have the students observe a created animal and determine if it’s radial or not.

Lecture Activity 23.3: Discussion or Make a List Contest of How Insects Impact Different Ecosystems and Humans Estimated Time to Complete: 10–20 minutes Section Reference 23.3 What Are the Major Animal Phyla?

Introduction Students should be familiar with the transmission of diseases via insects, based on their study of microbes in Chapter 19. They may be less familiar with the role of insects as pollinators for angiosperms. This should be a fun way to emphasize how different species depend on another for survival or assistance with reproduction.

Materials Needed No special materials are needed, unless prizes are awarded, which makes the activity more fun. Prizes could be small bags/boxes of Animal Crackers,TM candy, pencils, or other inexpensive items.

Procedures Give the students a few minutes to make a list of how insects impact different ecosystems and humans (you may want to give them advance notice so they can do some “research” if they’re inclined, or let them consult their textbook for ideas). Then give them an additional minute or two to consult with one or two classmates, to see if they can expand their lists.

Assessment Suggestions Follow up the contest with a discussion about students’ lists. Microbes are likely to have been covered prior to this chapter, so be sure the involvement of insects in the transmission of many diseases (such as malaria and West Nile virus) or other parasites (such as fleas that transmit tapeworms) comes up during the discussion. The importance of bees in the pollination process should be emphasized, as that has ecological implications as well as economic ones for humans (from a crop-production perspective).

For future assessment, include a question on an exam about the ecological importance of insects and their impact on humans from a health and economic perspective. A short paper about a specific insect and the impact it has on an ecosystem or humans could be assigned.

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Lecture Activity 23.4: Invertebrate Success Estimated Time to Complete: 10–20 minutes Section Reference 23.3 What Are the Major Animal Phyla?

Introduction Students tend to feel a bit overwhelmed by the volume of information associated with the invertebrate phyla. This might be a nice way to let them think more about the big picture instead of lots of facts about each individual phylum. It should encourage practice of analytical skills because students will first have to decide how to define success (is it sheer numbers, survival on land, or extent to which we find them?) and then which group best meets their definition.

Materials Needed No special materials are needed, unless prizes are awarded for the best justification of invertebrate success.

Prizes could be small bags/boxes of Animal Crackers™, candy (like gummy worms), pencils, or other inexpensive items.

Procedures Divide the class into small groups (three or four students) and have them select the group of invertebrates they consider to be the most successful. They should be prepared to describe how they defined success and justify their selections.

An alternative would be to assign each group of students an animal or group of animals and have them justify the selection of the assigned group as the most successful invertebrates.

Assessment Suggestions As a class, discuss students’ selections and justifications. Part of the discussion is likely to involve how success is to be defined.

For future assessment, include a question on an exam about invertebrate success and have the students justify their selection of a certain animal or phylum as successful. This could be done in a debate format, if desired.

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CHAPTER 24 ANIMAL DIVERSITY II: VERTEBRATES LECTURE OUTLINE Case Study: Fish Story â Lecture Activity 24.1: Food Animals, Predators, and Pets List

24.1 What Are the Key Features of Chordates? (Figure 24-1) A. All Chordates Share Four Distinctive Structures 1. Dorsal nerve cord a. This structure lies above the digestive tract 2. Notochord a. This is a stiff, but flexible, rod that extends along the length of the body 3. Pharyngeal gill slits a. These are located in the pharynx and develop into gills in some chordates 4. Post-anal tail a. This is an extension of the body that extends beyond the anus b. Humans are chordates and possess all four characteristics at some point in development i. The notochord, gill slits, and tail are all lost during development (Figure 24-2)

24.2 Which Animals Are Chordates?

A. Tunicates Include Sea Squirts and Salps (Figure 24-3a) 1. These are small, immobile, filter-feeding organisms 2. Most tunicates are hermaphroditic B. Lancelets Are Marine Filter-Feeders (Figure 24-3b) 1. These are small, fishlike organisms that retain all four chordate features as adults 2. Lancelets have separate sexes C. Craniates Have a Skull (Table 24-1) 1. The skull may be composed of bone or cartilage 2. Hagfishes are slimy residents of the ocean floor (Figure 24-4) a. This craniate has a cartilaginous skeleton and a rudimentary skull 3. Vertebrates have a backbone a. The vertebral column supports the body, provides attachment for muscles, and protects the nerve cord and brain â Case Study Continued: Fish Story

24.3 What Are the Major Groups of Vertebrates? â Lecture Activity 24.2: Tour an Animal Online or Online Adventures A. Some Lampreys Parasitize Fish (Figure 24-5) B. Cartilaginous Fishes Are Marine Predators (Figure 24-6) 1. This group of fish includes sharks, skates, and rays 2. Unlike hagfishes and lamprey, these fish have jaws a. Most are predators C. Ray-Finned Fishes Are the Most Diverse Vertebrates (Figure 24-7) 1. They are distinguished by the structure of their fins, which are formed by webs of skin supported by bony spines 2. These fish are a very diverse group and are a very important food source for humans D. Coelacanths and Lungfishes Have Lobed Fins (Figure 24-8) 1. These fish have fleshy, muscular fins 228

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Chapter 24 Animal Diversity II: Vertebrates 2. Lungfishes have both gills and lungs 3. One of their lineages is considered the ancestor of the tetrapods, organisms with four limbs E. Amphibians Live a Double Life (Figure 24-9) 1. These are the first organisms to live on land 2. These organisms have three-chambered hearts 3. Poorly developed lungs are supplemented by the use of the skin as a respiratory organ 4. External fertilization requires water 5. External development requires water â Earth Watch: Frogs in Peril (Figure E24-1) 6. Frogs and toads are adapted for jumping 7. Most salamanders have tails (Figure 24-9c) 8. Caecilians are limbless, burrowing amphibians (Figure 24-9d) F. Reptiles Are Adapted for Life on Land (Figure 24-10) 1. Reptiles have scales and shelled eggs a. Tough, scaly skin resists water loss and protects the body b. Internal fertilization evolved c. A shelled amniotic egg prevents the egg from drying out on land (Figure 24-11) i. An internal membrane, called the amnion, encloses the embryo d. More efficient lungs evolved; the skin is not needed as a respiratory organ e. Modified three-chambered heart minimizes mixing of oxygenated and deoxygenated blood 2. Lizards and snakes share a common evolutionary heritage a. Most lizards are small predators, but some can be quite large b. Most snakes are predatory carnivores with a variety of adaptations for feeding 3. Alligators and crocodiles are adapted for life in water 4. Turtles have protective shells 5. Birds are feathered reptiles (Figure 24-12) a. The first birds appear in the fossil record roughly 150 million years ago (Figure 24-13) b. Various adaptations help them fly i. Characteristics that minimize weight, such as lightweight bones ii. High metabolic rate; warm-blooded iii. Four-chambered heart iv. Lungs supplemented by air sacs G. Mammals Provide Milk to Their Offspring 1. Mammals have various adaptations a. Warm-blooded b. Protected and insulated by fur c. Four-chambered hearts d. Legs for running and bodies adapted to varied lifestyles e. Mammary glands produce milk to allow females to suckle their young f. Complex brain—increased learning ability g. Long periods of parental care 2. Monotremes are egg-laying mammals (Figure 24-14) a. Monotreme eggs have leathery shells b. These mammals lack nipples, but still produce milk 3. Marsupial diversity reaches its peak in Australia (Figure 24-15) a. Embryos are attached to the uterus by the placenta b. In marsupials, development is completed inside a pouch called the marsupium 4. Placental mammals inhabit land, air, and sea a. Development of the young is completed inside the uterus b. Placental mammals are very diverse and inhabit a wide variety of habitats â Lecture Activity 24.3: Vertebrate or Human Success â Lecture Activities 24.4 and 24.5: Zoo or Aquarium Visit

Case Study Revisited: Fish Story

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KEY TERMS amnion amniotic egg craniate mammary gland marsupial

monotreme nerve cord notochord pharyngeal gill slit placenta

placental post-anal tail vertebral column vertebrate

LECTURE ACTIVITIES Lecture Activity 24.1: Food Animals, Predators, and Pets List Estimated Time to Complete: 10–20 minutes Section Reference 24.3 What Are the Major Groups of Vertebrates?

Introduction The use of animals for food or as pets is not a specific chapter topic, and predators aren’t specifically covered until Chapter 27, but this could be a fun introduction to the vertebrates. Students’ lists are likely to be primarily of mammals, which might initiate a discussion about our bias toward animals/vertebrates most like us. If you did the list activity in Chapter 23 (Lecture Activity 23.1), your students could simply revisit those lists and identify the vertebrates they listed at that time.

Materials Needed No special materials are needed, unless prizes are awarded for the most extensive lists, which makes the activity more fun. Prizes could be small bags/boxes of Animal Crackers™, candy (gummy worms are fun), pencils, or other inexpensive items.

Procedures Give the students a few minutes to make a list of animals used for food or as pets and that are identified as predators. Then give them an additional minute or two to consult with one or two classmates, to see if they can expand their lists.

Assessment Suggestions Follow up the contest with a discussion about the students’ lists. Because the students’ lists are likely to emphasize mammals, it might make for a nice introduction to the variety of vertebrates.

Future assessment could involve asking a question on an exam based on the discussion that ensues or assigning a short paper that requires the students to research one vertebrate and the different ways it affects humans.

Lecture Activity 24.2: Tour an Animal Online Estimated Time to Complete: 10–15 minutes Section Reference 24.3 What Are the Major Groups of Vertebrates?

Introduction Because students tend to be most familiar with vertebrates that are mammals, it might be nice to start the vertebrate section with an online tour or adventure that exposes them to some of the other types of vertebrates.

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Chapter 24 Animal Diversity II: Vertebrates Materials Needed • Computer with access to the Internet and a method of projecting the images for the entire class to view

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Procedures Select one of the animal tours from the Web site http://animal.discovery.com/games/tourcentral/tourcentral.html.

Assessment Suggestions Include a question from the tour on the exam for this chapter or assign a research assignment that investigates the adaptations of a vertebrate to its habitat or further explores an animal from the lecture tour.

Lecture Activity 24.3: Vertebrate or Human Success Estimated Time to Complete: 10–20 minutes Section Reference 24.3 What Are the Major Groups of Vertebrates?

Introduction A question to consider regarding this chapter could be “Are humans a biological success?” A class discussion about the more general topic of vertebrate success or the specific topic of human success would be a nice way to wrap up discussion of the diversity of animals. Part of the discussion will probably need to be about the definition of success.

Materials Needed No special materials are needed, unless prizes are awarded for the best justification of vertebrate or human success. Prizes could be small bags/boxes of Animal Crackers™, candy (like gummy worms), pencils, or other inexpensive items.

Procedures For a more general discussion about vertebrate success, divide the class into small groups (three or four students) and have them select the group of vertebrates they consider to be the most successful. They should be prepared to describe how they defined success and justify their selections.

An alternative would be to assign each group of students an animal or group of animals and have them justify the selection of the assigned group as the most successful vertebrates.

The more specific topic of human success might be more interesting if done in a debate format. If that option is pursued, divide the class into two groups and have one prepare to defend that humans are a biological success and the other that humans are not a biological success.

Assessment Suggestions As a class, discuss the students’ selections and justifications. Part of the discussion is likely to involve how success is to be defined.

For future assessment, include a question on an exam about vertebrate success and have the students justify their selection of a certain animal or phylum as successful.

If a debate is done, have the students complete a grading rubric of some kind that allows them to evaluate the participation of their classmates in the debate preparation/presentation.

Lecture Activity 24.4: Zoo Visit Estimated Time to Complete: 2–3 hours, depending on the size of the zoo and what’s required of the students Section Reference 24.3 What Are the Major Groups of Vertebrates?

Introduction If you have a zoo nearby, this is a great way to encourage students to actually learn something during a visit to a zoo.

There are a number of activities that could be required of students for this assignment and lots of ways to emphasize major concepts in biology. .

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If you don’t have a zoo nearby, consider modifying this activity and the “guide” for what is available. You may have a local pond or forested tract, animal farms, or animal rehab facilities that could be used instead of a zoo.

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Materials Needed • Copies of a handout/guide so the students know what animals to look for or observe Procedures You could make arrangements with the zoo for the students to get free or reduced admission to the zoo. If it’s an optional assignment, that shouldn’t be necessary.

Provide the students with copies of, or access to, the guide (e.g., posted on the Internet).

Assessment Suggestions Have the students submit their handouts or guides for grading. If your course requires some kind of writing assignment, this is a great option (student feedback) to a traditional research paper.

Handouts or Display Handout of questions or guide. The one provided was written for a specific zoo and should be modified for what’s available at a zoo near you.

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Name:

Date:

Instructor:

Course Section:

Lecture Activity 24.4 Sample Handout—Zoo Visit Time and Date of Observation ______________________ Weather ______________________ (Please attach receipt to this handout) *You may need to consult some other sources to answer questions about what the animals’ natural habitats are like.

Visit the Black Bears exhibit and answer the following: What do black bears (naturally) eat and, based on this, are they herbivores, omnivores, or carnivores?

Describe the zoo habitat of the black bears. How similar is it to their natural habitat?

At the Crossroads answer the following: What habitat is characterized by few if any trees; soft-stemmed plants such as cattails, rushes, and water lilies; and ducks that lay their eggs here?

What habitat lessens erosion by slowing water flow, and filters out pollutants?

Find the White Rhino exhibit and answer the following: What are the natural enemies of rhinos?

How do rhinos keep in touch (communicate) with each other?

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Of what substance is the rhino’s horn composed?

What characteristic allows rhinos to clip grass?

Find the area where all the reptiles are located and answer the following: At what temperatures do developing alligators become females rather than males?

How does the habitat (where it lives) influence the color of the Malagasy tree boa?

What are the threats to the survival of the radiated tortoise? (They tortoises may not be displayed, but their sign should still be up.)

How might the reproductive practices of the radiated tortoise influence its survival?

How do the snapping turtles lure their prey to them?

Zoos are increasingly concerned about the quality of life of their animals and often provide enrichments (“toys” to simulate hunting or playing) to stimulate the animals. Describe any enrichments you observed and indicate the animal(s) for which the enrichments were provided.

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Find Chimp Ridge (the chimpanzee exhibit) and answer the following (you’ll have to visit the outdoor and indoor areas to find all the answers): Number of primates YOU observed: _______________

What does bobbing mean to chimpanzees?

What type of face is a chimp making when he/she grins but has the upper teeth covered?

Describe two sounds chimps make when they communicate with one another.

Find the Gorilla enclosure in Gorilla Valley and answer the following: Are the Knoxville Zoo’s gorillas exhibited (in their outdoor exhibit) as they would live naturally? Explain your answer.

What does a direct stare mean to a gorilla?

Find the River Otter display and answer the following: Describe their zoo habitat:

How does their zoo habitat compare with their natural habitat?

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Describe any behaviors you observe:

Of what importance to the survival of endangered and threatened species are zoos’ species survival plans? These plans include trading animals with other zoos for reproductive purposes.

List one or two species for which the Knoxville Zoo participates in a species survival plan.

Focal Time Sampling: Using a stopwatch or watch, time a fixed observational period (30-second intervals are recommended) to record the occurrence or onset of a behavior taking place by a specific individual animal (focal animal) from any of the groups you have observed.

Sample one animal for a 15-minute bout—that means every 30 seconds you will record the behavior you see taking place at that moment. At the end of the bout, you should have recorded a total of 30 behaviors, some of which may be duplicates.

Use the behavioral list below and record a “tick” (l) in the appropriate behavioral category every 30 seconds. Determine the frequency of behaviors that occurred during the 15-minute bout (by dividing the total number of each category by 30 and then multiplying by 100 for a percentage).

Repeat the process for a focal animal of another species and compare the behavioral profiles of each species on the following page.

Behavior locomoting resting sleeping feeding autogrooming allogrooming sexual vocalizing play aggression other (specify)

Species ___________

Species__________

Focal Sample Species Comparison: Be sure to mention why the two species you observed displayed different behaviors (this may be related to the naturalness of their exhibit, the number of animals with which they are exhibited, enrichments they’ve been provided, etc.).

Visit the cheetah enclosure. What adaptations for speed do the cheetahs display?

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How does the enclosure of the cheetahs compare to that of the snow leopard?

Visit the lion exhibit. How similar is it to their natural habitat?

Other interesting things you observed at the zoo (there should be SOMEthing!):

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Lecture Activity 24.5: Aquarium Visit Estimated Time to Complete: 2–3 hours, depending on the size of the aquarium and what’s required of the students Section Reference 24.3 What Are the Major Groups of Vertebrates?

Introduction If you have an aquarium nearby, this is a great way to encourage students to actually learn something during a visit to an aquarium. There are a number of activities that could be required of students for this assignment and lots of ways to emphasize major concepts in biology.

Materials Needed • Copies of the handout/guide, so the students know what animals to look for or observe Procedures You could make arrangements with the aquarium for the students to get free or reduced admission to the aquarium. If it’s an optional assignment, that shouldn’t be necessary.

Provide the students with copies of, or access to, the guide (e.g., posted on the Internet).

Assessment Suggestions Have the students submit their handouts or guides for grading. If your course requires some kind of writing assignment, this is a great option (student feedback) to a traditional research paper.

Handouts or Display Handout of questions or guide. The one provided was written for a specific aquarium and should be modified for what’s available at an aquarium near you.

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Name:

Date:

Instructor:

Course Section:

Lecture Activity 24.5 Sample Handout—Aquarium Visit Date of your visit _______________ Please attach (with a staple or paper clip) your ticket stub or evidence of admission.

The questions in this handout should follow the layout of the aquarium. Be sure to check for answers in the appropriate areas.

A. TROPICAL RAIN FOREST: 1.

What is the purpose of the blue stripe/red belly of the tetras?

2.

What is the purpose of the bright coloration of the poison dart frogs?

3.

How do the poison dart frogs get the toxin that makes them lethal?

4.

How can the mudskippers survive out of water?

5.

What do the eyes of the Anableps (four-eyed fish) allow it to do?

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B. OCEAN REALM: 1.

Why do fish travel in schools?

2.

How does the anglerfish (frogfish) catch its food?

3.

What is unusual about the development (remember, think embryos!) of the jawfish?

4.

What is unusual about the reproduction of seahorses?

C. AMAZON WATERFALL: 1.

What is surprising about the piranhas known as pacu?

2.

What is the function of the “whiskers” of a catfish? What are the “whiskers” really called?

D. CORAL REEF: 1.

What’s unusual about the Anthias fish?

E. SHARK LAGOON: 1.

How does the Jewfish scare off potential threats?

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2.

What is the purpose of the silvery color of the Lookdown fish?

3.

Name two species of sharks displayed and describe a unique feature of each.

F. DISCOVERY CENTER: 1.

You should have the opportunity to handle/touch a horseshoe crab. How did it feel?

2.

Into which animal phylum (you may need to check your text/notes) is the horseshoe crab classified?

3.

What connection (important theme in Unit 5) is there between the horseshoe crabs and migrating birds?

4.

What color is the oxygenated blood of the horseshoe crabs? What makes the blood that color?

5.

How can you distinguish between a male and a female horseshoe crab (you’ll probably have to ask about this one!)?

6.

How do pipefish and trumpet fish (headstanders) escape predation?

7.

How do porcupine and puffer fish escape predation?

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G. GALLERY OF THE SEAS (GOS): 1.

To which animal is the cuttlefish related? Into which animal phylum (you may need to check your text/notes) are they classified?

2.

Name a couple of different representatives of the phylum Cnidaria displayed in this area.

3.

What kind of animal is the leafy sea dragon? Into which class of the Chordate phylum are these animals classified?

4.

What is the purpose of the leafy sea dragon’s appendages?

H. STINGRAY BAY/TOUCH-A-RAY BAY: 1.

You should have the chance to touch a ray. How did it feel?

2.

To which animals are the rays related? Into which class of the Chordate phylum are the rays classified?

I. OTHER INFORMATION OF INTEREST:

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CHAPTER 25 ANIMAL BEHAVIOR LECTURE OUTLINE Case Study: Sex and Symmetry 25.1 How Do Innate and Learned Behaviors Differ? â Lecture Activity 25.1: Parasitic Mind Control A. Behavior Is Any Observable Activity of a Living Animal B. Innate Behaviors Can Be Performed Without Prior Experience 1. They are performed in reasonably complete form the first time 2. They can often occur immediately after the birth of an organism (Figure 25-1) C. Learned Behaviors Require Experience 1. The capacity to make changes in behavior on the basis of experience is called learning 2. Habituation is a decline in response to a repeated stimulus a. This behavior prevents wasting energy and attention on irrelevant stimuli b. It is seen in even the simplest organisms (Figure 25-2) 3. Conditioning is a learned association between a stimulus and a response a. Trial-and-error learning is an example of conditioning (Figure 25-3) i. Response to naturally occurring stimuli based on rewards and punishments ii. Often occurs during play or exploratory behavior b. Operant conditioning i. The laboratory technique that described this behavior involved the “Skinner box” ii. Animal trains itself through trial and error to perform a behavior to get a reward or avoid a punishment 4. Insight is problem solving without trial and error a. Sudden problem solving occurs without prior experience b. This behavior may involve mentally manipulating concepts to arrive at a solution D. There Is No Sharp Distinction Between Innate and Learned Behaviors 1. Seemingly innate behavior can be modified by experience a. Herring gull chicks come to recognize their own parents as they mature (Figure 25-4) b. Young birds learn to discriminate silhouettes of predatory birds as they age 2. Learning may be governed by innate constraints a. Robins learn only songs of adult robins b. Birds imprint on a “parent” only during the sensitive period in their development (Figure 25-5) 3. All behavior arises out of interactions between genes and the environment a. Bird migration behavior has an inherited component (Figure 25-6) â Lecture Activity 25.2: Learning in the Simplest of Organisms

25.2 How Do Animals Communicate?

A. Communication Is Defined as the Production of a Signal by One Organism That Causes Another Organism to Change Its Behavior in a Way Beneficial to One or Both B. Visual Communication Is Most Effective over Short Distances 1. Two types of visual signals have been observed a. Active visual signals (Figure 25-7) b. Passive visual signals (Figure 25-8) 2. Active and passive signals may be combined (Figure 25-9) C. Communication by Sound Is Effective over Longer Distances 1. Sound is more effective than visual signals over longer distances 2. Sound is better than visual communication in the dark, in dense forests, and in murky water 3. Different messages are conveyed by variations in pattern, volume, and pitch (Figure 25-10) â Lecture Activity 25.3: The Bird That Talks to Badgers (and People) .

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Instructor Guide Biology: Life on Earth D. Chemical Messages Persist Longer But Are Hard to Vary 1. Chemical substances that convey messages are called pheromones a. These messages persist longer than either visual or sound signals b. They can be effective over long distances â Links to Everyday Life: Mine Finders (Figure E25-1) c. They are harder to vary and may convey less information d. Pheromones can cause immediate changes in the behavior of the detecting animal (Figure 25-11) e. Pheromones can also cause physiological changes in the detecting animal f. Traps baited with sex-attractant pheromones have been used to keep insect pests under control E. Communication by Touch Helps Establish Social Bonds 1. Physical contact can help maintain social bonds among group members (Figure 25-12a) 2. This type of communication is important in human development 3. It can also be a prelude to sexual activity (Figure 25-12b)

25.3 How Do Animals Compete for Resources?

A. Aggressive Behavior Helps Secure Resources 1. Aggressive displays allow competitors to assess each other and have a winner without injury or death a. Animals may display weapons such as claws and fangs, or make a variety of vocal sounds (Figure 25-13) 2. Ritualized combat may test weapons, strength, or motivation in nonlethal ways (Figure 25-14) B. Dominance Hierarchies Help Manage Aggressive Interactions 1. Each animal establishes a rank that determines its access to resources 2. Dominant animals obtain the most resources (Figures 25-15) C. Animals May Defend Territories That Contain Resources 1. Animals defend territories that contain limited resources such as mates, food, and shelter (Figure 25-16) 2. Territoriality reduces aggression (Figure 25-17) 3. Competition for mates may be based on territories a. Females may choose males whose territories contain resources, increasing the survival chances of their offspring 4. Animals advertise their occupancy (Figure 25-20) a. Animals use sight, sound, and smell to advertise their territories

25.4 How Do Animals Find Mates?

A. Signals Encode Sex, Species, and Individual Quality 1. Many mating signals are acoustic a. Male grasshoppers, crickets, frogs, and birds all produce mating calls b. Females may compare songs to assess relative quality of males 2. Visual mating signals are also common a. Female choice may result in males being more brightly colored in comparison to females (Figures 25-19 and 25-20) b. Passive and active displays are used by males to attract the attention of females c. A complex series of signals exchanged between partners may result in elaborate mating rituals (Figure 25-21) 3. Chemical signals can bring mates together a. Some female insects produce sex pheromones that can attract males from miles away (Figure 25-22a) b. Fish commonly use a combination of pheromones and courtship movements c. Many female mammals release pheromones to attract males (Figure 25-22b)

25.5 Why Do Animals Play?

A. Animals Play Alone or with Other Animals 1. Young of the same species may play together 2. Social play includes a variety of activities (Figure 25-23) B. Play Aids Behavioral Development 1. Play allows young animals to gain experience in behaviors they will use as adults .

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25.6 What Kinds of Societies Do Animals Form?

A. Group Living Has Advantages and Disadvantages 1. Benefits to social animals include the following a. Increased abilities to detect, repel, or confuse predators â Lecture Activity 25.4: Predator Confusion—An Advantage of Living in a Group b. Increased hunting efficiency or increased ability to spot localized food resources c. Advantages resulting from the potential division of labor d. Increased likelihood of finding mates 2. On the negative side, social animals may encounter the following a. Increased competition with other group members b. Increased risk of infection c. Increased risk of offspring being killed by other members of group d. Increased risk of being spotted by predators B. Sociality Varies Among Species 1. Some animals are solitary, whereas others are either occasionally or permanently part of loose social groups (Figure 25-24) 2. A few species form complex societies a. Individuals may sacrifice their own interests for the good of the group i. This is called altruism, a behavior that decreases the reproductive success of one individual to benefit another C. Forming Groups with Relatives Fosters the Evolution of Altruism 1. Altruism promotes the survival of an individual’s alleles through behaviors that maximize the survival of a close relative a. This concept is called kin selection D. Honeybees Live Together in Rigidly Structured Societies 1. Honeybees, ants, and termites all live in highly structured societies 2. Individual insects are born into one of several castes within the society a. A division of labor exists among and within the castes b. Worker bees search for food i. Once they find a food source, they carry out a waggle dance that communicates the location of the food (Figure 25-25) 3. Pheromones play a major role in regulating the lives of social insects E. Naked Mole Rats Form a Complex Vertebrate Society (Figure 25-26) 1. The complexity of the society does not increase with the complexity of the nervous system 2. In naked mole rat societies, only the queen reproduces a. The queen maintains her dominance by aggression toward workers

25.7 Can Biology Explain Human Behavior?

A. Ethical Constraints with Human Experimentation Limit Our Ability to Study Human Behavior B. The Behavior of Newborn Infants Has a Large Innate Component 1. Sucking by newborn infants is innate (Figure 25-27) a. Infants have been shown to prefer their mothers’ voices and respond by sucking (Figure 25-28) C. Young Humans Acquire Language Easily D. Behaviors Shared by Diverse Cultures May Be Innate 1. Gestures and facial expressions are examples E. Humans May Respond to Pheromones 1. Pheromones may affect menstrual cycles in women â Case Study Continued: Sex and Symmetry F. Studies of Twins Reveal Genetic Components of Behavior G. Biological Investigation of Human Behavior Is Controversial

Case Study Revisited: Sex and Symmetry (Figure 25-29)

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KEY TERMS aggression altruism behavior communication dominance hierarchy ethology

habituation imprinting innate insight learning kin selection learning

operant conditioning pheromone territoriality trial-and-error learning waggle dance

LECTURE ACTIVITIES Lecture Activity 25.1: Parasitic Mind Control Estimated Time to Complete: 10 minutes or more, depending on the number of examples covered Section Reference 25.1 How Do Innate and Learned Behaviors Differ?

27.3 What Are the Results of Interactions Between Predators and Their Prey?

Introduction Presentation of this material can serve as a stimulating introduction not just to the chapter on animal behavior but to the whole unit on ecology. It shows how one species (a parasite) can alter the behavior of another (its host) in unusual and unpredictable ways. It is approached as a story of the bizarre side of biology with vivid storytelling, appropriate use of images and videos of the organisms involved, and the compelling hook at the end that you too may be under parasitic mind control! To save time, only one or two of the examples outlined here may be presented.

Materials Needed • The minimum requirement is some way of projecting images of the organisms involved (overhead projector, video projector hooked to a computer running PowerPoint, etc.)

• Computer hookups will allow showing video clips as discussed in the Procedures section Procedures Many parasites must infect more than one host species in order to complete their life cycles. Many of these, like the human pork tapeworm whose life cycle is detailed in the textbook, move from one host to the next when one host eats another, such as when humans eat undercooked pork. Although many of these parasites appear to be at the mercy of pure chance that this predation event will occur, it is now clear that some parasites increase their odds by altering the first host’s behavior to make predation more likely.

One example of this parasitic mind control is seen in the lancelet fluke Dicrocoelium dendriticum. (For more information, perform an Internet search using “Dicrocoelium dendriticum” as the search term.) The adult parasite lives in the “definitive” host, for example, a cow or steer, but larval stages infect first snails and then ants. Sexual reproduction by adult flukes in a cow produces eggs that leave the cow with its manure. If snails ingest these eggs, they become infected. The larval flukes then multiply, develop, and eventually migrate to the host snail’s lungs, where they are surrounded by the snail’s slime and cast off in slime balls. Ants find these slime balls delicious and devour them. Most of the fluke larvae in each slime ball transform into a digestive-resistant cyst embedded in the ant’s tissues, waiting for the ant to be consumed. However, some of the flukes migrate to a group of ganglia that control the ant’s behavior and exert their mind control by means that are still unclear. What is clear is that they cause the ant to crawl to the top of a grass blade at dusk and clamp onto the grass with the mandibles. This location makes them more likely to be consumed by a grazing cow. If not eaten by the next morning, the parasites “release” the ant from their control and the ant goes about its normal activities for the day, only to be “taken over” again by the parasites that evening. In this way, the ant and its parasites are not subjected to the hot afternoon sun and have repeated chances to be consumed by cows, at which time they burrow through the cow’s intestine and mature into adults. .

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Similar control is exerted on its land snail host by another fluke, Leucochloridium paradoxum. In this case the larval parasite migrates into the snail’s transparent eyestalk and undulates its body to flash its brightly colored bands through the snail’s skin, mimicking the movement of a caterpillar. (For more information, conduct an Internet search using “Leucochloridium paradoxum” as the search term.)

This attracts the attention of the fluke’s definitive host, an insect-eating bird. The display is made more visible by the action of the fluke on the snail’s activity: it causes the snail, usually reluctant to show itself during the day, staying on the underside of leaves, to recklessly move onto the upper surfaces of leaves where birds are more likely to spot them. If the bird eats the snail’s eyestalk, it not only doesn’t get the advertised caterpillar meal, it also becomes infected.

But what about humans? Are we ever subjected to such manipulation by any of our parasites? The answer appears to be, “Maybe.” The single-celled protozoan parasite Toxoplasma gondii requires two hosts to complete its life cycle: one is a cat (wild or domestic), and the other can be one of several mammals including rats, other cats, or humans. It has been clearly demonstrated that Toxoplasma-infected rats lose much of their fear of cats, spending more time in the open, for example. (For more information, conduct an Internet search using “Toxoplasma gondii” as the search term.) This activity would make them more likely to be encountered by, and consumed by, the cats. But what about the effects of Toxoplasma on humans? Preliminary studies suggest that the parasite may also affect “personality traits” and reaction times in infected humans, possibly increasing “risky” behavior and making them less vigilant of dangers in their environment as well. This may be a significant finding, as some experts estimate that as many as 50% of all humans may be infected by parasites, ingesting eggs released with the family cat’s feces, for example!

Although the primary danger is perceived to be deterioration of the general health of people with compromised immune systems or infection of newborns by their mothers, behavioral changes may also be significant.

Assessment Suggestions Although changes in the “prey” host’s behavior may be obvious, have the students develop a method to test the hypothesis that this change increases the likelihood of the prey host being eaten by the predator (i.e., the potential future host). Have them outline one experiment they might perform and their predicted outcome.

Have the students consider if it is possible for the parasite to make its host too reckless. What would they predict would happen if the prey host suddenly stopped exercising all caution? How might this affect the number of individuals in the prey host population? How might this affect the number of individuals in the parasite population?

Knowing what they do about behavior and the nervous system, have the students speculate on a mechanism by which the parasite might control its host’s behavior. How might they test their hypotheses?

If Toxoplasma does indeed alter human behavior, what might the implications be for public policy? If someone accused of committing a crime is determined to be infected, should this be considered during that individual’s trial or sentencing? Have the students explain their positions.

Handouts or Display No special handouts or displays are needed, although a printout of material from the Internet searches might be of interest.

Lecture Activity 25.2: Learning in the Simplest of Organisms Estimated Time to Complete: 8–10 minutes Section Reference 25.1 How Do Innate and Learned Behaviors Differ?

Introduction A common misconception held by many undergraduate students is that only more “complex” animals are capable of learning. To the contrary, very simple animals such as flatworms are capable of complex behaviors, including conditioned reflexes and learning to navigate mazes. This can be illustrated in a simple and quick classroom demonstration. Here, habituation (reduced response to a repeated, benign stimulus) will be demonstrated in a flatworm and/or a single-celled protistan.

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Materials Needed • A small number of live and active planarians (flatworms such as Dugesia sp.)

• A small culture of Spirostomum, Stentor, or other large protistans • A small culture dish with spring or pond water • A means of projecting the image of the organisms on the projection screen (e.g., ELMO, digital camera with macro lens and video projector, etc.)

• A small 20-cc syringe without a needle Procedures A couple of days before the demonstration, place the experimental organisms in the culture dish in water to be used in the demonstration.

Before class begins, set up the culture dish, projector or camera, and all other equipment needed to allow the organisms time to acclimate.

Begin the demonstration by describing the common misconception about learning mentioned earlier and explaining the process of habituation.

Then, using the syringe, blow a small puff of water over the organism and point out the withdrawal reflex exhibited.

After the organism has recovered, apply another puff of water and note the response. Continue in this way until the response is noticeably diminished. You have just demonstrated habituation!

Point out to the students that the magnitude of the response could be carefully measured and plotted, making habituation quantifiable. In fact, if organisms were used that had been “trained” the day before, the magnitude of their response would be noticeably less than that of naïve individuals.

You can conclude by explaining that conditioned reflexes, in which organisms come to respond to a harmless stimulus (such as the flashing of a light) after a period of training in which it was always presented along with a harmful stimulus (such as an electric shock), have also been demonstrated in planarians and other simple organisms. In fact, Pavlov’s dogs have nothing over these spineless worms in this regard!

Assessment Suggestions Ask the students for suggestions about how a single-celled organism such as a protistan can learn, given the layperson’s description of learning as “rewiring” the connections between neurons. How might information be stored within a single cell? How might you test your theory? Have the students provide additional ideas for studies to demonstrate other types of learning in other simple organisms.

Lecture Activity 25.3: The Bird That Talks to Badgers (and People) Estimated Time to Complete: 10 minutes Section Reference 25.2 How Do Animals Communicate?

27.1 Why Are Community Interactions Important?

27.2 What Is the Relationship Between the Ecological Niche and Competition?

27.3 What Are the Results of Interactions Between Predators and Their Prey?

Introduction The Greater Honeyguide (Indicator indicator) is one of the most interesting birds around when it comes to its behavior and interactions with other species. As such, it makes a good introduction to the unit on ecology and behavior.

To start with, the Greater Honeyguide communicates the location of beehives to the honey badger (or ratel) or, in their absence, humans, leading them directly to the hive while repeatedly uttering loud calls. After the bird’s human accomplices have broken into the hive and eaten their full of honey and, in the case of the ratel, bee larvae, the bird moves in to gorge on bees and wax. In fact, the first word reaching Europe of the existence of these African birds came from missionaries reporting a small bird that routinely stole and ate candles from the altar.

Although most animals cannot digest wax, Honeyguides have mutualistic bacteria in their guts that digest the wax, passing some of the digestion products on to the bird. This relationship benefits ratels (or humans), as they can locate hives more easily, and it benefits the bird, as it is too small and weak to break into hives itself. As such, it is another mutualistic relationship for the bird, in this case based on behavior. .

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A final twist to the story is that this bird is also a parasite, with its “host” being another bird! Like the cuckoo described in Section 25.1, female Honeyguides lay their eggs in the nests of other birds. Their chicks hatch earlier and grow faster than those of the nest owner, displacing and often killing any nest mates. The foster parents, unaware of the switch, raise the Honeyguide chicks as their own; thus the chicks parasitize the paternal instincts of their hosts.

Materials Needed • Images of the species involved can be easily obtained using the image search feature on any Internet search engine and added to presentations. Use “honeyguides” as the search term.

Procedures This material can be presented as a slideshow or PowerPoint presentation with an emphasis on the bizarre nature of the interactions involved.

Discussion or assessment may immediately follow presentation of each individual interaction or be postponed until the entire presentation has been completed.

Assessment Suggestions Ask the students to suggest ways the relationship between the bird and the badger may have evolved. What might have been the first step in their coevolution?

Lead a student discussion of the behaviors, or lack thereof, in the host birds that allow them to be victimized by the nest-parasitizing behavior of Honeyguides. Would they expect mammals to be as easily fooled? Why or why not?

Lecture Activity 25.4: Predator Confusion—An Advantage of Living in a Group Estimated Time to Complete: 10 minutes Section Reference 25.6 What Kinds of Societies Do Animals Form?

Introduction One of the advantages of living in a group (a herd of zebra, school of fish, etc.) listed in your textbook is a decreased risk of being eaten by predators. One component of this is the so-called confusion effect, in which a predator’s attention on one possible prey individual is disrupted by other prey passing by, decreasing the predator’s chance of catching any prey. This can be demonstrated simply by throwing different numbers of tennis balls (the prey) at a student (the predator) who has to try to catch a ball.

Materials Needed • Four tennis balls for each group of students participating in the demonstration (two groups of students are recommended) • For each group, one student to act as a predator (catcher) and four students to act as throwers • Chalk and a blackboard or other means of recording and diagramming results Procedures Briefly outline the advantages and disadvantages of living in groups, with special emphasis on the effects on prey species.

Introduce the concept of predator confusion as just described.

Ask for student volunteers to serve as throwers and catchers.

Coach the throwers to throw underhand, aiming at the catcher’s chest and throwing with sufficient velocity such that catching a single ball requires the attention of the catcher.

Supply each group of throwers with 15 strips of paper, each with a number written on it: five strips with the number 1, five with the number 2, and five with the number 4, shuffled so they are in random order.

Instruct the throwers to stand in a straight line, shoulder to shoulder, 10 feet from the catcher.

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Before each throw, have the throwers read the top slip of paper and decide which of them will throw balls if the number 1 or 2 is selected (the others will fake throwing, but not release the ball); this information should not be communicated to the catcher.

On the instructor’s mark, have all the throwers throw or fake throwing at the same time. Have a recorder for each group (another student volunteer) to record the number of balls thrown and whether the catcher was successful or not.

Repeat until all 15 trials have been concluded.

Tabulate the data for each group separately or for both groups combined and plot as a histogram with three bars, one for each treatment (1 ball, 2 balls, or 4 balls).

Analyze the data (eyeballing it should be sufficient) to determine if they support the predictions of the predator confusion hypothesis.

Assessment Suggestions Before throwing begins, have the students suggest ways of graphing the results and have them predict what the results should look like if the predator confusion hypothesis is valid.

After the results are tabulated and graphed, have the students state their opinions of the significance of the findings. Has predator confusion been demonstrated? Are the results significant? How could we increase our confidence in our findings?

Have the students discuss the validity of this experiment as a test for the predator confusion hypothesis. Is it realistic? Is it applicable to the real world of predators and prey? Can the students suggest other ways of testing this hypothesis?

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CHAPTER 26 POPULATION GROWTH AND REGULATION LECTURE OUTLINE Case Study: The Mystery of Easter Island 26.1 How Does Population Size Change?

A. A Population Consists of All the Members of a Particular Species That Live Within an Ecosystem 1. An ecosystem consists of all the living and nonliving components of a defined geographical area 2. A community is defined as a group of interacting populations 3. Ecology is the study of the interrelationships of organisms with each other and with their nonliving environment B. Changes in Population Size Result from Natural Increases and Net Migration 1. Births, deaths, and net migration can change the size of populations a. Net migration is the difference between immigration and emigration b. Population growth occurs when the number of births plus immigrants exceeds the number of deaths plus emigrants 2. Populations grow based on the birth rate, the death rate, and the population size a. The growth rate (r) of a population is the change in the population size per individual over some time interval i. Growth rate r = birth rate b – death rate d ii.Birth rate (b) is the average number of births per individual per unit time (e.g., if there are 5 births among 10 individuals, b = 5/10 = 0.5) iii. Death rate (d) is the proportion of individuals dying per unit time (e.g., if 4 of 10 individuals die, d = 4/10 = 0.4; then r = b – d = 0.5 – 0.4 = 0.1) b. To determine population growth (G) over the time period, multiply the growth rate (r) by the number in the population at the start of the interval (N) i. Population growth = rN 3. If births exceed deaths, exponential growth occurs a. A constant growth rate produces exponential growth i. This occurs when any individual produces more than one offspring that survives to reproduce ii.This type of growth can be graphed over time and produces a J curve (Figure 26-1) b. Death rate also affects exponential growth (Figure 26-2) C. Biotic Potential Determines the Maximum Rate at Which a Population Can Grow 1. Biotic potential is influenced by several factors a. The age at which the organism first reproduces b. The frequency at which reproduction occurs c. The average number of offspring produced each time d. The length of the organism’s reproductive life span e. The death rate of individuals under ideal conditions â Lecture Activity 26.1: Effects of Age at First Reproduction on Population Growth Rate

26.2 How Is Population Growth Regulated?

A. Environmental Resistance Curbs Population Growth 1. Examples include competition, predation, as well as natural events B. Exponential Growth Occurs Only Under Unusual Conditions 1. Exponential growth occurs in populations with boom-and-bust cycles a. Such cycles are often seen in short-lived, rapidly reproducing species in which a period of ideal conditions causing rapid population growth is followed by a massive die-off as conditions deteriorate .

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Instructor Guide Biology: Life on Earth i.Photosynthetic bacteria in a lake may exhibit roughly exponential growth when conditions are ideal, but crash when they have depleted their nutrient supply (Figure 26-3a) â Health Watch: Boom-and-Bust Cycles Can Be Bad News (Figure E26-1) ii.Lemming cycles are more complex and involve overgrazing of food supply, large migrations, and massive mortality caused by predators and starvation (Figure 26-4b) 2. Exponential growth occurs temporarily when environmental resistance is reduced a. When food supply is increased, the population can increase rapidly b. When predators are reduced or populations are protected, they can also increase c. Invasive species introduced into a new ecosystem may explode in numbers, as their natural enemies (predators, parasites, and competitors) may not be present to control their numbers â Case Study Continued: The Mystery of Easter Island C. Environmental Resistance Limits Population Growth 1. Logistic growth occurs when new populations stabilize as a result of environmental resistance a. The population size stabilizes at the carrying capacity (K), the maximum population size the ecosystem can support sustainably (Figure 26-5a) i.The curve that results is S-shaped â In Greater Depth: A Look at Logistic Population Growth b. A population that exceeds its carrying capacity may damage its ecosystem, actually decreasing the carrying capacity (Figures 26-5b and 26-6) c. Logistic population growth can occur in nature when a species moves into a new habitat (Figure 26-7) i.As population density increases, individuals begin to compete for resources ii.Laboratory experiments have confirmed the effects of environmental resistance on populations 2. Density-independent factors limit populations, regardless of density a. Climate, weather (including droughts and floods), and fires can cause massive mortality in local populations, irrespective of their densities b. Pesticide use, pollutant release, and overhunting and fishing by people can have similar effects â Case Study Continued: The Mystery of Easter Island 3. Density-dependent factors become more effective as population density increases a. Some species have evolved means of limiting their losses, such as seasonally migrating to a better climate or entering a period of dormancy when conditions deteriorate â Lecture Activity 26.2: Graphical Demonstration of Carrying Capacity and the S-Curve b. Predators exert density-dependent controls on populations i.Predation involves a predator killing a prey organism in order to eat it (Figure 26-8a) ii. Predator populations often grow as their prey becomes more available (Figure 26-8b) iii. An increase in predators can lead to a loss of prey, which can result in out-of-phase population cycles (Figure 26-9) iv. Predation can contribute to the overall health of prey populations and may maintain prey populations near carrying capacity â Lecture Activity 26.3: When the Pressure’s On, It’s Frog-Eat-Frog c. Parasites spread more rapidly among dense populations i.A parasite feeds on a host organism, usually without killing it ii. Examples include tapeworms, ticks, and disease-causing microorganisms iii. Although parasites seldom directly kill their hosts, they may weaken them enough that death due to other causes is more likely d. Competition for resources helps control populations i.Competition is the interaction among individuals attempting to use the same limited resource ii.Competition may be divided into two groups based on the species identity of the organisms involved 1. Interspecific competition is between individuals of different species 2. Intraspecific competition is between individuals of the same species iii. Scramble competition, common in plants and many insects, is described as a free-for-all scramble as individuals try to beat others to a limited pool of resources (Figure 26-10) iv.In contest competition, social interactions (especially territoriality and social hierarchies among animals) or chemical interactions (among some plants) determine access to important resources v.Intense competition may drive organisms to emigrate and colonize new areas (Figure 26-11) .

Chapter 26 Population Growth and Regulation 4. Density-independent and density-dependent factors interact to regulate population size

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26.3 How Are Populations Distributed in Space and Age? A. Populations Exhibit Different Spatial Distributions (Figure 26-12) 1. Organisms that live in groups exhibit a clumped distribution (Figure 26-12a) 2. Organisms with a uniform distribution maintain a relatively constant distance between individuals (Figure 26-12b) 3. Organisms with a random distribution are rare and found in areas where resources are fairly uniformly distributed (Figure 26-12c) B. Populations Exhibit Different Age Distributions 1. Survivorship tables track groups of organisms born at the same time throughout their lives (Figure 26-13a) a. Survivorship curves are graphs of these tables, and can show various patterns (Figure 26-13b) 2. Late-loss populations, such as humans and many other large animals, especially those with few offspring that receive substantial parental care, display convex curves, with low mortality until individuals reach old age 3. Constant-loss populations, such as some bird species, display straight lines, indicating an equal chance of dying at any age 4. Early-loss populations, such as most plants and many animals that produce many offspring that do not receive parental care, display concave curves due to high early mortality as most offspring fail to become established; thereafter, survivorship is much higher

26.4 How Is the Human Population Changing?

A. The Human Population Continues to Grow Rapidly 1. In the last few centuries, the human population has grown at nearly an exponential rate, yielding a Jshaped growth curve (Figure 26-14) 2. Humans have been able to overcome environmental resistance â Earth Watch: Have We Exceeded Earth’s Carrying Capacity? (Figure E26-2) B. A Series of Advances Has Increased Earth’s Capacity to Support People 1. Humans have manipulated the environment to increase resources available 2. Technical, agricultural, industrial, and medical advances have increased the rate of survival of humans C. The Demographic Transition Explains Trends in Population Size 1. Today, countries are often described as developed or developing a. As countries develop, they go through a series of phases that may result in a demographic transition (Figure 26-15) b. Populations stabilize when the adults of reproductive age have just enough children to replace themselves, a situation called replacement-level fertility (RLF) D. World Population Growth Is Unevenly Distributed 1. In developing countries, medical advances have decreased death rates and increased birth rates 2. Population growth is highest in countries that can least afford it 3. Of the 7 billion people on Earth in 2011, approximately 5.8 billion live in developing countries E. The Age Structure of a Population Predicts Its Future Growth 1. Age structure refers to the distribution of males and females of a population according to age groups 2. This can be shown graphically in an age structure diagram, where age is graphed on the vertical axis and the number of individuals in each age group is shown on the horizontal axis, with males and females placed on opposite sides a. Populations whose age structure diagrams have a broad base are expected to increase rapidly (Figure 26-16a) b. Populations whose age structure diagrams have narrower bases are expected to increase slowly (Figure 26-16b) c. Populations whose age structure diagrams have very narrow bases are expected to have zero growth or actually decline (Figure 26-16c) 3. The shape of the age structure diagram can be used to crudely predict the future growth of a population (Figure 26-17) 4. For the year 2050, the United Nations predicts that the world population will be over 9 billion and growing (Figure 26-18) â Lecture Activity 26.4: Demonstrating Dynamic Population Age Structure Diagrams .

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F. Fertility in Some Nations Is Below Replacement Level (Table 26-1) 1. In Europe, the annual change in the population is below the RLF a. This situation raises governmental concerns about the availability of future workers and taxpayers to support the increasing number of elderly people G. The U.S. Population Is Growing Rapidly 1. The U.S. population is the fastest growing of all industrial nations (Figure 26-19) a. The U.S. fertility rate is only 2.0, actually below RLF b. Continued immigration is adding people rapidly 2. The rapid growth of the U.S. population may have serious implications for the environment of both the United States and the Earth a. This is because Americans consume far more resources and produce far more pollution than the global average

Case Study Revisited: The Mystery of Easter Island

KEY TERMS age structure diagram biosphere biotic potential birth rate boom-and-bust cycle carrying capacity (K) clumped distribution community competition constant-loss population contest competition death rate demographic transition density-dependent density-independent

developed country developing country ecology ecosystem emigration environmental resistance exponential growth growth rate host immigration interspecific competition intraspecific competition invasive species J-curve late-loss population

logistic population growth natural increase parasite population population cycle predator prey random distribution replacement-level fertility (RLF) scramble competition S-curve survivorship curve survivorship table uniform distribution

LECTURE ACTIVITIES Lecture Activity 26.1: Effects of Age at First Reproduction on Population Growth Rate Estimated Time to Complete: 8 minutes Section Reference 26.1 How Does Population Size Change?

Introduction The textbook lists a number of factors that determine the biotic potential of a population. First on the list is the age at which organisms first reproduce. Although two text figures (Figures 26-1 and 26-2) allegedly illustrate this concept using eagles and bacteria as examples, other factors (such as the means of reproduction and differences in “brood” sizes and numbers) confound this concept. A simple graphical model, drawn on the board or overhead, can demonstrate this concept by comparing two hypothetical organisms that differ only in age at first reproduction.

Materials Needed • Chalkboard or whiteboard or overhead projector with appropriate writing instrument .

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Procedures Start by reminding the students of the importance of the age at first reproduction to the population growth rate.

Present or review the concept of life history of an individual. Note that an individual is born, has offspring (or not), and dies.

Illustrate a simple graph of a life history. Time moves from left to right. (Draw an arrow on the board and label it “time.”)

The birth of an individual is illustrated by a short vertical line (at the time of birth). From this a horizontal line extends to the right, representing the life of the individual. This line ends with another short vertical line at the individual’s death. Births can be represented by vertical lines coming off the “life line” of the parent at the time of their birth, then proceeding to the right to represent their lives. (See Figure 1.)

The simplest life history can be used to illustrate the concept of this exercise. Binary fission of an immortal organism is represented by a horizontal line starting with the “birth” of an individual (by a first act of binary fission) and ending at a vertical line leading to two new horizontal lines (representing the second act of binary fission and resultant “offspring”). (See Figure 2.)

Next, graph two populations that are identical except for the time required for each individual to “reproduce.”

Start each with one individual that divides into two, which divide (synchronously) into four, and so on. To make things less complicated, have one population take exactly twice as long to reproduce as the other. (See Figure 3.)

Finally, have the students tally the number in each population at each time interval (this is easier if a time grid is provided or the graphs are one over the other; they are tallied at time = t on Figure 3 as an example; Figure 4 provides a clean copy of the graph) and produce a geometric growth graph. Point out that the only thing that has been changed here is age at (first and only) reproduction, yet one population grows much faster than the other.

Assessment Suggestions Ask the students to consider the implications of more women staying in school or entering the out-of-house workforce in developed countries and delaying having children until later in life. How does this affect population growth rate in developed versus developing countries? What role does contraception play in this difference? How might religious or social traditions impact this factor?

Ask the students if this effect is limited to organisms that reproduce by binary fission or is more generally applicable to all life histories. Have one student who believes (correctly) that it is generally applicable illustrate his or her concept on the board.

Handouts or Display Although no special handouts are necessary, the life history diagrams discussed earlier are obviously central to this demonstration.

Although these could be prepared ahead of class and simply shown to the students to save time, they are so simple and drawing them while you develop the concepts is so valuable, that is not recommended. The figures to be drawn (mentioned earlier) are on the following pages.

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Chapter 26 Population Growth and Regulation

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Lecture Activity 26.2: Graphical Demonstration of Carrying Capacity and the S-Curve Estimated Time to Complete: 15 minutes Section Reference 26.2 How Is Population Growth Regulated?

Introduction Although most students do not find the concept of carrying capacity particularly difficult, they usually cannot make the logical jump from carrying capacity to the S-shaped growth curve. This demonstration, which involves a graphical representation of carrying capacity and some simple growth equations (not in the text), helps explain this connection in a very logical manner that helps all but the most math-challenged students.

Materials Needed • Chalkboard or whiteboard or overhead projector with appropriate writing instrument Procedures Begin by presenting (or reviewing) the underlying concepts: carrying capacity, density-dependent growth, the S-curve.

Present a hypothetical example. The ecosystem is an island (because the boundaries between this and other adjacent ecosystems are distinct). Draw its outline (a kidney-shaped oval works well). Our population lives on that island. It takes a given amount of resources to sustain each individual of that species, which we can illustrate as a “territory” for that individual. (Assume the island ecosystem is homogeneous in resources. Clearly we are talking about the one “limiting resource” that determines the growth of that population, i.e., the resource that is in shortest supply relative to its demand.)

Draw a square grid (as this is easiest to draw) over the island (Figure 1). Explain that each square represents the resources needed by one individual. Although space comes immediately to most students’ minds, point out that this could be food plants for an herbivore (which, of course, need space to grow), sunlight for a plant, and so forth. Count the number of full squares and devise a system for counting partial squares at the edges of the island.

For example, if a square is more than half “filled” with island, it is counted; if less than half filled it is not counted.

Explain that the total number of squares represents the carrying capacity of that ecosystem for that species.

Now consider the case where the population is very small. Many “spaces” are unfilled as resources are very plentiful. Point out that the population will grow at its maximal, exponential rate initially. The text gives the following formula for this growth: Population growth = rN Where r = the intrinsic growth rate of the population (in units of individual/individual/unit time) and N is the size of the population at any given time.

Draw an exponential growth curve (J-curve) and point out that this simply represents the slope of the curve at any point.

Explain that slope is simply “rise over run,” or how much the curve rises (or falls) for some given time interval. Because we are looking at an instantaneous rate, draw a tangent to the curve at that point and explain that the slope is then rise/run or dN/dt, where dN is the vertical rise of a segment of the tangent line and dt is the horizontal run of that same segment (Figure 2). We can then rewrite the exponential population growth equation as: Population growth = dN/dt = rN To illustrate the effect of density on population growth, we multiply the N on the right of this equation by a new expression that includes carrying capacity. This expression is (K – N)/K, where K is the carrying capacity of the ecosystem for this species. We start by noting that, when the population is very small (N = 0), this expression effectively becomes 1(K – 0)/K = K/K = 1, so our equation becomes: dN/dt = rN([K – N]/K) = rN([K – 0]/K) = rN(K/K) = rN(1) = rN Note that this is the exponential growth equation; recall that, initially, when N is small, we have exponential growth. .

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Now consider the case where N is large, approximately equal to K. (You can fill in the spaces on your island.)

Now most of the resources are “used up” by the existing organisms, with little left for additional births. As a result, birth rate might drop and/or death rate might rise. In the equation, N now approaches K, so we can substitute K for N: dN/dt = rN([K – N]/K) = rN([K – K]/K) = rN(0/K) = rN(0) = 0 Point out that a slope of 0 is plotted as a horizontal line, the “top” of the S-curve.

Further, illustrate on a new graph of N vs. t that the S-curve begins like the J-curve, but as N rises, the value of (K – N)/K, the “proportion of the environment still unoccupied and available for future growth,” becomes less than one. As a result, the output of the growth equation, and hence the slope of the growth curve, is progressively lower than that of the J-curve (exponential growth) at each time until we finally approach K, graphed as a horizontal line whose y-intercept is at N = K. Assessment Suggestions Although mathematically challenged students may not benefit from this exercise, it is very helpful for the more math-capable students. However, to assess understanding, the most crucial question centers around what happens if the population actually exceeds carrying capacity (i.e., N > K). This can be illustrated by drawing a point above the horizontal line representing K. Where will the population size go? What will be the initial slope of the curve? Using the equation, students should be able to work this out. When N > K (let’s say, N = 2K), the equation becomes: dN/dt = rN([K – N]/K) = rN([K – 2K]/K) = rN(=K/K) = rN(–1) = –rN So the slope is actually negative, and the population moves downward toward K. Of course, as it gets closer to K, the expression (K – N)/K becomes less negative (a smaller negative number), so the slope starts to level off. As a result, the population approaches K as an asymptote from above, instead of from below as in a standard S-curve.

Handouts or Display Although no special handouts or displays are necessary, the instructor may wish to have some key underlying concepts visible (e.g., on the chalkboard next to the projector screen) or prepare a handout of concepts, questions, and exercises to supplement the demonstration.

Lecture Activity 26.3: When the Pressure’s On, It’s Frog-Eat-Frog Estimated Time to Complete: 10 minutes Section References 19.4 What Are Viruses, Viroids, and Prions?

26.2 How Is Population Growth Regulated?

Introduction Cannibalism is generally viewed as a rare process and an aberration, the result of mental illness in humans (e.g., Jeffrey Dahmer) and an artifact of overcrowding in the laboratory. However, there is increasing evidence that it is widespread in nature (some well-studied examples include rodents, especially if their nests are invaded, and eusocial wasps) and may be involved in the origin of prions and the spongiform encephalopathies they cause.

Although many of these diseases are probably spread only within a species, some, such as bovine spongiform encephalopathy (“mad cow disease”), can spread between species, such as cattle and humans.

Materials Needed • As some figures showing cannibal versus noncannibal morphs and the act of cannibalism add to the impact of this presentation, some means of displaying them is helpful but not necessary. This may include overhead transparencies with an overhead projector or a computer linked to a large monitor or projector.

• Tadpoles or other aquatic amphibian larvae in the classroom help students visualize the dilemma faced by these animals when crowded together in a shrinking puddle or pond.

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Procedures You can begin by simply presenting the dilemma faced by amphibians that lay their eggs in temporary bodies of water as a case study. Why they choose such a habitat is worth mentioning: as the ponds and puddles dry up, they do not have populations of permanently aquatic species such as fish, which are normally major predators on amphibian larvae.

The concept of carrying capacity can be introduced as the number of larvae the pond can support at any given time. Note that the population can exceed carrying capacity if too many females lay their eggs in too small a pool, but carrying capacity may also shrink as the pool begins to dry up. Because there is too little food available per individual for that individual to survive, grow, and develop, getting the population down below carrying capacity can be accomplished by either decreasing the number of larvae or increasing the food available to them.

Cannibalism does both of these things for the cannibals.

You can point out that cannibalism is basically intraspecific predation. Predation is often a matter of bigger individuals eating smaller individuals, so note that the larvae that become cannibal morphs are larger and develop larger heads and mouths and bigger teeth. This metamorphosis into cannibals is also a good example of how the same genotype can produce different phenotypes in response to environmental cues. In fact, this polymorphism is often called polyphenism, to draw attention to the fact that it is not genetically determined.

That some of these cannibals can identify kin (siblings) and preferentially consume members of other families also helps explain how genes that “allow” this polyphenism could be selected for in a population.

You can mention that conspecifics (members of your own species) are often nutritionally superior to members of other species because they have the same biochemistry (amino acids, vitamins, minerals, etc.) as you.

However, you should point out that the danger of catching diseases from your prey is greater for cannibals, as the prey also suffer the same diseases to which you are susceptible.

Finally, you can bring up the interesting fact that prion diseases (spongiform encephalopathies) are readily spread in cannibalistic species. Because there is evidence that ancient humans may have been frequent cannibals, the occurrence of Creutzfeld-Jacob disease may have ancient origins.

Assessment Suggestions Present the following topics for discussion: If cannibalism was indeed commonly practiced by our ancestors, does this justify the actions of Jeffrey Dahmer, our most notorious modern human cannibal?

How do you feel about the actions taken by the Donner Party? Were they justified in sacrificing some individuals so others could survive? (An Internet search using “Donner party” as search terms will provide information on this.)

Jonathan Swift, best known as the author of Gulliver’s Travels, wrote a satirical essay entitled “A Modest Proposal” (perform an Internet search using “A Modest Proposal” as search terms for more information), in which he “advocated” that many of the babies of poor Irish families be used for food. The idea was that there would be fewer mouths to feed and more food and income available (if they sold the babies to the rich)—a benefit all around! Have the class discuss the merits and dangers of such a policy, both from a biological and social standpoint.

Handouts or Display Although no handouts are needed, displays of the different morphs in polyphenic species and the act of cannibalism (and possibly a drying pond) are helpful for supporting the story. More information or images may be obtained by performing Internet searches using “polyphonic species” or “cannibalism in nature.”

Lecture Activity 26.4: Demonstrating Dynamic Population Age Structure Diagrams Estimated Time to Complete: 10 minutes Section Reference 26.4 How Is the Human Population Changing?

Introduction The textbook assures students that the age structure of a population can be used to predict its future growth, but this dynamic concept lies flat on the printed page. Luckily, the U.S. Census Bureau comes to the rescue with a Web page that allows users to create dynamic age structure diagrams for some 227 countries and areas of the world. .

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The output is a series of age structure diagrams at 5-year intervals starting as early as 1950 (for the United States, though many other countries’ data begin only in 1990 or 1995) and going through population projections to the year 2050. By clicking a button below the image, the user can also view a table containing all of the data used to make the diagrams. By comparison of rapidly increasing, relatively stable, and declining populations, a real sense of the utility of these diagrams is gained.

Materials Needed • Computer with high-speed Internet access (slower access might work but will require considerable time to display images) and some way to show students output (projector attached to computer, large monitors, etc.)

• The URL of the Web site: http://www.census.gov/population/international/index.html Procedures Begin by reviewing the concept of population age structure and the underlying concepts in play here (e.g., survivorship and fertility).

For developing countries (Bangladesh being a good choice), point out that while death rates have declined sharply in recent decades, fertility rates often remain high (i.e., they have not yet completed the final stage of the demographic transition). Go to the U.S. census Web site listed earlier and click on the “Data” tab. On the next page, click on the “International Database (IDB)” link. The next page offers a number of options for analyzing the human populations in countries around the world. Under the heading “Select Country,” choose Bangladesh as an example. Click “submit.” This is the “Demographic Indicators” tab and shows a table of a variety of data, including fertility rate. Note the fertility rate for this country. Click on the “Search” tab above this table to return to the previous page. In the drop-down menu under the heading “Select Report,” select “Population Pyramid Graph.”

Then select Bangladesh as an example country again. The default setting for the year is set to the present year.

You can choose any year you are interested in seeing. Note that the age structure diagram has a very broad base, indicating that many individuals have not yet reached maturity.

Contrast this to the pattern seen in some developed countries with relatively stable populations. Sweden is an excellent example. Click the “Search” tab to go back to the country selection screen and select Sweden. In the “Select Report” section, choose “Demographic Overview” from the drop-down menu. Then click “Submit.” Note the fertility rate in the table. Compare this to the fertility rate of Bangladesh. Notice that it is lower. Following the previous instructions, access the “Population Pyramid Graph” for Sweden. Draw the students’ attention to the “straight sides” of the diagram. This age structure diagram is very different from that of Bangladesh.

Click on the “Search” tab again and select Japan and then access the “Demographic Overview” and the “Population Pyramid Graph.” This is a population that is actually expected to decline in size. Show that the base is very narrow. This clearly demonstrates the demographic dilemma Japan’s economy is expected to face as a huge proportion of the population will be of traditional retirement age and a far smaller proportion of the population of working age.

Additional countries can be chosen by the instructor or class. If the United States is chosen (which it probably will be), two cautions should be noted. First, the U.S. data go back to 1950, so the first half of the data is historical data, when worldwide fertility rates were higher. Also, recall that the present growth in the U.S. population is due almost entirely to immigration. The demographic dilemma discussed for Japan is also expected in the United States.

Assessment Suggestions Choose a country at random or allow the students to choose. Ask the students to predict the age structure diagram ahead of time. Then, after showing them the diagram, ask them to predict whether the population will grow, stay the same, or shrink.

Do the results match their expectations? Why or why not? Have them consider the effects of legislation on family size (e.g., in China) or social or religious traditions. Ask them to speculate on the economic effects of a changing age structure.

Handouts or Display Although no special handouts or displays are necessary, the instructor may wish to have some key underlying concepts visible (e.g., on the chalkboard next to the projector screen) or prepare a handout of concepts, questions, and exercises to supplement the demonstration.

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CHAPTER 27 COMMUNITY INTERACTIONS LECTURE OUTLINE Case Study: Mussels Muscle In 27.1 Why Are Community Interactions Important?

A. An Ecological Community Consists of All the Interacting Populations in an Ecosystem 1. Interactions between populations in a community help limit the size of the interacting populations, keeping them in balance with their resources 2. When populations interact, they act as agents of natural selection on each other a. This process is known as coevolution 3. Community interactions are varied (Table 27-1) a. Competition harms both species b. Predation benefits the predator but harms the prey c. Parasitism benefits the parasite but harms the host d. Mutualism benefits both species â Lecture Activity 27.1: Invasive Species—A Web Exploration

27.2 How Does the Ecological Niche Influence Competition?

A. The Ecological Niche Defines the Place and Role of Each Species in Its Ecosystem 1. The ecological niche encompasses all aspects of a species’ way of life, including: a. Its physical home or habitat b. All the physical environmental conditions necessary for its survival (e.g., temperature, pH of the water or soil, and degree of shade it can tolerate) c. The role that a species has in an ecosystem, such as what it eats and what organisms it competes with B. Competition Occurs Whenever Two Organisms Attempt to Use the Same, Limited Resources 1. Interspecific competition describes competitive interactions between two different species, which may use the same resources a. The greater the ecological niches of two species overlap, the greater the competition between them b. This type of competition is usually detrimental to both species involved â Lecture Activity 27.2: The Niche—Hutchinson’s “N-Dimensional Hypervolume” C. Adaptations Reduce the Overlap of Ecological Niches Among Coexisting Species 1. The competitive exclusion principle states that if two species occupy exactly the same niche, inevitably one will outcompete the other a. This hypothesis was formulated in 1934 by Russian microbiologist G. F. Gause based on laboratory experiments with protists i. Paramecium aurelia and P. caudatum have identical niches (feed on same food in same place) and invariably one excludes the other (Figure 27-1) ii. However, P. aurelia and P. bursaria can coexist as they feed in different places and have different niches 2. Ecologist R. MacArthur observed five species of North American warblers, all of which eat insects and nest in spruce trees a. He found that when species with largely overlapping niches are allowed to compete, the niche of each may narrow to focus on a different part of the resource spectrum i. Species minimize niche overlap by searching in different parts of a tree, using different hunting tactics, and nesting at different times b. This phenomenon is called resource partitioning and is the result of coevolution to reduce interspecific competition (Figure 27-2) i. This allows species to coexist in the same habitat D. Competition Among Species May Reduce the Population Size and Distribution of Each 264

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1. An experiment by J. Connell exhibited this phenomenon a. He found that the competition between barnacles in a specific intertidal zone caused them to inhabit different habitats within the zone E. Competition Within a Species Is a Major Factor Controlling Population Size 1. Intraspecific competition, competition among individuals of the same species, is the most intense form of competition â Case Study Continued: Mussels Muscle In

27.3 How Do Predator–Prey Interactions Shape Evolutionary Adaptations?

A. Predators Eat Other Organisms 1. Carnivores eat other animals and herbivores eat plants (Figure 27-3) 2. Predators are often less abundant than their prey B. Predator–Prey Interactions Shape Evolutionary Adaptations 1. Natural selection has favored characteristics in predators that increase their chances of catching prey (e.g., tearing claws of mountain lions and keen eyesight of hawks), as well as various characteristics among prey that allow them to avoid predation â Earth Watch: Invasive Species Disrupt Community Interactions (Figure E27-1) C. Some Predators and Prey Have Evolved Counteracting Adaptations 1. Night-hunting bats and their moth prey show a classic predator–prey coevolutionary arms race a. Bats evolved high-intensity, high-frequency sound pulses to “image” surroundings and locate moths b. Some moths evolved simple ears to detect bat pulses so they can take evasive maneuvers c. Bats can switch frequencies outside of moths’ sensitive range to avoid detection d. Moths can emit pulses to confuse bats e. Bats can turn off their pulses to listen for moths’ pulses D. Predators and Prey May Engage in Chemical Warfare 1. Both predators and prey have evolved toxic chemicals for attack and defense a. Plants have evolved a variety of chemicals to deter herbivores, such as the toxic and distasteful chemicals in milkweed i. But often some animals evolve ways to detoxify these chemicals, allowing them to eat the plants ii. Monarch butterfly larvae not only tolerate but actually use the deterrent chemicals of milkweed, acquired by a feeding caterpillar, to make themselves distasteful to predators (Figure 27-4) b. Spiders and poisonous snakes, such as the coral snake, use venom both to paralyze their prey and deter their predators c. Some marine mollusks, such as squid and octopus, emit clouds of ink when attacked to confuse predators d. Bombardier beetles spray attacking ants with boiling-hot spray emitted from the abdomen E. Looks Can Be Deceiving for Both Predators and Prey 1. Camouflage renders animals inconspicuous even when in plain sight a. It may include evolved colors, patterns, and shapes that resemble one’s surroundings (Figure 27-5) b. To avoid detection by predators, some animals have evolved to resemble specific objects such as bird droppings, leaves, or thorns (Figure 27-6a–c) c. Some plants have evolved to resemble rocks to avoid detection by herbivores (Figure 27-6d) d. Camouflage also helps predators ambush their prey i. The snow leopard is inconspicuous on the mountainside (Figure 27-7a) ii. The frogfish resembles rocks (Figure 27-7b) 2. Bright colors often warn of danger a. As opposed to camouflage, some animals have evolved bright warning coloration that attracts the attention of potential predators b. This advertises that they are distasteful or poisonous before predator attacks (Figure 27-8) 3. Some prey organisms gain protection through mimicry a. Once warning coloration evolved, other harmless organisms could gain selective advantage by resembling a poisonous species b. This is called mimicry, when a species evolves to resemble something else, usually another animal c. In Mullerian mimicry, two or more distasteful species may each benefit from a shared warning coloration pattern, as predators need only experience one to learn to avoid all i.Monarch and viceroy butterflies share orange and black pattern (Figure 27-9) .

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Instructor Guide Biology: Life on Earth d. In Batesian mimicry, the harmless hoverfly resembles bees (Figure 27-10a) i.Mountain king snakes resemble venomous coral snakes (Figure 27-10b) e. Some animals deter predators by employing startle coloration such as spots that resemble eyes of a large predator (Figure 27-11) f. Snowberry flies avoid predation by jumping spiders by mimicking these predators both visually and behaviorally (Figure 27-12) g. In aggressive mimicry, a predator resembles a harmless animal or part of the environment to lure prey (e.g., frogfish dangles wriggling lure that attracts curious fish that is then eaten) (Figure 27-6b) â Lecture Activity 27.3: Why Is the Earth (Still) Green?

27.4 What Are Parasitism and Mutualism?

A. Parasitism Harms, But Does Not Immediately Kill, the Host 1. Familiar parasites include tapeworms, fleas, and disease-causing protozoa, bacteria, and viruses, many of which have complex life cycles â Science in Action: A Parasite Makes Ants Berry Appealing to Birds (Figure E27-2) B. Parasites and Their Hosts Act as Agents of Natural Selection on One Another 1. Coevolution of parasites and hosts is intense a. Immune systems of hosts have evolved to detect and destroy invading parasites b. Parasites have evolved means to avoid detection c. For example, the malaria parasite has provided a strong selective pressure for humans to carry the defective hemoglobin gene that causes sickle-cell anemia but provides protection against malaria infection C. Both Species Benefit from Mutualistic Interactions 1. Many mutualistic relationships are symbiotic a. Lichens, which are entities formed by fungi and algae living together—the algae provide the food by photosynthesis and the fungi provide protection (Figure 27-13a) b. Clownfish and sea anemones: the fish obtain protection and the anemones obtain protection, cleaning, and scraps of food (Figure 27-13b) c. Flowering plants and their pollinators in which the plants obtain gene transfer in exchange for food

27.5 How Do Keystone Species Influence Community Structure?

A. Keystone Species Play Major Roles in Determining Community Structure That Are Much Greater Than Their Abundance Alone Would Predict â Lecture Activity 27.4: Demonstrating the Importance of a Keystone 1. By grazing on shrubs and trees, the large but scarce African elephants help maintain the grass savanna, which supports many species (Figure 27-14a) 2. Large predators have a surprising impact on terrestrial ecosystems (Figure 27-14b) 3. When sea otters declined on the coast of western Alaska, their sea urchin prey exploded in numbers and their overgrazing decimated the kelp forests, which provided food and shelter for many species (Figure 27-14c) â Case Study Continued: Mussels Muscle In

27.6 How Do Community Interactions Cause Change over Time?

A. Succession Is a Gradual Change in a Community and Its Nonliving Environment over Time 1. The sequence of events is reasonably predictable a. Early organisms modify the environment in ways that favor later organisms b. End-stage organisms produce a stable community c. There is a general trend toward more species and longer-lived species 2. Succession is usually preceded by a disturbance, an event that disrupts the ecosystem either by altering the community, its abiotic structure, or both a. Succession begins with arrival of a few hardy invaders called pioneers i.These may alter the ecosystem in ways that favor other species, which gradually displace them ii. Succession often progresses to a relatively stable and diverse climax community iii. However, recurring disturbances can set back the progress of succession, maintaining communities in subclimax stages B. There Are Two Major Forms of Succession: Primary and Secondary .

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1. Primary succession occurs where there is no trace of a previous community (e.g., on bare rock [Figure 27-15a]) 2. Secondary succession occurs after a disturbance changes but does not destroy an existing community (e.g., leaving behind soil and seeds, often taking just hundreds of years [Figure 27-15b, c]) 3. Primary succession may begin on bare rock a. An example of primary succession is that seen on Isle Royale, Michigan (Figure 27-16) i.Bare rock is colonized by lichens, which scavenge nutrients and start soil formation by dissolving some of the rock ii.This creates conditions ideal for drought-resistant mosses, which generate a moisture-retaining and nutrient-rich mat that allows bluebell and yarrow to move in, and so forth iii. After thousands of years, the tall climax forest tree species outcompete subclimax shrubs and smaller trees for light 4. An abandoned farm will undergo secondary succession a. Secondary succession is illustrated on an abandoned farm in the southeastern United States (Figure 27-17) i. Pioneer annual weeds such as crabgrass, ragweed, and Johnson grass rapidly establish themselves, but are soon displaced by perennial species that shade them out ii. In turn, these give way to fast-growing deciduous trees, and finally the climax community of shade-tolerant, slow-growing hardwoods like oak and hickory b. Because the soil and seeds are already present at the start, this whole process takes just a couple hundred years 5. Succession also occurs in ponds and lakes a. Processes inside the body of water and the influx of nutrients and sediments from the runoff it drains can cause a succession from open water to bog to meadow to forest (Figure 27-18) C. Succession Culminates in a Climax Community 1. Unless disturbances intervene, succession usually ends with a relatively stable climax community 2. Species in climax communities have narrower niches than pioneer species, which allows many species to coexist in diverse climax stands without replacing one another 3. Also, climax species tend to be larger and longer-lived than pioneer species 4. The exact nature of the climax community at a site reflects local geological and climatic conditions (e.g., type of bedrock, temperature, and rainfall)—a biome is a class of climax community that exists over a broad geographical range, such as a desert, grassland, or deciduous forest D. Some Ecosystems Are Maintained in Subclimax Stages 1. Frequent disturbances maintain subclimax communities in some ecosystems 2. Examples of this include: a. The tallgrass prairie that once covered northern Missouri and Illinois, as periodic fires, caused by lightning or deliberately set by Native Americans to increase grazing land for buffalo, prevented forest from encroaching b. Agriculture, where plowing and herbicides keep competing weeds and shrubs from taking over

Case Study Revisited: Mussels Muscle In

KEY TERMS aggressive mimicry biome camouflage climax community coevolution community competition competitive exclusion principle ecological niche herbivore

host interspecific competition intraspecific competition invasive species keystone species mimicry mutualism parasite pioneer predator

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primary succession resource partitioning secondary succession startle coloration subclimax succession warning coloration

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LECTURE ACTIVITIES Lecture Activity 27.1: Invasive Species—A Web Investigation Estimated Time to Complete: 20 minutes Section References 27.1 Why Are Community Interactions Important?

27.2 How Does the Ecological Niche Influence Competition?

Introduction Ecologists and the general public have only recently begun to appreciate the devastating effects that invasive, exotic, or introduced species can have on communities and ecosystems. By whichever name you choose to call them, these species can explode in numbers in their new homes. This appears to be due to the fact that these new frontiers often lack the species’ natural enemies (predators, competitors, and parasites) that keep them in check “back home.” In this activity, the students will use the Internet to gather information on an exotic species of their choosing.

Materials Needed • Access to browser-equipped computers linked to the Internet • This activity works best in a computer laboratory or classroom where the instructor can demonstrate the steps involved on a screen using a projector. However, in small classes students can simply gather around a single monitor or TV hooked up to a computer.

Procedures Begin by introducing the ever-increasing impacts of exotic species on communities and ecosystems in the modern world.

Point out that the explosion in transportation has not only allowed us to move ourselves and our goods around the world more quickly, but has also provided a vector for moving other species around as well, often unintentionally.

Pick one species that is locally or regionally significant to illustrate the severity of the situation, pointing out where it came from, how and when it got “here,” how rapidly it has increased in numbers and spread, and so forth. You can pre-research the following questions and quiz the students first before giving them the answers to see just how much they already know.

Explain to them that one of the important aspects of a good education is learning how to find things out for themselves.

Stress that one of the greatest storehouses of information available to them is the Internet, and one of the most powerful tools for finding just the right information is a search engine.

Have the students work in groups of two or more. The exact size of groups may depend on the number of computers available.

Each group will research one species. The students may choose their own species, but try to avoid duplication between groups. Direct the students to a search engine. Briefly describe how search terms are entered and some of the strategies for getting only the “hits” you want (e.g., narrowing the search using Boolean logic).

Have them research all or some of the following questions for their species, compiling the results for presentation to the whole class: What are the common and scientific (genus and species) names of your organism?

What is its historical range; that is, where did it come from and evolve?

What new areas has it recently invaded?

How did it get from “there” to “here,” and what barrier(s) prevented it from making the trip earlier?

What damage has been documented that is reasonably attributable to this species?

Have any control measures been proposed or tried to reduce its numbers or effects? If so, what are they?

Have they been, or do you expect them to be, successful?

Have the groups hand in their findings or post them on the board or class Web site.

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Assessment Suggestions After the results are disseminated, ask the students if they see any trends in the data. Are there any characteristics that are shared by all or most invasive species?

Have the students discuss the likelihood that a single introduction will be successful in establishing the species in its new home. Although we always hear about the “success stories” (or perhaps “horror stories” is more appropriate), how many unsuccessful introductions do they think go completely unnoticed?

A question or two on a short quiz at the end of the activity, the answer based on each own group’s species, will ensure an honest effort from most students.

Handouts or Display There are no special handouts or displays needed for this activity, but a list of the questions to be answered could be compiled, copied, and distributed.

Lecture Activity 27.2: The Niche—Hutchinson’s “N-Dimensional Hypervolume” Estimated Time to Complete: 10 minutes Section Reference 27.2 How Does the Ecological Niche Influence Competition?

Introduction Unlike habitat, which is the physical location or “address” of a species in the environment, the niche of a species is an abstract concept. As a result, many beginning students have a tough time getting a handle on exactly what a niche is. To help them visualize the niche concept, we will explore a time-tested model from the annals of community ecology—G. E. Hutchinson’s “N-Dimensional Hypervolume.”

Materials Needed • The handout (or display) figures at the end of this activity Procedures You can begin by asking the students what “ecological niche” means to them. You might remind them that a (nonecological) niche is a cubbyhole, a space carved out of a wall specifically to hold a given object, such as a religious statue. The analogy draws attention to the fact that the ecological niche is the “place” of that species in the community or ecosystem. But it is far more than its physical location, more aptly called its habitat. It also includes all of the parameters—conditions, resources, competitors, and so on—that influence that species.

We can portray this graphically in a series of drawings. Figure 1 shows the niche of a species with respect to a single parameter, such as temperature, light intensity, nitrogen levels, and so forth. Most species tolerate only a limited range of a given environmental factor (shown by the thicker bar along the axis in Figure 1). This is the species’ niche with respect to that parameter.

We can add a second factor by adding a second axis to our drawing (see Figure 2). If the first factor was, say, temperature, the second might be oxygen concentration—a fish might serve as an example. Now, rather than being a one-dimensional distance, the niche is a two-dimensional area, shaded in the figure.

Likewise, we can add a third factor by adding a third dimension (see Figure 3), giving us a niche that is a three-dimensional volume. In our fish example, perhaps the third factor is the range of sizes of insect larvae the fish eats.

Hutchinson then asked us to make a logical jump to a fourth, fifth, and so forth, dimension, adding additional environmental parameters. Because the most we can visualize is a three-dimensional volume, Hutchinson referred to this niche concept as an N-dimensional hypervolume, where N is the number of environmental factors involved (which is virtually limitless) and the organism resides within the limits of the hypervolume created.

This model also helps us visualize the contraction of the niche of a species that can result from the presence of a competitor, as seen by Joseph Connell’s classic experiments with barnacles on the Scottish intertidal coast, described in the textbook.

Figure 4 shows the niches (three-dimensional volumes), as they would exist if no competitors were present, of two species overlapping (transparent volumes with dashed borders). Note the area of overlap. We call these niches the fundamental niches of each species, because they are elemental characteristics of each species.

However, when the two are together, they might compete for the shared resources (in the volume of overlap); in .

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this case, species 2 is the better competitor for this space, as it “moves” species 1 out. Species 1 now occupies a more constrained niche, called its realized niche, as this is all it could occupy under the circumstances. This is essentially what Connell saw in the barnacles on the Scottish coast—the area of overlap was the upper reaches of the intertidal zone, but Balanus was a better competitor for space there, so it displaced Chthamalus from those areas when both species were present.

Assessment Suggestions To determine if this concept has sunken in, quiz the students on the dimensions of the human niche.

Ask them what the effects of human technology have been on the size of our “hypervolume.” For example, have clothing, central heating, and air conditioning expanded our temperature axis?

Ask them to consider and discuss the effects of this on the carrying capacity of the Earth for humans.

Handouts or Display The following pages can serve as a handout or be projected for display during presentation of this activity.

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Lecture Activity 27.3: Why Is the Earth (Still) Green?

Estimated Time to Complete: 20 minutes Section References 26.2 How Is Population Growth Regulated?

Chapter 26 Scientific Inquiry: Cycles in Predator and Prey 27.3 How Do Predator–Prey Interactions Shape Evolutionary Adaptations?

Introduction Despite the fact that a vast array of animals feed on plants, these herbivores are unable to significantly suppress plant growth in most ecosystems. As a result, the Earth remains green. This activity invites the students to explore what keeps herbivores from driving to extinction the plants on which they feed.

Materials Needed • Photographs of various herbivores (see Procedures section) would be helpful, but are not necessary. These may be shown on an overhead or computer screen, or blowups held before a small class.

Procedures A dramatic way to begin this activity is to show (or, at least, describe) the vast array of animals that feed on plants. Pictures can be shown of ruminant mammals (cows, sheep, giraffe, etc.), phytophagous insects (caterpillars, grasshoppers, etc.), gorillas, beaver, slugs, rabbits, koalas, kangaroos, elephants, pandas, tortoises, and so on. You can point out that a great many species of animals have evolved to eat plants and, in fact, most animals (based on either numbers or biomass) do just that!

You can then broach the question, “With all these hungry herbivores about, why is the Earth (still) green?” In other words, why haven’t the animals eaten all of the plants?

You can open this up for answers, comments, and discussion at this point. From here on I will simply describe some of the “answers” that ecologists have put forth. Your students might find others!

One way to explain the green Earth is to note that predators keep the abundance of herbivores low in many ecosystems much of the time. Predation can thus prevent the herbivores from reaching large enough numbers to eat enough plant matter to have a serious impact on the primary producers. Ecologists call this “top-down regulation” (i.e., from a “higher” trophic level) of herbivore abundance. (This is opposed to “bottom-up regulation,” where competition for resources—from a lower trophic level—controls abundance.)

You can ask the students if they know of any evidence that would tend to support or refute this hypothesis.

I can think of two ideas—both of which support it—offhand: (1) elimination of wolves and other predators on deer have caused deer numbers to explode, causing serious overgrazing in many areas; and (2) introduction of rabbits to Australia, where they had no natural predators, led to decimation of native plants and concomitant desertification, soil erosion, and other effects.

Another explanation for why the Earth is (still) green takes note of the fact that many plants have evolved chemical and physical defenses that help protect them against herbivores. These include chemicals that make herbivores sick or disoriented, and thorns and hairs that prevent them from getting a good bite.

Again, you can ask the students if they can think of any examples that bear on this hypothesis. I can think of one: selective breeding to eliminate bitter or “off” flavors in crop plants has reduced the quantities of the defensive chemicals that both protect the plants and produce these flavors. This is one of the reasons why crop plants often suffer much greater insect damage than their “wild” ancestors. (Other reasons include growth in monocultures, reduced genetic diversity, etc.).

A third possible answer to why the Earth is (still) green brings into play temporal variation and predator–prey cycles. Periodic fluctuations in the amounts of plant matter available to herbivores (e.g., when deciduous trees shed their leaves in the winter or dry season) significantly reduce the food available to herbivores. This can cause herbivore numbers to crash. As a result, herbivores cannot become abundant enough to do any serious damage to the plants.

This seems intuitive, but there is a problem with this hypothesis. Tropical rain forests have the greatest plant standing crops of any terrestrial biomes, but they are also the least variable! Although many trees periodically lose their leaves, this loss is staggered, and (apparent) food for herbivores is always plentiful. As a result, this may be a factor but it cannot (alone) answer the question of why the Earth is (still) green.

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Assessment Suggestions As this activity is set up as a discussion, the students’ responses (both listing answers and providing evidence) should allow you to assess their understanding.

You can also ask them (individually or in groups) to design experiments to test each of these hypotheses.

Testing the first would involve manipulating predatory abundance. Testing the second could involve manipulating levels of toxic chemicals (note: plants previously subjected to herbivory produce more defensive chemicals than those not so treated), manually removing spines, and so forth.

Short-answer questions could also be asked during a quiz immediately following the activity or on a subsequent test.

Handouts or Display No special handouts are necessary. See the Materials Needed section for a note on displays.

Lecture Activity 27.4: Demonstrating the Importance of a Keystone Estimated Time to Complete: 10 minutes Section Reference 27.5 How Do Keystone Species Influence Community Structure?

Introduction One of the most significant new concepts in community ecology over the last few decades is that of the keystone species. Its inventor, Robert T. Paine, coined the metaphorical name to aptly describe the crucial role of these organisms. Unfortunately, many students (both majors and nonmajors) have no idea what a keystone is, so the phrase “keystone species” has little resonance with them. In this activity the role of a keystone is demonstrated to the students, and the analogy is explicitly stated and developed.

Materials Needed • A model of an arch containing a keystone made out of “blocks” of balsa wood, Styrofoam, or other easily cut material.

The diagram (Figure 1) can serve as a guide. Thin sheets of Styrofoam insulation can be used and easily cut with a sharp razor blade or craft (X-Acto®) knife.

Procedures Start by explaining the keystone species concept. Briefly, some species perform crucial roles that help maintain the structure or function of the entire community. This effect is far greater than would be predicted by their abundance (or biomass) alone.

If such a species is lost, the community changes dramatically, often losing many other species as a consequence.

Now for the keystone. Explain the importance of arches in early stone or brick construction. Arches permit openings to be made in walls (such as doors and windows) without allowing the wall above the opening to collapse. Likewise, arches support canals (aqueducts) and roads (bridges; viaducts) over rivers or similar obstructions. The arch carries the weight above it laterally.

The weight on the tapered stones of the arch holds them close together, but until the keystone is in place, the whole arch must be supported by scaffolding or other means.

The effects of removing the keystone are easily demonstrated. The arch collapses, with most if not all of the other stones (representing other species in the community) tumbling down in the process (i.e., going extinct). The arch itself clearly ceases to function, analogous to the failure of ecosystem functions (energy transfer, nutrient recycling, etc.) following the loss of keystone species.

Another concept from community ecology, that of redundancy of species, can also be demonstrated using this model. Simply put, this concept states that many roles in the community can be filled by more than one species. If the primary species performing this function is lost, another can step in to take its place. In our arch model, this can be visualized by splitting one of the blocks in the arch—even one in the position of the keystone—into three slices (see Figure 2). Then, removing one of these slices—especially the middle one—will not cause the arch to collapse. Clearly, none of the three species (slices) can now be called a keystone species, due to this redundancy. .

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Assessment Suggestions Ask the students to discuss the usefulness and limitations of this model. Does it help drive home the importance of keystone species? Would another analogy be more appropriate?

Ask the students to outline an experiment to determine if a species is truly a keystone species. What would be an appropriate “control” for such an experiment? How easy would such an experiment be to perform?

Handouts or Display There are no special handouts needed for this activity. The arch model described earlier and shown on the next page can be used to illustrate the concepts discussed.

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CHAPTER 28 ENERGY FLOW AND NUTRIENT CYCLING IN ECOSYSTEMS? LECTURE OUTLINE Case Study: Dying Fish Feed an Ecosystem 28.1 How Do Nutrients and Energy Move Through Ecosystems?

A. Two Basic Principles Underlie Ecosystem Function (Figure 28-1) 1. Nutrients constantly cycle and recycle within and among ecosystems 2. Energy moves in a one-way flow through communities within ecosystems 3. Nutrients are atoms and molecules that organisms obtain from their environment and are required for survival a. Nutrients change in form and distribution, even moving between ecosystems, but remain on Earth 4. The energy to drive life’s activities comes from the sun a. This energy is used and transformed in the chemical reactions that power life b. It is ultimately converted to heat that radiates back into space â Lecture Activity 28.1: Ecosystem Complexity: Lessons from Biosphere 2

28.2 How Does Energy Flow Through Ecosystems?

A. Electromagnetic Waves, Including Heat, Light, and Ultraviolet, Carry Energy from Nuclear Reactions on the Sun to the Earth 1. Most of solar energy reaching Earth is reflected or absorbed 2. Less than 0.03% of energy that reaches Earth is available for photosynthesis B. Energy Enters Ecosystems Through Photosynthesis 1. Photosynthetic organisms capture the energy of sunlight to produce biological molecules a. Solar energy is used in reactions that store energy in chemical bonds of these molecules C. Energy Is Passed from One Trophic Level to the Next 1. Energy flows through ecosystems from photosynthetic organisms through several layers of non-photosynthetic organisms a. Each category is called a “trophic level” b. Autotrophs (“self-feeders”) or producers make their own food using nonliving nutrients and energy they obtain from their environment i. Most autotrophs are photosynthetic organisms, from oak trees to single-celled diatoms, obtaining their energy from sunlight c. Organisms that cannot synthesize their own food obtain it directly or indirectly from producers and are called heterotrophs (“other-feeders”) or consumers; they acquire their energy and many of their nutrients prepackaged in the molecules that compose the bodies of other organisms d. Consumers occupy several trophic levels i. Consumers that feed directly on producers are called herbivores (“plant eaters”) or primary consumers ii. Consumers that feed on primary consumers are called carnivores (“meat eaters”) or secondary consumers iii. Some carnivores occasionally eat other carnivores, acting as tertiary consumers

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Instructor Guide Biology: Life on Earth D. Net Primary Production Is a Measure of the Energy Stored in Producers 1. This determines how much life a particular ecosystem can support a. Biomass is a good measure of the energy stored in organisms’ bodies (Figure 28-2) b. The net primary production of an ecosystem is influenced by the availability of nutrients, sunlight, and water to producers, and by factors like temperature i. In the open ocean, nutrients are limiting at the surface and light is limiting at depth ii. Tropical rain forests have abundant resources and high productivity â Lecture Activity 28.2: The “Limiting Nutrient” Concept E. Food Chains and Food Webs Describe Feeding Relationships Within Communities 1. A food chain is a linear feeding relationship with just one representative identified at each trophic level (Figure 28-3) a. Different ecosystems have radically different food chains i. Plants are the dominant producers in terrestrial ecosystems (Figure 28-3a) ii. Phytoplankton are the dominant producers in aquatic ecosystems (Figure 28-3b) b. However, natural communities rarely contain well-defined groups of primary, secondary, and tertiary consumers i. A food web shows the actual feeding relationships in a community, including its many interconnecting food chains (Figure 28-4) ii. Some animals (like humans) are omnivores (“eating all”), acting as primary, secondary, and occasionally tertiary consumers at different times 2. Detritivores and Decomposers Release Nutrients for Reuse a. Detritus feeders live on dead organic matter, including the bodies of other organisms, fallen leaves, and wastes (detritus means “debris”) b. Detritus feeders form a complex network including earthworms, millipedes, vultures, and various other organisms c. Decomposers are primarily fungi and bacteria i. They secrete enzymes outside their body that break down nearby organic material ii. They absorb the nutrients they need; the rest are made available for other organisms 3. Detritus feeders and decomposers release most of the stored energy in dead organic matter a. They also convert most of the chemicals in the bodies of dead organisms into simple molecules (e.g., carbon dioxide, water, and minerals) i. As a result, they recycle nutrients, making them available again for primary producers ii. If they are absent, nutrients would be unavailable to other organisms, with organisms at higher levels dying off F. Energy Transfer Between Trophic Levels Is Inefficient 1. Only a small percentage of the energy available at one trophic level is transferred to the next higher trophic level because: a. Conversion of energy from one form to another always involves losses as low-level heat (second law of thermodynamics; Chapter 6) b. Some energy is used by each trophic level for maintenance, repair, movement, etc. c. Some of the molecules in organismscannot be digested or absorbed 2. Energy pyramids illustrate energy relationships between trophic levels a. The net energy transfer between trophic levels is roughly 10% efficient, called the “10% law” i. We can represent this graphically as an energy pyramid, with primary producers on the bottom and higher trophic levels stacked on top (Figure 28-5) ii. Sometimes biomass is used as a measure of the energy stored at each trophic level, and a similar biomass pyramid can be constructed b. This pattern of energy transfer has some important ramifications i. Plants dominate most communities because they have the most energy available to them, followed by herbivores and carnivores ii. Also, since organisms consume a large biomass of organisms in the trophic level below them, they can amplify some persistent toxic chemicals move up the food chain, a process called biological magnification â Lecture Activity 28.3: Decomposers and Detritus Feeders â Health Watch: Biological Magnification of Toxic Substances (Figure E28-1) â Case Study Continued: Dying Fish Feed an Ecosystem

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28.3 How Do Nutrients Cycle Within and Among Ecosystems?

A. Nutrients Are Elements and Small Molecules That Form All the Chemical Building Blocks of Life 1. Macronutrients are required by organisms in large quantities (e.g., water, carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, and calcium) 2. Micronutrients are required only in trace quantities (e.g., zinc, molybdenum, iron, selenium, and iodine) 3. Nutrient cycles, also called biogeochemical cycles, describe the pathways these substances follow back and forth between communities and the nonliving portions of ecosystems 4. Reservoirs are sources and storage sites of nutrients a. Major reservoirs are usually in the nonliving (abiotic) environment B. The Hydrologic Cycle Has Its Major Reservoir in the Oceans 1. The hydrologic cycle describes the pathway that water takes as it travels from its major reservoir, the oceans, through the atmosphere to reservoirs in freshwater lakes, rivers, and groundwater, and then back to the oceans (Figure 28-6) a. The biotic portion of an ecosystem plays only a small role 2. Solar energy evaporates water, which condensed in the atmosphere and falls back to Earth as precipitation 3. The major reservoir of water is the ocean, containing more than 97% of Earth’s water, another 2% is trapped in ice, and only 1% is available to the biosphere 4. Most water evaporates from the surface of the ocean, returning as precipitation falling onto its surface 5. Water falling on land takes various paths a. Some evaporates from the soil, lakes, and streams b. Some runs off the land back to the ocean c. A small amount enters underground reservoirs called aquifers 6. Plants absorb water through their roots, absorbing nutrients with it C. The Carbon Cycle Has Major Reservoirs in the Atmosphere and Oceans 1. The carbon cycle describes the movement of carbon through an ecosystem (Figure 28-8) a. The biotic portion of an ecosystem plays a major role 2. Carbon enters communities through capture of CO2 during photosynthesis a. Producers on land get their CO2 from the atmosphere, which is 0.039% of all the gases present b. Aquatic producers get their CO2 from what is dissolved in the water 3. Primary consumers eat the producers and acquire the carbon stored in their tissues a. These herbivores release some of the carbon through respiration as CO 2 b. They store the rest, which may be consumed by higher trophic levels c. If not eaten, when organisms die their bodies are broken down by detritivores and decomposers d. Cellular respiration by all of these organisms releases CO2 into the atmosphere and oceans; CO2 passes freely between these two great reservoirs e. The complementary processes of cellular respiration and photosynthesis cycle carbon through an ecosystem 4. Phytoplankton extract CO2 from the water and combine it with calcium to form calcium carbonate for their shells a. After death, their shells may be buried and form limestone b. If geological events expose this limestone, it may be dissolved, making the carbon available again for living organisms 5. Fossil fuels (coal, oil, and natural gas) are formed when the remains of prehistoric organisms were buried and subjected to high temperatures and pressures for millions of years a. Burning these fossil fuels releases the stored energy in these hydrocarbons b. Burning also releases their carbon into the atmosphere as CO2 D. The Nitrogen Cycle Has Its Major Reservoir in the Atmosphere 1. Nitrogen is a crucial component of proteins, many vitamins, DNA, and RNA 2. The nitrogen cycle describes the movement of nitrogen through an ecosystem (Figure 28-8) 3. Although nitrogen gas (N2) makes up 78% of the atmosphere, which is its major reservoir, this form of nitrogen cannot be utilized by plants a. N2 is converted to ammonia by certain bacteria in a process called nitrogen fixation i. Some of these bacteria live in water and soil ii. Others live in symbiotic associations with plants called legumes, including alfalfa, soybeans, clover, and peas 4. Decomposers produce ammonia from the dead bodies and wastes they consume .

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Instructor Guide Biology: Life on Earth â Lecture Activity 28.4: Tight Nutrient Cycling in Corals a. As it passes through the food web, some of the nitrogen is released in wastes and dead bodies b. Denitrifying bacteria in wet soils, swamps, and estuaries complete the nitrogen cycle by breaking down nitrate, releasing N2 back to the atmosphere 5. Application of chemical fertilizers, produced using energy from fossil fuels to artificially “fix” atmospheric N2, may change the composition of plant communities a. Burning of forests and fossil fuels releases nitrogen and can cause environmental concerns E. The Phosphorus Cycle Has Its Major Reservoir in Rock 1. The phosphorus cycle describes the process by which phosphorus moves through an ecosystem (Figure 28-9) 2. The phosphorus cycle lacks an atmospheric component; its major reservoir is in rock combined to oxygen as phosphate a. Phosphate in exposed rock can be dissolved by rain and flowing water b. It is readily absorbed by consumers, where it is incorporated into biological molecules c. These phosphorus-containing molecules can pass through food webs d. At each level, excess phosphorus is excreted, and decomposers release the phosphorus in dead bodies back to the soil and water as phosphate e. This phosphate may be reabsorbed by autotrophs or reincorporated into rock 3. At one time, guano (droppings) from seabirds was collected and used as a phosphate-rich fertilizer a. This has now largely been replaced by the mining of phosphate-rich rock

28.4 What Happens When Humans Disrupt Nutrient Cycles?

A. Many of Our Present Environmental Problems Are Due to Human Interference with Ecosystem Function 1. Since the Industrial Revolution, we have relied heavily on fossil fuels for heat, light, transportation, industry, and agriculture a. Human activity is disrupting global nutrient cycles B. Overloading the Nitrogen and Phosphorus Cycles Damages Aquatic Ecosystems 1. The use of chemical fertilizers increases the amount of phosphates and nitrogen in soils a. When water deposits into the soil, it washes these chemicals into bodies of water i. This can cause overgrowth of phytoplankton, called “blooms,” that use up available oxygen in the water and can kill off other aquatic life (Figure 28-10) C. Overloading the Sulfur and Nitrogen Cycles Causes Acid Deposition 1. Burning of fossil fuels combines atmospheric nitrogen with oxygen, producing nitrogen oxides a. Sulfur dioxide is also produced from this burning 2. Excess production of sulfur dioxide and nitrogen dioxides, when combined with water vapor in the atmosphere, are converted to nitric acid and sulfuric acid, respectively a. This was identified in the 1960s as the cause of acid rain, or acid deposition 3. When the acids fall, they eat away at statues and buildings, damage trees and crops, and alter lake communities (Figure 28-11) 4. Acid deposition damages life in lakes and forests a. Many lakes and ponds in the Adirondack Mountains are too acidic to support fish b. On land, acid rain leaches away essential plant nutrients and kills decomposing bacteria, causing the death of many plants i. Plants become weak and more vulnerable to infection (Figure 28-12) c. Since 1990, government regulations have resulted in substantial reductions in emissions of both sulfur dioxides and nitrogen dioxides from power plants in the United States, but nitrogen emissions remain high as more gasoline is being burned by automobiles d. Damaged ecosystems recover slowly D. Interfering with the Carbon Cycle Is Changing Earth’s Climate 1. Carbon dioxide and other greenhouse gases trap heat in the atmosphere (Figure 28-13) a. Some of the energy from sunlight that reaches the Earth is reflected back into space, but much of it reaches the Earth and is converted to heat b. Atmospheric CO2 and other greenhouse gases trap some of the energy once it has been converted to heat

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c. These gases contribute to the greenhouse effect, which is the ability of greenhouse gases to trap the sun’s energy in a planet’s atmosphere d. Although the greenhouse effect is a natural process that allows life on Earth as we know it, elevated levels of greenhouse gases have resulted from human activity 2. Burning Fossil Fuels Is Causing Climate Change a. Since the mid-1800s, burning of the fossil fuels released CO2 into the air b. Of the increase in CO2 in the atmosphere, 80–85% is attributable to burning fossil fuels c. Deforestation accounts for 15–20% of the added CO2 d. Since 1850, the amount of CO2 in the atmosphere has increased by almost 40% (Figure 28-14a) e. Global temperature increases have paralleled increases in atmospheric carbon dioxide (Figure 28-14b) f. The overall impact of greenhouse gases is climate change, which includes global warming and other effects on Earth’s climate and ecosystems i. Glaciers and ice sheets have been melting at unprecedented rates (Figure 28-15) g. Predictions indicate significant increases in global temperatures (Figure 28-16) 3. Continued Climate Change Will Disrupt Ecosystems and Endanger Many Species a. More increases in global temperature are predicted and may already be occurring b. Community interactions may be disrupted i. Biologists worldwide are documenting changes in plant and animal wildlife related to climate change ii. Polar organisms will have nowhere to go iii. Tropical diseases such as malaria may increase their range â Earth Watch: Geoengineering—A Solution to Climate Change? (Figure E28-2)

Case Study Revisited: Dying Fish Feed an Ecosystem

KEY TERMS abiotic acid deposition aquifer autotroph biological magnification biomass biotic carbon cycle carnivore climate change consumer decomposer deforestation denitrifying bacteria detritivore

ecosystem energy pyramid food chain food web fossil fuel greenhouse effect greenhouse gas herbivore heterotroph hydrologic cycle macronutrient micronutrient net primary productivity nitrogen cycle

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nitrogen fixation nutrient nutrient cycle omnivore phosphorus cycle phytoplankton primary consumer producer reservoir secondary consumer tertiary consumer trophic level zooplankton

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LECTURE ACTIVITIES Lecture Activity 28.1: Ecosystem Complexity: Lessons from Biosphere 2 Estimated Time to Complete: 15–20 minutes Section References 28.1 How Do Energy and Nutrients Move Through Ecosystems?

28.2 How Does Energy Flow Through Ecosystems?

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Introduction Most of the central concepts in this chapter of the textbook can be introduced using the story of the first “mission” of humans inside Biosphere 2. The four men and four women locked inside the massive greenhouse in the Arizona desert in 1991 were to have all of their needs for the next 2 years met by the myriad other organisms sealed inside with them. In fact, no materials were to enter or leave, and the only energy fluxes would be sunlight in and heat out, just like the Earth (“Biosphere 1”) itself. But things went very wrong very fast, demonstrating just how complex and delicately balanced ecological systems are, and just how much we have left to learn about them.

Materials Needed • Photos of the Biosphere 2 structure and its five synthetic biomes and agricultural plot can be obtained by performing an Internet search using “Biosphere 2” as key words.

• Some means of displaying these photos, such as inserting them electronically onto PowerPoint slides or copying them onto overhead transparencies Procedures You can begin this activity by pointing out that Biosphere 2 was envisioned as a smaller model of “Biosphere 1,” the Earth, built to test hypotheses about the ecological functioning of the latter. Like the Earth, Biosphere 2 is a sealed system with respect to materials, as none either enter or leave—they are simply recycled among the organisms and abiotic components inside. In fact, Biosphere 2 has been called the most tightly sealed structure ever built, 30 times tighter than even a space shuttle! Also like the Earth, energy moves through Biosphere 2 in a one-way flow. It enters as concentrated and useful sunlight, some of which is trapped by photosynthesis and enters the food web, being passed inefficiently from organism to organism, but all of the energy ultimately leaves as waste heat, radiating out into space. It was hoped that this project would also provide a foundation for similar facilities on the moon and other planets or onboard long interplanetary space flights.

Built in the late 1980s at a cost of ~$200 million, the structure covers 3.1 acres and has a volume of 7.2 million cubic feet.

Biosphere 2’s first “mission” began on September 26, 1991, when its crew of four men and four women were sealed inside for a 2-year voyage of discovery. Along with them were ~3,500 species of plants and animals, collected from around the world and organized into five synthetic “biomes” housed in linked domes. These included a tropical rain forest, a coral reef, a mangrove swamp, a grassy savanna, and a fog desert. Also included was an agricultural facility in which the “biospherians” were to grow their own food. This featured a vegetable garden, orchard, rice paddy, and chickens and goats.

Decomposers in the soil and water would recycle the humans’ wastes, and the resulting nutrients would nourish the plants.

The plants would also take up the respired carbon dioxide from all of the animals, decomposers, and plants as they carried on photosynthesis. The food produced by the plants would nourish the humans and other animals.

The plants would also provide oxygen for aerobic respiration. The plan was to balance these components so that initial conditions would be maintained throughout the “experiment.”

However, soon after the system was sealed, things started to go wrong. Carbon dioxide began to build up almost immediately, reaching three to seven times normal values and fluctuating diurnally and seasonally.

Artificial carbon dioxide scrubbers had to be turned on. Over the first year and a half, oxygen levels dropped from 21% to just 14%, at which point oxygen was added to prevent the crew from suffering “high-altitude sickness.”

A large number of the plant and animal species went extinct over the 2-year period as well, including 19 of the 25 species of vertebrates and all of the insect pollinators. The latter fact required the humans to .

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hand-pollinate their crops. Also, a number of species exploded in numbers, including cockroaches, katydids, and crazy ants. Fast-growing vines, introduced after the start of the experiment to act as a sink for carbon dioxide, grew uncontrollably, overrunning the crops and requiring weeding by hand. Excessive nutrient runoff into the aquatic systems caused algal blooms that had to be controlled by harvesting mats of algae. In short, there was little “balance” either in the community or in the abiotic environment.

Food production was also less than expected, causing all of the biospherians to lose considerable weight during the mission.

The Biosphere 2 mission clearly failed in its stated goal of maintaining resilient, persistent, complex, and evolving ecosystems.

Loss of biodiversity is also a major problem in “Biosphere 1.”

After the mission ended, many speculated on the cause(s) of the oxygen and carbon dioxide changes. It was mentioned that the unusually rich soil used in the agricultural area might have been responsible, as microbial decomposers broke down the organic material under these hot and moist conditions, consuming oxygen and producing carbon dioxide in the process.

But it was estimated that the amount of decomposition needed to consume that much oxygen would have produced even more carbon dioxide than was measured. It was later discovered that much of the “missing” had combined chemically with a chemical in the concrete structure of the facility to become the mineral calcium carbonate.

In many ways, the first mission of Biosphere 2 was a failure. However, it did serve as a warning of just how much we don’t know about the functioning of Earth’s ecological systems, and just how much our meddling can alter the system. Whereas the inhabitants of Biosphere 2 could receive help from outside and leave if things got too bad, we on Biosphere 1 don’t have that option.

Assessment Suggestions 1. Ask the students to discuss how loss of species can affect system stability. Consider redundancy of species (several performing the same task) and Paul Ehrlich’s “rivet hypothesis.”

(In diverse ecosystems, several species can perform a given task; if one is lost, another can take over with little effect. However, if a crucial species is lost, such as the last or only one performing a specific function, the system may collapse, like an airplane losing a crucial rivet.)

2. Global warming is melting what was previously permafrost in large areas of the Arctic. These soils are often rich in organic matter (peat), which is decomposed by microbes after it melts, much like what happened in Biosphere 2. Ask the students to discuss how this could create a self-perpetuating positive feedback that could, due to the greenhouse effect, be catastrophic for life on Earth.

(Warming causes some permafrost to melt, raising CO 2 concentration as its organic matter decomposes. This higher concentration of CO2 increases temperature further by the greenhouse effect, which melts more permafrost, releasing more CO2, and so on, leading to lethal temperature increase.)

3. The “Gaia” hypothesis states that Earth functions like a single self-regulating organism that maintains conditions needed for its own survival. Have the students discuss what the failure of Biosphere 2’s mission tells us about this hypothesis.

(If Biosphere 2 is a valid model of the Earth [Biosphere 1], this apparent lack of regulation of the atmosphere and extinction of many species indicates that the Gaia hypothesis is invalid.)

Handouts or Display There are no special handouts or displays needed for this activity. As stated earlier, images of the facility and biomes can be shown to augment the presentation.

Lecture Activity 28.2: The “Limiting Nutrient” Concept Estimated Time to Complete: 15 minutes Section References 28.2 How Does Energy Flow Through Ecosystems?

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

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Instructor Guide Biology: Life on Earth

Introduction Chapter 28 discusses four of the major nutrient cycles and makes mention of how scarcity can limit primary productivity in plants. However, it does not present the “limiting nutrient” concept, which can help explain competition and coexistence, the role of fertilizers in agriculture, and one extreme recommendation for reducing greenhouse gases in the atmosphere. This activity presents the limiting nutrient concept in an easily understood way.

Materials Needed • Some means of showing students the image of Liebig’s barrel analog, such as adding it electronically to a PowerPoint slide or showing it on an overhead projector, may be required. The same methods can be used to show pictures of stunted, nutrient-starved plants, which can help students visualize nutrient limitation. Images of such plants, and of Liebig himself, can be obtained by performing an Internet search using “Liebig’s barrel” as search terms.

Procedures The following is a brief outline of a presentation on Justus von Liebig (1803–1873) and his limiting nutrient concept.

Liebig began his career as a basic chemist. At this time he developed the concept of a “rate-limiting step” in a multistep chemical reaction. Put simply, if a series of steps is needed to convert one substance into another, the rate of that overall process will be equal to the rate of the slowest of the steps. For example, in the reaction A→B→C→D→E→F, if the conversion of B to C is the slowest step, that will equal the rate of the conversion of A to F. Later on, Liebig switched his attention to agriculture and physiology. He had the insight that one could view the growth of a plant as a multistep process as well. The plant needs to make cellulose, proteins, and so forth. The rate of growth of the plant (and primary productivity of a community of plants), then, would be determined by the slowest of the steps.

These various steps or processes need various nutrients: a source of carbon (as carbon dioxide or bicarbonate ion), a source of nitrogen (as ammonia or nitrate), a source of phosphorus (as phosphate), and so forth. The nutrient whose availability (or supply) is lowest relative to its need by the plant is then the “limiting nutrient,” the one that limits the growth of the plant.

The supply of the various nutrients in the environment varies considerably, but so too does the plant’s needs for each. We crudely divide nutrients into two groups based on how much plants need of them: (1) macronutrients (carbon, nitrogen, phosphorus, potassium, etc.) are needed in relatively large amounts; (2) micronutrients (zinc, iron, selenium, etc.) are needed in smaller amounts. (Some authors and authorities also add a third group, the ultra-trace nutrients, needed in extremely small amounts.) It must be kept in mind, though, that although plants need comparatively little of the micronutrients, their growth is impaired just as much by deficiency of these as by deficiency of one of the macronutrients. Also, because the needs for micronutrients are so low, many plants cannot tolerate excessively large quantities of them, so they can more easily reach levels toxic to the plants.

The implications of this for agriculture are obvious: If you want to increase (primary) productivity, you need to identify the limiting nutrient and add more of that as a fertilizer. As you add more, productivity will increase until you reach a point where another nutrient becomes limiting. In most terrestrial and aquatic systems, nitrogen and phosphorus are the most common limiting nutrients, and primary producers often compete intensely for them. However, any nutrient may be the limiting nutrient for a given plant.

A good way to visualize this is through Liebig’s own analogy of a barrel. (See the figure on page 286.)

The height of the water in the barrel represents the productivity of the plant. The staves that make up the sides of the barrel each represent a single nutrient, such as calcium, copper, nitrogen, and so on. The width of each stave represents the plant’s requirement for that nutrient: Macronutrient staves will be wide, whereas those for micronutrients will be narrow. The supply relative to demand is then represented by the height of the stave: If there is a good supply relative to demand, the stave is high; if the nutrient is relatively scarce compared to the plant’s need, the stave is shorter. The shortest stave, then, determines how high the water can go before it overflows (i.e., how productive the plant will be). If you want to increase productivity, you can add to the supply of the limiting nutrient (i.e., raise the height of that stave), but at some point it will be taller than another stave, that of the “new” limiting nutrient.

Assessment Suggestions 1. Ask the students if they think Liebig’s concept can also be applied to animals.

(It can.)

2. If so, what are the nutrients involved? .

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(Any essential nutrient, such as the essential amino acids or vitamins, can be listed, as can water.)

Also, ask the students if other resources besides chemical nutrients, such as sunlight for plants and nesting spaces for birds, can also be added to this concept.

(They can.)

The students’ understanding of this concept can also be assessed by discussing the late John Martin’s controversial “iron hypothesis.”

Briefly, it states that atmospheric CO2, the greenhouse gas whose levels have been rising due to the burning of fossil fuels and deforestation, can be taken out of the atmosphere and sequestered in the deep ocean by fertilizing large areas of the “southern ocean” with iron. (Perform an Internet search using “John Martin iron hypothesis” as search terms for more information.) Primary productivity of the phytoplankton in these waters is unusually low, even for the open ocean, and lower than expected given the measured quantities of nitrogen and phosphorus.

John Martin speculated that the limiting nutrient in these waters was iron, and that primary productivity could be stimulated simply by adding iron. This would stimulate photosynthesis, taking more carbon dioxide out of the water and, because CO2 in the air above readily passes into the water, out of the atmosphere as well, tying it up in the carbohydrates and other molecules of the phytoplankton cells. Because many of these phytoplankton die and sink into deep water before they decompose and the carbon can be released as CO 2, this carbon takes thousands of years to return to the atmosphere.

Effectively, it is sequestered permanently in these deep waters and cannot contribute to global warming.

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Handouts or Display There are no special handouts or displays needed for this activity. However, the figure of Liebig’s barrel analogy on the next page is helpful.

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Lecture Activity 28.3: Decomposers and Detritus Feeders Estimated Time to Complete: 15–25 minutes, depending on steps actually performed Section Reference 28.2 How Does Energy Flow Through Ecosystems?

Introduction Most students are familiar with at least some representative species of producers, primary consumers, secondary consumers, and so forth. But few have had much experience with, or have much knowledge of, decomposers and detritus feeders. Because their crucial role in recycling nutrients is a central theme of this chapter of the textbook, this activity aims to expose students to examples of each group.

Materials Needed • A series of food items (bread, vegetables, or fruit; do NOT use meat or animal products) that have been colonized by fungi or bacterial decomposers, preferably in different stages of decay. You can set these out uncovered at room temperature for several days before the demonstration.

• If available, some taped-shut Petri dish cultures of benign bacteria (decomposers) • A collection of various types of mushrooms, both domesticated and “wild.” Bracket fungi from tree trunks should be included, if possible. If none are available, pictures will do.

• A sample of forest-floor leaf litter, rich organic topsoil (especially if it has a mulch on top), or leaves and other debris with some substrate from a fast-flowing, shallow stream, season permitting. These will contain detritusfeeding communities.

• A Berlese (pronounced “Burr-Lace-Ee”) or similar large funnel. This is used to extract detritus feeders from the sample listed immediately above. Perform an Internet search using “Berlese funnel” as search terms for instructions on making the funnel using a 2-liter soda bottle.

• A stand to hold the funnel, a small dish to place beneath it to collect animals, and a lamp with incandescent bulb to place over the top of the funnel (see previous Internet search instructions).

Procedures Begin by informing (or reminding) the students of the crucial importance of decomposers and detritus feeders.

Stress that if these organisms were to vanish, primary production would soon stop as resupply of available nutrients would cease and “bodies” would begin piling up.

You can also inform them that some ecosystems, such as on the forest floor (leaf litter), deep water of lakes and oceans, and fast-flowing, shallow mountain streams in forested areas, are “fed” primarily on dead organic matter, as low light or other limitations seriously impair photosynthesis. You can add your leaf litter or similar material (see Materials Needed section) to the assembled funnel apparatus and turn on the light at this time, so the extraction of animals can proceed while you talk.

You can note that bacteria are so tiny that individuals are invisible to the unaided eye, and fungi usually grow predominantly underground or inside the organism they are decomposing. As a result, we seldom see either, which explains why most people still classify organisms as “animals or plants.” (The predominantly single-celled protists also are usually overlooked for the same reasons.) Explain that the most visible decomposers are the mushrooms; reproductive organs of fungi that exist mostly as tiny threads (hyphae) extending throughout the soil; or, in the case of bracket fungi, throughout the wood of dead trees. At this time you can show your specimens or photos of a variety of mushroom types. Many forest mushrooms are startlingly beautiful, a descriptor we seldom associate with death and decay!

This discussion sets up your presentation of the moldy bread or other material you have prepared ahead.

Fungal hyphae should be visible with the unaided eye (though a projector or dissecting microscope could also be used). If decaying food was exposed to fungal spores (by leaving it out at room temperature without a cover), a simple life cycle may be evident.

You can then show your Petri dish(es) of bacterial cultures. Explain that each culture is a clone started by a single bacterial cell; the colony is visible and has recognizable qualities that help identify it.

Finally, you can explain the function of your Berlese funnel, noting that the animals flee the heat of the light and are hence easily extracted from their “substrate.” Note that such a community includes not just decomposers and the detritus feeders that eat them (and the dead organic matter), but also predators on the detritus feeders,

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and predators on the predators, and so on. Detrital food webs can be as productive and complex as photosynthetic food webs.

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Assessment Suggestions 1. Ask the students where else they might expect to see detritus-dominated ecosystems. How about where large rivers dump their loads of organic matter into the bay at their mouths?

(Yes. Other detritus-dominated ecosystems include the deeper waters of lakes and the ocean, where there is insufficient light for photosynthesis and dead organisms sink down from above [see Chapter 42], and the headwaters of many streams, where insufficient nutrients leach into the water for photosynthesis, but dead leaves from deciduous trees fall into the water each fall.)

2. Start a discussion of human death rituals and practices. What are the potential differences between burying (embalmed in a casket) versus cremation on the biogeochemical cycling of nutrients? Have we removed valuable minerals from ecosystems by trying to forestall our own decomposition?

(Both processes sequester important nutrients, at least for some time. Although embalming slows decomposition, it does eventually occur. Insect larvae, worms, bacteria, and fungi will eventually breach the casket, break down the body, and redistribute the nutrients locally. Cremation burns off carbon, hydrogen, and oxygen as CO2 and H2O, and likely nitrogen as nitrogen oxides, recycling these rapidly into the region receiving the exhaust. But the ash left behind, which is usually buried, likely contains potassium, phosphorus, and calcium, all important plant nutrients as well, which may be lost for a long time. Given the present size of the human population and our biomass, it is likely these practices are beginning to have effects on biogeochemical cycling of nutrients.)

3. Have the students suggest ways to test the contributions of decomposers to community function. Is it possible to stop decomposition without having much effect on producers or consumers?

(The best test is probably to eliminate them from the system and see the effects. However, this is difficult in most complex ecosystems, as these organisms [and their resistant spores] are everywhere. They also share much of the same metabolism and biology with producers and consumers, so anything that kills decomposers will likely have a major effect on these other groups as well. Simple microcosms with very few species added aseptically can be constructed without decomposers to test the effects of their absence.)

Handouts or Display There are no special handouts or displays needed for this activity. However, Figures 2-9 and 2-10 from Wright and Nebel’s Environmental Science 9e, 2002, may help students visualize a detrital food web and see the trophic arrangements.

Lecture Activity 28.4: Tight Nutrient Cycling in Corals Estimated Time to Complete: 20 minutes Section References 28.2 How Does Energy Flow Through Ecosystems?

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

Introduction Coral reef ecosystems are among the most productive on Earth, yet they occur in extremely nutrient-poor waters.

How is this possible? Corals are symbiotic “super-organisms” that have a very tight cycling of nutrients between their primary producers—the microscopic, single-celled algae (dinoflagellates) or “zooxanthellae”—and their primary “consumers”—the cnidarian polyps. This tight coupling ensures that nutrient losses to the environment are minimal, allowing both groups to be productive in an environment that is poor in both mineral nutrients and prey.

Materials Needed • Having living corals on display sparks interest, but is not often feasible or necessary.

• Photographs or video clips of corals and coral reefs, along with close-ups showing their zooxanthellae, are helpful. They can be obtained from the Internet (perform an Internet search using “coral reefs” as search terms) and inserted into PowerPoint presentations or printed onto overhead transparencies.

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Procedures You can begin by introducing or reviewing the concepts of trophic levels and nutrient cycling. Point out that, in most ecosystems, the cycling of nutrients from one organism to another is loosely coupled and rather wasteful.

For example, much of the primary production in the upper waters of a lake (by microscopic algae called phytoplankton) is lost to decomposers, as many algae die and sink into deeper waters, making this resource unavailable to the primary consumers in the lake, tiny zooplankton.

Set the stage by noting that the waters in which most coral reefs are located have very low concentrations of nutrients needed for primary production, namely usable forms of nitrogen and phosphorus. (This is because there is a continual loss of nutrients into deeper waters as just described for lakes, though in deeper parts of the oceans these nutrients are never returned to the surface.) Also, because this lack of N and P means little photosynthesis occurs by “free-living” producers outside of corals, there is a scarcity of prey available for predators such as cnidarians.

Explain next that the cnidarians don’t actually eat the algae. Rather, they house the algae inside their tissues.

The algae carry on photosynthesis inside the transparent bodies of the polyps, and 90% or more of their “photosynthate” is passed on to the cnidarian, mostly as glycerol (C3H8O3) molecules. This is a primary source of energy and carbon for the cnidarian, which it supplements with rather meager catches of tiny zooplankton prey.

As its prey contain excesses of both N and P beyond its needs, the cnidarian releases these to the algae, which use them to synthesize their proteins, nucleic acids, ATP, and so on.

Point out that most animals would simply “urinate” these materials into the environment, where they would disperse and be diluted before being taken up by producers.

You can point out that although this relationship is rather one-sided—the cnidarian polyps seem to benefit more than the algae, which have to pay a high “rent” for their accommodations—it obviously works well. You need only show an image of a densely populated (by fish) coral reef to demonstrate this.

It is also interesting to note here that a somewhat different kind of relationship is seen between a few species of small, marine gastropod mollusks (“sea slugs”) and their algae “prey,” whose chloroplasts they hijack and retain within their branching digestive tracts. Whereas the ingested algae soon die, their chloroplasts survive and function for weeks, passing the photosynthate they produce on to their molluscan captors. It is in fact hard to say if this relationship is an example of mutualism, parasitism (in which the host lives inside the parasite!), or predation. (Perform an Internet search using “sea slug” as search terms for more information.)

Finally, you can point out that this relationship is so good at retaining nutrients in nutrient-poor environments that many coral reefs are apparently being damaged by increased nutrient inputs. These occur as rivers carry fertilizer and sewage into their waters. This appears to “allow” free-living, fleshy corals (“seaweeds”) to grow on the surface of the corals, shading out their zooxanthellae. Without the added nutrients, the seaweeds cannot grow. This may be one of the causes of the dramatic worldwide declines noted in coral reefs, one of the hot spots for biodiversity.

Assessment Suggestions 1. Ask the students to speculate on how this relationship may have evolved. What were the likely first steps?

What accommodations must two species make to live with each other?

(It may have started out as a predatory relationship, but those cnidarians that didn’t kill the algae may have benefited. The algae have to be “leaky” so they lose lots of glycerol, and the cnidarians cannot digest the algae.)

2. Ask the students if they can think of any other nutrient-poor environments that might have mutualisms similar to the corals.

(Lichens occur on bare rock, tree bark, etc. In lichens, the two trophic levels are primary producers [the algae] and nutrient-scavenging decomposers [the fungi], however.)

3. Ask the students why, if this relationship is so beneficial, it is not more common. Are there any potential drawbacks or problems?

(Whenever your well-being depends on another, you would suffer if something happens to the other.)

Handouts or Display There are no special handouts or displays needed for this activity.

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CHAPTER 29 EARTH’S DIVERSE ECOSYSTEMS LECTURE OUTLINE Case Study: Food of the Gods 29.1 What Determines the Distribution of Life on Earth?

A. Four Fundamental Resources Are Required for Life 1. Nutrients from which to construct living tissue 2. Energy to power metabolic activities 3. Liquid water to serve as a medium for metabolic activities 4. Appropriate temperatures at which to carry out these processes B. The Distribution of Life on Earth Is Largely Determined by the Requirements of the Photosynthesizers C. Two Generalizations Regarding the Location and Abundance of Organisms on Earth Can Be Made 1. In the oceans, sunlight energy, nutrients, and temperature are usually the factors that determine the distribution of life in aquatic ecosystems 2. Temperature and precipitation largely determine the distribution of life on land D. The Requirements for Life Occur in Specific Patterns and Locations 1. This results in large-scale communities of organisms in various regions, called biomes 2. Weather patterns that prevail for long periods of time are called climate a. Different biomes typically have characteristic climates (Figure 29-1)

29.2 What Factors Influence Earth’s Climate?

A. Both Climate and Weather Are Driven by the Sun 1. Solar energy reaching the outer atmosphere includes ultraviolet, visible, and infrared light a. Ultraviolet (UV) has short wavelengths and high energy b. Visible light has intermediate wavelengths and is used for photosynthesis and vision c. Infrared (IR) has long wavelengths and low energy, and generates radiant heat 2. Before solar energy reaches Earth’s surface it is modified by the atmosphere a. The ozone layer, or stratosphere (middle layer), is rich in ozone (O3) and absorbs much of the sun’s UV light, converting it to heat â Earth Watch: Plugging the Ozone (Figure E29-1) 3. Solar energy drives both weather and climate, as it drives the wind, the ocean currents, and the global water cycle â Lecture Activity 29.1: The Unfortunate (Double) Legacy of Thomas Midgley, Jr. B. Earth’s Curvature and Tilt on Its Axis Determine the Angle at Which Sunlight Strikes the Surface 1. Latitude is a measure of the distance north or south of equator, and is measured in degrees a. At the equator (0°), sunlight strikes Earth directly throughout the year b. Farther north or south, sunlight strikes Earth less directly, which spreads light over a greater area 2. The tilt of Earth on its axis also produces pronounced seasons at higher latitudes as directness of sunlight changes considerably over the year (Figure 29-2) a. When the Northern Hemisphere is tilted toward the sun, sunlight is more direct and the region experiences summer; when tilted away, that region has winter; the opposite happens in the Southern Hemisphere b. Tilting hardly affects angle of sunlight at the equator, so there are no seasons C. Air Currents Produce Large-Scale Climatic Zones That Differ in Temperature and Precipitation (Figure 29-3) 1. At the equator, the direct angle of the sun heats the air, causing it to rise a. The air is saturated with water evaporated at the surface by solar heat i. As air rises, it cools, causing the water to condense and fall as rain 290

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b. Air then flows north and south from the equator to near 30°, where it has cooled and become dense enough to sink i. As the air sinks, it is warmed by heat radiated from Earth but remains dry ii. This produces bands of major deserts at 30°N and 30°S latitude (Figure 29-2) c. This general circulation pattern is repeated further north and south, with moist zones at 60°N and 60°S and extremely dry zones at the north and south poles d. The location of biomes matches the air current pattern fairly well (Figure 29-4) D. Climate Variability Is Affected by Proximity to Oceans 1. Ocean currents are driven by Earth’s rotation, winds, and by direct heating of water by the sun a. Continents interrupt the currents, producing circular gyres i. Gyres rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere (Figure 29-5) ii. The Gulf Stream moves warm water from the Caribbean up the eastern shore of North America, creating a warmer, moister climate E. Mountains Complicate Climate Patterns 1. Variations in elevation within continents impact climate zones a. At higher altitudes, temperature drops about 3.5°F (2°C) for every 1,000 feet (305 meters) rise in elevation, resulting in snowcapped mountains even in the tropics (Figure 29-6) 2. Mountains also modify precipitation patterns a. When water-laden air is forced over a mountain, it cools i. Cooler air holds less moisture, so rain or snow falls on the windward side ii. As air moves down the far side of mountain, it warms but stays dry, which results in a local dry area called a rain shadow (Figure 29-7) â Lecture Activity 29.2: Air Pressure, Temperature, and Moisture Content

29.3 What Are the Principal Terrestrial Biomes?

A. Tropical Rain Forests 1. This biome is found near the equator and has constant, high temperatures (77–86°F; 25–30°C) and rainfall (100–160 in.; 250–400 cm) throughout the year (Figure 29-8) a. Extensive rain forests are found in Central and South America, Africa, and Southeast Asia b. Biodiversity refers to the total number of species within a given region i.Rain forests have the greatest biodiversity of any biome on Earth ii.Rain forests cover less than 5% of Earth’s total land area but are home to 5–8 million species, representing one-half to two-thirds of the world’s biodiversity c. Tropical rain forests have several layers of vegetation i.The tallest trees reach 150 ft (50 m) ii.Below is a continuous canopy at 90–120 ft (30–40 m), with a layer of shorter trees below this iii. Smaller plants have enormous leaves to trap scant sunlight reaching the forest floor iv.Edible plant material near the ground is scarce, so most animals live in the trees, including birds, monkeys, and insects â Lecture Activity 29.3: Rain Forest Methods from Pest Control, Mountaineering, and Construction v.Almost all the nutrients are stored in the vegetation, so the soil is relatively infertile d. Human impacts i.Agriculture often degrades soils quickly ii.Cutting for lumber and burning for ranching and farming are occurring at alarming rates, estimated at about 50,000 square miles annually (Figure 29-9) iii. Fortunately, some areas are being set aside as protected preserves, and reforestation efforts are under way â Lecture Activity 29.4: Saving the Rain Forests at the Breakfast Table â Case Study Continued: Food of the Gods B. Tropical Deciduous Forests 1. Slightly further from the equator than tropical rain forests, this biome has less constant rainfall and produces pronounced wet and dry seasons a. These forests occur in Southeast Asia and parts of South and Central America b. During the dry season, trees shed leaves to reduce water loss c. Human impacts i. Human activities that impact the tropical rain forests also affect the tropical deciduous forests .

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Instructor Guide Biology: Life on Earth C. Tropical Scrub Forests and Savannas 1. The tropical scrub forest is dominated by short, deciduous trees 2. In the savanna, with less rainfall, grasses grow beneath trees; savanna occurs where grasses become the dominant vegetation, with only scattered trees (Figure 29-10) a. Rainfall averages 12 in. (30 cm) or less, with most falling during the rainy season b. Grasses adapted to this grow rapidly during the rainy season, dying back to drought-resistant roots during the dry season c. Few trees, such as thorny acacia and water-storing baobab, are adapted to survive dry seasons also d. The African savanna features diverse array of large mammals e. Human impacts i.impacts include poaching of endangered black rhinos and African elephants, and overgrazing by cattle D. Deserts 1. If rainfall drops below 10 inches, grasses cannot survive; desert biomes result a. Deserts occur on every continent, especially from 20–30°N and S latitude and in rain shadows of major mountain ranges b. Deserts may be hot and/or cold c. The desert biome includes a variety of environments: i.The Sahara Desert gets virtually no rain and has no vegetation (Figure 29-11a) ii.Most deserts have widely spaced vegetation with much bare ground (Figure 29-11b) d. Many are dominated by cacti and euphorbs i.Large, shallow roots quickly soak up water after infrequent storms ii.A waterproof, waxy coating on the rest of the plant prevents evaporative loss e. Annual wildflowers race through their life cycle in a month or less following a storm (Figure 29-13) f. Desert animals are also adapted to survive in the heat and with little water i.Most spend the day in underground burrows, coming out only at night (Figure 29-14) ii.Smaller animals can get all of their water from their food and as a by-product of cellular respiration iii. Larger animals need permanent water holes g. Human impacts i.Human impact on deserts can last centuries due to the slow growth of plants ii.Desertification is the process by which land is converted to desert because of overuse iii. The spread of the Sahara Desert is an example of desertification (Figure 29-15) E. Chaparral 1. Chaparral is found in many coastal regions that border deserts, such as Southern California and much of the Mediterranean (Figure 29-16) a. Most of the 30 inches of annual rainfall comes during cool, wet winters; summers are hot and dry b. Vegetation consists of mainly drought-resistant small trees and large shrubs c. Chaparral is adapted to frequent summer fires started by lightning d. Human impacts i.Development by humans is a major threat to this biome F. Grasslands 1. Located in centers of continents, they receive 10–30 inches (25–75 cm) of rain annually a. They have a continuous cover of grass and virtually no trees except along rivers i.Tallgrass prairies from Texas to Canada support 200 to 400 different species of native plants (Figure 29-17) ii.Areas further west are drier (Figure 29-18) b. Grasslands lack trees due to fires from lightning and fires set by Native Americans to maintain grazing land for bison c. Human impacts i.Nearly all tallgrass prairies have been plowed for agriculture ii.Shortgrass prairie is often overgrazed by cattle, forming sagebrush desert (Figure 29-19) G. Temperate Deciduous Forests (Figure 29-20) 1. These form in areas that receive 30–60 inches (75–150 cm) of rain a. They are seen in North America east of grasslands, Western Europe, and East Asia b. Enough soil moisture exists for trees to grow, which shades out grasses .

Chapter 29 Earth’s Diverse Ecosystems c. In winter, frozen water is unavailable, so trees shed leaves to conserve water d. Wildflowers bloom on the forest floor in spring before tree leaves fully open

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Instructor Guide Biology: Life on Earth e. Decaying leaf litter on the forest floor supports decomposers and detritus feeders i. Many arthropods feed on these and on each other f. Human impacts i. Reductions in large predatory mammals (wolves, black bear, etc.) by hunting or habitat loss have allowed deer to become more plentiful ii. Clearing for lumber, agriculture, and housing has left little virgin forest H. Temperate Rain Forests 1. Relatively rare, this biome is found on the U.S. Pacific Coast from Washington State to Alaska, the southeastern coast of Australia, the southwestern coast of New Zealand, and parts of Chile and Argentina (Figure 29-21) a. Abundant precipitation and mild winters mean moisture is available year round b. Temperate rain forests are dominated by conifers, covered by mosses and ferns c. So little light reaches the forest floor that new seedlings are often limited to light gaps produced by tree falls, often growing atop fallen logs d. Human impacts i. Many of these forests have been logged, which has led to the demise of some animal species I. Northern Coniferous Forests 1. Also called taiga, this biome lies north of the grasslands and temperate forest of all of North America, Scandinavia, and Siberia (Figure 29-22) a. Conditions are harsher than in temperate deciduous forests, with longer and colder winters and a shorter growing season i. About 16–40 inches (40–100 cm) of rain falls annually b. Trees are mostly conifers with narrow, waxy needles to reduce evaporation during winter c. Mammals large and small still roam the taiga d. Human impacts i. Clear-cutting for lumber has destroyed huge expanses of forest in North America, but some areas are being protected (Figure 29-23) J. Tundra 1. Arctic tundra is a vast treeless region between the taiga and polar ice cap on the Arctic Ocean (Figure 29-24) a. It is a treeless, “freezing desert” with winter temperatures to –40°F (–55°C), howling winds, and precipitation averaging 10 inches (25 cm) or less b. Freezing can occur even in summer and the growing season is just a few weeks c. Permafrost is a permanently frozen soil layer less than 2 feet below the surface i. It prevents water from soaking in, so tundra is a huge marsh in summer, a superb mosquito habitat ii. Trees can’t survive, as root growth is limited to the topmost meter of soil d. Tundra supports a surprising abundance and variety of life i. The ground is carpeted with small perennial flowers and dwarf willows often covered by lichen called “reindeer moss,” a favorite food of caribou ii. Vegetation also supports lemmings and other rodents, which are eaten by wolves and other predators e. Human impacts i. Impacts are localized around oil drilling sites, pipelines, mines, and military bases ii. The greatest threat to the tundra is climate change

29.4 What Are the Principal Aquatic Biomes?

A. Life in Water Is Affected by a Variety of Conditions 1. Aquatic ecosystems have abundant water and appropriate temperature 2. Temperatures are more moderate than in terrestrial ecosystems, as water is slower to heat and cool than air and land 3. Light decreases rapidly with depth, as water absorbs much solar energy, leaving insufficient light for photosynthesis at 600 ft (200 m) a. Suspended sediment or microorganisms greatly reduce this depth 4. Nutrients tend to be concentrated near bottom sediments, where light levels are often too low to support photosynthesis, limiting aquatic life B. Freshwater Lakes .

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1. Large lakes have distinct life zones (Figure 29-25) a. The littoral zone is near the shore with shallow water, abundant light for anchored plants, and adequate nutrients from bottom sediments i.Highly diverse and productive community ii.Cattails and bulrushes abound nearshore; water lilies, submerged vascular plants, and algae dominate farther out iii. Microscopic plankton among anchored plants includes phytoplankton (“drifting plants”; photosynthetic protists and bacteria) and zooplankton (“drifting animals”; protozoa and tiny crustaceans) iv.Invertebrates include small crustaceans, insect larvae, snails, flatworms, and hydra; vertebrates include frogs, minnows, aquatic snakes, and turtles b. The limnetic zone occurs farther from shore where plants cannot anchor to the bottom and still receive enough light for photosynthesis c. The profundal zone lies below the limnetic zone i.Light levels are insufficient for photosynthesis ii.Nutrients are abundant, as detritus falls down from other zones and sediments wash in iii. Inhabitants include a few fish, decomposers, and detritivores 2. Freshwater lakes are classified according to their nutrient content a. Oligotrophic lakes are very low in nutrients i.Many are formed by glaciers that scrape depressions in bare rock, and fed by mountain streams carrying little sediment ii.Water is clear, as little sediment or microscopic life exists iii. Light penetrates deeply, and photosynthesis (and oxygen produced) can extend deeply; the limnetic zone can even reach the bottom, with oxygen-loving fish such as trout thriving b. Eutrophic lakes receive larger inputs of sediments, organic material, and inorganic nutrients (such as phosphates and nitrates) from surroundings (Figure 29-26) i.Can support dense plant communities ii.The lighted limnetic zone is shallower here than in oligotrophic lakes, as water is murkier from suspended sediment and denser phytoplankton populations iii. Dead bodies of the limnetic zone inhabitants fall into the profundal zone, where decomposition depletes oxygen c. Oligotrophic lakes accumulate nutrient-rich sediments over time, becoming more eutrophic, a process called eutrophication 3. Human impacts a. Accelerated eutrophication due to nutrients carried in from farms, feedlots, and other sources C. Streams and Rivers 1. Streams often begin in mountains where water runoff from rain and melting snow moves over rock, called the source region (Figure 29-27) a. At lower elevations, in the transition region, small side streams or tributaries merge, forming wider, slower-moving streams and small rivers b. As the land becomes lower and flatter, the river warms and widens c. Rivers drain into lakes or other rivers that ultimately lead to oceans i.Estuaries are formed at the intersection of the freshwater and salt water d. Human impacts i.Channeling of rivers for recreation has led to increased erosion ii.Dams have altered fish populations D. Freshwater Wetlands 1. Wetlands are regions saturated with water a. They act as natural water filters and purifiers b. They provide breeding, sheltering, and feeding sites for many types of animals c. Human impacts i.Draining of freshwater wetlands for housing, commercial uses, and agriculture has reduced the extent of wetlands in the United States E. Marine Biomes 1. The oceans are divided into life zones (Figure 29-28) a. The photic zone occurs in the upper layer of water, where light is strong enough to support photosynthesis (to about 650 ft or 200 m depth) .

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c. The intertidal zone is where the land meets the water d. The nearshore zone extends out to sea, where it meets the open ocean 2. As in lakes, most nutrients are at or near the bottom, carried there in bodies of organisms falling from the photic zone, but there is too little light for photosynthesis here 3. Nutrients are resupplied to the photic zone by two processes: a. Rivers carry nutrients from the land into the ocean b. Upwelling, upward flow brings cold, nutrient-laden water to the surface i.Prevailing winds displace surface water, which is replaced from below ii.Occurs along western coastlines of California, Peru, and West Africa 4. Shallow-water marine biomes a. The greatest concentrations of marine life occur where abundant light combines with a source of nutrients i.This occurs in the shallow waters of the nearshore zone b. Estuaries i.These occur where rivers meet oceans (Figure 29-29a) ii.The salinity of the water here varies iii.This zone supports high biological productivity and diversity c. Intertidal zones i.Organisms must be adapted to withstand exposure to air and pounding waves ii.Life here is very diverse (Figure 29-29b) d. Kelp forests i.These are dense stands of kelp, and found throughout the world in cool waters (Figure 29-29c) ii.They provide food and shelter for abundant fish, invertebrates, and mammals e. Coral reefs i.Corals build skeletons of calcium carbonate that form reefs (Figure 29-29d) ii.They are most abundant in the tropical waters of the Pacific and Indian Oceans, the Caribbean, and the Gulf of Mexico as far north as southern Florida, with maximum temperatures from 68– 86°F (20–30°C) iii.Corals provide anchorage for algae and shelter and food for the most diverse assemblage of invertebrates and fish in the oceans, rivaling tropical rain forests in biodiversity iv.Reef-building corals have photosynthetic protists (dinoflagellates) within their tissues, a mutually beneficial relationship v.Corals thrive in the photic zone at depths less than 130 ft (40 m), where light for photosynthesis is available for the algae f. Human impacts i.Development for housing, harbors, marinas, and energy extraction affect coastal ecosystems ii.Pollution by runoff from farming can destroy estuarine communities iii. Runoff from farming and logging carries silt and excess nutrients iv.Overfishing and destructive collecting of fish and invertebrates for shell collectors and the aquarium trade damage ecosystems and threaten species v.Coral reefs are vulnerable to global warming vi.Many conservation efforts are under way to preserve coral reefs around the world 5. The open ocean a. Vast areas of ocean beyond coastal waters have bottoms too deep to allow plants to anchor and still collect enough light to grow b. Most life in the open ocean depends on microscopic phytoplankton i.These are consumed by zooplankton, such as tiny crustaceans ii.Zooplankton are food for larger invertebrates, small fish, and some whales (Figure 29-30) c. The amount of life in the open ocean varies from place to place i.Nutrients in the photic zone are replinished by runoff and upwelling of water from the depths d. Human impacts i.Pollution and overfishing are the primary impacts of humans ii.Pollution includes deliberate dumping, inadvertent spills, and agricultural runoff from land iii. Overfishing has depleted many fish populations, with some fishing practices killing many nontarget species iv.Regulations on fishing have been established in some areas e. Marine reserves increase diversity, numbers, and size of animals .

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Case Study Revisited: Food of the Gods

KEY TERMS aphotic zone biodiversity biome chaparral chemosynthesis climate coral reef desert desertification estuary eutrophic lake grassland gyre hydrothermal vent community

kelp forest intertidal zone limnetic zone littoral zone nearshore zone northern coniferous forest oligotrophic lake open ocean ozone hole ozone layer permafrost photic zone phytoplankton plankton

profundal zone rain shadow savanna temperate deciduous forest temperate rain forest tropical deciduous forest tropical rain forest tropical scrub forest tundra upwelling wetlands zooplankton

LECTURE ACTIVITIES Lecture Activity 29.1: The Unfortunate (Double) Legacy of Thomas Midgley, Jr. Estimated Time to Complete: 10–30 minutes, depending on number of topics addressed Section Reference 29.2 What Factors Influence Earth’s Climate?

Introduction Time can dramatically alter our opinion of events. This is clearly demonstrated by the two primary career accomplishments of Thomas J. Midgley, Jr.: the discovery that tetraethyl lead can stop internal combustion engines from knocking and the development of Freon® as a refrigerant. In this activity, the technical problems these inventions solved are presented, as well as the public health and environmental problems they created.

Finally, a classroom discussion is outlined concerning the balance of “good” and “bad” in both cases.

Materials Needed • Although no special materials are needed, images of Midgley, an internal combustion engine (preferably showing its pistons), ads for “Ethyl” gasoline, and the ozone hole over Antarctica help involve students. These can be located by performing an Internet search using “internal combustion engine,” “ethyl gasoline,” and “ozone hole” as search terms. Images can be displayed on a computer or copied onto overhead transparencies. .

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Procedures Present the following information to your students.

In 1921, Midgley discovered that small quantities of tetraethyl lead (TEL) added to gasoline could eliminate damaging engine knock, caused by premature ignition of fuel during compression. It allowed engines to be designed with greater compression ratios, boosting power and/or efficiency (i.e., mileage). However, lead was already known to be a neurotoxin and, within a year of the beginning of production in 1923, workers on the “Ethyl” gasoline production line began getting ill. (The corporation’s name was no doubt selected to give a nonthreatening image, as “Ethel” was a popular female name at the time. In fact, the image of a modern working woman named “Ethyl” was used in the company’s ads for a while.) Several of these workers went insane and died of acute lead poisoning. When news of this leaked out, TEL use was temporarily banned until an investigation of the risks of Ethyl gasoline could be conducted. To alleviate fears, Midgley held a press conference in which he poured concentrated TEL over his hands and inhaled the vapor. (Only recently has it been discovered that Midgley, suffering from severe lead poisoning, subsequently took a prolonged leave of absence in 1924 to recover.

He was paralyzed in 1940 by what was diagnosed as polio, though at least one author has speculated he may have suffered from misdiagnosed lead poisoning. He was strangled in 1944 when the harness he devised to lift himself into and out of bed became tangled. It is possible he died, in a way, from his own invention, TEL.) Despite testimony by many prominent scientists about the potential public health risks of using TEL in gasoline, the ban was lifted shortly thereafter, with a call for funding more complete studies in the near future.

However, these studies were never carried out. For the next several decades nearly all the research on the potential risks of leaded gasoline were funded by the Ethyl Corporation. Not surprisingly, no conclusive evidence of public health effects was ever found and the Ethyl Corporation fails to acknowledge any health effects even to this day.

The U.S. Environmental Protection Agency (EPA) began phasing out leaded gasoline use in the 1970s, a process that was largely completed in 1986 and fully accomplished for on-road vehicles in 1996. But this ban was as much because lead fouled the newly mandated catalytic converters as it was due to concerns over lead contamination of the environment. (Catalytic converters reduce emissions of nitrogen oxides, hydrocarbons, and carbon monoxide from exhaust, alleviating smog.) It has been estimated that over the circa 60 years of its use, 7 million tons of lead were released into the environment from the burning of leaded gasoline in the United States alone (and 70 million tons worldwide). This increased our average lead exposure to 300 to 500 times that of “normal” (pre-Midgley) levels. As many as 68 million young children are believed to have received toxic levels of lead between 1927 and 1987, and as many as 5,000 deaths per year may have been caused by lead-related heart disease before TEL use was phased out. But lead burdens in humans have already declined dramatically since the phase-out. TEL is still used in several developing countries, still supplied by the American Ethyl Corporation and by the British Octel Corporation.

In 1928, Midgley was called on to solve another problem. The refrigerants of the day, gases that were cyclically compressed to a liquid and then allowed to vaporize, absorbing heat, were either very toxic or highly flammable, or both. And because many were also corrosive, they tended to leak, resulting in many deaths. Midgley sought a gas that avoided these problems and, reportedly in just three days, found one. It was dichlorofluoromethane, the first of the chlorofluorocarbons or “CFCs,” a group later trademarked “Freons.”

Midgley demonstrated dichlorofluoromethane’s benign properties at a meeting of the American Chemical Society in 1930 by inhaling a lung-full of the gas and gently blowing it over a lit candle, which was extinguished. (Midgley appeared to suffer no lasting effects from this demonstration, unlike his earlier show using TEL. In fact, CFCs were used as propellants in inhalers for asthmatics until recently.) Other CFCs followed quickly, and they were also used for aerosol propellants, for expanded foam, in air conditioners, and other products.

In 1974, Mario Molina and F. Sherwood Rowland published a paper describing how stratospheric ozone gas, which absorbs harmful ultraviolet radiation from the sun, was being destroyed by chlorine released during the breakdown of CFCs. In 1995 they, along with Paul Crutzen, shared the 1995 Nobel Prize for Chemistry “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.”

Although ozone levels worldwide were soon shown to be dropping fast, of particular concern was the vast reduction in ozone levels noted each year in the Southern Hemisphere around Antarctica in the so-called “ozone hole.” Before long, a sharp rise in skin cancer rates was noticed in the area, presumably due to elevated UV levels.

It turns out that the stability of CFCs, a plus for their role as refrigerants, worked against them in the environment, as it allowed many molecules to reach the stratosphere before being split by the intense ultraviolet radiation there. To make matters worse, CFCs were discovered to be greenhouse gases with Earth-warming potentials thousands of times as great as carbon dioxide. Given the serious health and climate implications, industrialized nations signed the Montreal Protocol (1987) and subsequent treaties to phase out CFC production and use.

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In light of these two rather dubious (in hindsight) inventions, historian John McNeill remarked in his book on the environmental history of the twentieth century that Midgley “had more impact on the atmosphere than any other single organism in earth history.” As poet James Russell Lowell wrote, “Time makes ancient good uncouth.”

Assessment Suggestions 1. Have your students discuss the “pros” and “cons” of tetraethyl lead use in gasoline. (“Pros” include reduced engine wear and hence maintenance costs; increased fuel efficiency and hence less demand for oil, less production of greenhouse gases, and potentially less international strife over oil reserves; “cons” include the obvious human public health problems and irreversible contamination of the environment.)

2. Have them reassess the balance of good and evil of TEL use after presenting the following additional information. Even before TEL was developed as a gasoline additive, it was known that ethyl alcohol (or ethanol) could eliminate knocking when added to gasoline in just 10–15% by volume. And it does this without contaminating the environment. In fact, Midgley’s own research proved the feasibility of the resulting “gasohol” even before 1921. It has been suggested that this alternative, renewable additive was suppressed because the Ethyl Corporation could not corner the market and hence reap huge profits on ethanol like it could on TEL. (This additional information makes it clear that TEL needn’t have ever been used. As a result, all of the costs of leaded gasoline use were entirely avoidable.)

3. Tell your students that the Ethyl Corporation also developed MMT (methylcyclopenta-dienyl manganese tricarbonyl) as an anti-knock additive. It was adopted by Canada and an unspecified number of other countries (the Ethyl Corporation refuses to tell how many or which). Because use of this additive releases manganese into the environment and manganese is also a known neurotoxin, ask your students if MMT is a good substitute for TEL from a health perspective.

(It is not.)

4. After telling your students that Canada was successfully sued by the Ethyl Corporation after it tried to ban the use of MMT in 1997, using restraint-of-trade clauses in the North American Free Trade Agreement (NAFTA), have them discuss the dangers of the “free trade at all costs” attitude such agreements promote for the environment, for public health, and for national sovereignty.

(Such agreements can prevent officials in one country from passing laws that protect their citizens or environment if the laws can be shown to restrict trade with another country.)

5. Similarly, have your students discuss the “pros” and “cons” of chlorofluorocarbons. (“Pros” include saving lives and property with these less flammable and toxic refrigerants. You might also argue that refrigeration reduced food spoilage, increasing food availability and decreasing food-related illness. The growth of air conditioning made life more comfortable, especially in the “sun belt,” which boomed in population and productivity as a result. “Cons” clearly include increasing skin cancer rates and associated deaths and damage to primary producers from increased ultraviolet levels at ground level [mentioned in the textbook].)

6. Have the students discuss the lessons learned from the TEL story for deregulation of industry. Can industries be trusted to police themselves? For example, should we trust industry claims that genetically modified food organisms and irradiated foods are safe? Do we really need regulatory agencies like the Environmental Protection Agency (EPA) and Food and Drug Administration (FDA)?

(The TEL story clearly indicates that industry cannot be trusted to do the “right thing” with respect to public health and the environment. For example, the Ethyl Corporation misrepresented the need for TEL—claiming there were no good alternatives when ethanol was already a proven anti-knock additive—and covered up the health risks for decades. As a result, government regulation in the form of the EPA and FDA are crucial in protecting the health of the population and integrity of the environment.)

Lecture Activity 29.2: Air Pressure, Temperature, and Moisture Content Estimated Time to Complete: 10–15 minutes Section Reference 29.2 What Factors Influence Earth’s Climate?

Introduction This chapter describes two distinct instances in which air rises and cools, resulting in condensation of its water vapor into precipitation (rain and/or snow). One is near the equator in the tropics, where the rising is caused by .

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the heating of the air by intense solar radiation, causing it to expand and its density to fall. The other is when wind pushes air up over a mountain range. In either case, part of the cooling is due simply to the expansion of each “parcel” of air, as the pressure on it from the column of air above it is lessened. The results are high precipitation in the tropics and on the windward sides of mountain ranges. This activity demonstrates that when air expands, it cools. It also describes or demonstrates condensation of water vapor as air cools. The converse process of heating of air as it is compressed is discussed, and evaporation is demonstrated. It is pointed out that evaporation rates increase as temperature rises. These latter processes result in deserts at roughly 30°N and S latitude and the “rain shadows” on the leeward sides of mountain ranges.

Materials Needed • Can of compressed air used for cleaning computers (often called a “Duster”), available at most computer and office supply stores (at room temperature) • Thermometer (at room temperature) • Glass soda bottle (at room temperature) • A few small toy balloons • Two water baths (plastic dishpans work well) • Hot water for hot water bath (very hot tap water or water heated on a hot plate) • Ice and cold water for cold water bath and for drinking glass to demonstrate condensation (if using) • Drinking glass to demonstrate condensation (if using) Procedures To demonstrate that heated air expands: You can trap a “parcel” of air inside a glass soda bottle by placing a balloon over its opening. The base of the balloon must be tight fitting and the balloon should be limp.

Place the bottle into the warm water bath, keeping the top and balloon above the surface and in full view. In a short time, the heating of the air inside the bottle will cause the air to expand, blowing up the balloon slightly.

(Alternatively, you can start with the glass soda bottle cooled in an ice water bath, then add the balloon and allow it to return to room temperature or place it in the warm water bath. Don’t have the water so warm that the thermal shock breaks the glass, however.) Ask the students why this happened. (Air molecules speed up; move away from each other faster; exert more pressure against balloon.)

Point out that this expanding air is less dense and rises (e.g., in the tropics), and that this same principle causes hot air balloons to rise.

To demonstrate that expanding air cools: Point out that as air rises (either because it has been heated or is forced over a mountain), there is less pressure from the column of air above it pressing down, so it tends to expand. This expansion actually causes the air to cool. This can be demonstrated by allowing the compressed air inside a bottle of computer cleaning “Duster” to escape.

First, have a student read aloud the ambient room temperature on a thermometer. (Make sure the student doesn’t touch the thermometer bulb, which would raise the temperature.) Then, release the air in a stream over the bulb of the thermometer for a few seconds, and have the same student read aloud the new, lower temperature. Point out that temperature is a measure of the density of kinetic energy in the air; because the same amount of air now occupies more space, and heat energy has not been added or subtracted, the temperature has fallen.

Point out that this is the principle behind refrigeration, as compressed gas (formed by the compressor, which actually heats the gas, see following discussion) is allowed to expand and cool.

To describe (or demonstrate) that cooling air holds less water vapor, causing water vapor to condense: Most students will have had one or more experiences with this. Examples you can relate are: (1) The water vapor that condenses on the outside of a glass of an iced beverage on a hot and humid day; (2) the condensation of water vapor in your exhaled air into a “cloud” as it cools on a cold day (i.e., “seeing your breath”); (3) water vapor condensing on the inside of a windshield on a cold day (moisture mostly from your exhaled air); (4) “steam” that forms on a mirror when you take a shower; (5) fog that forms when the temperature drops after a warm, wet period, as the water vapor condenses into low-level clouds; and (6) condensation that forms on the surface of pipes carrying cooled gas in air conditioners, and “frost” in freezers. If you are performing this activity on a warm, humid day, you can actually demonstrate the first example just listed in class.

Point out that this condensation normally starts on a surface, such as the beverage glass, windshield, or mirror, but in the atmosphere the surface is a dust particle called a “condensation nucleus.” Clouds form first, as vapor condenses into an aerosol of fine particles. As these coalesce, they eventually become too large to be suspended in the air and fall as precipitation. .

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To demonstrate that cooling air contracts, becoming more dense: In the atmospheric circulation (i.e., Hadley cell) described in the text, air that rose in the tropics cools and moves horizontally until it reaches about 30°N or S latitude. At that point, it has cooled sufficiently to sink. We can demonstrate that cooling air causes it to contract (making it more dense) with our glass soda bottle and balloon used earlier.

This time, we start with the balloon slightly inflated (either coming out of the hot water bath or by blowing into it and placing it on the bottle without letting the air escape). We then place the bottle in the ice water bath (cold water with ice added). The balloon should soon noticeably deflate. You can again ask the students what happened.

(The molecules slowed down, and because they were not pushing away from each other as fast, the parcel of air was condensed.)

To describe how falling air is compressed and heats: Although it is difficult to demonstrate in the classroom, the facts that falling air is compressed and compressed air heats up can be inferred as they are the reverse of two processes demonstrated earlier. As air falls (either as it cools as it moves away from the equator or as it moves down the leeward side of a mountain), it now has a larger column of air pressing down on it from above, which compresses it. You can point out that if we had a bicycle pump hooked up to a sensitive thermometer, we could see the temperature rise as we compressed the air in the cylinder (if the air is prevented from leaving the pump).

You can also note that the compressor that is part of an air-conditioning unit generates heat (beyond the normal waste heat associated with friction, etc.). The key to an air conditioner’s cooling performance is that much of this heat is allowed to dissipate “outside” (under the hood of the automobile or outside the building) before the (now cooler) compressed air is allowed to expand and cool further “inside” (in the passenger compartment or inside the building).

To describing/demonstrate how heated air holds more water and speeds evaporation: Evaporation is easily demonstrated in a classroom equipped with blackboards.

Simply wipe the board with a damp sponge. The water darkens the surface of the board. Within a few seconds (the exact time depending on the temperature and humidity of the room air), the color begins to lighten as the water evaporates. Ask the students what happened to the water. (It evaporated: Molecules in the liquid water with sufficient kinetic energy “escaped” into the air.)

Ask them to suggest ways to speed up this evaporation.

(Create air flow over the board: This carries away water-laden air from the surface of the board. Heat the board or the air: This increases the average kinetic energy of water molecules and speeds the rate of evaporation.)

Describe how both a hair dryer and a clothes dryer employ both of these strategies. Also note that as the air warms, it can hold more water. In the case of air falling at 30°N or S latitude or on the leeward side of a mountain, this air has already lost most of its moisture as precipitation (in the tropics or on the windward side of the mountain), so it is relatively dry (i.e., has low relative humidity). As a result, it can pick up moisture from the land (like the air from a hair dryer picks up moisture from your hair), leaving the land warm and dry. This causes the bands of desert at 30°N and S latitude and the rain shadow on the leeward sides of mountains.

Assessment Suggestions Assessment questions are integrated into the steps outlined in the Procedures section. Suggested answers are in parentheses and italicized.

Ask the students what effect(s) global warming (a rise in average global temperature) might have on precipitation levels, evaporation rates, and overall water availability for land plants.

(It may decrease precipitation rates, as the warmer air can hold more moisture. It may increase evaporation rates, as water molecules speed up and more readily escape into the gaseous phase. Both of these would decrease water availability for land plants.)

Handouts or Display There are no special handouts or displays needed for this activity.

Lecture Activity 29.3: Rain Forest Methods from Pest Control, Mountaineering, and Construction Estimated Time to Complete: 10–15 minutes Section Reference 29.3 What Are the Principal Terrestrial Biomes? .

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Introduction We’ve all heard that tropical rain forests are biodiversity hot spots, containing far more of the world’s species than their land area alone would predict. Less well known, however, is the fact that many of these species, and much of the workings of the rain forest for that matter, were unknown until just a couple of decades ago. The primary reason for this is that most of the primary production occurs, and many of the species only exist, in the forest canopy, 30 meters (100 feet) or more off the ground. This activity describes how methods developed for pest control, rock climbing, and building construction have been borrowed and adapted by forest ecologists.

These methods have allowed the scientists to efficiently bring mobile organisms down from the canopy (in the case of insecticide foggers) or take themselves up to it (in the cases of climbing ropes and construction towers), greatly increasing the types of research they can do. Our understanding and appreciation of this important ecosystem has increased dramatically as a result.

Materials Needed • No special materials are needed for this activity, although images of the rain forest and its canopy and of the methods and equipment described (insecticide foggers, climbing ropes and walkways, construction towers in the forest, etc.) aid comprehension and pique interest. These may be obtained from an Internet search using “rain forest pest management,” “climbing ropes and walkways in rainforests,” and “construction towers in rainforests” as search terms.

Procedures Begin by reminding the students of the tremendous vertical scale of the tropical rain forest, with trees rising as high as 50 meters (150 feet) above the forest floor. (You may wish to comment here that this reflects an intense competition for sunlight, as each tree tries to avoid being shaded out by its neighbors, balanced by the physical limits on height imposed by mechanics and transpiration.)

(Or, ask the students why trees grow so high, and what limits their height. A photo or two here looking up at the canopy from below can help make these points.)

Next, point out that a limited amount of information can be obtained by studying the tropical rain forest, or any forest for that matter, from the ground. Birds and monkeys can be studied using binoculars and/or by listening to their vocalizations, and material that has fallen (or been shot down) from the canopy can be collected and analyzed. But these crude methods often lead to false generalizations and severe underestimation of the number of species present and the complexity of their interactions. Relate the story of Terry Erwin, the Smithsonian Institution scientist who developed the method of using insecticide foggers to collect canopy arthropods. These foggers, basically blowers that create an aerosol of insecticide that can be directed up into the canopy from the ground, were developed for pest control. Erwin had the idea of using these in the rain forest and setting out collectors on the ground to get representative samples of the huge number of insects, arachnids, and other creatures that fell from the trees. This method allowed Erwin to collect many species not formerly identified. Using this information, along with his finding that many plant-eating insects appeared to be limited to just one host tree species, Erwin revised the estimate of the number of insect species in the tropical rain forest from the previous 1.3 million to 30 million. Although it was later revealed that many of these insects actually utilize more than one tree species in the same genus, resulting in a downward revision of the estimated number of species to 6 million, Erwin’s work pointed out the importance of conserving large, interconnected blocks of forests, not just small fragments. (For more information, perform an Internet search using “Terry Erwin” as the search terms.)

You can tell the students that Erwin’s method had obvious limitations (it didn’t tell him anything about the workings of the system and failed to collect species living inside bromeliads, for example) and drawbacks (it killed almost everything in the tree!), so means to access the canopy directly were needed. Methods to climb trees and suspend oneself within the canopy in relative safety and comfort were adapted from rock climbing and mountaineering. Basically, a “beanbag” can be thrown, or a lead weight slingshot, over a sturdy branch. This is attached to a light line that is then used to pull a heavier climbing line over the branch.

Using climbing gear (harnesses, block and tackle, carabiners, etc.), researchers can hoist themselves up into the canopy, where they can construct slings, walkways, and so forth. These platforms ease their efforts considerably. (For more information, perform an Internet search using “tree climbing gear” as the search terms.)

Finally, you can inform the students of one of the more recent developments in forest canopy access, the construction of canopy cranes. These were developed for construction of tall buildings, but several have recently been built in various forest ecosystems throughout the world. They are flown in by helicopter in sections and assembled on the site. The gondolas, suspended beneath the large movable arms, allow researchers to work for

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extended periods safely. (For more information, perform an Internet search using “canopy crane” as the search terms.)

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Assessment Suggestions The benefits of these new methods to the advancement of forest ecology are unquestionable. However, their adoption by the ecotourism industry is controversial, as is the growing recreational sport of tree climbing. Have the students discuss the pros and cons of this type of ecotourism and of this new sport.

(Pros include raising needed capital while maintaining the forest and raising public awareness and concern about conservation. Cons include potential damage to trees [for example, novice climbers standing on branches have destroyed centuries-old moss mats covering branches in the Pacific Northwest temperate rain forests], bringing development [e.g., roads and sewage] into the forest, disturbing wildlife, etc.)

Lecture Activity 29.4: Saving the Rain Forests at the Breakfast Table Estimated Time to Complete: 15 minutes Section Reference 29.3 What Are the Principal Terrestrial Biomes?

Introduction The destruction of many natural ecosystems, such as the tropical rain forests, is driven not by stupidity or greed but by basic economic need. Local peoples require food, shelter, and fuel. If they cannot collect or produce these themselves, they need an income to buy them. This lecture activity investigates some of the ways in which indigenous peoples have managed to make a living while maintaining local forest ecosystems by the production of nontimber forest products (“NTFPs”) and by agroforestry (growing crops within the forest setting). By buying products such as “shade coffee,” produced in a manner that preserves much of the nature of the rain forest, we can provide indigenous peoples with a much-needed income and help save the rain forests while sipping our morning coffee, seated comfortably at our breakfast tables.

Materials Needed • No special materials are needed for this activity, although pictures can be found by performing an Internet search using “eco-friendly products” as search terms.

Procedures You can begin by stating the dilemma facing many indigenous forest peoples. Those that do actually have land rights are under tremendous pressure to sell them to firms that will clear-cut the forests for timber and development of short-lived agriculture or low-quality grazing or to miners so they can create strip mines. All of these alternative land uses are environmentally disastrous, as many forest species are lost, forest soils rapidly degrade, and so on. But it is hard to make a living in a forest. So, many forest people have been forced to sell out to developers. But there is another way!

Many forest cultures have long traditions of producing nontimber forest products for their own use and consumption.

(An extensive list of these “NTFPs” can be found by performing an Internet search using “nontimber forest products” as search terms.) These include items such as nuts, fruits, and herbs, collected in the intact forest, and rattan, a “value-added” commodity produced by indigenous artisans from locally collected vines. All of these are renewable resources that can be exploited (within reason) without degrading the fragile forest ecosystem. Efforts have been made to band small local producers together into cooperatives to promote and market their products to consumers throughout the world.

The classic success story of NTFPs is the rattan industry. Rattan is produced from canes and fibers from a number of species of vines native to Indonesia. Indigenous peoples collect the raw materials, process them, and fashion them into finished products—furniture, baskets, and other items. These are then sold on the international market. The rattan industry generates $3 billion in sales annually. It has been so profitable, in fact, that other areas, such as Brazil, have been trying to break into the market using rattan-like vines that grow elsewhere.

Assessment Suggestions 1. Ask the students to discuss the value they place on maintaining the world’s forests. Are they willing to spend a little extra to purchase a product that preserves forests instead of one that destroys them? How much more? .

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Instructor Guide Biology: Life on Earth (Answers will vary.)

Have the class discuss the potential for fraud and the need for oversight of “green business” certification.

If consumers are willing to spend more for forest-protecting products, isn’t there a strong incentive for companies to “fake it”?

(Fraud is always a potential problem. Even some gasoline companies have tried to market their products as being environmentally friendly! Oversight and certification can help consumers make informed choices but are not foolproof.)

Elicit opinions on the relative merits of agroforestry and outright conservation of rain forest ecosystems.

What do completely undisturbed forests give us that agroforestry systems (such as shade coffee plantations) do not? Is it better to allow complete development of 1,000 hectares while completely conserving 4,000 hectares than to develop agroforestry systems in all 5,000 hectares, for example? What happens if the proportion of developed land increases?

(Answers will vary. It is possible that many species, such as large mammals, will be completely excluded from agroforestry stands. These would be lost in the latter instance. But the benefits of increasing habitat for other species such as songbirds may outweigh these costs. As the proportion of developed land increases, agroforestry becomes a more attractive alternative.)

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CHAPTER 30 CONSERVING EARTH’S BIODIVERSITY LECTURE OUTLINE Case Study: The Migration of the Monarchs 30.1 What Is Conservation Biology?

A. Conservation Biology Is the Branch of Biology Dedicated to Understanding and Preserving Earth’s Biological Diversity 1. Biodiversity is the variety of living organisms on Earth a. Conservation biology seeks to preserve biodiversity at different levels i.Genetic diversity ii.Species diversity iii. Ecosystem diversity

30.2 Why Is Biodiversity Important?

A. Ecosystem Services Are Practical Uses for Biodiversity 1. Ecosystem services are the benefits people obtain from ecosystems and are grouped into two general categories (Figure 30-1) a. Natural substances and other benefits that people use directly b. Processes that are required to sustain the direct benefits 2. Some ecosystem services provide direct benefits to people a. Oxygen i.Photosynthetic organisms produce almost all the oxygen in the atmosphere b. Water i.Natural ecosystems purify water c. Food i.People throughout the world eat wild-grown food d. Wood i.In some less developed countries, people use wood for heating and cooking ii.Wood is also exported to other countries e. Medicines i.In many less developed countries, traditional medicines are derived from wild plants ii.Many medicines prescribed in the United States are extracted from plants f. Recreation i.People use ecosystems for a variety of activities ii.Ecotourism is a rapidly growing recreation activity (Figure 30-2) 3. Some ecosystem services sustain the direct benefits a. Soil formation i.People rely on soils to decompose waste products from various industries ii.Soil communities are crucial to nearly every nutrient cycle b. Erosion and flood control i.Plants help regulate erosion, and wetlands help control flooding (Figure 30-3) c. Climate regulation i.Plant communities have a major impact on local climates d. Genetic resources i.Researchers have identified genes in wild plants that might be transferred into crops to increase productivity and provide greater resistance to disease, drought, and salt accumulation in irrigated soil e. Recreation 304

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i.Ecosystems provide for ecotourism and other forms of recreation (Figure 30-3) B. Ecological Economics Attempts to Measure the Monetary Value of Ecosystem Services 1. Ecological economics attempts to place values on ecosystem services to assess the trade-offs that occur when natural ecosystems are damaged to make way for human profit-making activities 2. An excellent example of ecosystem preservation is the government planning that took place to protect areas of the Catskill Mountains in New York (Figure 30-4) â Earth Watch: Restoring the Everglades (Figures E30-1 and E30-2) 3. What Is the Monetary Value of Earth’s Ecosystem Services? a. In 1997, a team of ecologists calculated that Earth’s ecosystem services provide about $33 trillion in benefits b. A 2005 report concluded that 60% of Earth’s ecosystem services were being degraded C. Biodiversity Supports Ecosystem Function 1. The “redundancy hypothesis” states that several species in an ecosystem have similar roles and if some are eliminated, the others will perform the same services 2. The “rivet hypothesis” states that similar species in an ecosystem may have very different roles, and the elimination of some will cause the ecosystem to collapse 3. Some species, called keystone species, are fundamentally essential to the function of an ecosystem â Earth Watch: Whales—The Biggest Keystones of All? (Figure E30-3)

30.3 Is Earth’s Biodiversity Diminishing?

A. Extinction Is a Natural Process, But Rates Have Risen Dramatically in Recent Years 1. Scientists hypothesize that, in the absence of cataclysmic events, extinctions occur naturally at a very low rate, called the background extinction rate 2. In contrast, the fossil record provides evidence of five previous mass extinctions, during which many forms of life were eliminated in a relatively short period of time 3. The majority of biologists believe that human activities are now causing a sixth mass extinction, rivaling prehistoric events a. The Millennium Ecosystem Assessment recently estimated that the current extinction rate is between 50 and 1,000 times the background rate estimated in the absence of people b. Many undescribed species have certainly been lost, and some newly discovered species are already endangered 4. The International Union for Conservation of Nature (IUCN) has established a “Red List” of at-risk species a. Species may be considered critically endangered, endangered, or threatened

30.4 What Are the Major Threats to Biodiversity?

A. The Worldwide Decline in Biodiversity Has Two Principal Causes 1. The increasingly large fraction of the Earth’s resources being used to support humans 2. The direct impact of human activities affecting ecosystems worldwide B. Humanity’s Ecological Footprint Exceeds Earth’s Resources 1. The human ecological footprint estimates the area of Earth’s surface required to produce the resources we use and the waste we generate 2. Biocapacity estimates the sustainable resources and waste-absorbing capacity actually available on Earth a. In 2007, findings suggested that humanity had exceeded the capacity of Earth to support it on a continuing basis (Figure 30-5) b. Running such an ecological deficit is possible only on a temporary basis C. Human Activities Directly Threaten Biodiversity 1. Habitat destruction is the most serious threat to biodiversity a. Loss of habitat impacts over 85% of endangered mammals, birds, and amphibians b. Approximately half of all tropical rain forests have been cut down in the last 11,000 years, providing wood for export and land for agriculture (Figure 30-6) 2. Habitat fragmentation splits natural ecosystems into small pieces surrounded by regions devoted to human activities and is a serious threat to wildlife (Figure 30-7) a. This may result in populations that are too small to survive i. Established preserves must have a minimum viable population (MVP) of organisms to be effective .

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Instructor Guide Biology: Life on Earth ii. Many countries are working to preserve critical habitat â Earth Watch: Saving Sea Turtles (Figure E30-3) 3. Overexploitation threatens many species a. Overexploitation refers to hunting or harvesting natural populations at a rate that exceeds their ability to replenish their numbers (Figure 30-8) b. Overfishing is a serious threat to marine life c. The purchase of illegal products such as elephant ivory also contirbutes to overexploitation 4. Invasive species displace native wildlife and disrupt community interactions a. Humans have transported many species around the world b. Sometimes nonnative species become invasive, increasing in number at the expense of native species, competing for food and habitat c. Island ecosystems are particularly vulnerable to invasive species d. Lakes are also especially vulnerable (Figure 30-8) 5. Pollution is a multifaceted threat to biodiversity a. Pollutants include synthetic chemicals that enter the air, soil, and water and then accumulate to toxic levels in animal tissues, as well as substances released by mining and the burning of fossil fuels 6. Global climate change is an emerging threat to biodiversity a. The use of fossil fuels has substantially increased atmospheric levels of carbon dioxide, possibly leading to global climate change b. Likely impacts are varied i. Deserts may get hotter and drier ii. Species may relocate, but those that can’t may not survive iii. Cool habitat may disappear (Figure 30-9a) iv. Insect pests may spread (Figure 30-9b) v. Coral reefs may die (Figure 30-9c) â Lecture Activity 30.1: Threats to Biodiversity

30.5 How Can Conservation Biology Help to Preserve Biodiversity?

A. Conservation Biology Has Four Important Goals 1. To understand the impact of human activities on living organisms and their environments 2. To preserve and restore natural communities 3. To reverse the escalating loss of Earth’s biodiversity 4. To foster sustainable use of Earth’s resources B. Habitat Preservation Is Essential to Preserving Biodiversity 1. Core reserves preserve all levels of biodiversity a. Core reserves are natural areas protected from most human uses b. To establish these areas, conservationists must know the minimum critical areas required to sustain minimum viable populations of species 2. Corridors connect critical animal habitats a. Wildlife corridors are strips of protected land linking core reserves (Figures 30-10 and 30-11)

30.6 Why Is Sustainability Essential for a Healthy Future?

A. The Important Characteristics of Sustainable Ecosystems Are Varied 1. Diverse communities 2. Relatively stable populations remain within the carrying capacity of the environment 3. Recycling and efficient use of raw materials occurs 4. Reliance on renewable sources of energy B. Sustainable Development Promotes Long-Term Ecological and Human Well-Being 1. According to the IUCN, sustainable development “meets the needs of the present without compromising the ability of future generations to meet their own needs” 2. However, evidence from all parts of the world shows that development of any kind is affecting natural communities 3. Biosphere reserves provide models for conservation and sustainable development a. Biosphere reserves are designed to maintain biodiversity and evaluate techniques for sustainable human development while preserving local cultural values (Figure 30-12)

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4. Sustainable agriculture preserves productivity with reduced impact on natural communities (Table 30-1) a. No-till cropping leaves the residue of harvested crops in the fields to form mulch for next year’s crops (Figure 30-13) b. Organic farming reduces the use of chemical fertilizers and pesticides C. The Future of Earth Is in Your Hands 1. Three interrelated questions must be considered related to conservation a. What should human lifestyles look like? b. What technologies can support those lifestyles sustainably? c. How many people can the Earth support and in what lifestyle?

2. Changes in lifestyle and use of appropriate technologies are essential a. The only truly effective way to conserve life on Earth is to make fundamental changes in the way we interact with our environment 3. Human population growth is unsustainable a. As the human population grows, so does its ecological footprint (Figure 30-14) 4. The choices are yours â Links to Everyday Life: What Can Individuals Do? â Lecture Activity 30.2: What Can You Do to Help Preserve Biodiversity? â Lecture Activity 30.3: Role Playing: Whose Earth Is It Anyway?

Case Study Revisited: The Migration of the Monarchs

KEY TERMS biocapacity biodiversity biosphere reserve conservation biology core reserve critically endangered species ecological economics

ecological footprint ecosystem services endangered species habitat fragmentation keystone species mass extinction minimum viable population (MVP)

no-till overexploitation sustainable development threatened species vulnerable species wildlife corridor

LECTURE ACTIVITIES Lecture Activity 30.1: Threats to Biodiversity Estimated Time to Complete: 20–25 minutes Section Reference 30.4 What Are the Major Threats to Biodiversity?

Introduction Human use of Earth’s resources and human activity are the two main threats to biodiversity. These general categories include a number of specific threats to biodiversity: depleting Earth’s “ecological capital,” habitat destruction, overexploitation, introduction of invasive species, pollution, and global warming.

Materials Needed • Handouts (following page) • Textbook

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Procedures This activity can be assigned as individual or group homework or done in cooperative groups during class time.

Using the diagram that follows (the Frayer Model), ask the students to use the diagram to better understand the various threats to biodiversity.

If done in groups during class time, assign a different threat to each group and have the groups learn what they can about the assigned threat using the textbook and Internet searches (if possible), and then fill in the diagram cooperatively (allow 10–15 minutes for this portion of the activity). In the “Definition” box, ask the students to define their assigned threat to biodiversity in their own words. In the “Characteristics” box, have the students describe two or three characteristics of the threat to biodiversity they were assigned. Statements included in this box may be similar to the definition. In the “Examples” box, have them list examples of activities that contribute to their assigned threat to biodiversity. In the “Non-examples” box, have the students list activities that are related but not specific to their assigned threat to biodiversity. Examples may be as follows: If the students were assigned “invasive species” as their threat, a non-example of this would be pollution.

Then have all groups present what they wrote in their diagrams and what they learned to the rest of the class (allow 5–10 minutes for this portion of the activity).

Assessment Suggestions Ask the student groups to turn in their diagrams and then grade them for accuracy and/or creativity.

Handouts See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 30.1 Handout—The Frayer Model

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Lecture Activity 30.2: What Can You Do to Help Preserve Biodiversity?

Estimated Time to Complete: 20–25 minutes Section References 30.4 What Are the Major Threats to Biodiversity?

30.5 How Can Conservation Biology Help to Preserve Biodiversity?

30.6 Why Is Sustainability Essential for a Healthy Future?

Introduction There are many threats to biodiversity that have been perpetuated by human activity. However, there are ways that individuals can stop the reduction in biodiversity and the destruction of ecosystems worldwide.

Materials Needed • Paper • Computers for Internet searching • Textbook Procedures Organize the students into groups of three or four. Instruct the students to use their textbooks and Internet searches (using “sustainable living” as search terms) to develop a list of four or five ways that they can help stop the reduction in biodiversity and promote sustainable living. Give the groups approximately 15–20 minutes to research and discuss their findings. Then have the entire class conduct a discussion on what each group came up with.

Assessment Suggestions Ask the student groups to hand in their lists and grade them for feasibility and creativity.

Handouts None

Lecture Activity 30.3: Role Playing: Whose Earth Is It Anyway?

Estimated Time to Complete: 30–45 minutes (depending on how the discussion proceeds) Section Reference 30.6 Why Is Sustainability Essential for a Healthy Future?

Introduction Resolving conflicts over the use of natural resources is a difficult process that requires the balancing of the needs of many different individuals and organizations. Sustainable living and development are integral in promoting the long-term well-being of many ecosystems on the Earth, as well as that of the humans who live in them and require their resources.

In this activity, the students will form groups and play various roles in an attempt to resolve a conflict regarding the development and usage of an area of tropical rain forest in Brazil. Organize the class into the following four groups: • Group 1: Big Business Members of this group are interested in clear-cutting an area of rain forest in order to harvest the hardwood and then turn the area into a vacation resort. Their interests are primarily financial and profit-oriented. From their point of view, development is inevitable.

• Group 2: The Conservationists Members of this group are interested in the long-term well-being of tropical rain forests everywhere. They contend that clear-cutting this area of forest will drive the frog and bird species to extinction, thus upsetting the balance in this particular ecosystem. From their point of view, any development of natural areas should be stopped at all costs. .

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• Group 3: Local Government Members of this group are interested in the tax revenue and employment that could be generated by the development of resorts. However, they have to answer to the public that elected them, so they are at the center of this conflict. They are interested in trying to balance the benefits of development with the costs to the local ecosystem.

• Group 4: The Native Villagers Members of this group are primarily interested in their own day-to-day survival. The local native peoples rely on the forest for subsistence, including fruits and wild game for food. They understand the benefit of development, but feel that their needs are not being heard by either the government or the businesspeople.

They believe that this is their land and that they should have input on what happens to it. They are not completely opposed to the clear-cutting, but want the land to be used for agriculture rather than a resort.

Materials Needed • Handouts of each group’s point of view (previous list) • Handout of the conflict scenario (described in Procedures section) Procedures Organize your class into four groups. If you have a large class, you may need to split the class into manageable portions and then organize four groups within each portion. Explain to the students that an American hotel chain is interested in developing a vacation resort in Brazil in an area of rain forest in which two or three endangered species of tree frogs and two or three species of birds live, and native people still reside. An international conservation group is trying to stop the development from proceeding by organizing the local natives and petitioning the local government. The local government is torn between the potential revenue generation and the destruction of this area of rain forest.

Assign one group to be “Big Business,” one to be “The Conservationists,” one to be “The Native Villagers,” and one to be “Local Government.” “Big Business,” “The Conservationists,” and “The Native Villagers” all need to convince “Local Government” to take their side and make a decision concerning the area in question. Give groups 15–20 minutes to discuss their points of view and plans. During this time, the “Local Government” group members should discuss and speculate on what they think they will hear and attempt to devise a plan. Once all groups are done with their discussions, give “Big Business,” “The Conservationists,” and “The Native Villagers” each approximately 5 minutes to state their case. Then allow approximately 10 minutes of discussion. This part of the activity will require the instructor to act as the moderator so that all groups have an opportunity to speak.

Last, give “Local Government” 5–10 minutes to come to a decision.

After “Local Government” delivers the decision, facilitate a class discussion in which the instructor debriefs the activity.

Ask members of each group to discuss how it felt to take the point of view they were assigned. Ask the class to relate this to real-life development, including retail and housing development that may be occurring in your area.

An alternative to save class time would be to assign the groups, and then have them discuss their points of view and what they would present as homework. Then have the presentations and class discussion during class time.

Assessment Suggestions Formal assessment is not necessarily required, but could be done in the following ways: If the activity is done only during class time, group members (as a team or individually) could be required to submit a written document of their position and what they presented.

If the group point of view is assigned as homework, require group members (as a team or individually) to submit a written document of their position and what they will present.

Handouts Make handouts of each group’s position for distribution to the class.

Another handout that may help but is not required would be one describing the scenario listed in the Procedures section.

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CHAPTER 31 HOMEOSTASIS AND THE ORGANIZATION OF THE ANIMAL BODY LECTURE OUTLINE Case Study: Overheated 31.1 Homeostasis: How Do Animals Regulate Their Internal Environment?

A. Homeostasis Describes the Process by Which an Organism Maintains Its Internal Environment Within the Limits That Allow Optimal Cell Functioning B. The Internal Environment Is Maintained in a State of Dynamic Constancy 1. Physical and chemical parameters are kept within a range that cells require to function 2. Conditions regulated by homeostatic mechanisms include temperature, water and salt concentrations, glucose concentrations, pH, and oxygen and carbon dioxide concentrations a. These conditions ensure the production of ATP by cells to sustain various processes C. Animals Vary in Their Homeostatic Abilities 1. Animals vary in how—and how well—they regulate body temperature (Figure 31-1) a. Ectotherms derive most of their body heat from the environment b. Endotherms maintain a constant body temperature as a result of their metabolism c. Body temperature can affect the rate of metabolism in living organisms D. Feedback Systems Regulate Internal Conditions 1. Negative feedback reverses the effects of changes a. Negative feedback maintains body temperature and other body conditions b. Negative feedback systems contain three principal components (Figure 31-2a) i. The sensor detects changes in the system ii.The control processes the information from the sensor iii.The effector makes changes in the system to return it to a homeostatic level c. Endotherms use negative feedback to maintain body temperature (Figure 31-2b) â Lecture Activity 31.1: Nonbiological Examples of Feedback â Lecture Activity 31.2: Orthostatic Stress Response as an Example of Negative Feedback 2. Positive feedback enhances the effects of changes a. Positive feedback produces a response that intensifies the original change b. Positive feedback produces labor and childbirth â Lecture Activity 31.3: Simple Demonstration of Positive Feedback with an Audio Squeal â Case Study Continued: Overheated â Earth Watch: Positive Feedback in the Arctic (Figures E31-1 and E31-2)

31.2 How Is the Animal Body Organized?

A. The Basic Hierarchy of Organization in Animals Is as Follows: Cells—Tissues—Organs—Organ Systems (Figure 31-3) B. Animal Tissues Are Composed of Similar Cells That Perform a Specific Function 1. Epithelial tissue covers the body, lines its cavities, and forms glands (Figure 31-4) a. Epithelial tissue consists of sheets of cells firmly attached to one another b. Epithelial tissue is often classified by cell layers i. Simple epithelium is only one cell thick ii.Stratified epithelium is several layers thick c. Epithelial cells are continuously lost and replaced

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d. Glands are cells or groups of cells specialized to secrete substances outside the cell i. Exocrine glands secrete substances into a body cavity or onto the body surface ii.Endocrine glands secrete hormones into the extracellular fluid 2. Connective tissues have diverse structures and functions (Figure 31-5) a. These tissues secrete large quantities of extracellular matrix among living cells b. Loose connective tissue i. This is the most abundant form of connective tissue and connects, surrounds, and protects other tissues (Figure 31-5a) c. Dense connective tissue i. This tissue is packed with collagen fibers and is found in tendons and ligaments (Figure 31-5b) d. Specialized connective tissues i. Cartilage covers the ends of bones in joints and supports various structures (Figure 31-5c) ii.Bone contains hardened deposits of calcium phosphate (Figure 31-6) iii. Adipose tissue is modified for long-term energy storage (Figure 31-7) iv. Blood and lymph consist of various types of cells in a fluid matrix (Figure 31-8) â Lecture Activity 31.4: Case Study on Connective Tissues 3. Muscle tissue has the ability to contract a. There are three types of muscle tissue (Figure 31-9) i. Skeletal muscle is voluntary and moves the skeleton (Figure 31-9a) ii. Cardiac muscle is located only in the heart (Figure 31-9b) iii. Smooth muscle is found throughout the body in the walls of most organs (Figure 31-9c) 4. Nerve tissue is specialized to produce and conduct electrical signals (Figure 31-10) a. This tissue is composed of cells called neurons (Figure 31-10a) i. These cells are specialized to generate and conduct electrical signals b. Glial cells surround, protect, and support neurons (Figure 31-10b) C. Organs Include Two or More Interacting Tissue Types 1. Organs are formed from two or more tissue types that function together 2. The skin illustrates the properties of organs (Figure 31-11) a. This organ contains all four tissue types in varying organization D. Organ Systems Consist of Two or More Interacting Organs (Table 31-1) 1. Organs function together to perform a common function

Case Study Revisited: Overheated

KEY TERMS adipose tissue blood bone cardiac muscle cartilage connective tissue dermis ectotherm endocrine gland endotherm epidermis

epithelial tissue exocrine gland gland glial cell hair follicle homeostasis hormone ligament lymph negative feedback nerve tissue

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neuron organ organ system positive feedback simple epithelium skeletal muscle smooth muscle stratified epithelium tendon tissue

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LECTURE ACTIVITIES Lecture Activity 31.1: Nonbiological Examples of Feedback Estimated Time to Complete: 15 minutes Section Reference 31.1 Homeostasis: How Do Animals Regulate Their Internal Environment?

Introduction In this activity, students are asked to describe nonbiological examples of feedback and identify if they are positive or negative feedback systems.

Materials Needed None Procedures With students in small groups, have them list as many nonbiological examples of feedback that they can think of.

The thermostat example used in the textbook is a good example of a nonbiological negative feedback system.

When students have had 5–10 minutes for discussion, have the groups report to the class and write the results down on a list that is visible for the class.

Once the list is assembled, assign each group one or two of the examples and have them explore the various components of the feedback systems to see if they can identify the CONTROL CENTER, EFFECTORS, and SENSORS in each system.

Assessment Suggestions If computers are available in the classroom, students can perform an Internet search using “homeostasis” as the search term to help them with their discussions.

Lecture Activity 31.2: Orthostatic Stress Response as an Example of Negative Feedback Estimated Time to Complete: 15 minutes Section Reference 31.1 Homeostasis: How Do Animals Regulate Their Internal Environment?

Introduction In this activity, negative feedback can be demonstrated using heart rate and its control on blood pressure.

Materials Needed • A clean area where students can lay flat comfortably • A watch or clock with a second hand Procedures Begin with a general description of factors that affect blood pressure. Blood pressure is essentially a measure of how much blood leaves the heart per unit of time (cardiac output) and the amount of resistance that the blood faces (peripheral resistance).

Heart rate is one way that cardiac output can increase or decrease.

While we are lying down, the blood is evenly distributed throughout the body. With gravity less of an obstacle, normal blood pressure can be maintained at a lower heart rate than what is required when we are standing. As soon as we stand up, because of the presence of gravity, all of the blood rushes down to our legs, and there is a drop in our blood pressure, as the body does not expect the sudden change in posture. This causes the dizziness that we sometimes feel when standing up quickly.

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Pressure receptors near the aorta and carotid arteries feel this drop in pressure and send a signal to the brain. The brain then sends a signal to the heart, which causes an increase in heart rate. This increase in heart rate causes an increase in cardiac output and a restoration of normal blood pressure. All of these changes happen within seconds of standing and represent an excellent example of negative feedback.

Have the students work with a partner.

While seated and rested, have the students measure their resting heart rate (count the number of beats in 15 seconds and multiply by 4).

Have one student in each pair lay flat and rest comfortably for 7–10 minutes.

Just before the end of the rest period, and before getting up, have them take their pulse to determine their heart rate.

Now have the students stand up quickly with support from their partners.

NOTE: It is very important that the partners be near enough to support the students in case they feel dizzy when standing up quickly.

Make a measurement of heart rate immediately and continue to take measurements for the next 3–5 minutes.

If time permits, you can switch roles within the student pairs so that everyone experiences the response.

Assessment Suggestions 1. In this example of negative feedback, what is the CONTROL CENTER, SENSOR, and EFFECTOR in the system?

2. Explain any differences in heart rate that you measured from rest (while sitting and rested) to rest (while flat and rested).

3. Explain any differences in heart rate that you measured from rest to standing up quickly.

4. How is this an example of negative feedback?

Lecture Activity 31.3: Simple Demonstration of Positive Feedback with an Audio Squeal Estimated Time to Complete: 3 minutes Section Reference 31.1 Homeostasis: How Do Animals Regulate Their Internal Environment?

Introduction Using an audio file, this activity will demonstrate how an audio “squeal” generated by an audio system is a good example of positive feedback.

Materials Needed • A computer with the ability to play audio files (.wav format), Internet access, and audio speakers loud enough for the classroom to hear Procedures Go to www.wikipedia.com, and enter the search term “audio feedback.” The page that will appear has an audio file of audio feedback. Play this for your class.

Description of the positive feedback loop: Most people have experienced the painful squeal from an audio system. Audio feedback squeal is produced by the creation of a positive feedback loop in the microphone/amplifier/speaker system. This occurs when the microphone is located in a sound field generated by the speaker driven by an amplifier with its level set too high.

The sound that leaves the speaker is picked up by the microphone and then amplified. This amplified signal is then picked up by the microphone again and sent back to the amplifier.

Assessment Suggestions Use this activity as a classroom demonstration of positive feedback. The following questions can be used as discussion: In this simple positive feedback loop, what is the variable that is being controlled by this system? What components represent the control center, sensor, and effector in this feedback system?

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Lecture Activity 31.4: Case Study on Connective Tissues Estimated Time to Complete: 20 minutes Section Reference 31.2 How Is the Animal Body Organized?

Introduction In this activity, a simple case study is used to explore dense connective tissues and their structure.

Materials Needed • A handout of the case (following page) and the questions that follow (a copy for each student) Procedures Have the students work in small groups (three or four students) so that they can discuss the details of the case and answer the questions that follow. Hand out copies of the case to the students and read the case to the entire class. Have the groups discuss their answers to the questions that follow the case.

Assessment Suggestions The answers to the questions can be graded as an individual or group assignment, or the groups can reassemble for a large classroom discussion of the answers.

Answers to case questions: 1. What types of human tissues are represented by the injuries suffered by this patient?

(Ligaments are considered a form of fibrous connective tissue. Cartilage is considered a form of specialized connective tissue.)

2. Describe the structure of the two different types of tissues that have suffered damage.

(Ligaments contain collagen fibers, which are densely packed together in an orderly parallel arrangement.

Cartilage contains widely spaced cells that are surrounded by a thick, nonliving matrix [space] filled with collagen.)

3. Using what you know about the structure of these tissues, explain how they are designed to withstand the stress placed on this joint during a football game.

(Collagen fibers are very strong and flexible. In addition, the arrangement of the collagen fibers within a tissue can affect the strength of the tissue. Ligaments and cartilage are strong because they contain collagen, and the orderly arrangement of the fibers in ligaments adds to the strength needed to hold the knee joint together when it is under stress.)

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 31.4 Handout—Case Study on Connective Tissues The Football Game Andre Billings, a 24-year-old male, presented in the emergency room with complaints of severe left knee pain and knee instability. The patient described a violent “hit” that caused his left knee to buckle. The patient described hearing a “pop” as he fell to the playing field.

An initial examination of the knee revealed inflammation and a reduced range of motion. Flexion (bending) was reduced to 64° and extension (straightening) was incomplete. An examination of the joint revealed a major instability. The physician orders a magnetic resonance imaging (MRI) scan and schedules an exploratory arthroscopic knee surgery for the following week. The results of the tests show that Andre has torn his anterior cruciate and medial collateral ligaments. In addition, there is a tear in the medial meniscus (knee cartilage).

Questions 1.

What types of human tissues are represented by the injuries suffered by this patient?

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Describe the structure of the two different types of tissues that have suffered damage.

3.

Using what you know about the structure of these tissues, explain how they are designed to withstand the stress placed on this joint during a football game.

Suggested Text Readings Section 31.2: How Is the Animal Body Organized?

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CHAPTER 32 CIRCULATION LECTURE OUTLINE Case Study: Running with Heart 32.1 What Are the Major Features and Functions of Circulatory Systems?

A. All Circulatory Systems Have Three Major Parts 1. A pump, the heart, that keeps blood circulating 2. A liquid, blood, that serves as a medium for transport 3. A system of tubes, blood vessels, that conducts the blood throughout the body B. Two Types of Circulatory Systems Are Found in Animals 1. Open circulatory systems are found in many invertebrates, including arthropods and mollusks a. Animals with these systems have one or more simple hearts, vessels, and a space within the body cavity called the hemocoel (Figure 32-1a) b. Tissues and organs are bathed with hemolymph 2. Closed circulatory systems are found in some invertebrates and mollusks and all vertebrates (Figure 32-1b) a. Blood is confined in a continuous vascular network with a pumping heart C. The Vertebrate Circulatory System Has Diverse Functions 1. It transports O2 and CO2 to and from the tissues 2. It distributes nutrients from the digestive system to body cells 3. It transports waste and toxic substances to the liver 4. It distributes hormones from glands and organs to body cells 5. It regulates body temperature 6. It prevents blood loss by producing blood clots 7. It protects the body against disease

32.2 How Does the Vertebrate Heart Work?

A. The Vertebrate Heart Consists of Muscular Chambers Capable of Strong Contractions 1. Atria collect blood and pump it to the ventricles 2. Ventricles circulate blood to the lungs and the rest of the body B. The Two-Chambered Heart of Fishes Was the First Vertebrate Heart to Evolve 1. The hearts of fish have two main contractile chambers: a single atrium and a single ventricle (Figure 32-2a) C. Increasingly Complex and Efficient Hearts Evolved in Terrestrial Vertebrates 1. Amphibians and most reptiles have three-chambered hearts (Figure 32-2b) a. An important adaptation in these terrestrial vertebrates is double circulation, which creates two separate circuits of blood i. The pulmonary circuit directs blood from the heart through the lungs ii. The systemic circuit carries blood between the heart and the rest of the body D. Four-Chambered Hearts Consist of Two Separate Pumps 1. Birds, mammals, and some reptiles have four-chambered hearts (Figure 32-2c) a. This type of heart acts like two hearts beating as one (Figure 32-3) i. The “right heart,” consisting of the right atrium and ventricle, deals with oxygen-poor blood ii. Veins carry blood to the heart, and arteries carry blood away iii. The right ventricle pumps blood to the lungs iv. The “left heart,” consisting of the left atrium and ventricle, deals with oxygen-rich blood v. The left ventricle pumps blood to the body E. Valves Maintain the Direction of Blood Flow 1. Atrioventricular valves allow blood to flow from atria to ventricles, but not the reverse

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2. Semilunar valves allow blood to enter the pulmonary artery and aorta when the ventricles contract, but prevent backflow of blood F. Cardiac Muscle Is Present Only in the Heart 1. Cardiac muscle cells are small and branched and have a striped appearance (Figure 32-4) a. Cardiac muscle cells are linked to one another by intercalated discs G. The Coordinated Contractions of Atria and Ventricles Produce the Cardiac Cycle 1. Each heartbeat is a series of coordinated events called the cardiac cycle (Figure 32-5) 2. The cardiac cycle generates the forces measured when blood pressure is taken (Figure 32-6) a. Systolic pressure is measured during ventricle contraction b. Diastolic is the minimum pressure in the arteries as the heart rests between contractions c. Hypertension is high blood pressure â Health Watch: Repairing Broken Hearts (Figures E32-1, E32-1, and E32-3) â Case Study Continued: Running with Heart H. Electrical Impulses Coordinate the Sequence of Heart Chamber Contractions 1. The contraction of the heart is initiated and coordinated by a pacemaker a. The sinoatrial node (SA node) is the heart’s pacemaker and initiates a wave of contraction (Figure 32-7) b. The atrioventricular node (AV node) channels the contraction impulse c. The impulse is then conducted to other parts of the heart 2. When the pacemaker fails, fibrillation can occur I. The Nervous System and Hormones Influence Heart Rate 1. The parasympathetic nervous system decreases heart rate 2. The sympathetic nervous system increases heart rate 3. Hormones can have differing effects on heart rate â Lecture Activity 32.1: Demonstrating Coronary Artery Disease

32.3 What Is Blood?

A. Blood Has Two Major Components 1. A liquid, called plasma, makes up about 55–60% of the blood 2. The cell-based component includes red and white blood cells and platelets (Figure 32-8 and Table 32-1) B. Plasma Is Primarily Water in Which Proteins, Salts, Nutrients, and Wastes Are Dissolved 1. Plasma is approximately 90% water 2. It contains molecules of dissolved proteins, hormones, nutrients, ions, and wastes 3. Plasma contains three major plasma proteins a. Albumins b. Globulins c. Fibrinogen C. The Cell-Based Components of Blood Are Formed in Bone Marrow 1. All three cell-based components of the blood originate from cells in the bone marrow D. Red Blood Cells Carry Oxygen from the Lungs to the Tissues 1. Red blood cells are called erythrocytes (Figure 32-8a) a. These make up 99% of the total cellular component in the blood 2. Red blood cells contain hemoglobin that transports O2 from the lungs to the tissue (Figure 32-9) 3. Negative feedback regulates red blood cell numbers a. Erythropoietin is produced by the kidney in response to oxygen deficiency and stimulates the production of red blood cells (Figure 32-10) â Lecture Activity 32.2: Understanding Anemia â Case Study Continued: Running with Heart E. White Blood Cells Defend the Body Against Disease 1. White blood cells are called leukocytes a. There are five types of leukocytes (Figure 32-8b) b. These cells make up 1% of the total cellular component of blood 2. Monocytes, a type of white blood cell, turn into macrophages that can engulf bacteria (Figure 32-11) F. Platelets Are Cell Fragments That Aid in Blood Clotting 1. Platelets are pieces of large cells called megakaryocytes .

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b. When the process is completed, a clot forms (Figure 32-13) c. Hemophilia is a genetic disorder; those affected lack a protein called clotting factor â Lecture Activity 32.3: Case Study: The Baseball Injury

32.4 What Are the Types and Functions of Blood Vessels?

A. Blood Circulates Through the Body Within a Network of Vessels (Figure 32-14) 1. Blood leaving the heart travels from arteries to arterioles to capillaries to venules to veins and back to the heart (Figure 32-15) B. Blood Vessels Are Composed of a Variety of Tissues â Health Watch: Repairing Broken Hearts (Figures E32-1, E32-1, and E32-3) C. Arteries and Arterioles Carry Blood Away from the Heart 1. The walls of arteries are thicker and have elastic tissue to withstand high pressure 2. Arteries branch into smaller arterioles D. Capillaries Allow Exchange of Nutrients and Wastes 1. Arterioles branch into capillaries a. These tiny vessels are a single cell thick for easy diffusion (Figure 32-16) 2. These vessels exchange materials between blood and the fluid that bathes body cells, called interstitial fluid a. Substances diffuse through the capillary walls b. High pressure in the capillaries causes them to leak fluid, which drains to the lymphatic system E. Veins and Venules Carry Blood Back to the Heart 1. They provide a low-resistance pathway for blood flow back to the heart a. Veins are thin-walled vessels that are more expandable than arteries b. Veins contain valves to prevent the backflow of blood (Figure 32-17) 2. Blood pressure in veins is low, but breathing and the contraction of skeletal muscles helps return blood to the heart F. Arterioles Control the Distribution of Blood Flow 1. The muscular walls of the arterioles control blood flow 2. The flow is influenced by nerves, hormones, and other chemicals released from nearby tissues 3. Muscles called precapillary sphincters further control blood flow â Lecture Activity 32.4: Vessel Diameter and Blood Pressure

32.5 How Does the Lymphatic System Work with the Circulatory System?

A. The Lymphatic System Is Composed of Organs and Vessels That Eventually Feed into the Circulatory System (Figure 32-18) 1. This system has a variety of functions a. Return excess interstitial fluid to the bloodstream b. Transport fats from the small intestine to the bloodstream c. Filter aged blood cells and debris from the blood d. Defend the body by exposing bacteria and viruses to white blood cells B. Lymphatic Vessels Resemble the Capillaries and Veins of the Circulatory System 1. These vessels are highly permeable and “dead-end” in the extracellular fluid surrounding body cells (Figure 32-19) 2. Lymphatic vessels have one-way valves, as in veins (Figure 32-20) C. The Lymphatic System Returns Interstitial Fluid to the Blood 1. Blood capillaries leak fluid into the extracellular spaces a. The fluid is forced into lymphatic capillaries, which transport it back to the circulatory system i. This transport is extremely important to the body, and malfunctions can cause serious health problems (Figure 32-21) D. The Lymphatic System Transports Fats from the Small Intestine to the Blood E. Lymphatic Organs Help Defend the Body 1. Organs of the lymphatic system are important in the immune response a. The thymus, tonsils, lymph nodes, and spleen are all involved

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KEY TERMS angina arteriole artery atherosclerosis atrioventricular (AV) node atrioventricular valve atrium (plural, atria) blood blood clotting blood vessel bone marrow capillary cardiac cycle cardiac muscle closed circulatory system diastolic pressure erythrocyte

erythropoietin fibrillation fibrin heart heart attack heart rate hemocoel hemoglobin hemolymph hypertension intercalated disc leukocyte lymph lymph node lymphatic capillary lymphatic system open circulatory system

plaque plasma platelet precapillary sphincter pulmonary circuit semilunar valve sinoatrial (SA) node spleen stroke systemic circuit systolic pressure thrombin thymus tonsil vein ventricle venule

LECTURE ACTIVITIES Lecture Activity 32.1: Demonstrating Coronary Artery Disease Estimated Time to Complete: 5 minutes Section References 32.2 How Does the Vertebrate Heart Work?

Case Study: Running with Heart Health Watch: Repairing Broken Hearts Introduction For more information on coronary artery disease, perform an Internet search using “coronary artery disease” as search terms. Prior to performing the activity, perform the Internet search in order to find useful Web sites to reference. This activity is a demonstration.

Materials Needed • Computer instructor station with projection system; computer must have Internet access Procedures 1. Using the Web sites you accessed in the Internet search, show the students how coronary artery disease develops.

Assessment Suggestions As a demonstration, there would be no formal assessment of this activity; however, a discussion of the process might be helpful to improving student understanding of it.

Lecture Activity 32.2: Understanding Anemia Estimated Time to Complete: 5–10 minutes if Part II is used as a take-home, or 25–30 minutes if Part II is used in class Section Reference 32.3 What Is Blood? .

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Introduction In this activity, the students will be able to explore a specific type of anemia called pernicious anemia (or megaloblastic anemia).

Materials Needed • Students should have access to a copy of the text as a reference.

• A copy of the case and the questions should be handed out to each student or projected for the class to read. Do not hand out the research part (Part II) until the case (Part I) has been discussed in the small groups.

Procedures 1. Put the students into discussion groups of three or four students.

2. Hand out Part I. 3. Give the groups a chance to see if they can use the information to account for the patient’s symptoms. They do not need to diagnose the person, but they should be able to relate the symptoms to the blood test results.

Students may need to look up what a normal hematocrit would be for a male.

4. Let them discuss the results of the blood tests and see if they can come up with an explanation of what the problem might be.

5. Follow up by handing out the research questions (Part II).

6. Part II can be done in class if resources are available (Internet access, other text references, etc.) or it can be handed out as an assignment.

Information for the instructor: A review of the blood tests reveals a low red blood cell count and a low amount of hemoglobin. The platelet count is normal.

Students should see this as evidence that this person is not suffering from a bleeding disorder. Although this person has a low number of RBCs, the ones that he does have are very large. This also accounts for the high amount of hemoglobin per cell.

This person has pernicious anemia. The low amount of hemoglobin in the circulation can account for the complaints of fatigue, dizziness, and difficulty completing simple tasks. There are many causes of this condition. Often referred to as megaloblastic anemia, this condition can be caused by a deficiency in vitamin B 12 (a derivative of folic acid). An important substance called intrinsic factor, which is produced by the stomach, is needed for proper absorption of this vitamin. In pernicious anemia, this factor is often deficient. Vitamin B 12 is important for development and division of red blood cells in bone marrow. Without this vitamin, the cells do not divide (low number) but continue to grow and enlarge (large volume).

Assessment Suggestions The research portion of the activity can be done as a take-home assignment. Answers to the research questions can be handed in as an assignment or for comments.

Handouts or Display See the following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 32.2 Handout—Understanding Anemia Part I: Why am I so tired?

A 48-year-old male complains that he is becoming progressively more fatigued at the end of his work day.

Seemingly simple tasks take enormous amounts of effort to complete. In many instances, the simple tasks lead to dizziness and shortness of breath and difficulty in breathing. The patient reports frequent headaches and difficulty in sleeping. Blood tests revealed the following results: Hematocrit: A hematocrit measures the percentage of blood volume that the red blood cells account for. In this person, the value is 29%.

Hemoglobin level (measured as grams per 0.1 liters): Low Average volume of a red blood cell: High Average amount of hemoglobin per red blood cell: High Platelet count: Normal Can you come up with an explanation of the symptoms that this patient is describing?

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Part II: Research This person is suffering from a disease called pernicious anemia. Some people refer to this disease as megaloblastic anemia. The “mega” makes reference to the fact that the red blood cells are very large in this condition. Using resources from the library, the Internet, and other text references, explore the following questions: 1.

What causes this type of anemia?

2.

What are the treatments for this disease?

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Can you explain the results of the blood tests for this patient from what you know about this disease?

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Lecture Activity 32.3: Case Study: The Baseball Injury Estimated Time to Complete: 20–30 minutes Section Reference 32.3 What Is Blood?

Introduction In this activity, the students will review a case study and work through a series of directed questions relating to the case. The activity will be set up as a “jigsaw” activity. In this format, individual students will take responsibility for specific content questions and then they will report their findings to each other. The groups will then be asked to use their knowledge to work through the group discussion questions.

Materials Needed • Students should have a copy of the textbook with them to use as a reference.

• A copy of the case study and the questions should be given to each student.

Procedures This case can be used as either a review of material already covered in class (lecture review), or as a teaching tool to introduce the students to the concepts for the first time.

Place the students into groups of four. Four students will be ideal, because in the jigsaw format, each student will be responsible for one of the content questions. If a group has only three students, then one student can be responsible for more than one question. Hand out a copy of the case and the questions to each student. Explain that they need to assign a question to each student in the group. The discussion questions will be addressed after the students have had a chance to work on the content questions.

Using textbook Section 32.3, and any other resources available (such as the Internet), the students should work on their individual questions. After about 10 minutes, the students should assemble in their groups and report to each other on what they have found. Encourage the students to ask each other questions. After 5–10 minutes of discussion, have the groups work together to address the group discussion questions. After 5–10 more minutes, the groups can be given a chance to report what they have discussed to the entire class.

Assessment Suggestions A general assessment of student understanding from the group and class discussions can be done. In addition, answers to the individual questions or entire set of questions can be turned in for comments and/or a grade.

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 32.3 Handout—The Baseball Injury You are a specialist who has been contacted by a surgeon regarding a new patient. The patient is an 8-year-old male with a history of a chronic hematoma (deep bruise) following a sports-related injury. The patient was hit with a baseball on the right thigh 3 weeks prior to the hospital visit. An initial exam made by the family physician revealed full flexion (bending) and extension (straightening) of the knee and hip joint and mild tissue edema (swelling). An X-ray exam revealed no signs of any fractures.

Initially the area had been described by the patient as “tender.” The edema has increased progressively since the injury, and the patient presents to you with pain in the foot and thigh. The patient has been icing the injury daily, and drug treatment has consisted of Tylenol and Advil. Physical examination is negative, except for a swollen, tender right thigh with bruising that will not resolve (go away). Tests were run to determine that the patient maintains normal liver function. The following results are from a blood test: Hematocrit: A hematocrit measures the percentage of blood volume that the red blood cells account for. In this person, the value is 28.8%.

Hemoglobin levels: Low Platelet count: Normal Activated Partial Thromboplastin Time (APTT): This is a test that measures how fast a person’s blood is able to produce a clot. In this patient, the value is 60 seconds. This is about two times longer than what you would normally find.

Individual Content Questions 1.

Is the hematocrit for this patient normal? What would a normal hematocrit be for this person? Would the normal value be different if this patient were female?

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What is the function of hemoglobin? How is the amount of hemoglobin related to the amount of red blood cells in a person’s blood? What symptoms might you find in someone with very low hemoglobin levels?

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3.

Where in the body are platelets made? What is their role in blood clot formation? Under what conditions do platelets become “sticky”?

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Explain the process of clot formation. In your description, discuss the role of the various plasma proteins that are involved. How do these plasma proteins interact with platelets?

Group Discussion Questions 1.

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3.

From the various pieces of evidence that you have reviewed in this case, explain why this boy has the following symptoms: a hematoma that will not heal bruising that will not go away low hemoglobin levels How is it possible that this patient is having difficulty forming a clot when the platelet count is normal?

If the problem appears to be with the blood, explain why tests were run on the liver.

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Lecture Activity 32.4: Vessel Diameter and Blood Pressure Estimated Time to Complete: 5–10 minutes Section Reference 32.4 What Are the Types and Functions of Blood Vessels?

Introduction Using simple analogies, the principle of pressure and vessel diameter can be demonstrated and related to blood pressure and cardiovascular disease.

Materials Needed None Procedures This can be done in a full-class discussion, or in small groups of two or three students. Each description is followed up with discussion questions relating to important principles.

The material below can be read to the class or handed out as individual scenarios for discussion: Consider the following: A hose is hooked up to a faucet and the water is turned on. Water leaves the end of the hose under a specific amount of pressure.

What happens to the pressure in the hose as I put my thumb over the opening? What is happening to the pressure in the hose?

Hoses are built to withstand a certain amount of pressure. What would happen to the hose if the pressure were always near its maximum pressure? How is this related to what happens in a vessel in someone with atherosclerosis?

A hose is hooked up to a faucet and the water is turned on. Water leaves the end of the hose under a specific amount of pressure.

You now attach another hose to the end of this one that has a much larger diameter. How does water leaving this hose compare to the water leaving the hose with the smaller diameter? What happens to the pressure as water leaves the narrow hose and enters the hose with the larger diameter? How does this relate to vessel diameter and blood pressure?

Assessment Suggestions Student understanding can be assessed from the answers to the class discussion questions. This activity works well as a class discussion.

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CHAPTER 33 RESPIRATION LECTURE OUTLINE Case Study: The High Life Can Lead to Death 33.1 Why Exchange Gases and What Are the Requirements for Gas Exchange?

A. The Exchange of Gases Supports Cellular Respiration 1. Respiration is the process by which organisms exchange gases with the environment a. Oxygen is taken in and carbon dioxide is released B. Gas Exchange Through Cells and Tissues Relies on Diffusion 1. All animal respiratory systems meet three requirements that facilitate the diffusion of O 2 and CO2 a. The respiratory surface must be moist b. The respiratory surfaces are thin c. Respiratory surfaces must have a large surface area 2. The movement of air across the respiratory surface is called bulk flow

33.2 How Do Respiratory Adaptations Minimize Diffusion Distances?

A. Relatively Inactive Animals May Lack Specialized Respiratory Organs B. Some Animals in Moist Environments Lack Specialized Respiratory Structures 1. Sponges live in aquatic environments and use ciliated cells to create a current of water from which they can absorb gases (Figure 33-1a) 2. Sea jellies, corals, and anemones have thin skin that allows gas exchange by diffusion (Figure 33-1b) a. Flatworms also have thin skin and a large surface for diffusion (Figure 33-1c) 3. Other animals, such as earthworms, combine skin surface with complex circulation for delivery to cells C. Respiratory Systems and Circulatory Systems Often Work Together to Facilitate Gas Exchange (Figure 33-2) 1. Air or water moves past respiratory surfaces by bulk flow 2. Oxygen and carbon dioxide are exchanged by diffusion 3. Gases are transported to tissues by bulk flow 4. Gases are exchanged with tissues and the circulatory system by diffusion D. Gills Facilitate Gas Exchange in Aquatic Environments (Figure 33-3) 1. Gills are adapted to have a large surface area 2. Fish create a continuous current over their gills by pumping water into their mouths and ejecting it through the operculum 3. Fish exchange gases by countercurrent exchange â In Greater Depth: Gills and Gases—Countercurrent Exchange (Figures E33-1 and E33-2) E. Terrestrial Animals Have Internal Respiratory Structures 1. Natural selection has favored structures whose thin membranes are protected, supported, and kept moist 2. Insects respire using tracheae (Figure 33-4) a. Openings called spiracles open into tracheae, which deliver air to body cells 3. Terrestrial vertebrates respire using lungs a. Lungs are chambers containing moist respiratory surfaces that are protected within the body b. Amphibians use a combination of methods to exchange gases (gills, skin, lungs) (Figure 33-5a, b) 4. Reptiles have a waterproof skin, so they rely completely on their lungs, which have a large surface area (Figure 33-5c) 5. Bird lungs have special adaptations that allow exceptional gas exchange (Figure 33-6) a. Air sacs serve as reservoirs for air

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33.3 How Is Air Conducted Through the Human Respiratory System?

A. The Human Respiratory System Can Be Divided into Two Parts 1. The conducting portion carries air to the gas-exchange portion B. The Conducting Portion of the Respiratory System Carries Air to the Lungs 1. The conducting portion consists of many different structures (Figure 33-7) a. The upper parts include the pharynx, larynx, epiglottis, and esophagus i. If the larynx gets clogged, the Heimlich maneuver can be used to dislodge the clog (Figure 33-8) b. The vocal cords are within the larynx i. As air passes through them, different sounds can be made c. Air travels from the larynx through the trachea, and then into the internal parts of the conducting portion, which includes the bronchi and bronchioles i. Bronchioles lead to the alveoli â Health Watch: Smoking—A Life and Breath Decision (Figure E33-3) C. Air Is Inhaled Actively and Exhaled Passively 1. Breathing occurs in two stages: inhalation and exhalation a. During inhalation, the diaphragm is contracted, which pulls it downward (Figure 33-9a) i. This draws air into the lungs b. During exhalation, the diaphragm is relaxed and moves upward (Figure 33-9b) i. This pushes air out of the lungs â Lecture Activity 33.1: Forced Exhalation and Emphysema D. Breathing Rate Is Controlled by the Respiratory Center of the Brain 1. The respiratory center is in the medulla 2. Signals are provided by the concentration of carbon dioxide levels in the blood a. These can increase or decrease the breathing rate â Lecture Activity 33.2: The Cough â Case Study Continued: The High Life Can Lead to Death

33.4 How Does Gas Exchange Occur in the Human Respiratory System?

A. Gas Exchange Occurs in the Alveoli 1. Alveoli are sacs covered with capillaries (Figure 33-7b) 2. They contain a single layer of epithelial cells a. Surfactant prevents the collapse of alveoli 3. The respiratory membrane consists of the alveolar wall and the capillary wall a. Gases only need to diffuse a short distance (Figure 33-10) â Case Study Continued: The High Life Can Lead to Death B. Oxygen and Carbon Dioxide Are Transported in Blood Using Different Mechanisms 1. Blood picks up O2 and transports it to body tissues and also picks up CO2 for transport to the lungs a. Both gases diffuse down their concentration gradients (Figure 33-10) b. Nearly all the O2 in blood is carried by hemoglobin (Figure 33-11a) 2. Carbon dioxide is transported in the blood in three ways by various mechanisms (Figure 33-11b) a. Dissolved in the plasma (10%) b. Bound to hemoglobin (20%) c. Most is transported in the plasma as bicarbonate (70%) â Lecture Activity 33.3: Dissolved Gases—Soda Bottle Demonstration â Lecture Activity 33.4: pH and the Transport of Carbon Dioxide

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KEY TERMS alveolus (plural, alveoli) bronchiole bronchus (plural, bronchi) bulk flow conducting portion countercurrent exchange diaphragm epiglottis

exhalation gas-exchange portion gill Heimlich maneuver hemoglobin inhalation larynx lung

pharynx respiration respiratory center respiratory membrane respiratory system spiracle trachea tracheae vocal cords

LECTURE ACTIVITIES Lecture Activity 33.1: Forced Exhalation and Emphysema Estimated Time to Complete: 15–20 minutes Section Reference 33.3 How Is Air Conducted Through the Human Respiratory System?

Introduction In this activity, the students explore the forces associated with a forced exhalation in both a normal lung and the lung of an emphysema patient. The students should be familiar with the anatomy of the lung and the structure and function of the trachea, bronchi, bronchioles, and alveoli.

Materials Needed • Handouts of the simplified pictures of the lungs (see the following pages) • Transparency or overhead diagram of the anatomy of the human lung showing the pleural space Procedures Part I: Normal Lung Hand out a copy of the picture for an exhalation in a normal lung to each student and orient them to the various parts. Emphasize that this picture has been simplified for demonstration purposes.

The instructor should have a transparency or projected image of these pictures that can be shown to the class during the activity.

Discuss the three forces that cause air to leave the lungs during exhalation: chest collapses, diaphragm moves upward, and the lungs recoil like a rubber band. These forces put pressure on the lungs and the air is forced out.

Discuss what happens during a forced exhalation: additional forces added by contracting muscles to collapse chest and abdomen.

Using simple numbers, work with the students to show how these forces work together to create the positive pressures in the lungs that help expel the air.

Begin by having the students write a “40” in the box next to the CHEST WALL AND DIAPHRAGM label. This will represent the value of these forces during exhalation.

Next, have the students write a “15” next to the ELASTIC LUNG label. This represents additional force placed on the air in the lungs when the lung recoils like a rubber band during an exhalation.

ASK: “What would be the total force on the air in the alveoli?”

(The total force would be 55. Have the students write a “55” in the box inside the ALVEOLI.)

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Explain that as this air is leaving the lung, it is entering larger and larger tubes (larger and larger bronchioles, bronchi, and trachea).

ASK: “What is going to happen to the pressure of this air as it enters these larger and larger tubes?”

(The pressure will drop as it moves up the respiratory tree.)

A useful analogy to use here is to describe water flowing through a hose of a specific diameter under constant pressure. If a hose with a much larger diameter is attached to the end of the smaller hose, what happens to the water pressure as it moves into the larger hose?

Using the figure, have the students move up the tube to each box and drop the pressure by 5 as they go to each one. The sequence should now read 55 – 50 – 45 – 40 – 35 – 30.

Have the students identify the point at which the pressure in the “tube” drops below the pressure exerted by the CHEST WALL AND DIAPHRAGM. ASK: “Why is this point significant?”

(Because the lungs are enclosed in the chest cavity, all of the bronchioles and bronchi feel the pressure exerted by the chest during the forced exhalation. The result is that the chest could cause the tube to collapse when the pressure inside the tube falls below the pressure exerted by the chest. The very force that helps expel the air can interfere with its ability to leave the lungs. This “airway collapse” would interfere with a person’s ability to exhale.)

ASK: “Why do the airways in a normal lung not collapse when we perform a forced exhalation?

(In a normal lung, the point at which the pressure in the “tube” falls below the pressure exerted by the chest is very high in the respiratory tree. If the students are familiar with the anatomy of the respiratory system, they will remember that at these “high points,” the pathway is reinforced with semicircular bands of stiff cartilage that help prevent these tubes from collapsing under pressure.)

At this point, the students should be able to explain why the airway in a normal lung does not collapse when a forced exhalation is performed.

Move on to Part II to explore this concept in the lung of an emphysema patient.

Part II: Emphysema Lung Hand out the picture of the emphysema lung diagram to each student.

In this activity, it is useful to assemble the students in small groups of three or four students to work on the discussion questions. Explain that in an emphysema patient, the elasticity of the lung is lost as the alveoli disintegrate and the elastic tissue degrades.

ASK: “What will this do to the forces that are used in a forced exhalation?”

(The elastic recoil force becomes much smaller and emphysema patients begin to rely on the contraction of muscles to perform a forced exhalation.)

Have students write a “40” in the box for the CHEST WALL AND DIAPHRAGM force and a “5” in the ELASTIC LUNG box. Emphasize the lower number for the elastic force of the lung and how this relates to emphysema.

Using concepts similar to those in Part I, have the students fill in the rest of the boxes and then consider the following discussion questions in their small groups or as a classroom: What happened to the point at which the pressure in the tube fell below the CHEST WALL AND DIAPHRAGM force?

(This point moves further down in the respiratory tree.)

What implications would this have for the emphysema patient?

(Because chest pressure overcomes “tube” pressure much earlier, the tubes are likely to be collapsible. Bronchioles of various sizes do not have the cartilage support seen much higher in the respiratory tree. If the airway collapses, the person will not be able to move the air and a much smaller volume of air will be exhaled.)

Why do emphysema patients need to perform forced exhalations?

(Without the elasticity of the lung helping to move the air, an emphysema patient will exhale a much smaller volume of air during a normal breath. In order to exhale more air, a forced exhalation must be performed.)

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For further discussion: When emphysema patients rely on normal breathing, the volume of air that is exhaled is reduced when compared to a normal lung (this is due to the loss of lung elasticity). Over time, the amount of CO 2 in the blood will build and the control center of the brain will signal the body to increase respirations to help expel this excess gas. Forced exhalations are necessary in order to prevent the hyperventilation that would occur as the CO 2 levels build. The irony is that a forced exhalation in an emphysema patient has the potential of causing an airway collapse, which would interfere with the removal of CO2. Conscious control of breathing rate and depth in severe emphysema is an important part of the management of this disease. One way to significantly reduce your risk of developing this debilitating disease is to quit smoking (or never smoke at all).

Assessment Suggestions None Handouts or Display See the following pages.

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Lecture Activity 33.2: The Cough Estimated Time to Complete: 30–40 minutes Section References 33.3 How Is Air Conducted Through the Human Respiratory System?

Health Watch: Smoking—A Life and Breath Decision Introduction In this activity, a case study is used to help students explore the role of the respiratory system and how smoking can interfere with this function on multiple levels. Within this activity, the students are asked to make connections to the earlier material on blood and circulation.

The case can be used prior to introducing respiration to encourage the students to explore material in the text before it is introduced in class. If the case is to be used this way, more time must be devoted in class so that the students have ample time to read and ask questions. Another possibility is to have the students complete the case as an assignment prior to the introduction of material in the classroom.

Alternatively, the case can be used to encourage the application of concepts related to the respiratory and cardiovascular systems after they have been presented in class. The case can be completed in small groups during a class period or as an assignment done outside of class time.

Materials Needed • A copy of the handout of the case and case questions to each student • A copy of the textbook or other reference material on respiration and chronic obstructive pulmonary disease (COPD) for each student Procedures Several of the questions that follow the case challenge students to make connections to a variety of concepts.

In order to facilitate this process, it is helpful to have the students in small groups of three or four students to encourage discussions.

After handing out the case, have a student in each group volunteer to read the case to their group and act as a facilitator to work through the case questions and discuss the answers. It is important that the groups have the textbook or other material on COPD available to use as a reference.

When the small groups have had 20–25 minutes to discuss the answers, the classroom can be reassembled for a class discussion.

Have the groups take turns reporting question answers to the class and encourage other groups to add additional information as the discussion continues.

Assessment Suggestions None Handouts or Display See the following pages.

Handout Answer Key 1. What is hypertension? What is the likely cause of this patient’s hypertension? What is “average” blood pressure, and how does this patient’s blood pressure compare?

(Hypertension is a chronic condition in which the blood pressure is abnormally elevated. Normal blood pressure is often considered to be 120/80. The blood pressure in this patient is elevated. Smoking is very likely a contributing factor in this case.)

2. A “blood gas test” was performed to measure oxygen levels. Explain why the blood was taken from an artery (arterial) and not a vein.

(The fluid in the lungs and “blue” appearance of this patient suggest that this person is not delivering enough oxygen to the tissues. The blood was drawn from an artery because these vessels (other than the pulmonary artery) are responsible for delivering oxygenated blood to the tissues. A measure of the amount of oxygen in the blood of these vessels will help determine if there is a problem.) .

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In the blood gas test, the oxygen measurement is reported as “saturation.” How is oxygen carried in the blood, and what exactly is being “saturated” with oxygen?

(Oxygen in the blood is bound to a protein called hemoglobin that is carried in the red blood cells. As oxygen mixes with blood, the hemoglobin becomes 100% “saturated” when there is no more room for oxygen to bind.)

Why does this person have low oxygen saturation? What is preventing him from having saturations in the normal range?

(The fluid in the lungs is preventing the normal diffusion of oxygen from the air into the blood at the alveoli.

Less oxygen is diffusing into the blood of this patient and the amount of oxygen in the blood is lower than normal.)

How does the abnormal oxygen saturation value relate to the patient’s cyanotic (blue) appearance?

(When oxygen binds to hemoglobin, this protein turns a bright red color. When hemoglobin is not bound to oxygen, it is much darker and appears blue under the skin. The low oxygen saturation in this patient means that there is more of the deoxygenated hemoglobin. This produces the blue appearance [cyanotic].)

How does the abnormal oxygen saturation value relate to the patient’s elevated heart rate?

(Because this patient is carrying an abnormally low level of oxygen in the blood, the heart must compensate by moving the blood faster to deliver an adequate amount of oxygen to the tissues. This delivery rate can be increased with an elevated heart rate.)

If you had to choose between emphysema and chronic bronchitis as your diagnosis, which would you choose, and what evidence did you use to make this choice?

(Although these conditions often occur together, the more likely diagnosis is chronic bronchitis. The elevated white blood cell count and fever suggest an infection. Emphysema is not an infection. Chronic bronchitis is a persistent lung infection that produces the symptoms seen in this patient [cough, fever, excess mucus or fluid].)

Explain why doctors are using antibiotics and bronchodilators to treat this patient. How will these help to improve this patient’s condition? (The term bronchodilator can be broken down into “broncho” and “dilator” to understand its meaning.)

(A bronchodilator is a drug that helps relax the smooth muscle that surrounds the bronchioles and bronchi in the lungs. This relaxation allows these tubes to dilate (open wider), which allows for more airflow. With greater airflow, more air can be brought into the lungs to deliver more oxygen to the blood.

The antibiotics will help to treat the bacterial infection that is evident in the symptoms (fever, high white blood cell count, mucus production). The infection is the major contributing factor to the fluid accumulation in this patient. By reducing the infection, oxygen delivery to the blood will become more efficient.)

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Lecture Activity 33.2 Handout—The Cough Raymond Harrison, a 64-year-old male, was admitted to the hospital with a history of fever, shaking chills, a nonproductive cough, and chest pain for 6 days. A chest X-ray revealed extensive accumulation of fluid in both lungs. The patient had mild hypertension and a 275 pack/year smoking history. A physical exam revealed a blood pressure of 150/90, a body temperature of 101.8°F, and the patient was cyanotic (looked blue) and in respiratory distress. The patient’s heart rate was elevated at 100 beats per minute.

An arterial blood gas test was performed and the oxygen saturation of the arterial blood was 72% (normal would be 94% to 100%). The blood test revealed an elevated white blood cell count. Initial treatment consisted of antibiotics and bronchodilators.

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What is hypertension? What is the likely cause of this patient’s hypertension? What is “average” blood pressure, and how does this patient’s blood pressure compare?

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A “blood gas test” was performed to measure oxygen levels. Explain why the blood was taken from an artery (arterial) and not a vein.

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In the blood gas test, the oxygen measurement is reported as “saturation.” How is oxygen carried in the blood, and what exactly is being “saturated” with oxygen?

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Why does this person have low oxygen saturation? What is preventing him from having saturations in the normal range?

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How does the abnormal oxygen saturation value relate to the patient’s cyanotic (blue) appearance?

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How does the abnormal oxygen saturation value relate to the patient’s elevated heart rate?

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If you had to choose between emphysema and chronic bronchitis as your diagnosis, which would you choose, and what evidence did you use to make this choice?

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Explain why doctors are using antibiotics and bronchodilators to treat this patient. How will these help to improve this patient’s condition? (The term bronchodilator can be broken down into “broncho” and “dilator” to understand its meaning.)

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Lecture Activity 33.3: Dissolved Gases—Soda Bottle Demonstration Estimated Time to Complete: 10–15 minutes Section Reference 33.4 How Does Gas Exchange Occur in the Human Respiratory System?

Introduction Henry’s law states that the amount of gas dissolved in a solution is proportional to the partial pressure of the gas over the solution. A bottle of soda helps demonstrate Henry’s law. When the bottle is opened to the air, the carbon dioxide (CO2) in the mixture will slowly escape (diffuse) until the pressure of CO2 in the liquid is the same as the pressure of CO2 in the air. The soda will then be “flat.” A bottle of soda opened on top of a mountain at 15,000 feet will foam and overflow. The opposite will happen with soda opened under pressurized conditions. A champagne cork won’t pop in a pressure chamber where air pressure is increased to five times what it would be in the air at sea level.

Why do we not see this foaming action in our blood when it reaches the lungs? The answer is simple, but students need to think about Henry’s law and how to apply it to this simple scenario. The gas dissolved in a soda was forced into the solution under high pressure. As a bottle of soda sits on a shelf, it is not equalized with the pressure in the room air. The cap on the bottle prevents this equalization from happening. When the cap is opened, the CO2 diffuses into the room. The change from the dissolved form to the gaseous form can be seen with the formation of bubbles. When the pressure inside the bottle is lost as the cap is removed, CO 2 within the fluid column “comes out” of the solution as a gas bubble. This bubble rises to the top of the column and then escapes as a gas into the air.

The gases dissolved in blood were not “forced” into the blood under pressure, and therefore the difference in pressures are not as great as they would be in a soda bottle. Small gradients in concentration help account for the movement of oxygen and carbon dioxide as we breathe, but these differences are small enough that we do not experience “foaming” in the blood.

SCUBA divers face a problem that is similar to what is seen with a soda bottle. A diver breathes air that is pressurized in a cylinder in a column of water where the external pressure increases as you go deeper. In this case, the respiratory gases are entering the blood at much higher concentrations (partial pressures) than they would be if you were simply breathing room air at sea level. When a diver returns to the surface, the gases come out of solution because the external pressure decreases as you move into shallow water. The gases dissolved in the blood under pressure will now diffuse back out as they equalize with the lower-pressure conditions. If a diver ascends rapidly, the dissolved gases can come out of solution too quickly and form gas bubbles similar to what you see with the bottle of soda. Nitrogen gas bubbles forming in the blood when a diver returns to the surface too quickly is very dangerous and is responsible for a condition called the “bends.” To prevent this from happening, divers are trained to return to the surface very slowly to allow the dissolved nitrogen to diffuse as a gas into the lungs without the formation of bubbles in the blood. By the time the diver reaches the surface, the gases dissolved in the blood are equalized with the air and the danger is reduced. A small amount of this excess nitrogen remains in the blood after the dive, and it may take some time before full equalization is achieved.

For more information on this condition, perform an Internet search using “the bends” as search terms.

Materials Needed • Three 16-oz. or 20-oz. unopened sodas • Paper towels Procedures 1. Begin with a discussion on how CO2 is carried in the blood and why it leaves the blood and enters the air that we exhale.

(This helps the students understand how a gas can dissolve in blood. Most students will be more comfortable understanding how solids [such as salt] dissolve, but they may not understand the concept of dissolved gases. A very simple chemical definition of a dissolved substance is one that exists as a molecule or ion in water.)

2. Using one of the soda bottles, discuss how (and why) the CO2 dissolved in the soda is similar to blood.

3. Discuss Henry’s law (see Introduction above).

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Open one of the soda bottles and have the students describe what is happening to the CO 2 and why it leaves the soda and enters the air.

5. Discuss the problem faced by a SCUBA diver (see Introduction).

6. Gently shake the two remaining bottles of soda.

7. Using one of the bottles, discuss what happens when a diver returns to the surface too quickly, and then open the cap on the bottle and remove it (have some paper towels handy for cleanup).

8. The concept of the “bends” can be discussed as the bottle foams.

9. Using the other bottle, explain how divers returning to the surface can avoid the bends by ascending slowly.

Very gently “crack” open the cap on the bottle and let air escape as slowly as possible. If foaming does begin to occur, the cap can be opened and closed several times to slowly release the pressure.

10. Have the students compare the amount of “foaming” that occurred between the two demonstrations and emphasize why it is so important for a diver to return to the surface slowly.

Assessment Suggestions None

Lecture Activity 33.4: pH and the Transport of Carbon Dioxide Estimated Time to Complete: 20–25 minutes Section Reference 33.4 How Does Gas Exchange Occur in the Human Respiratory System?

Introduction Before beginning this activity, the students should be familiar with the concept of pH and the relationship between pH and the concentration of hydrogen ions in the solution. In addition, the students should be comfortable reading chemical equations like the one below.

This activity can be completed as a lecture demonstration or as a small-group activity. The activity is designed to demonstrate the consequences of transporting carbon dioxide dissolved in plasma. When carbon dioxide reacts with water, it forms an acid (carbonic acid). Excess amounts of this gas in the blood can cause a shift in pH if the body is unable to compensate. When the body does not fully compensate, a condition called acidosis can result.

This activity explores this concept.

H2O + CO2 → H2CO3 → HCO– + H+ For nonmajors, it is often useful to explain that an equilibrium equation like the one you see above runs “downhill” from the “high spot.” This type of language avoids the need for equilibrium calculations from actual concentrations. For example, by adding additional CO2 into water, you are increasing the amount of this gas in the solution. The left side of the equation becomes the “high spot” and runs “downhill” to the right. This drives the production of H+ with the associated pH change. When excess bicarbonate is added, it creates a new “high spot” and drives the reaction to the left. The concentration of H+ will fall and a pH change will be noted again.

To explore acidosis in more detail, perform an Internet search using “acidosis” as the search term.

Materials Needed • Gloves • Goggles • Phenol red solution (see Procedures) • Sodium bicarbonate, solid (NaHCO3) • Test tubes • Test tube racks • Straws • Textbook Procedures If this is being completed as a lecture demonstration, prepare a couple of test tubes of phenol red solution (filled halfway) and place them in a test tube rack. .

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If this is being used as a small-group activity, put the students into small groups and provide them with test tube racks and test tubes half filled with phenol red.

NOTE: Although there is very little safety concern, students susceptible to dizziness or fainting spells should not attempt this because it requires blowing into a solution for an extended period of time. The students should wear gloves and goggles during this activity.

Begin with a discussion of the following concepts: Discuss how phenol red is an indicator of pH (see the following description of the solution).

Discuss the various ways that CO2 is transported in blood.

Using a straw, very slowly begin blowing bubbles into the phenol red solution. Continue until a significant color change is noted (pink changes to orange or yellow).

Discuss how this process caused a drop in pH and what this means in terms of the concentration of H +.

ASK: “If a drop in pH involves an increase in the concentration of H+, how is it possible that this change could be caused by simply increasing the amount of CO2 in the solution?”

(Students should note that there is no hydrogen in this molecule and can be directed to Section 33.3 in the text [“Oxygen and Carbon Dioxide Are Transported Using Different Mechanisms”] to help them in this discussion. At this point, the equilibrium equation can be explored [see Introduction] to understand how a pH change could result.)

ASK: “If this drop in pH were to happen as a result of excess CO2, what could be done to correct this problem?”

(At this point, the students should be familiar with how the equation works. By increasing respiration rate, more CO 2 could be taken out of the blood, which would drive the reaction to the left. Another option is to add HCO 3 to drive the equation to the left.)

OPTIONAL: To demonstrate how the addition of the bicarbonate ion can help drive the equation to the left, add a small amount of sodium bicarbonate to the test tube and swirl. A color change back to pink occurs as the pH increases.

Phenol red solution (1 L) The preparation of the phenol red solution may require some trial-and-error testing due to differences in the mineral composition of local tap water. Begin with 1 L of dH2O and add a small pinch (0.2–0.4 g) of phenol red crystals. The solution should be approximately pH 7.0 and appear pink in color when placed in a beaker.

If it is not pale pink, adjust the color by adding a drop or two of dilute HCl or NaOH to adjust the color. The solution will appear yellow-orange when it moves into the acidic range and bright pink as it moves into the alkaline range. Adjust the color (or pH) so that it is close to pH 7.0 or slightly above. Test the solution by using a straw to blow into a small volume placed in a test tube or beaker. About 90 seconds of blowing should cause the color to change from pink to the yellow-orange color.

Assessment Suggestions None

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CHAPTER 34 NUTRITION AND DIGESTION LECTURE OUTLINE Case Study: Dying to Be Thin 34.1 What Nutrients Do Animals Need?

A. Nutrients Are Substances Obtained from the Environment That Organisms Need for Their Growth and Survival 1. There are six major categories of nutrients a. Carbohydrates b. Lipids c. Proteins d. Minerals e. Vitamins f. Water â Lecture Activity 34.1: Nutritional Analysis B. Most Energy Is Provided by Carbohydrates and Lipids 1. Cells rely on a constant supply of energy to maintain various activities a. Nutrients that provide energy are carbohydrates, fats, and proteins i. These molecules are broken down by digestion and the remaining parts are used to produce ATP during cellular respiration 2. Energy from nutrients is measured in calories a. A calorie is the amount of energy it takes to raise the temperature of 1 gram of water by 1°C b. The calorie content of foods is measured in units of 1,000 calories, or Calories with a capital “C” c. The speed at which people use calories is called the metabolic rate (Table 34-1) 3. Carbohydrates Are a Source of Quick Energy a. Carbohydrates include sugars, cellulose, starch, and glycogen i.Cells derive most of their energy from glucose ii.Starch is a major energy source for animals and is the primary storage form of carbohydrates for plants iii. Glycogen is used by animals for short-term energy storage 4. Fats and oils are the most concentrated energy source a. When an animal’s diet provides more energy than it expends, most of the excess carbohydrates and fats are stored as body fat i.In addition to energy storage, body fat also provides insulation for animals (Figure 34-1) 5. An evolutionary tendency to store fat can lead to obesity when food is abundant a. The body mass index (BMI) is a common tool for estimating a healthy weight â Health Watch: Eating to Death? (Figure E34-2) â Case Study Continued: Dying to Be Thin C. Essential Nutrients Provide the Raw Materials for Health 1. Essential nutrients are needed by animals but are not synthesized by the body a. They must be supplied by the diet and differ for different animals 2. Certain fatty acids are essential in the human diet a. These fatty acids function in the absorption of fat-soluble vitamins, cell division, fetal development, and the immune response 3. Amino acids form the building blocks of proteins a. Proteins perform a variety of functions in the cell b. Essential amino acids must be obtained from food i.Depending on the age of a human, there are either 9 or 10 essential amino acids .

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Instructor Guide Biology: Life on Earth c. Protein deficiency can cause severe health issues (Figure 34-2) 4. Minerals are elements required by the body a. Minerals play many crucial roles in animals (Table 34-2) b. No animal can synthesize them, so they must be obtained from the diet 5. Vitamins play many roles in metabolism (Table 34-3) a. Vitamins are organic molecules that animals cannot synthesize and require in small amounts (Table 34-3) b. Water-soluble vitamins i.These include vitamin C and the B-vitamin complex and cannot be stored in the body ii.These vitamins typically function as coenzymes in metabolism iii. Deficiencies in these vitamins can cause various health problems (Figure 34-3) c. Fat-soluble vitamins i.These include vitamins A, D, E, and K and can be stored in body fat ii.These vitamins have many functions (Table 34-3) iii. Deficiencies in these vitamins can cause various health problems (Figure 34-4) d. Nutritional guidelines help people obtain a balanced diet i.Important information about nutrients can be found on food labels (Figure 34-5) â Lecture Activity 34.2: Demonstration of Vitamin C as an Antioxidant D. The Human Body Is About 60% Water 1. Water is the principal component of most body fluids

34.2 How Does Digestion Occur?

A. Digestion Is the Process That Physically Grinds Up Food and Then Chemically Breaks It Down 1. The digestive system takes in food, digests it, and absorbs it 2. Digestive systems must accomplish five different tasks a. Ingestion is when food is brought into the system through an opening b. Mechanical digestion is the physical breakdown of food c. Chemical digestion is when food is chemically broken down into smaller subunits d. Absorption is when the subunits of food are transported out of the digestive system and into the body e. Elimination is when the indigestible materials are expelled from the body B. In Sponges, Digestion Occurs Within Single Cells 1. Sponges are the only animals that rely exclusively on intracellular digestion (digestion occurring within individual cells) (Figure 34-6) C. The Simplest Digestive System Is a Chamber with One Opening 1. All other organisms have evolved a chamber within the body where food is broken down chemically outside of the cells a. This process is called extracellular digestion 2. Cnidarians have one of the simplest chambers a. The digestive chamber is called the gastrovascular cavity b. Food processing is a multistep process in these organisms (Figure 34-7) D. Most Animals Have Tubular Digestive Systems with Specialized Compartments 1. A saclike digestive system is inadequate for animals that must eat frequently 2. Most animals have digestive systems that are one-way tubes that process the food in an orderly sequence a. Food is digested, absorbed, and wastes eliminated b. The earthworm provides a good example (Figure 34-8) E. Vertebrate Digestive Systems Are Specialized According to Their Diets 1. Different types of animals have different diets a. Carnivores eat other animals, herbivores eat plants, and omnivores eat both 2. Teeth accommodate different diets a. Different organisms have teeth that have been selected for their different diets (Figure 34-9) 3. Birds’ stomachs grind food a. Birds eat their food whole and have a gizzard that grinds it up (Figure 34-10) 4. Specialized stomach chambers allow ruminants to digest cellulose a. Ruminants also have multiple stomach chambers in which to accomplish digestion (Figure 34-11) b. Ruminant animals can obtain energy from cellulose due to the symbiotic microorganisms they harbor in their stomachs .

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i.The microorganisms help break down the cellulose 5. Small intestine length is correlated with diet a. Herbivores have larger small intestines than carnivores â Lecture Activity 34.3: Nutritional Mystery: Exploring Animal Digestion

34.3 How Do Humans Digest Food? (Figure 34-12 and Table 34-4) A. Mechanical and Chemical Digestion Begin in the Mouth 1. When you take a bite of food, the chewing begins its breakdown 2. The salivary glands release saliva, which contains digestive enzymes and antibacterial agents and lubricates the food for swallowing 3. The muscular tongue pushes food into the pharynx so it can enter the esophagus (Figure 34-13a) a. The pharynx also connects to the trachea, which is covered by the epiglottis to prevent food from entering (Figure 34-13b) B. The Esophagus Conducts Food to the Stomach, Where Mechanical and Chemical Digestion Continue 1. The esophagus is a muscular tube that “propels” food from the mouth to the stomach 2. It moves the food through the channel by peristalsis 3. The stomach is a muscular sac with folds so that it can expand (Figure 34-14) a. Food is retained in the stomach by two sphincter muscles at the top and bottom 4. The stomach has four distinct functions a. It stores food and releases it gradually into the small intestine b. It mechanically breaks down large food particles c. It begins protein breakdown using secretions from gastric glands i.These glands secrete mucus, hydrochloric acid, and the protein pepsinogen ii.Pepsinogen is converted to pepsin, which is a protease and breaks down proteins iii. Mucus serves as a protective barrier to self-digestion iv. The gastric glands secrete hormones that regulate digestion d. The gastric glands also secrete other substances i. Mucus protects the lining ii.Hydrochloric acid destroys microbes iii. The protein pepsinogen is converted to pepsin, and enzyme that breaks down proteins â Science in Action: Do Bacteria Cause Ulcers? (Figure E34-1) 5. Food in the stomach is gradually converted to chyme, partially digested food and digestive secretions 6. Only a few substances, including some drugs and alcohol, are directly absorbed into the bloodstream by the stomach â Case Study Continued: Dying to Be Thin C. Most Chemical Digestion and Nutrient Absorption Occur in the Small Intestine 1. The small intestine is a long muscular tube that receives food from the stomach 2. The main functions of the small intestine are to continue digestion of food into smaller molecules and absorb the molecules into the body a. This organ is divided into three segments 3. Various digestive substances are found in the small intestine (Figure 34-15) a. The liver produces bile i.Bile disperses fat into small particles that the enzyme lipase can attack ii.Bile is stored in the gallbladder b. The pancreas supplies pancreatic juice i.Pancreatic juice neutralizes acidic chyme, and contains amylase for carbohydrate digestion and lipase for lipid digestion ii.It also includes proteases for protein digestion c. Enzymes in the intestinal wall complete digestion i.Absorption is facilitated by microvilli, which produce a large surface area for absorption and carry enzymes that digest peptides and carbohydrates â Lecture Activity 34.4: The Sick Child 4. Most absorption occurs in the small intestine a. The intestinal lining provides a huge surface area for absorption b. The entire length of the tube contains folds (Figure 34-16a) i.Tiny protrusions called villi cover the wall of the small intestine (Figure 34-16b,c)

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Instructor Guide Biology: Life on Earth ii.The plasma membranes of the epithelial cells are folded into microvilli, which further increase the surface area for absorption (Figure 34-16d) c. Nutrients are absorbed by various means i.Most nutrients absorb into the capillaries ii.Fatty acids are assembled as chylomicrons, which are released into the villus iii. Each villus has capillaries and a single lymph capillary called a lacteal iv.Chylomicrons are transported by they lymphatic system â Health Watch: Eating to Death? (Figure E34-2) D. Water Is Absorbed and Feces Are Formed in the Large Intestine 1. Digestive leftovers are concentrated and transported to the rectum 2. Bacterial populations synthesize vitamins B12, thiamine, riboflavin, and K 3. After absorption is complete, feces are produced and stored until defecation E. Digestion Is Controlled by the Nervous System and Hormones (Table 34-5) 1. Food triggers nervous system responses a. The sight, smell, and taste of food trigger nervous responses that prepare the digestive system 2. Hormones help regulate digestive activity a. Hormones secreted by the digestive system enter the bloodstream and act on specific receptors in the digestive tract i.Nutrients in chyme stimulate the stomach to release gastrin ii.Secretin and cholecystokinin are released by the small intestine and help regulate various digestive activities 3. Hormones regulate hunger a. Leptin stimulates hunger and ghrelin reduces it

Case Study Revisited: Dying to Be Thin (Figure 34-17)

KEY TERMS absorption amylase bile body mass index (BMI) calorie Calorie carnivore chemical digestion cholecystokinin chylomicron chyme colon digestion digestive system elimination epiglottis esophagus essential amino acid essential fatty acid

essential nutrient extracellular digestion feces food vacuole gallbladder gastric gland gastrin gastrovascular cavity ghrelin herbivore ingestion intracellular digestion lacteal lactose intolerance large intestine leptin lipase liver lysosome mechanical digestion

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metabolic rate microvillus (plural, microvilli) mineral mouth nutrient omnivore pancreas pancreatic juice peristalsis pharynx protease rectum ruminant secretin small intestine sphincter muscle stomach villus (plural, villi) vitamin

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LECTURE ACTIVITIES Lecture Activity 34.1: Nutritional Analysis Estimated Time to Complete: 5–10 minutes as a demonstration; 20–25 minutes as a classroom activity Section Reference 34.1 What Nutrients Do Animals Need?

Introduction NAT 2.0 is an online nutritional analysis tool that is provided as a public service by the Food Science and Human Nutrition Department at the University of Illinois. In this activity, students will be producing a detailed analysis of their own diet. The NAT 2.0 Web site can be found at http://www.nat.illinois.edu/mainnat.html.

Materials Needed If using this activity as a demonstration, Internet access and a means of projection will be required. The students will need access to the Internet if this activity is going to be used with students in the classroom.

Procedures Log on to the NAT Web site (see link above) and demonstrate how to use this tool to analyze diet. For this activity, the food consumed in a single day should be used for the analysis.

If doing this as a demonstration, the food consumed by a volunteer student or the instructor can be used for the analysis.

For consistency, the food consumed in a single day should be analyzed.

Information for the instructor: This activity can be done outside of class and then students can bring in their own nutritional analyses to class for discussion.

Make sure that they are analyzing what they have eaten in a single day. In some cases, the specific foods may not exist in the NAT database, so encourage the students to select items that closely resemble what they have eaten.

Assessment Suggestions As an extension to this activity, students can use the tool to see how the analysis changes when certain foods are substituted.

This can then be compared to the initial analysis.

For more information on how to use this tool, refer to the NAT 2.0 Help Page: http://www.nat.illinois.edu/NAThelp.html.

Lecture Activity 34.2: Demonstration of Vitamin C as an Antioxidant Estimated Time to Complete: 5–10 minutes as a demonstration Section Reference 34.1 What Nutrients Do Animals Need?

Introduction In this demonstration, the activity of vitamin C as an antioxidant can be demonstrated using a simple reaction that occurs naturally in fruit.

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Materials Needed • Lemon juice or fresh lemons (or vitamin C tablets) • Apple • Banana • Potato • 2 bowls for each fruit being demonstrated Procedures 1. Peel the banana and cut it into slices. If demonstrating with the apple and potato, cut these in half.

2. Split up the sliced fruit into the two bowls and quickly cover the fruit in one bowl with lemon juice or evenly coat the fruit with crushed vitamin C tablets that you make into a powder. Make sure the fruit is evenly coated with the lemon juice or vitamin powder.

3. Let the fruit sit and make an observation of the color of the fruit every 5 to 10 minutes.

4. Because this reaction takes some time, it can be prepared in front of the class and then returned to later for discussion.

5. The action of antioxidant activity will become evident (see the following information for a description of the chemistry).

Information for the instructor: When the fruit is cut open, the components of an oxidation reaction come in contact with each other. An oxidase enzyme called catechol oxidase catalyzes this reaction. Catechol oxidase catalyzes the removal of electrons and hydrogens from catechol, a phenolic compound found in plant cells. Catechol is converted to benzoquinone, a pigment product. The hydrogens stripped from catechol with the electrons will combine with oxygen, forming water.

An antioxidant prevents this oxidation reaction (the removal of the hydrogens from catechol). Without the ability to remove the hydrogens, the reaction shuts down and catechol is not converted to the brown product. To make an analogy, the fruit can be compared to our DNA, which is subject to oxidative damage when mediated by free radicals. Antioxidants such as vitamin C have a protective effect and prevent oxidation reactions.

Assessment Suggestions None

Lecture Activity 34.3: Nutritional Mystery: Exploring Animal Digestion Estimated Time to Complete: 15–20 minutes Section Reference 34.2 How Does Digestion Occur?

Introduction In this demonstration, small groups of students are asked to consider information about the anatomy of three different animals.

Using this information, they try to answer questions about the diet and nutrition of these animals.

Materials Needed • A copy of the textbook • A copy of the handout for each student in the class Procedures 1. Organize the students into groups of two to four students.

2. Hand out a copy of the activity to each student.

3. Give the small groups 15 minutes to consider the questions and then bring everyone together for class discussion.

Information for the instructor: Because this activity challenges students to apply knowledge of nutrition and digestion, it is best to use this activity as a wrap-up for this topic. .

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Information about these animals: Animal A: Although little information is available to determine diet, this animal is most likely an omnivore.

This small animal has feeding structures resembling those found in hydra and other very simple animals.

Animal B: With legs (locomotion) and two rows of dagger-sharp teeth designed for tearing flesh, this animal is a carnivore. The large stomach can expand (folds) to accommodate large meals of flesh and the gallbladder size suggests meals high in fat. The short intestine suggests that much of the material is easily digestible with the appropriate enzymes.

Animal C: This animal is an herbivore. The incisors are designed for the chopping of plant material, and the back teeth are designed for grinding the plant material. The complex stomach and small intestine suggest the need for extensive mechanical digestion of plant food.

Animals B and C are adapted for more frequent eating because they have separate openings for ingestion and excretion. Animal B eats less frequently than C, as evidenced by the large stomach designed to expand. This suggests very large (but fewer) meals.

Assessment Suggestions None Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 34.3 Handout—A Nutritional Mystery While rummaging around the basement of a natural history museum, a curator came across a case of preserved animals that were collected in the early 1900s by a British expedition to Brazil. None of the museum’s experts can determine the species-level identity of any of the specimens; the labels have been lost, and many of the animals are now extinct or very rare. As part of the effort to study the specimens, the museum director has asked you to form small teams to examine the digestive systems of the mysterious animals.

Animal A B C

Type Invertebrate Legged vertebrate Legless vertebrate

Size 7.6 cm 0.6 meters 0.9 meters

Digestive system Tube with one opening Tube with two openings Tube with two openings

Anatomical descriptions: Animal A: Very flat body; no limbs; no eyes; a simple, long narrow digestive tube with a single opening.

Animal B: Two rows of 30 “dagger-shaped” teeth; a very large and very muscular stomach with signs of highly extensive folding; short and relatively straight small intestine; large gallbladder.

Animal C: One row of incisor teeth and two rows of back teeth with a rough surface and a very large surface area; a three-chambered stomach with a long, highly coiled small intestine; no gallbladder.

Discussion Questions 1. Try to label each of these animals as a carnivore, herbivore, or omnivore. Be prepared to use each of the following pieces of evidence to support your labeling: a. Dentition (teeth) b. Stomach anatomy c. Small intestine anatomy d. Presence or absence of a gallbladder 2.

What can you say about how frequently these animals eat? What evidence did you use to determine this?

3.

For each animal, explain how the anatomy of the digestive system is adapted to the animal’s diet.

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Lecture Activity 34.4: The Sick Child Estimated Time to Complete: 20–25 minutes Section Reference 34.3 How Do Humans Digest Food?

Introduction In this activity, students will be exploring a case of lactose intolerance and the importance of a healthy small intestine for the efficient digestion of carbohydrates.

Materials Needed The students should have access to a copy of the text as a reference.

A copy of Part I of the case should be handed to each student or projected for the class to read. In addition, the students should receive information on lactose intolerance (see following information) or they should be directed to sources where they can obtain this information. Alternatively, the case could be handed out as an out-of-class assignment that is followed up with a class discussion.

Following a short discussion on Part I, Part II of the case can be handed out to the students for a more detailed exploration of this topic.

In order to work with this case in class, additional resources on lactose intolerance should be made available to the students. Have the students perform an Internet search using “lactose intolerance” as search terms.

Procedures 1. Put the students into discussion groups of three or four students.

2. Hand out a copy of the case (Part I) and any supporting materials on lactose intolerance. If Internet access is available, the small student groups should work around or near the computer for access to resources on lactose intolerance.

3. Give the groups a chance to see if they can use the information to account for the patient’s symptoms. They do not need to diagnose the person, but they should be able to relate the symptoms to the presence of high quantities of lactose in the stool.

4. Let them discuss the case and see if they can come up with an explanation of what the problem might be.

5. After 5–10 minutes, a short class discussion covering the details of the case can be used to make sure everyone is focusing on lactose intolerance.

6. Follow up by handing out the research questions (Part II).

7. Part II can be done in class if resources are available (Internet access, other text references, etc.) or it can be handed out as an assignment. The students should have a copy of the textbook available for questions relating to the basic biology of the digestive system.

Information for the instructor: This child is lactose intolerant. In this case, the severe gastrointestinal infection that this child suffered is responsible for his condition. The damage to the small intestine from this infection is responsible for the reduced ability of this structure to produce the disaccharidases (in this case, lactase). Under normal conditions, lactase produced by the small intestine is able to hydrolyze lactose into glucose and galactose. These monosaccharides are then absorbed by the small intestine. In lactose intolerance, the lactose remains in the small intestine undigested. This undigested sugar is responsible for many of the symptoms, such as abdominal pain (bacteria ferment the sugar and give off gas). In addition, this child is dehydrated because of the severe diarrhea. The undigested lactose produces an osmotic gradient that pulls water into the intestine and makes it difficult for the large intestine to reclaim the excess water.

Assessment Suggestions The research portion of the activity can be done as a take-home assignment. Answers to the research questions can be handed in as an assignment or for comments.

Handouts or Display See following pages.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 34.3 Handout—The Sick Child Part I: The Sick Child Melissa Laydon brings her son Tyler into the Emergency Room. The child has a fever, flushed skin tone, excessive thirst, mental confusion, lethargy, abdominal pain, and severe diarrhea. An interview with the mother reveals that the child has recently recovered from a severe gastrointestinal infection that was treated with antibiotics. Stool cultures have been free of infection for several weeks and the patient has been free of symptoms for a month.

The mother described this recent illness as being very different from the previous infection. A stool culture revealed that the patient continues to be free of infection. Further discussions revealed a pattern of symptoms following meals that contained whole milk. A chemical analysis of the patient’s stool revealed high quantities of lactose. Lactose is a disaccharide found in many dairy products such as milk (see figure below).

Make a list of this child’s symptoms. Can you come up with an explanation for the symptoms that this patient is having?

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Chapter 34 Nutrition and Digestion Part II: Research This person is suffering from lactose intolerance. Using information from your text, and/or resources from the library, the Internet, and other text references, explore the following questions: 1.

What part of the digestive system is normally responsible for digesting disaccharides such as lactose?

2.

Why would a person normally not have large quantities of lactose in the stool? Where does it go?

3.

Why does Tyler have large quantities of lactose in his stool?

4.

Diarrhea is a condition in which excess water is mixed with undigested food. What part of the digestive system is normally responsible for removing this excess water?

5.

Can you come up with an explanation as to why Tyler’s system is unable to remove this excess water?

6.

Describe the condition that Tyler has. Can you come up with an explanation as to how he developed this condition?

7.

What treatments are available for Tyler? How do these treatments specifically address his problem?

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CHAPTER 35 THE URINARY SYSTEM LECTURE OUTLINE Case Study: Paying It Forward 35.1 What Are the Major Functions of Urinary Systems?

A. Urinary Systems Are Organ Systems That Produce and Eliminate Urine 1. Urine is a watery fluid that has been filtered from the blood 2. Urinary systems play two major roles in most animals a. They excrete cellular wastes b. They maintain homeostasis B. Excretion Eliminates Wastes from the Body 1. Excretion is a general term for eliminating wastes and excess substances from the body 2. The primary cellular wastes in urine are ammonia, urea, and uric acid a. These are nitrogenous wastes formed when cells break down amino acids (Figure 35-1) C. Homeostasis Maintains Relatively Constant Internal Conditions 1. Urinary systems play a crucial role in homeostasis by filtering the blood and interstitial fluid

35.2 What Are Some Examples of Invertebrate Urinary Systems?

A. Protonephridia Filter Interstitial Fluid in Flatworms 1. Flame cells draw water in (Figure 35-2a) 2. Wastes diffuse out of the body B. Malpighian Tubules Filter the Hemolymph of Insects 1. Wastes and salts move from the surrounding hemolymph into the tubules, where they are excreted from the digestive tract (Figure 35-2b) C. Nephridia Filter Interstitial Fluid in Annelid Worms and Mollusks (Figure 35-2c) 1. Fluid is concentrated into the nephrostome 2. Excretion is through the nephridiopore

35.3 What Are the Structures of the Mammalian Urinary System?

A. The Urinary System Consists of a Number of Structures 1. The urinary system consists of the kidneys, ureters, bladder, and urethra B. Different Structures of the Human Urinary System Produce, Store, and Excrete Urine 1. Kidneys are paired organs located at approximately waist level in a human (Figure 35-3) 2. Kidneys have several structures (Figure 35-4) a. The renal cortex is the outer layer b. The renal medulla is the inner layer and concentrates the urine c. The renal pelvis collects urine and conducts it to the ureter 3. The ureter sends urine to the bladder a. Urine exits the body through the urethra C. Large Quantities of Blood Flow Through the Kidneys 1. The kidneys filter large amounts of blood a. Blood enters through a renal artery and exits through a renal vein b. All of the blood plasma is filtered through the kidneys 60 times daily c. The immense filtering capacity of the kidney explains why kidney donors and recipients can survive on only one â Health Watch: When the Kidneys Collapse (Figure E35-1) â Case Study Continued: Paying It Forward

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D. Nephrons in the Kidneys Filter Blood and Produce Urine (Figure 35-5) 1. The renal cortex contains large numbers of nephrons a. Blood carried to the kidney enters each nephron through an arteriole i. This arteriole branches and forms the glomerulus, a dense meshwork of capillaries ii. The arteriole then gives rise to peritubular capillaries, which form a network around the nephron 2. Each nephron has two major parts a. The glomerulus is where fluid is filtered out of the blood b. A long, twisted tubule begins with the Bowman’s capsule that surrounds the glomerulus and receives the fluid c. From Bowman’s capsule, fluid travels through the following tubes i. Proximal tubule ii. Loop of Henle iii. Distal tubule, which empties into a collecting duct

35.4 How Is Urine Formed?

A. Urine Is Produced in the Nephrons During Three Processes 1. In filtration, water and most small dissolved molecules are filtered out of the blood 2. In tubular reabsorption, water and necessary nutrients are restored to the blood 3. In tubular secretion, wastes and excess ions are secreted into the urine 4. As urine is formed, essentially all small organic molecules are filtered out, and then returned to the blood â In Greater Depth: How the Nephron Forms Urine (Figure E35-2) B. Filtration Removes Small Molecules and Ions from the Blood 1. Filtration occurs when water carrying small molecules and ions is forced through the capillaries that form the glomerulus (Figure 35-6) a. Filtration produces fluid called filtrate â Lecture Activity 35.1: Demonstration of Glomerular Pressure C. Tubular Reabsorption Returns Important Substances to the Blood 1. In this process, nearly all the water, essential ions, and organic nutrients removed during filtration are returned to the blood (Figure 35-6) a. Water and nutrients such as glucose and salt are reabsorbed D. Tubular Secretion Actively Transports Substances into the Tubule for Excretion 1. Remaining wastes and excess ions move from the blood into the proximal and distal tubules a. When the filtrate leaves the distal tubule, it becomes urine

35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

A. Vertebrate Urinary Systems Help Maintain Homeostasis in Several Ways 1. Retaining small organic nutrients and inorganic ions within the blood and interstitial fluid 2. Retaining the water and ion content of the blood 3. Maintaining the proper pH of the blood 4. Secreting substances that help regulate blood pressure and blood oxygen content B. The Kidneys Regulate the Water and Ion Content of the Blood 1. The kidneys regulate blood osmolarity, which is a measure of its concentration of ions and other solutes 2. Reabsorption of water occurs passively through the tubule and collecting duct a. Osmosis occurs as the filtrate travels through the tubule and collecting duct b. Depending on water intake, urine will be dilute or concentrated based on precise regulation of water reabsorption i.The permeability of the tubule and collecting duct to water regulates the reabsorption c. The loop of Henle functions in water reabsorption also (Figure 35-6) i.It reabsorbs some water and salt from the filtrate ii.It creates a high salt concentration in the extracellular fluid in the medulla iii.This causes water to be reabsorbed and concentrates urine â Lecture Activity 35.2: Kidney Problems â Lecture Activity 35.3: Measuring Risk for Diabetes

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Instructor Guide Biology: Life on Earth 3. Water permeability of the distal tubule and collecting duct is regulated by antidiuretic hormone (ADH) a. The permeability is controlled by the number of aquaporins, water channel proteins in the membranes of the tubule and collecting duct i. ADH controls this, which allows these structures to fine-tune the water content of urine b. Dehydration stimulates the release of ADH from the brain (Figure 35-7) c. Blood osmolarity is controlled by negative feedback 4. Mammalian nephrons are adapted to the availability of water a. Mammals have two types of nephrons, one with a long loop of Henle and another with a short loop of Henle i. Longer loops of Henle allow for maximum reabsorption of water b. Mammals adapted to dry climates have kidneys with a higher percentage of long loops of Henle (Figure 35-8) c. Desert rodents have an extraordinary ability to concentrate urine and can rely on food and metabolic reactions the produce water d. Mammals adapted to wet climates have kidneys with short loops of Henle C. The Kidneys Help Maintain Blood pH 1. The kidneys do this by releasing hydrogen ions into the tubule and reabsorbing bicarbonate ions into the blood 2. When oxygen levels in the blood decrease, the kidneys release erythropoietin, which stimulates red blood cell production D. The Kidneys Help Regulate Blood Pressure and Oxygen Levels 1. The renin–angiotensin system combats low blood pressure 2. When oxygen levels in the blood decrease, the kidneys release erythropoietin, which stimulates red blood cell production â Case Study Continued: Paying It Forward E. Fish Face Special Challenges in Their Aquatic Environments 1. Animals that live immersed in the water have evolved special mechanisms to maintain a homeostatic balance of water and salt in their bodies a. This process is called osmoregulation b. Freshwater fish live in a hypotonic environment and gain water by osmosis i. They take in salt from food and their gills, but rarely drink any water (Figure 35-9a) c. Saltwater fish live in a hypertonic environment and lose water by osmosis i. Most saltwater fish drink to restore the water and excrete excess salt through their gills (Figure 35-9b) â Lecture Activity 35.4: The Car Accident

Case Study Revisited: Paying It Forward

KEY TERMS ammonia angiotensin antidiuretic hormone (ADH) aquaporin bladder Bowman’s capsule collecting duct distal tubule erythropoietin excretion filtrate filtration glomerulus

homeostasis kidney loop of Henle Malpighian tubule nephridium (plural, nephridia) nephron osmolarity osmoregulation peritubular capillaries protonephridium (plural, protonephridia) proximal tubule renal artery renal cortex

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renal medulla renal pelvis renal vein renin tubular reabsorption tubular secretion tubule urea ureter urethra urinary system urine

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LECTURE ACTIVITIES Lecture Activity 35.1: Demonstration of Glomerular Pressure Estimated Time to Complete: 10 minutes Section Reference 35.4 How Is Urine Formed?

Introduction One of the more difficult concepts related to renal physiology is the autoregulation of glomerular pressure by the kidneys.

In the cardiovascular chapter, students learn that pressure rises when vessels constrict and then pressure falls when vessels dilate. For the kidney, students often mistakenly see this principle as reversed. In the nephron, the glomerular pressure (and therefore filtration rate) depends on the amount of blood entering the glomerulus (afferent arteriole) and the amount of resistance it faces when trying to leave (efferent arteriole). Water running through a tube or hose can be used to demonstrate this concept. If a classroom sink is not available, this idea can be described and used as an analogy.

Materials Needed (if demonstrating) • Classroom sink with running water • Tubing or hose to connect to sink • Tubing or hose clamp Procedures 1. Connect the hose or tube to the sink and turn on the water about 50% of its maximum.

2. Explain that water is being pushed through the hose under pressure by the sink and that this is analogous to systemic blood pressure.

3. Using a clamp, slowly constrict the tube or hose at some point near the center and have the students observe the water as it pours out of the opening.

4. The students should notice the drop in pressure near the end of the tube as the tube is constricted.

5. Now turn on the water to 100% of its maximum and explain that this represents a rise in blood pressure.

6. ASK: If the kidney does nothing to respond, what will happen to the filtration rate?

(Students should note the rise in pressure as water runs out of the tubing at a greater rate.)

7. ASK: What can the kidney do to restore the pressure it had prior to the rise in blood pressure? (constrict the afferent arteriole) 8. Confirm the response to the questions by constricting the hose further to restore the pressure of the water “downstream” of the constriction point.

Assessment Suggestions In the kidney, when the afferent arteriole constricts, there is less blood flow into the glomerulus, which leads to a drop in pressure. With less pressure in the glomerulus, there is a lower filtration rate and an associated drop in urine volume. This autoregulation is the mechanism that kidneys use to control filtration rate as systemic blood pressure.

Questions for class discussion: 1. What is happening to the pressure “downstream” of the constriction? (the pressure is dropping) 2. What part of the kidney is being represented by the restriction point? (the vasoconstriction of the afferent arteriole) 3. What is happening to the pressure “upstream” of the constriction? (the pressure is rising)

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Lecture Activity 35.2: Kidney Problems Estimated Time to Complete: 30–40 minutes Section Reference 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

Introduction In this activity, a case study is used to help the students explore diabetes and the role of the kidney in maintaining normal levels of substances dissolved in the blood. Within this activity, the students are asked to make connections to the earlier material on blood and circulation.

The case can be used prior to introducing the kidney to encourage students to explore material in the text before it is introduced in class. If the case is to be used this way, more time must be devoted in class so that the students have ample time to read and ask questions. Another possibility is to have the students complete the case as an assignment prior to the introduction of material in the classroom.

Alternatively, the case can be used to encourage the application of concepts related to the urinary system after they have been presented in class. The case can be completed in small groups during a class period, or as an assignment done outside of class time.

Materials Needed • A copy of the handout of the case and case questions for each student • A copy of the textbook or other reference material on diabetes • Access to the Internet would be useful for students to find information, as noted on the handout.

Procedures Several of the questions that follow the case challenge the students to make connections to a variety of concepts.

In order to facilitate this process, it is helpful to have the students in small groups of three or four to encourage discussions.

After handing out the case, have a student in each group volunteer to read the case to their group and act as a facilitator to work through the case questions and discuss the answers. It is important that the groups have the textbook or other material on diabetes available to use as a reference.

When the small groups have had 20–25 minutes to discuss the answers, the class can be reassembled for a class discussion.

Have the groups take turns reporting question answers to the class, and encourage other groups to add additional information as the discussion continues.

Assessment Suggestions None Handouts or Display See the following pages.

Handout Answer Key 1. What component of the breath and urine is causing the “fruity” acetone smell?

(In a diabetic, the cells are unable to metabolize glucose. In order to meet their energy needs, they switch over to metabolizing primarily fats. Ketones are the metabolic by-product of this type of metabolism. As the level of ketones in the blood builds, it begins to spill over into the urine and diffuses across the surface of the lungs.

Ketones have an acetone smell that can be detected in the breath and in the urine.)

2. How are the ketones in the blood and urine related to the pH of these fluids?

(SEE ABOVE: Ketones are organic acids that cause the pH of the blood and urine to drop when their levels build up in a diabetic patient. This produces a condition called diabetic ketoacidosis [DK].)

3. Explain how polyuria is related to the elevated level of solute (glucose, ketones, sodium, and potassium) in the urine.

(The filtrate produced by a diabetic has a very high solute concentration. The osmotic gradient that results from this promotes the movement of water from the blood and into the filtrate and inhibits the reabsorption of water from the filtrate. This leads to elevated urine production.) .

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4. Explain why a positive test for glucose in urine is an abnormal result. Why do healthy people not have glucose in their urine?

(In a healthy person, the glucose that enters the filtrate during filtration gets reabsorbed by the nephron. In a diabetic, the excess amount of glucose overloads the kidney’s capacity to reabsorb all of the glucose and some is able to “spill over” into the urine.)

5. What disease does this patient have? What were the most important test results that directed you toward that diagnosis?

(This person has diabetes [possibly type 2 due to her age]. The glucose and ketone tests are very important for making this diagnosis, along with the symptoms of polydipsia, polyuria, and polyphagia.)

6. What are ketones? Where do they come from? How are they related to the disease that you described in Question 5?

(SEE QUESTIONS 1 and 2.)

7. How are ketones in the urine related to sodium and potassium levels in the urine?

(Ketones are organic acids that carry a negative charge. They attract the positively charged sodium and potassium ions into the filtrate.)

8. Why is this patient dehydrated? How is this related to blood pressure and heart rate?

(The patient is dehydrated because of the excess urine production. This loss of water leads to a drop in blood volume. A drop in blood volume leads to a drop in blood pressure.)

9. Explain why this patient has polydipsia and how it is related to blood pressure.

(The drop in blood volume is involved in triggering the thirst centers of the brain. If the person increases his or her fluid intake, this would help to increase blood volume to restore blood pressure.)

10. Explain why this patient has polyphagia and how it is related to glucose and ketones in the blood and urine.

(With glucose unavailable to cells, the body acts as if it is in a nutritional deficit and begins to respond as if it is in a starvation condition. The hunger centers of the brain become activated to try to increase food intake. The ketones are the result of the body switching over to primarily lipid metabolism to supply the cell’s energy needs.)

11. What types of treatments need to be administered? You should describe treatments that will be needed in both the short term and the long term.

(Students should discuss dietary control of diabetes along with the role of insulin injections for insulindependent diabetics. There are a wide variety of lifestyle changes and medications related to treatments that can be discussed with the class.)

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 35.2 Handout—Kidney Problems Carolyn Hoffberg, a 68-year-old female, was admitted to Finger Lakes Community Hospital with symptoms of dehydration.

The patient was administered IV fluids as part of the rehydration therapy. The patient complained of polyuria (frequent urination), polydipsia (excessive thirst), and polyphagia (excessive hunger). In addition, the patient complained of periods of what she termed “uncontrolled anxiety” with an elevated heart rate and dizziness with associated nausea and vomiting. While being admitted to the hospital, a “fruity” acetone smell was noted on the patient’s breath. After an initial consult with an endocrinologist and an interview with the patient, several tests were ordered. Blood and urine tests revealed hyperglycemia (high blood sugar), elevated glucose and ketones in the urine, and ketoacidosis. What follows is a summary of the notable test results: General: BP: 95/58 HR: 110

Blood: PH: 7.1 Glucose: elevated Ketones: positive and elevated

Urine: Odor: “fruity acetone” pH: 4.3 Glucose: positive Ketones: positive Sodium: elevated Potassium: elevated

Case Questions 1.

What component of the breath and urine is causing the “fruity” acetone smell?

2.

How are the ketones in the blood and urine related to the pH of these fluids?

.

3.

Explain how polyuria is related to the elevated level of solute (glucose, ketones, sodium, and potassium) in the urine.

4.

Explain why a positive test for glucose in urine is an abnormal result. Why do healthy people not have glucose in their urine?

5.

What disease does this patient have? What were the most important test results that directed you toward that diagnosis?

6.

What are ketones? Where do they come from? How are they related to the disease that you described in Question 5?

7.

How are ketones in the urine related to sodium and potassium levels in the urine?

8.

Why is this patient dehydrated? How is this related to blood pressure and heart rate?

.

9.

Explain why this patient has polydipsia and how it is related to blood pressure.

10.

Explain why this patient has polyphagia and how it is related to glucose and ketones in the blood and urine.

11.

What types of treatments need to be administered? You should describe treatments that will be needed in both the short term and the long term.

References For more information on diabetes, perform an Internet search using “diabetes type 1” and “diabetes type 2” as search terms.

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Lecture Activity 35.3: Measuring Risk for Diabetes Estimated Time to Complete: 10–15 minutes Section Reference 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

Introduction The American Diabetes Association has an online resource for people seeking information on diabetes.

It provides a variety of tools for managing health, and support for those who seek information. In this activity, the students will do a brief assessment of their risk for developing diabetes. This personal assessment is then followed by a discussion on the actions that can be taken to reduce those risks.

Materials Needed • Computer instructor station with projection system (computer must have Internet access with a Web browser) • Student computer stations with Internet access Procedures 1. For this activity, have the students enter the following address into the browser window: http://www.diabetes.org. Have students place the mouse over the “Diabetes Basics” tab. A menu will appear, and then have them select “Risk Test.”

2. Have the students click on “Next” in the center of the screen to begin the test.

3. Have the students follow the instructions for using the tool to assess their risk for diabetes.

Assessment Suggestions When the students have had a chance to assess their own risks, a class discussion can be used to review the various risk factors associated with diabetes. What seem to be the important factors associated with diabetes risk? In your discussion, classify the risk factors into two groups: 1. Controllable risk factors (e.g., diet and exercise) 2. Uncontrollable risk factors (e.g., genetics and age)

Lecture Activity 35.4: The Car Accident Estimated Time to Complete: 15–20 minutes Section Reference 35.6 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

Introduction In this activity, a case study is used to help the students explore the role that the kidney plays in homeostasis, and the role of the kidney in maintaining normal levels of substances dissolved in the blood. Within this activity, the students are asked to make connections to the earlier material on respiration.

The case can be used prior to introducing the kidney to encourage the students to explore material in the text before it is introduced in class. If the case is to be used in this way, more time will need to be devoted in class so that the students have ample time to read and ask questions. Another possibility is to have the students complete the case as an assignment prior to the introduction of material in the classroom.

Alternatively, the case can be used to encourage the application of concepts related to the urinary system after they have been presented in class. The case can be completed in small groups during a class period, or as an assignment done outside of class time.

Materials Needed • A copy of the handout of the case and case questions for each student • A copy of the textbook or other reference material on renal physiology • Access to the Internet would be useful for students to take advantage of online material that they might want to review to answer the questions. .

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Procedures The questions that follow the case challenge the students to make connections to a variety of concepts. In order to facilitate this process, it is helpful to have the students in small groups of three or four students to encourage discussions.

After handing out the case, have a student in each group volunteer to read the case to their group and act as a facilitator to work through the case questions and discuss the answers. It is important that the groups have the textbook or other material on renal physiology available to use as a reference.

When the small groups have had 10–15 minutes to discuss the answers, the classroom can be reassembled for a class discussion.

Have the groups take turns reporting question answers to the class and encourage other groups to add additional information as the discussion continues.

Assessment Suggestions None Handouts or Display See the following page.

Handout Answer Key 1. Why is it important to know what the bicarbonate levels in the blood are?

(Bicarbonate is the major buffering ion in the blood and is important for controlling blood pH. The kidneys play a primary role in regulating the levels of bicarbonate in the blood.)

2. Why do you think Mr. Henderson had an elevated level of carbon dioxide in his blood? You may want to refer back to Chapter 33 on respiration.

(After hitting the steering wheel, the lungs began to fill with fluid, which was discovered during the exam. This interfered with normal gas exchange and ultimately caused the elevation of carbon dioxide in the blood.)

3. The high pCO2 and the low pH are related to each other. Explain this relationship.

(When carbon dioxide combines with water, it forms an acid called carbonic acid. When there is excess amounts of carbon dioxide in the blood, the acid formation can lead to a drop in blood pH.) 4. Explain how the kidneys are able to help compensate for Mr. Henderson’s problem. Is this compensatory mechanism working in this patient? What evidence did you use to determine this?

(The kidneys are attempting to compensate in two different ways, both of which are evident in this case. The kidneys dump hydrogen ions into the filtrate through tubular secretion [notice the low urine pH], and also they are involved in the formation of excess bicarbonate ions that can help buffer the blood when there are changes in pH [notice the elevated bicarbonate level in the blood].)

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 35.4 Handout—The Car Accident Mr. Henderson, a 52-year-old male, was brought to the hospital after being involved in a motor vehicle accident. A large bruise on his chest indicated that he suffered a blunt trauma due to the impact from the steering wheel. The initial lung exam revealed that he had some fluid collecting in the lungs. Mr. Henderson came to the hospital with a rapid breathing rate, blurred vision, dizziness, headache, nausea, muscle weakness, and a feeling of mental confusion. Several tests were run and the results are as follows: Blood pH: Respirations: pCO2: bicarbonate: urine pH:

7.0 (normal is approximately 7.4) elevated (frequency of breathing) elevated (concentration of carbon dioxide in the blood) elevated (concentration of bicarbonate in the blood) 4.0 (normal is approximately 5.0–8.0)

1.

Why is it important to know what the bicarbonate levels in the blood are?

2.

Why do you think Mr. Henderson had an elevated level of carbon dioxide in his blood? You may want to refer back to Chapter 33 on respiration.

3.

The high pCO2 and the low pH are related to each other. Explain this relationship.

4.

Explain how the kidneys are able to help compensate for Mr. Henderson’s problem. Is this compensatory mechanism working in this patient? What evidence did you use to determine this?

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CHAPTER 36 DEFENSES AGAINST DISEASE LECTURE OUTLINE Case Study: Flesh-Eating Bacteria 36.1 How Does the Body Defend Itself Against Disease?

A. The Environment Teems with Microbes 1. Examples include bacteria, protists, fungi, and viruses 2. Not all microbes contribute to disease, but those that do are called pathogens a. Many have been identified b. In recent years, many new pathogens have arisen â Lecture Activity 36.1: Transmission of Disease B. Vertebrate Animals Have Three Major Lines of Defense: Nonspecific External Barriers, Nonspecific Internal Defenses, and Specific Internal Defenses (Figure 36-1) 1. Nonspecific external barriers include anatomical structures such as skin and secretions such as tears 2. Nonspecific internal defenses include the innate immune response a. Some white blood cells b. Inflammation and fever 3. Specific internal defenses include the adaptive immune response a. This defense system can remember different invaders 4. Innate immunity and adaptive immunity have some similarities and differences (Table 36-1) 5. The internal defenses involve a number of different types of cells (Table 36-2) C. Invertebrate Animals Possess Nonspecific Lines of Defense

36.2 How Do Nonspecific Defenses Function?

A. The Skin and Mucous Membranes Form Nonspecific External Barriers to Invasion 1. The skin and its secretions block entry and provide an inhospitable environment for microbial growth a. The outer surface of the skin consists of dry, dead cells i. Microbes that land on the skin have little moisture for survival b. Secretions from sweat and oil glands contain natural antibiotics 2. Mucus, antibacterial proteins, and ciliary action defend the mucous membranes against microbes a. Mucus traps microbes, and cilia sweep them out (Figure 36-2) B. The Innate Immune Response Nonspecifically Combats Invading Microbes 1. The innate immune responses fall into three types a. Protection by white blood cells b. The inflammatory response c. Fever 2. Phagocytes and natural killer cells destroy invading microbes a. Macrophages, neutrophils, and dendritic cells ingest dead cells, cellular debris, and microbes by phagocytosis (Figure 36-3) b. Natural killer cells strike at the body’s own cells that have been invaded by viruses i. The major histocompatibility complex (MHC) is a class of proteins that cells present on their surface ii.These proteins allow natural killer cells to recognize the body’s own cells as “self” and others as “non-self” 3. The inflammatory response attracts phagocytes to injured or infected tissue a. This process begins when histamine is released from mast cells in an area of damaged tissue (Figure 36-4) i. Capillary walls become “leaky“ ii.Blood flow increases 366

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iii. Macrophages are attracted to the area b. Blood clots isolate the injury site 4. Fever combats large-scale infections a. Serious infections in the body trigger fever b. Bacteria and some phagocytes release pyrogens, which cause an increase in body temperature i. An elevated body temperature increases the activity of phagocytic white blood cells and slows bacterial reproduction â Case Study Continued: Flesh-Eating Bacteria

36.3 What Are the Key Components of the Adaptive Immune System?

A. The Immune System Can Recognize and Attack Specific Invaders B. The Adaptive Immune System Consists of Cells and Molecules Dispersed Throughout the Body (Figure 36-5) 1. The immune system consists of three major parts a. Immune cells i. Lymphocytes such as B and T cells b. Tissues and organs i. Lymph nodes are scattered throughout the lymphatic system ii.The thymus, which is essential for the development of immune cells iii. The spleen, which exposes blood to white blood cells iv. The tonsils, which include macrophages and other white blood cells c. Secreted proteins i. Cytokines are used for communication between cells ii.Complement assists the immune system in killing microbes iii.Antibodies are proteins produced by B cells that help the immune system recognize invading microbes and destroy them

36.4 How Does the Adaptive Immune System Recognize Invaders?

A. The Adaptive Immune System Recognizes Invaders’ Complex Molecules 1. Your immune system cells distinguish between your body’s cells and foreign cells 2. Foreign invaders exhibit characteristic antigens a. These may be found on the surfaces of microbes or on the surfaces of immune cells that have engulfed them 3. Antibodies and T-cell receptors recognize and bind to foreign antigens a. Lymphocytes generate two types of proteins that recognize and help destroy specific antigens i. The proteins are antibodies and T-cell receptors 4. Antibodies are Y-shaped proteins composed of two pairs of peptide chains, a heavy and light chain (Figure 36-6) a. Both chains consist of a constant and variable region b. The variable sites bind to antigens 5. Antibodies serve two functions in the adaptive immune response a. They recognize foreign antigens and trigger the response against invaders b. They help destroy the invading cells or molecules that bear the antigens (Figure 36-7) â Lecture Activity 36.2: Antibody Diversity 6. T-cell receptors recognize invaders and help to trigger an immune response B. The Adaptive Immune System Can Recognize Millions of Different Antigens 1. The adaptive immune system recognizes and responds to virtually all of the millions of potentially harmful antigens a human might encounter 2. Antibodies and T cells are not made to fit specific antigens a. The human body randomly synthesizes millions of different antibodies and T-cell receptors â In Greater Depth: How Can the Immune System Recognize So Many Different Antigens? (Figure E361) C. The Adaptive Immune System Distinguishes Self from Non-Self 1. Proteins called the major histocompatibility complex (MHC) are unique to each person a. These proteins can act as antigens in other people’s bodies, such as when transplanted organs are rejected b. The immune system also destroys immune cells that might attack the body .

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36.5 How Does the Adaptive Immune System Attack Invaders?

A. An Immune Response Takes Time to Develop 1. It usually takes about 1 to 2 weeks to mount a good immune response to the first exposure to an invading microbe B. The Adaptive Immune System Launches Two Types of Attacks Against Invaders 1. Humoral immunity and cell-mediated immunity work together C. Humoral Immunity Is Produced by Antibodies Dissolved in the Blood 1. When an infection occurs, antibodies produced by a few B cells bind to antigens on the invader (Figure 36-8) a. The B cells divide rapidly in a process called clonal selection i. Memory cells produced play an important role in future immunity ii.Plasma cells mass-produce the required antibody 2. Humoral antibodies have multiple modes of action against invaders a. Antibodies may bind to an invader and neutralize it (Figure 36-9a) â Lecture Activity 36.3: Neutralization of Toxins by Antibodies b. Antibodies may coat the surface of an invader and make it easier for macrophages to destroy it (Figure 36-9b) c. When antibodies bind, they interact with complement proteins, which can kill microbes or promote phagocytosis â Case Study Continued: Flesh-Eating Bacteria 3. Humoral immunity fights invaders that are outside cells D. Cell-Mediated Immunity Is Produced by Cytotoxic T Cells 1. T cells attack infected or cancerous cells a. Cytotoxic T cells bind to antigens on the surface of infected cells or cancerous cells and release proteins that disrupt the infected cell’s plasma membrane (Figure 36-10) E. Helper T Cells Enhance Both Humoral and Cell-Mediated Immune Responses 1. When a receptor on a helper T cell binds an antigen, the cell multiplies rapidly a. The daughter cells release cytokines that stimulate division and differentiation of B cells and cytotoxic T cells (Figure 36-11)

36.6 How Does the Adaptive Immune System Remember Its Past Victories?

A. Some of the Daughters of the Original B and T Cells Remain and Differentiate into Memory B and T Cells 1. Upon subsequent infection, remaining memory cells mount such a large, quick response that the invader cannot cause illness (Figure 36-12) a. This is called acquired immunity and can last a long time â Health Watch: Exotic Flu Viruses (Figure E36-2) â Lecture Activity 36.4: Immunity

36.7 How Does Medical Care Assist the Immune Response?

A. Antibiotics Slow Down Microbial Reproduction 1. Antibiotics are chemicals that combat infection by slowing down the multiplication of bacteria, protists, or fungi B. Vaccinations Produce Immunity Against Disease 1. A vaccine stimulates an immune response by exposing a person to antigens produced by a pathogen â Science in Action: The Discovery of Vaccines (Figure E36-3)

36.8 What Happens When the Immune System Malfunctions?

A. Allergies Are Misdirected Immune Responses 1. Binding of allergens to “allergy antibodies” on a special type of B cells occurs a. This B cell proliferates and pours out allergy antibodies into the plasma (Figure 36-13) b. The antibodies bind to mast cells and stimulate release of histamine, initiating the inflammatory response B. An Autoimmune Disease Is an Immune Response Against the Body’s Own Molecules 1. Examples of autoimmune diseases include type I diabetes, rheumatoid arthritis, and multiple sclerosis 2. At this time, there are no cures for these types of diseases .

Chapter 36 Defenses Against Disease C. Immune Deficiency Diseases Occur When the Body Cannot Mount an Effective Immune Response 1. Severe combined immune deficiency is an inherited disorder a. Common infections can prove fatal for individuals with this disease b. One form of treatment is a bone marrow transplant from a healthy individual 2. AIDS is an acquired immune deficiency disease a. AIDS is caused by the human immunodeficiency virus (HIV) b. HIV is transmitted by body fluids c. HIV infects and destroys helper T cells (Figure 36-14) d. There are partially effective treatments, but no cures for AIDS i. AIDS vaccine research is under way to find a vaccine against all strains of HIV

36.9 How Does the Immune System Combat Cancer?

A. The Immune System Recognizes Most Cancerous Cells as Foreign 1. Natural killer cells and cytotoxic T cells screen for and kill cancerous cells B. Vaccination Can Prevent Some Cancers 1. Vaccination against the human papilloma virus (HPV) can prevent some types of cervical cancer C. Vaccines May Someday Help to Cure Cancer D. Most Medical Treatments for Cancer Depend on Selectively Killing Cancerous Cells 1. Surgery is used to remove localized tumors 2. Radiation is used to kill localized patches of cancer cells 3. Chemotherapy and drug treatment kill dividing cells

Case Study Revisited: Flesh-Eating Bacteria

KEY TERMS acquired immune deficiency syndrome (AIDS) adaptive immune response adaptive immune system allergy antibiotic antibody antigen autoimmune disease B cell cancer cell-mediated immunity clonal selection complement constant region cytokine cytotoxic T cell

dendritic cell fever helper T cell histamine human immunodeficiency virus (HIV) humoral immunity inflammatory response innate immune response leukocyte lymph node lymphocyte macrophage major histocompatibility complex (MHC) mast cell memory B cell memory T cell

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microbe natural killer cell neutrophil pathogen phagocyte plasma cell regulatory T cell severe combined immune deficiency (SCID) T cell T-cell receptor thymus tonsil vaccine variable region

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LECTURE ACTIVITIES Lecture Activity 36.1: Transmission of Disease Estimated Time to Complete: 5–8 minutes Section Reference 36.1 How Does the Body Defend Itself Against Disease?

Introduction Microbes are all around us, but we only occasionally get sick. Our amazing immune systems have evolved in the face of this onslaught to become very efficient machines. This lecture activity demonstrates how easily microbes can be passed from person to person. This is done by placing a tracer powder on the door of the classroom, then determining how many students picked up the tracer. This is a very effective way to start the discussion of the immune system, because it emphasizes the fact that we are constantly bombarded by microbes. The fact that we aren’t constantly sick attests to the competence of the immune system and sets the stage for exploring how the immune system does its job so well.

Materials Needed • Fluorescent powder • Battery-operated handheld UV lamp • Dusting brush All three of these can be found in fingerprint kits available through various online retailers.

Procedures 1. Before-class preparation: Purchase fingerprint kit or other source of fluorescent/UV-reflective powder and UV lamp.

2. Arrive at class early, before the students get there, and dust the doorknob with the UV-reflective powder.

3. During class: Introduce the chapter and the topic of microbes in our environment.

4. Go around the room with your handheld UV lamp and illuminate the students’ hands to find out if they have picked up the tracer and how much they picked up. (In large classrooms, you could recruit 10–15 volunteers to be screened at the front of the class instead of testing the whole class.) Explain to them that you dusted the door with a tracer to show them how frequently they encounter microbes from their environment.

Assessment Suggestions The following questions could be used for a post-demonstration discussion, quiz, or homework assignment, or on the exam for this chapter.

1. If we are constantly bombarded by microbes, but we are only occasionally sick, what does this say about the immune system?

(This demonstrates that we have an immune system that is very effective at fighting off microbes.)

2. What are the characteristics of our bodies that are so attractive to microbes?

(Our warm, wet, nutrient-rich bodily fluids are an ideal habitat for many microbes.)

3. What do you think makes some infections annoying and others deadly?

(This open-ended question is better for a discussion format. Try to guide the discussion toward comparisons of microbial characteristics, such as ability to infect versus postinfection activity—what they do once inside the body.)

Lecture Activity 36.2: Antibody Diversity Estimated Time to Complete: 5 minutes Section Reference 36.4 How Does the Adaptive Immune System Recognize Invaders?

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Introduction Our immune systems have the capability of recognizing a seemingly limitless number of microbes. This activity addresses the immune system’s ability to recognize so many different antigens. The students act as B cells and create their own antibody by combining fragments from three different groups of fragments. This is a good way to introduce the section on antibody diversity.

It can also be done after the discussion of antibody diversity to give the students a “hands-on” idea of just how much diversity you can get from recombining genes from multiple “decks” of hundreds of possibilities.

Materials Needed • PowerPoint slide, overhead transparency, or chalkboard/white board Procedures 1. Before-class preparation: Put the following three columns on the slide—1st column: list C1–C14 (avoid the numbers 3, 5, 7, and 13); 2nd and 3rd columns: list V1–V14 (avoid the numbers 3, 5, 7, and 13). The letters and numbers in each column represent different antibody fragments.

2. During class: Put up the slide.

3. Tell the class that each student is going to play the role of a developing B cell and must pick one antibody fragment from each of these columns to construct his or her own antibody.

4. Give them seconds to make their selections.

5. After they have made their selections, have the students share the structure of their antibodies with the rest of the class. (In a smaller classroom, you can have each student share the structure of his or her antibody. In a large classroom, have only some students share their structures, and then ask if anyone else in the class had an identical match.)

6. Discuss how recombination can lead to great diversity and why there were few, if any, students with the same antibody.

Assessment Suggestions Use the following questions for generating discussion or for post-activity assessment.

1. How many different antibodies could you construct from these three columns?

(1,000 [10 * 10 * 10]) Discussion: Now think about what that number would look like if the columns had hundreds of different fragments per column.

2. How are antibodies able to recognize so many different antigens that they have never seen before?

(Through sheer diversity. This question can lead into a discussion of the potential for different antibodies if real B cells have multiple “columns” with hundreds of different fragments each to choose from. This can also lead into the coverage of antibody diversity in the lecture.)

3. How does T-cell receptor diversity compare to antibody diversity?

(They come by their diversity in the same way, so their level of diversity will be similar.)

Lecture Activity 36.3: Neutralization of Toxins by Antibodies Estimated Time to Complete: 2–3 minutes Section Reference 36.5 How Does the Adaptive Immune System Attack Invaders?

Introduction Toxins, such as snake or insect venom, cause damage by interacting with cellular components in the body and impairing their function. This causes cell and tissue damage, which could lead to death. Antibodies recognize and bind to antigens on toxins in the blood or extracellular fluid. By binding to toxins, the antibodies change their shape and thwart their ability to do damage.

This demonstration of how antibodies neutralize toxins is a quick, simple way to reinforce the concepts of the “lock-in-key” interaction between antibodies and their antigens, as well as the importance of structure to function, particularly when discussing proteins.

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Materials Needed • Old doorknob assembly with key that fits it

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Procedures 1. During class: Hold up the key and compare it to a toxin. Many toxins are proteins and can cause their damaging effects only by interacting with molecules in a cell. Their ability to function is dependent on their shape.

2. Hold up the doorknob and compare it to an antibody.

3. Put the key in the keyhole of the doorknob. Antibodies bind to their antigens in a lock-in-key fashion.

Assessment Suggestions Open discussion with Question 1 or use the following for a post-demonstration quiz.

1. Can the toxin function with the antibody attached to it? Why or why not?

(No. Because the shape has changed, the toxin can no longer function properly.)

2. What is antivenin? How is it made?

(Antibodies against a particular venom. It is made by extracting venom and injecting it in small doses to an organism such as a horse or rabbit, to elicit an immune response. Then the antibodies against the venom are purified and used to counteract the effects of the toxin.)

3. On the basis of what you know about proteins, describe how you think the following environmental conditions would affect antibody function: Extreme heat High acidity Very high salt concentrations (Because antibodies are proteins, their shape is both crucial to function and dependent on their environment.

Extreme changes in environmental conditions would change the shape of the antibody and impair its ability to function.)

Lecture Activity 36.4: Immunity Estimated Time to Complete: 8–10 minutes Section Reference 36.6 How Does the Adaptive Immune System Remember Its Past Victories?

Introduction The immune system remembers microbes that it has encountered, due to the creation of memory cells. Because closely related microbes can share antigens, sometimes we have pre-immunity to microbes that we have not encountered. This activity introduces students to the concepts of immunity and pre-immunity and relates these to the transmission of diseases. This is a good follow-up to discussion of the role of memory cells in immunity. Using SARS as an example, you can introduce this activity by asking the class why some people have come down with SARS and others have not.

Materials Needed • Pack of index cards Procedures 1. Before-class preparation: Make up index cards with different immunity profiles on them (~5 different profiles for small classes and ~20 different profiles for large classes). The immunity profile should contain five categories, each representing a variant of the flu virus. (See Handout or Display section for template.)

Make enough index cards so that each student has one.

2. During class: Hand out the index cards and inform the students that these represent their immunity profiles (the antigens to which they have been exposed).

3. Now “release” your virtual flu variant into the classroom. (On the chalkboard, write the antigens that are on the new flu variant; see following example.)

4. Poll the class to find out how many have immunity to this new variant.

5. For students with immunity, have them tell from which flu variant and antigen they got immunity.

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Assessment Suggestions Open the post-activity discussion with Question 1.

1. Why doesn’t everyone come down with SARS, or with this year’s version of the flu?

(Other than the simple matter of exposure, we each have different immunities and pre-immunities based on our past experiences. Some closely related microbes [for example, variants of the flu virus] share the same antigen or have only very slight differences between particular antigens. An individual’s reaction to the new microbe is dependent on which antigen from that microbe his or her immune system recognizes. It is possible for one person to be exposed to the flu and recognize a very general antigen that is shared by many variants, whereas another person exposed to the same flu will recognize a different, more specific antigen. The first person will develop pre-immunity to several flu variants, whereas the second person will have immunity only to the version to which he or she was exposed.)

2. How can you have immunity to something that you have never seen before?

(You can be pre-immune to a microbe if it has an antigen that is exactly like or very similar to an antigen that you have been exposed to on a different microbe.)

Handouts or Display See the following page.

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Chapter 36 Defenses Against Disease Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

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Lecture Activity 36.3 Handout—Immunity Example of Immunity Profile Flu Variant

A

B

C

D

E

Antigen 1

A1

B1

C1

D1

E1

Antigen 2

A2

Antigen 3

A3

C2

Antigen 4

E2

C4

Antigen 5

B5

D5

Antigen 6

E6

Antigen 7

B7

Row 1: Flu variants.

Rows 2–6: Different antigens on the flu variants.

Antigen 1 is the most general and is conserved among all variants.

Antigens 2 and 5 are less conserved and found on only a few variants.

Antigens 3, 4, 6, and 7 are very specific and found on only a single variant.

Columns A–E: Examples of five different flu variants. This profile appears on every card.

Put a capital “Y” next to an antigen to signify previous exposure; for example, a few students in the class might get the following profile: Flu Variant

A

B

C

D

E

Antigen 1

A1

B1

C1

D1

E1

Antigen 2

A2 Y

Antigen 3

A3

C2

Antigen 4 Antigen 5

E2

C4 Y B5

D5

Antigen 6 Antigen 7

E6 Y B7 Y

Example of a new virtual flu variant: Flu F has antigens 1, 5, and 8.

The above immunity profile would not confer immunity to this new flu variant. .

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CHAPTER 37 CHEMICAL CONTROL OF THE ANIMAL BODY: THE ENDOCRINE SYSTEM LECTURE OUTLINE Case Study: Life-Changing Hormones 37.1 How Do Animal Cells Communicate?

A. Communication Between Cells Falls into Four Broad Categories (Table 37-1) 1. Direct communication from the inside of one cell to the next occurs through gap junctions 2. In synaptic, paracrine, and endocrine communication, cells send chemical messengers that bind to receptors on the target cells a. There are three types of chemical messengers i. Hormones are secreted into the interstitial fluid and then enter the bloodstream ii.Local hormones affect nearby cells, whereas endocrine hormones affect multiple parts of the body iii.Neurotransmitters are produced by nerve cells and act at close range 3. Synaptic communication is used in the nervous system B. Paracrine Communication Acts Locally 1. In paracrine communication, cells release local hormones that diffuse through the interstitial fluid to nearby cells a. Local hormones include histamine, cytokines, and prostaglandins b. Prostaglandins are modified fatty acids that have a variety of roles i. Acetaminophen and ibuprofen relieve pain by blocking prostaglandin synthesis C. Endocrine Communication Uses the Circulatory System to Carry Hormones to Target Cells Throughout the Body 1. Endocrine communication begins with the secretion of hormones by endocrine glands (Figure 37-1) a. The hormones diffuse into the capillaries and are carried throughout the body by the bloodstream b. Some changes brought about by endocrine hormones may be prolonged and irreversible, whereas others are temporary and reversible

37.2 How Do Endocrine Hormones Produce Their Effects?

A. There Are Three Classes of Vertebrate Endocrine Hormones 1. Peptide hormones are chains of amino acids 2. Amino acid derived hormones are composed of one or two modified amino acids 3. Steroid hormones are synthesized from cholesterol B. Hormones Act by Binding to Receptors on or in Target Cells (Figure 37-2) â Lecture Activity 37.1: Endocrine Hormone Distribution and Target Cells 1. Hormone-receptor binding causes two major effects a. Changes in metabolism in the cell by activating or inhibiting enzymes may occur b. Gene transcription is altered, changing the types and amounts of proteins produced C. Peptide Hormones and Amino Acid Derived Hormones Usually Bind to Receptors on the Surfaces of Target Cells (Figure 37-2) 1. Hormone-receptor binding activates an enzyme that synthesizes a second messenger inside the cell a. cAMP acts as a second messenger that conveys the signal from membrane receptors to the inside of the cell b. Reactions to this process depend on the hormone, the second messenger, and the target cell â Lecture Activity 37.2: Hormones Bind to Specific Receptors on Target Cells .

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Instructor Guide Biology: Life on Earth D. Steroid Hormones Usually Bind to Receptors Inside Target Cells (Figure 37-3) 1. Steroid hormones are lipid soluble and can diffuse through the plasma membrane a. Once inside the cell, they bind to receptors, triggering various effects â Health Watch: Anabolic Steroids—Fool’s Gold? (Figure E37-1) â Case Study Continued: Life-Changing Hormones E. Hormone Release Is Regulated by Feedback Mechanisms 1. Most hormones are controlled by negative feedback, which inhibits further hormone release a. Antidiuretic hormone (ADH) secretion is controlled by negative feedback 2. In a few cases, positive feedback is used to amplify hormone release a. Oxytocin secretion during childbirth is controlled by positive feedback, which ends when the child is born F. Vertebrate and Invertebrate Endocrine Hormones Often Have Similar Mechanisms of Action 1. Insect molting is controlled by a steroid hormone (Figure 37-4) a. Ecdysone controls the molting process in insects

37.3 What Are the Structures and Functions of the Mammalian Endocrine System?

A. The Mammalian Endocrine System Consists of the Endocrine Glands and the Hormones They Produce (Figure 37-4 and Table 37-2) B. Hormones of the Hypothalamus and Pituitary Gland Regulate Many Functions Throughout the Body 1. The hypothalamus is a part of the brain and contains neurosecretory cells (Figure 37-5) a. The neurosecretory cells produce peptide hormones 2. The pituitary gland is connected to the hypothalamus a. This gland has two parts, the anterior and posterior pituitary (Figure 37-5) 3. The anterior pituitary produces and releases multiple hormones a. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are involved in the production of gametes and sex hormones b. Thyroid-stimulating hormone (TSH) stimulates the thyroid to release its hormones c. Adrenocorticotropic hormone (ACTH) causes the adrenal cortex to release cortisol d. Prolactin, in conjunction with other hormones, stimulates the development of milk-producing mammary glands in the breasts during pregnancy e. Growth hormone regulates body growth (Figure 37-6) i. Dwarfism results from too little growth hormone during development ii. Gigantism results from too much growth hormone during development f. Hypothalamic hormones control the release of hormones in the anterior pituitary (Figure 37-5) i. Releasing hormones from the hypothalamus cause secretions of specific hormones from the anterior pituitary ii. Inhibiting hormones from the hypothalamus stop secretions of specific hormones from the anterior pituitary 4. The posterior pituitary releases hormones synthesized by cells in the hypothalamus (Figure 37-5) a. ADH helps prevent dehydration b. Oxytocin is involved in lactation and childbirth, as well as in some behaviors (Figure 37-7) C. The Thyroid and Parathyroid Glands Influence Metabolism and Calcium Levels 1. The thyroid gland lies at the front of the neck just below the larynx and secretes two major hormones (Figure 37-8) a. This gland produces thyroxine and calcitonin 2. The parathyroid gland consists of two pairs of two small disks that are on the back of the thyroid gland a. This gland produces parathyroid hormone 3. Thyroxine influences energy metabolism a. It is an iodine-containing amino acid derivative and influences gene activity related to metabolism b. Iodine deficiencies cause an enlargement of the thyroid gland called a goiter (Figure 37-9) 4. Thyroxine release is controlled by the hypothalamus and anterior pituitary (Figure 37-10) a. Levels of thyroxine in the bloodstream are fine-tuned by negative feedback 5. Thyroxine has varied effects in different vertebrates 6. Parathyroid hormone and calcitonin regulate calcium metabolism a. When blood calcium levels are low, parathyroid hormone causes the bones to release calcium b. When blood calcium levels are high, calcitonin inhibits the release of calcium .

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D. The Pancreas Has Both Digestive and Endocrine Functions 1. Islet cells of the pancreas produce two endocrine hormones 2. Insulin and glucagon control glucose levels in the blood (Figure 37-11) a. When blood glucose levels rise, insulin promotes uptake of glucose by cells b. When blood glucose levels decline, glucagon promotes the breakdown of glycogen by the liver, increasing blood glucose concentrations 3. Diabetes results from a defective insulin control system a. Lack of insulin production or the failure of target cells to respond to insulin results in diabetes mellitus b. There are two forms of diabetes i. In type I, a malfunctioning immune system destroys the insulin-producing islet cells ii. In type II, cells are insulin resistant â Lecture Activity 37.3: Case Study: Diabetes Mellitus Types 1 and 2 E. The Sex Organs Produce Both Gametes and Sex Hormones 1. The testes produce several steroid hormones, called androgens a. Testosterone stimulates sperm cell production in males 2. The ovaries secrete two types of steroid hormones a. Estrogen and progesterone stimulate egg production, which affect the menstrual cycle and pregnancy 3. Sex hormone levels increase during puberty a. Puberty starts when the hypothalamus starts secreting hormones i. These stimulate the anterior pituitary to secrete LH and FSH, which cause the testes and ovaries to secrete higher levels of sex hormones ii. The sex hormones initiate sperm and egg development and the development of secondary sexual characteristics â Earth Watch: Endocrine Deception (Figure E37-2) F. The Adrenal Glands Secrete Hormones That Regulate Metabolism and Responses to Stress (Figure 37-12) 1. The adrenal cortex produces steroid hormones a. The glucocorticoids, such as cortisol, are released in response to stress by increasing blood glucose levels and promoting the use of fats for energy b. Aldosterone is a mineralocorticoid that regulates sodium content in the blood c. A small amount of testosterone is secreted by this gland in both males and females 2. The adrenal medulla produces amino acid derived hormones a. Epinephrine and norepinephrine are released in response to emergency situations to prepare the body for action G. Hormones Are Also Produced by the Pineal Gland, Thymus, Kidneys, Digestive Tract, Heart, and Fat Cells 1. The pineal gland is located in between the two hemispheres of the brain above the hypothalamus and secretes melatonin in a daily rhythm a. Melatonin is thought to play a role in regulating seasonal reproductive cycles in some mammals â Lecture Activity 37.4: Circadian Rhythms and the Endocrine System 2. The thymus gland is located in the chest cavity behind the breastbone a. Thymosin regulates the development of T cells, which play an important role in the immune system 3. The kidneys are important endocrine organs that produce two hormones a. Erythropoietin increases red blood cell production b. Renin catalyzes the production of angiotensin, which constricts blood vessels and raises blood pressure 4. The digestive tract secretes a variety of peptide hormones, including gastrin, ghrelin, secretin, and cholecystokinin, and others that help regulate digestion 5. The heart secretes a peptide hormone to help regulate blood volume a. Atrial natriuretic peptide (ANP) stimulates the release of ADH and aldosterone, causing increased output of sodium and water by the kidneys, decreasing blood volume 6. Fat cells release a peptide hormone, leptin, thought to be involved in regulation of body weight and a variety of other possible functions (Figure 37-13)

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KEY TERMS adrenal cortex adrenal gland adrenal medulla adrenocorticotropic hormone (ACTH) aldosterone amino acid derived hormone androgen angiotensin anterior pituitary antidiuretic hormone (ADH) atrial natriuretic peptide (ANP) calcitonin cortisol cyclic adenosine monophosphate (cyclic AMP) diabetes mellitus endocrine communication endocrine disrupter endocrine gland endocrine hormone endocrine system epinephrine erythropoietin

estrogen follicle-stimulating hormone (FSH) glucagon glucocorticoid goiter growth hormone hypothalamus inhibiting hormone insulin islet cell leptin local hormone luteinizing hormone (LH) melatonin mineralocorticoid negative feedback neurosecretory cell norepinephrine ovary oxytocin pancreas paracrine communication parathyroid gland

parathyroid hormone peptide hormone pineal gland pituitary gland positive feedback posterior pituitary progesterone prolactin prostaglandin receptor releasing hormone second messenger steroid hormone synaptic communication target cell testis (plural, testes) testosterone thymosin thymus thyroid gland thyroid-stimulating hormone (TSH) thyroxine

LECTURE ACTIVITIES Lecture Activity 37.1: Endocrine Hormone Distribution and Target Cells Estimated Time to Complete: 5 minutes Section Reference 37.2 How Endocrine Hormones Produce Their Effects?

Introduction Endocrine hormones are carried from their site of synthesis to distant targets by the circulatory system. In this way, the endocrine system is very much a “broadcast” system. The signal is distributed to almost every cell in the body, but only those cells with the appropriate receptor can “receive” and respond to the signal. This activity is a very simple but efficient way to demonstrate this concept. Use this activity to open the discussion on target cells.

Materials Needed • Portable radio Procedures 1. Before-class preparation: Take your radio to the classroom and make sure that you can pick up at least one radio station.

2. During class: Open this activity with the following question: If hormones of the endocrine system are carried by the bloodstream to almost every cell in the body, then why doesn’t every cell respond to every hormone?

3. After recruiting a few answers from the classroom, introduce the concept of target cells. Cells need the appropriate receptors to be able to sense and respond to a receptor.

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Ask the class to name some of the signals that are in the classroom right now that they can sense. If they need help getting started, you can point out that they can see you and many other objects and people in the room, they can hear your voice, and they can feel the temperature of the room and the pens or pencils in their hands.

Now ask them to name some possible signals in the room that they can’t sense. Then pull out the radio and turn it on. Compare the radio to a hormone receptor. The signals were always there in the room, but only with the appropriate equipment could those signals be received.

Assessment Suggestions Use the following question to begin a post-demonstration discussion: 1. Where does the radio analogy break down?

(Because the radio is the receptor in the analogy and the radio waves are the hormones, then the radio can “respond to” or pick up many different stations, but real hormone receptors usually respond to only one, maybe two hormones.)

Lecture Activity 37.2: Hormones Bind to Specific Receptors on Target Cells Estimated Time to Complete: 10 minutes Section Reference 37.2 How Do Endocrine Hormones Produce Their Effects?

Introduction Peptide and amino acid hormones are water soluble and must use membrane receptors. Many times, the hormone acts as a first messenger to deliver the message to the cell. Upon binding the membrane receptor, a second messenger pathway is initiated that relays the message inside the cell. cAMP is a common second messenger.

Once the second messenger has been activated, it initiates a cascade of enzyme-catalyzed reactions. Each stage of the cascade involves more molecules, which greatly amplifies the original signal. In this activity, the students play the roles of the different signaling molecules and act out the activation of a second messenger system.

Materials Needed None Procedures 1. During class: You will need to recruit volunteers as follows: 1 person to act as the hormone 1 person to act as the receptor 1 person to act as cAMP 2. The first row of seated students should act as the first level of inactive enzymes waiting to be activated by cAMP. 3. The second row of seated students should act as the second level of inactive enzymes waiting to be activated by the first level of activated enzymes.

4. The third row of seated students should act as the reactants waiting to be turned into product as the last step in the pathway.

5. A touch on the arm represents activation, and once activated, cAMP and the enzymes will be active for 5 seconds (counted off by the student).

6. To start the reaction, the hormone approaches the receptor and activates the receptor. The receptor then reaches out and activates cAMP. cAMP then walks to the first row and taps as many students as possible in the 5-second time period.

7. When students (enzymes) in the first two rows are tapped (activated), they should stand up and tap as many students in the next row as possible during the 5-second time period. Enzymes should sit down after their 5 seconds are up.

8. Students in the third row should stand up when tapped and remain standing. The students left standing in the third row after the signaling pathway is complete represent the number of end-product molecules produced by the single hormone messenger.

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Assessment Suggestions Use the following questions for a post-demonstration discussion or quiz: 1. What are two significant effects that we get from this type of system?

(Amplification and persistence—the effects can long outlast the hormone–receptor interaction.)

2. What are possible sites to shut off this response? (block the receptor; block cAMP; block any of the enzymes) 3. How could you get even further amplification from this system? (by increasing the amount of time that the hormone is bound to the receptor or that any of the components of the pathway are active) This last question can lead into an interesting class discussion about the effects of drugs like Viagra that enhance second messenger systems.

Viagra—mechanism of action: cGMP is the second messenger in the signaling pathway that causes erections.

It promotes smooth-muscle relaxation, increased blood flow to the penis, and erection. Viagra inhibits cGMPspecific phosphodiesterase 5 (PDE5—the enzyme that breaks down cGMP), thus increasing the amount of time that cGMP is active.

Lecture Activity 37.3: Case Study: Diabetes Mellitus Types 1 and 2 Estimated Time to Complete: 10 minutes Section Reference 37.3 What Are the Structures and Functions of the Mammalian Endocrine System?

Introduction Malfunctions in the insulin signaling pathway lead to increased levels of blood glucose that fluctuate with ingestion of food: This condition is known as diabetes mellitus. There are two basic forms of diabetes: Type 1 diabetes, also called insulin-dependent diabetes mellitus (IDDM), is caused by an autoimmune disorder that destroys insulin-producing cells in the pancreas, which results in little or no secretion of insulin. Type 2 diabetes, also called non-insulin-dependent diabetes mellitus (NIDDM), is often caused by an insensitivity of tissues to insulin. So, even though insulin levels may be normal, tissues aren’t able to respond to insulin, and blood glucose levels remain high.

Materials Needed Two patient profiles are provided on the following page.

Procedures Put up the first patient profile slide. The class will act as a doctor and diagnose the illness based on the symptoms.

If necessary, guide the class to the diagnosis with hints about blood glucose level and the glands/hormones involved in controlling it. The first diagnosis should be pretty easy.

Once the class has successfully made the first diagnosis, put up the second slide. Point out similarities and differences between the two patients. This diagnosis will be a little trickier and will point out the importance of all parts of the signaling system.

Assessment Suggestions Post-activity discussion question: 1. If insulin levels are normal in type 2 diabetes, then where is the problem?

(If hormone secretion and distribution are normal, then the defect has to be in the response system.)

Have the class come up with a list of all the possible places where a defect could cause hormonal signaling to go awry, and discuss examples of these from the text.

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 37.3 Handout—Case Study on Diabetes Mellitus Types 1 and 2

Characteristics Age Sex Exam

Patient one profile 14 Male Not obese Blood pressure: low High blood glucose Low levels of insulin

Lab Tests

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Patient two profile 40 Male Obese Blood pressure: high High blood glucose Normal levels of insulin

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Lecture Activity 37.4: Circadian Rhythms and the Endocrine System Estimated Time to Complete: Students will collect data over a 48-hour period, but in-class time should not exceed 10 minutes Section Reference 37.3 What Are the Structures and Functions of the Mammalian Endocrine System?

Introduction Circadian rhythms are cycles of activity that occur in a 24-hour period. The pineal gland secretes the hormone melatonin in a circadian rhythm. Melatonin secretion is inhibited by daylight and increases at night. In some vertebrates, the skull is thin enough for sunlight to directly impact the pineal gland. In mammals, photoreceptors in the retina send signals about light levels to both the pineal gland and to a special part of the hypothalamus that is part of the human biological clock. Secretion of some hormones by the hypothalamus is influenced by this clock, which means that secretion of hormones by the pituitary gland is also affected. The daily secretions of several hormones, such as ACTH, cortisol, and aldosterone, are well documented. Rhythmic secretion of these and other molecules causes rhythmic changes in certain behaviors and physiological states.

In this activity, students will track changes in a behavior, yawning, and a physiological state, body temperature, over a 48-hour period.

Materials Needed • 5 × 7 note cards • PowerPoint template for body temperature/yawn diary on following page Procedures 1. At the end of the class period before discussing the pineal gland and rhythmic secretion of hormones: Hand out note cards to the class and tell students to copy the template schedule from your PowerPoint slide or overhead. Announce that you will be discussing the pineal gland and circadian rhythms in the following class, and in preparation, the class is going to track one behavior, yawning, and one physiological state, body temperature, to see if they are rhythmic.

2. The students should try to maintain as normal a sleep–wake cycle as possible during the 48 hours.

3. Body temperature should be taken in the same way each time and the students shouldn’t eat or drink anything right before taking body temperature. Body temperature measurements should be taken at least three times: 6 a.m., noon, and 9 p.m.

4. The students should carry their note cards with them at all times to record their yawns. Yawn schedules can be grouped into three periods: the number of yawns that occur from 6 a.m. (or waking) to noon, from noon to 6 p.m., and from 6 p.m. to midnight (or sleeping).

5. During the following class: Collect data from the students. For body temperature: get a show of hands for the number of people who had their highest body temperature at 6 a.m., noon, or 9 p.m., then the same for their lowest body temperature.

(Documented averages for daily changes in body temperature: typically highest in early evening; typically lowest right before waking. Yawns typically occur right before bedtime and soon after waking.)

Assessment Suggestions Compare the class numbers to the known averages and discuss similarities or differences. If class values differ from known averages, discuss factors involving the schedules of college students that might play a role.

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 37.4 Handout—Circadian Rhythms and the Endocrine System Templates for Schedules Body Temperature Measurement Schedule Time

Day 1 (temp in °F)

Day 2 (temp in °F)

6 a.m.

Noon 9 p.m.

Yawn Occurrence Schedule Time

Day 1 (# of yawns)

6 a.m.–noon Noon–6 p.m.

6 p.m.–midnight (or sleeping)

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Day 2 (# of yawns)

CHAPTER 38 THE NERVOUS SYSTEM LECTURE OUTLINE Case Study: How Do I Love Thee?

38.1 What Are the Structures and Functions of Nerve Cells?

A. The Nervous System Has Two Principal Cell Types, Neurons and Glia B. The Functions of a Neuron Are Localized in Separate Parts of the Cell 1. A neuron has four distinct parts: dendrites, a cell body, an axon, and synaptic terminals (Figure 38-1) 2. These parts of the neuron perform four functions a. Neurons receive information from the environment b. Neurons process information and produce an electrical signal c. Neurons conduct signals over distances d. Neurons transmit signals to other neurons, or the cells of muscles or glands 3. Dendrites respond to stimuli a. These structures receive information, usually in the form of chemicals called neurotransmitters 4. The cell body processes signals from the dendrites a. These electrical signals are positive or negative b. If a signal is sufficiently positive, the neuron produces an electrical signal called an action potential 5. The axon conducts action potentials over long distances a. Axons are typically bundled into nerves 6. At synapses, signals are transmitted from one cell to another a. The synapse is the site where one neuron communicates with another cell b. A typical synapse consists of a synaptic terminal, a dendrite or cell body, and a small gap separating the two cells

38.2 How Do Neurons Produce and Transmit Information?

A. Information Within a Single Neuron Is Carried by Electrical Signals 1. Most neurons have a negative resting potential, which is the difference in voltage across its membrane 2. If the membrane potential reaches the threshold potential, the neuron will generate an action potential (Figure 38-2) â In Greater Depth: Electrical Signaling in Neurons 3. Myelin Speeds Up the Conduction of Action Potentials a. Many vertebrate axons have myelin covering them (Figure 38-3) b. Between each myelin wrapping are nodes of exposed axon i. Action potentials jump from node to node, speeding up their transmission B. Neurons Use Chemicals to Communicate with One Another at Synapses (Figure 38-4) 1. The presynaptic neuron transmits a signal by releasing neurotransmitter molecules that are stored in vesicles in the presynaptic terminal into the synaptic cleft) 2. The postsynaptic neuron receives the signal because it has specialized receptor molecules that bind to the neurotransmitter and cause changes in the cell 3. Synapses produce inhibitory or excitatory postsynaptic potentials (Figure 38-4) a. A postsynaptic potential is a small brief change in voltage of the neuron b. Inhibitory postsynaptic potentials (IPSPs) move the resting potential further from the threshold potential and make the cell less likely to generate an action potential c. Excitatory postsynaptic potentials (EPSPs) move the resting potential closer to the threshold potential and make the cell more likely to generate an action potential (Figure 38-4) â In Greater Depth: Synaptic Transmission (Figures E38-1 and E38-2)

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4. Neurotransmitter action is usually brief 5. Integration of postsynaptic potentials determines the activity of a neuron a. The dendrites and cell body of a neuron receive EPSPs and IPSPs from thousands of presynaptic neurons i. The voltages of all of these are added up by the postsynaptic neuron through a process called integration â Case Study Continued: How Do I Love Thee?

38.3 How Does the Nervous System Process Information and Control Behavior?

A. Most Behaviors Are Controlled by Pathways Composed of Four Elements 1. Sensory neurons respond to a stimulus, either internal or external to the body 2. Interneurons receive signals from many different sources and often activate motor neurons 3. Motor neurons receive messages from sensory neurons and interneurons and activate muscles or glands 4. Effectors, such as muscles and glands, perform the response directed by the nervous system B. These Four Elements Carry Out the Basic Operations Required of Any Nervous System 1. Nervous systems must determine the type of stimulus 2. Nervous systems must determine and signal the intensity of a stimulus 3. Nervous systems must integrate information from many sources â Lecture Activity 38.1: Convergence/Divergence 4. Nervous systems must initiate and direct appropriate responses C. The Nature of a Stimulus Is Encoded by Specialization of Sensory Neurons and Their Connections to Specific Parts of the Brain 1. Sensory neurons respond to different stimuli a. Information gathered by the senses is converted to action potentials, which are sent to the brain b. All nervous systems interpret what a stimulus is by monitoring which neurons are firing action potentials D. The Intensity of a Stimulus Is Encoded by the Frequency of Action Potentials (Figure 38-5) 1. Intensity can also be coded by the number of similar neurons that fire at the same time E. The Nervous System Processes Information from Many Sources 1. The brain receives sensory stimuli from many different sources F. The Nervous System Produces Outputs to Muscles and Glands 1. The nervous system stimulates activity in muscles and glands, which produce behaviors G. Behaviors Are Controlled by Networks of Neurons in the Nervous System 1. Simple behaviors such as the reflex may be controlled by activity in as few as two or three neurons 2. Complex behaviors are organized by interconnected neural pathways

38.4 How Are Nervous Systems Organized?

A. All Animals Have Two Basic Types of Nervous Systems 1. Radially symmetrical animals have a diffuse network of neurons called a nerve net (Figure 38-6a) 2. Bilaterally symmetric animals have a centralized nervous system in which cell bodies tend to be clustered in the “head” region and along the central axis of the animal (Figure 38-6b, c)

38.5 What Are the Structures and Functions of the Human Nervous System? (Figure 38-7) A. The Nervous System of All Mammals Is Divided into the Peripheral Nervous System (PNS) and the Central Nervous System (CNS) (Figure 38-7) B. The PNS Links the CNS with the Rest of the Body 1. The PNS consists of three major categories of axons a. Axons of sensory neurons that carry sensory information from all parts of the body b. Axons of motor neurons that control the skeletal muscles, regulating voluntary movements c. Axons of motor neurons that control involuntary movements 2. The somatic nervous system controls voluntary movement a. Most neurons of this system synapse with skeletal muscles 3. The autonomic nervous system controls involuntary actions (Figure 38-8) a. The sympathetic division of the autonomic nervous system prepares the body for “fight or flight” b. The parasympathetic division of the autonomic nervous system dominates during “rest and digest” .

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Instructor Guide Biology: Life on Earth C. The CNS Consists of the Spinal Cord and Brain 1. The skull and backbone form the first line of defense around the CNS 2. A triple layer of connective tissue, called the meninges, is the second line of defense 3. Cerebrospinal fluid between the meninges aids in cushioning the CNS 4. The blood–brain barrier, a wall of brain capillaries that are much less permeable than capillaries in the rest of the body, forms the third line of defense D. The Spinal Cord Controls Many Reflexes and Conducts Information to and from the Brain (Figure 38-9) 1. The spinal cord has axons of both sensory neurons and motor neurons 2. The center of the spinal cord, called the gray matter, consists mostly of cell bodies of neurons 3. The outer part of the spinal cord, called the white matter, consists mostly of the myelin-coated axons of the neurons 4. The neurons that control many reflexes reside in the spinal cord and PNS a. A reflex is an involuntary movement of a body part in response to a stimulus b. The pain-withdrawal reflex is a good example (Figure 38-10) 5. Some complex actions are coordinated within the spinal cord a. Neurons needed for a variety of complex actions, such as walking and running, are found in the spinal cord E. The Brain Consists of Many Parts That Perform Specific Functions 1. All vertebrate brains consist of three main parts: the hindbrain, the midbrain, and the forebrain (Figure 38-11a) a. In nonmammalian vertebrates, the three divisions are prominent (Figure 38-11b, c) b. In mammals, the brain regions are significantly modified (Figure 38-11d, e) c. The human brain has a variety of structures (Figure 38-12) 2. The hindbrain consists of the medulla, pons, and cerebellum (Figures 38-11e and 38-12a) a. The medulla controls several automatic functions b. The pons plays a role in the transition from sleep to wakefulness, as well as between the stages of sleep c. The cerebellum is crucial in coordinating movements of the body 3. The midbrain contains clusters of neurons that contribute to movement, arousal, and emotion (Figures 38-11 and 38-12) a. The midbrain is quite small in humans â Health Watch: Drugs, Neurotransmitters, and Addiction (Figure E38-3) â Lecture Activity 38.2: Addiction Discussion b. The reticular formation is an important relay and filtering station that extends from the medulla into the lower regions of the forebrain 4. The forebrain includes the thalamus, hypothalamus, and cerebrum (Figure 38-12a, b) a. The thalamus channels sensory information from all parts of the body to the limbic system and cerebral cortex b. The hypothalamus, through its hormone production and neural connections, helps maintain homeostasis c. The cerebrum consists of two cerebral hemispheres i.Each hemisphere is composed of an outer cerebral cortex d. Structures in the Interior of the cerebrum i.The amygdala produces sensations of pleasure, fear, or sexual arousal ii.The hippocampus is critical for the formation of long-term memory iii. The basal ganglia are important in the overall control of movement e. The limbic system is a group of structures that produce our most basic emotions, drives, and behaviors (Figure 38-13) f. The cerebral cortex i.The cerebral cortex is folded into convolutions ii.The cerebral cortex is divided into two hemispheres connected by a large band of axons, called the corpus callosum iii. Each hemisphere is divided into four anatomical regions: the (1) frontal, (2) parietal, (3) occipital, and (4) temporal lobes, which all have specific functions (Figure 38-14) â Case Study Continued: How Do I Love Thee?

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5. How do neuroscientists learn about the functions of brain regions? a. The functions of different parts of the brain were discovered by examining the behaviors and abilities of people who suffered brain injuries, such as the case of Phineas Gage (Figure 38-15) â Lecture Activity 38.3: Brain Dissection â Science in Action: Neuroimaging—Observing the Brain in Action (Figures E38-4 and E38-5) F. The Left and Right Sides of the Brain Are Specialized for Different Functions 1. Studies in which the corpus callosum has been cut have shown the differing functions of each hemisphere a. Axons from the eyes go to opposite sides of the brain (Figure 38-16) 2. Further studies have confirmed the different functions of each hemisphere G. Learning and Memory Involve Biochemical and Structural Changes in Specific Parts of the Brain 1. Learning has two phases a. Short-term memory and long-term memory 2. The frontal and parietal lobes and some of the basal ganglia deep in the cerebrum are the primary sites of short-term memory 3. Short-term memory probably requires repeated activity, whereas long-term memory involves structural changes

Case Study Revisited: How Do I Love Thee?

KEY TERMS action potential amygdala autonomic nervous system axon basal ganglia blood–brain barrier brain cell body central nervous system (CNS) cerebellum cerebral cortex cerebral hemisphere cerebrum corpus callosum dendrite dorsal root ganglion effector excitatory postsynaptic potential (EPSP) forebrain ganglion (plural, ganglia)

glia gray matter hindbrain hippocampus hypothalamus inhibitory postsynaptic potential (IPSP) integration interneuron limbic system long-term memory medulla midbrain motor neuron myelin nerve nerve net neuron neurotransmitter parasympathetic division peripheral nervous system (PNS)

LECTURE ACTIVITIES Lecture Activity 38.1: Convergence/Divergence Estimated Time to Complete: 10 minutes Section Reference 38.3 How Does the Nervous System Process Information and Control Behavior? .

pons postsynaptic neuron postsynaptic potential (PSP) presynaptic neuron reflex resting potential reticular formation sensory neuron short-term memory sodium-potassium (Na+-K+) pump somatic nervous system spinal cord sympathetic division synapse synaptic cleft synaptic terminal thalamus threshold white matter

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Introduction Two basic functions of the nervous system are to (1) receive information from the world (external or internal), and (2) use that information to direct appropriate responses. In between those two is a third crucial function, integration. The processes of integrating information from many different sources and then using that to coordinate complex responses are called convergence and divergence, respectively. For example, when we have a conversation with another person, our nervous systems integrate many different types of visual and auditory information about that person, in addition to signals from our own bodies about where we are in space. This allows us to perceive a coherent picture of the scene with the person’s voice coming from the same place as the visual image of that person. In addition, we can appropriately orient ourselves in space, so that we are facing the other person and not talking blindly into the space over the person’s left shoulder.

This demonstration highlights the importance of convergence by altering a single, specific input and looking at the effects on the production of a motor behavior. During this demonstration, prism lenses are used to shift the visual world by 15° to the left or right. Then the effect of the shifted visual field is observed on a relatively simple motor act, such as throwing a beanbag at a target. The motor system can adapt fairly quickly to the shift, so that after 10–12 throws, the thrower will be able to hit the target again. Now that the motor system has adapted to the shifted visual field, the prism lenses are removed and the behavior is observed again. The thrower will now throw to the opposite side of the target. There is typically a quite satisfying gasp from students when this happens, because they don’t yet appreciate the adaptation of the motor system and expect that when the lenses are removed the thrower will be back to normal immediately.

Materials Needed • Prism lenses, 30 diopter (Fresnel Prism and Lens Co., LLC, www.fresnel-prism.com) • Safety goggles • 6–10 small beanbags (juggler’s beanbags work well) Procedures 1. Before class: Assemble the goggles according to the instructions on the lenses. Briefly cut prism lenses to fit over the lenses of the safety goggles. Be sure to line up the lenses so that the prisms for each lens are in the same direction. Place the lenses on the goggles with a small amount of water (prism lenses will adhere to safety goggles without adhesive).

2. During class: Recruit a pair of volunteers from the class—one student to throw beanbags and the other to catch.

3. Place the pair of students 10 feet apart at the front of the classroom.

4. Have the thrower toss (not meant to be a hard throw) the beanbags to the catcher, to demonstrate his or her initial accuracy.

5. Next, have the thrower repeat Step 4 while wearing the prism lenses. The initial throws will be to the left or right of the catcher, depending on the direction of the shift in visual field. Prompt the student NOT to intentionally compensate for the deviation in the throw. The thrower should continue until his or her accuracy is close to normal.

6. Finally, have thrower remove the goggles, and then throw again. This time the throw should go to the opposite side of the target.

Assessment Suggestions The following are suggested questions that could be used as a post-demonstration quiz, or to prompt discussion about the demonstration: 1. Why does the thrower miss the target after putting on the prism glasses?

(The prism lenses shift the incoming visual information, so that objects that are directly in front of the thrower are perceived to be 15° to the left or right. Because the thrower’s motor system does not “know” about the visual shift, it will throw to where the target is perceived to be.)

2. Why does the thrower’s accuracy improve with successive throws while still wearing the prism glasses?

(When the thrower misses the target, this information is used to help retune the motor output to the new visual information and improve accuracy. This adaptation is taking place at the motor output level.)

3. Why isn’t the thrower accurate immediately after removing the prism lenses?

(When the glasses are removed, the image that is perceived to be in front of the thrower actually is in front of the thrower, but the thrower’s motor system has learned that the visual system is off by 15° to the right or left, so it will continue to throw that way until experience teaches it otherwise.) .

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If the thrower put the prism lenses on and sat quietly for several minutes without throwing a beanbag, do you think that the accuracy of the throw would be impaired after removing the lenses? Why or why not?

(No. The visual field has been shifted by the lenses, but because the student is not physically interacting with the environment, there is no feedback to the nervous system to let it know that the visual information is inaccurate, so no adaptation of the motor system is taking place.)

Handouts or Display None

Lecture Activity 38.2: Addiction Discussion Estimated Time to Complete: 40–50 minutes (or entire class period), depending on how long the teacher wants the discussion to last Section Reference 38.5 What Are the Structures and Functions of the Human Nervous System?

Introduction Drug and alcohol addiction have become very prevalent in the United States. The Centers for Disease Control (CDC) reported that in 2006, over 35,000 people died due to alcohol use or abuse. The Department of Transportation reported that in 2006, 19% of drivers ages 16–20 who died in traffic accidents had been drinking alcohol. The CDC also reported that from 1999–2006, the number of deaths related to opioid use (including cocaine and heroin) doubled. Obviously, the use of alcohol and illicit drugs can be dangerous to human health, yet there are still many people who use and abuse them. The purpose of this discussion is to get the students thinking about the dangers of alcohol and drug abuse.

Materials • Computer lab with Internet access Procedures Organize the students into groups of three or four. Have each student perform Internet searches on the characteristics and health impacts of one of the following substances: alcohol, cocaine, heroin, or other illicit drugs (the teacher can choose these or allow the students to choose). Have the students research what the substance does in the human brain (i.e., what neurotransmitters it substitutes for), the type of feelings it elicits (e.g., euphoria), and three short- and long-term health impacts on the human body. Allow approximately 15–20 minutes for the students to perform their research.

Once the students have completed their research, have them get in their groups and spend approximately 15 minutes sharing what they learned with each other.

Have each group report to the entire class one substance, its function in the human brain, one feeling it generates, and one health risk.

Ask the students the following questions during the whole-class discussion: 1. Alcohol and drugs have significant negative effects on human health. That being the case, why is alcohol and drug abuse so prevalent in the United States?

2. How can alcohol and drug abuse be prevented among adolescents?

3. What are the potential warning signs of alcohol or drug abuse? If you suspected that a friend or family member was abusing drugs or alcohol, what could you do to help that person?

Assessment Suggestions Include questions on a quiz or exam related to alcohol or the various illicit drugs and their effects in the brain, their effects on health, and their addiction issues.

Handouts or Display None

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Lecture Activity 38.3: Brain Dissection Estimated Time to Complete: Approximately 1 hour, depending on the level of detail that is preferred Section Reference 38.5 What Are the Structures and Functions of the Human Nervous System?

Introduction The brains of most mammals are similar in overall structure due to their evolutionary ancestry. Many structures in the brain can be visualized in a simple dissection of sheep brains, which are readily available from various biological companies. In this activity, students will dissect and identify the major structures in a mammalian brain. Students can work in groups of two to four in this activity. This is a good activity to engage students in learning the anatomy of the brain.

Materials • Dissection pans • Scalpels • Blunt probes • Latex or vinyl examination gloves • Sheep brains (these can be purchased from any biological supply company) • Sinks with appropriate drainage • Labeled images of sheep brains (these usually come with the brains but could also be found through an Internet search using “sheep brain” as search terms) Procedures 1. Students must first put on examination gloves before handling the brains. After they do this, ask them to obtain a scalpel, blunt probe, and dissection pan.

2. Ask the students to rinse the brains in the sink under cold water before they work with them. This will get rid of some of the preservative and eliminate some of the smell.

3. The students will place the brains in their dissection pans.

4. Ask the students to identify the main structures of the brain that are visible from the outside. These may include (but are not limited to) the cerebrum (including all four lobes), cerebellum, pons, medulla oblongata, and spinal cord. Ask them to look for the pituitary gland on the underside of the brain. This may not be found because it is on a small stalk and often will break off during preservation.

5. The students will now slice the brain in half through the space between the right and left hemispheres of the cerebrum using a scalpel. Ask them to be careful as they are cutting.

6. Ask the students to identify the corpus callosum, thalamus, hypothalamus, gray matter, and white matter.

Assessment Suggestions Include a diagram or picture of a brain on an exam or quiz and ask students to identify different structures. As an option, set up sheep brains around the classroom with labeled pins located in different structures and ask students to identify them on a quiz or exam.

Handouts or Display None

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CHAPTER 39 THE SENSES LECTURE OUTLINE Case Study: Bionic Ears 39.1 How Do Animals Sense Their Environment?

A. A Receptor Is a Structure That Changes When It Is Acted upon by a Stimulus and Then Produces Some Sort of Response 1. A sensory receptor is a specialized cell that produces an electrical signal in response to specific stimuli (Table 39-1) a. Many sensory receptors are nerve cells with specialized dendrites called free nerve endings b. Other sensory receptors are housed in a sense organ such as the ear or eye B. The Senses Inform the Brain About the Nature and Intensity of Environmental Stimuli 1. Sensory receptors are linked to a specific set of axons that connects to particular places in the brain or spinal cord a. The type of stimulus is encoded by the specific set of neurons in the brain that is activated 2. Determining the intensity of a stimulus begins with sensory receptor cells a. When a sensory receptor is stimulated, it produces an electrical signal called a receptor potential (Figure 39-1) 3. Unlike action potentials, receptor potentials vary in size a. The stronger the stimulus, the larger the receptor potential (Figure 39-2) 4. The intensity of a stimulus is encoded by the frequency of action potentials reaching the brain â Lecture Activity 39.1: Touch Detection/Discrimination â Case Study Continued: Bionic Ears

39.2 How Are Mechanical Stimuli Detected?

A. Mechanoreceptors Are Found Throughout the Body 1. Some respond to touch, vibration, or pressure 2. Stretch receptors are found in many internal organs 3. Sound, gravity, and movement receptors are found in the ear 4. The skin of humans is very sensitive to touch, with a variety of mechanoreceptors (Figure 39-3) 5. Receptors in the joints and muscles combine to inform the brain of the position, angle, and movement of the extremities

39.3 How Is Sound Detected?

A. The Ear Converts Sound Waves into Electrical Signals 1. The outer ear captures sound waves and aids in sound-source localization (Figure 39-4a) â Lecture Activity 39.2: Sound Localization 2. The middle ear transmits sound waves to the inner ear a. The eardrum and three tiny bones conduct these sound waves 3. The inner ear converts vibrations from sound waves into electrical signals 4. Vibrations are converted into electrical signals in the cochlea a. The cochlea is a fluid-filled chamber consisting of two membranes, basilar and tectorial, and sensory receptors called hair cells (Figure 39-4b, c) i.The basilar membrane vibrates in response to sound waves ii.Vibrations of the basilar membrane cause hair cells to bend, which generates receptor potentials iii. Larger vibrations bend hair cells more, which is perceived as louder sounds iv.Very loud or prolonged sounds can damage hair cells (Figure 39-5) v.Different parts of the basilar membrane vibrate at different frequencies of sound waves, allowing for perception of different pitches

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39.4 How Are Gravity and Movement Detected?

A. The Vestibular Apparatus Detects Gravity and Movement (Figure 39-6) 1. The vestibule contains the utricle and saccule, which detect the direction of gravity and the degree of tilting the head a. Each of these contains hair cells that detect movement 2. Three semicircular canals detect head movement a. These also contain hair cells for detecting movement of the head

39.5 How Is Light Perceived?

A. Different Animal Species Vary in How Well They Can See 1. All animal vision uses cells called photoreceptors to detect light a. These cells contain photopigments that change shape when they absorb light B. The Compound Eyes of Arthropods Produce a Mosaic Image 1. Compound eyes consist of light-sensitive subunits called ommatidia (Figure 39-7) 2. By human standards, the image formed by a compound eye is pixilated (Figure 39-8) C. The Mammalian Eye Collects and Focuses Light and Converts Light into Electrical Signals 1. The mammalian eye contains two major parts (Figure 39-9) a. Accessory structures hold the eye in place, control the amount of light that enters, and focus the light rays b. The retina contains the photoreceptors that respond to light 2. Light enters through the cornea, and then passes through the aqueous and vitreous humor a. The iris controls how much light enters, changing the size of the pupil b. Light then strikes the lens, which focuses it c. Light then hits the retina 3. The lens focuses light on the retina a. The visual image is focused on the fovea b. The lens is rounded or flattened to focus on objects (Figure 39-10a) 4. If the eyeball is too long, the image is focused in front of the retina, which results in nearsightedness a. If the eyeball is too short, or the lens has stiffened with age, the image is focused behind the retina, which results in farsightedness b. Both of these conditions can be corrected (Figure 39-10b, c) 5. The retina detects light and produces action potentials in the optic nerve a. Rods and cones gather light signals at the rear of the retina b. Photoreceptors and neurons in the retina capture light, process the resulting electrical signals, and ultimately produce action potentials in the optic nerve c. Electrical signals are transmitted and processed as they pass forward through layers of neurons to ganglion cells at the front of the retina d. As the axons of ganglion cells carry signals to the brain, they must pass back through the retina, causing a blind spot (Figure 39-11) 6. Rods and cones differ in distribution and light sensitivity a. Cones are concentrated in the fovea and allow for color vision i. Humans have three varieties of cones, each containing a slightly different photopigment b. Rods are concentrated in the periphery of the eyeball and are responsible for vision in dim light 7. Binocular vision allows depth perception a. Predators and omnivores have eyes that face forward and have slightly different but extensively overlapping visual fields (Figure 39-12a) i. This binocular vision allows depth perception b. Herbivores have eyes on the side of their heads, giving them better peripheral vision (Figure 39-12b)

39.6 How Are Chemicals Sensed?

A. Chemoreceptors Allow Animals to Sense Many Things in Their Environment B. Olfactory Receptors Detect Airborne Chemicals (Figure 39-13) 1. Olfactory receptor neurons have long dendrites that detect chemicals in the air a. This detection sends nerve impulses to the brain b. Humans have 350–400 different olfactory receptor proteins c. Many animals detect odor better than humans .

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â Lecture Activity 39.3: Olfaction Contributes to Taste Perception C. Taste Receptors Detect Chemicals Dissolved in Liquids 1. The human tongue has taste buds for detecting taste (Figure 39-14a) a. The taste buds contain clusters of different cell types (Figure 39-14b) 2. There are five known tastes a. Sour, salty, bitter, sweet, and umami (deliciousness) 3. Humans perceive a great variety of tastes a. One substance may stimulate multiple receptor types

39.7 How Is Pain Perceived?

A. Pain Is a Subjective Feeling Produced by the Stimulation of Pain Receptors 1. Pain receptors are free nerve endings B. Many Types of Damaging Stimuli Are Perceived as Painful 1. There are many types of pain receptors a. Some respond to heat, stretching, pressure, and damage to cells

Case Study Revisited: Bionic Ears (Figure 39-15)

KEY TERMS anvil aqueous humor auditory canal auditory nerve auditory tube basilar membrane binocular vision blind spot chemoreceptor choroid cochlea compound eye cone cornea farsighted fovea hair cell

hammer inner ear iris lens mechanoreceptor middle ear nearsighted ommatidium (plural, ommatidia) optic nerve outer ear oval window pain receptor photopigment photoreceptor pinna pupil receptor

receptor potential retina rod round window saccule sclera semicircular canal sensory receptor stirrup taste bud tectorial membrane tympanic membrane utricle vestibular apparatus vitreous humor

LECTURE ACTIVITIES Lecture Activity 39.1: Touch Detection/Discrimination Estimated Time to Complete: 10 minutes Section Reference 39.1 How Do Animals Sense Their Environment?

Introduction Our perception of, and interaction with, our environment is entirely dependent on our senses. Each organism has its own unique “view” of the world, based on the types of sensory receptors that it possesses, as well as the sensitivities and ranges of energy detected by those receptors. We have many different types of receptors in our skin that allow for the detection of touch, vibration, heat, cold, pain, and other stimuli. This activity exploits one of those types of mechanoreceptors in the skin to demonstrate some basic features of sensory receptors, such as detection threshold and discrimination of characteristics of the signal. .

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Materials Needed • 1 blindfold • 7 paper clips • Several different gauges of monofilament fishing line (from a local hardware store) • Popsicle sticks • Glue Procedures Before class: 1. Build your own Von Frey hairs by cutting a piece of each gauge of fishing line and gluing one each (at right angles) to the end of a popsicle stick. Write the gauge of the line on the popsicle stick.

2. Unfold the paper clips and bend them so that the tips are different distances (1, 2, 3, 4, 5, 8, and 10 mm) from one another. Bend a piece of opaque tape back on itself and tape it to the curved end of each paper clip.

Write the distance between the tips on the tape.

During class: Recruit two volunteers from the class.

Threshold detection: 1. Blindfold the first student.

2. Touch the skin with the different gauges of fishing line, applying enough pressure to just bend the line. Ask the student if he or she felt anything after each touch. Repeat on different parts of the body, such as the fingertip, the palm, and the forearm.

Two-point discrimination: 1. Blindfold the second student.

2. Using light pressure, touch the skin with different paper clips to determine the minimum distance necessary to distinguish the two points. Repeat on different parts of the body, such as the fingertip, the palm, and the forearm.

Assessment Suggestions Use the following questions to initiate and direct a post-activity discussion or quiz: 1. What could account for the differences in detection threshold or two-point discrimination accuracy?

(Differences in the densities of all receptors or specific types of tactile sensory receptors could account for the difference in performance between different body parts. In addition, greater representation of an area of the body in the somatosensory cortex [put up a picture of a somatosensory cortex homunculus] means a higher ratio of cortical association neurons to receptor cells, which could lead to a more accurate representation of certain features of the signal. Pick areas from the picture of the homunculus and ask the class to decide which area would have lower detection thresholds or better two-point discrimination based on their representation in the somatosensory cortex.)

2. Is our “picture” of the world an exact representation? How do our senses “color” our perception?

(No, our picture of the world is shaped by the types of receptors that we have and the ranges and sensitivities of those receptors to the energies that they transduce. Although it isn’t an exact representation, it is accurate enough that we can do what we need to do to stay alive.)

You can expand this discussion by introducing examples of energies (magnetic fields, electric fields) and ranges of energies (ultraviolet, ultrasonic, etc.) that other animals detect that we cannot.

Lecture Activity 39.2: Sound Localization Estimated Time to Complete: 10 minutes Section Reference 39.3 How Is Sound Detected?

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Introduction Sound cues are crucial environmental signals that allow animals to locate prey or mates and avoid predators or other types of danger in their environment. Animals such as bats and barn owls that rely heavily on sound for hunting are extremely good at locating prey using their sense of hearing. They can locate small prey with extreme accuracy in both the vertical (elevation) and horizontal (azimuth) planes. Although humans aren’t as good as owls at locating sounds in the vertical plane, we are almost as good in the horizontal plane. Both birds and mammals use interaural time differences (ITDs), or the difference in arrival of the sound at the two ears, to localize sounds in the azimuth.

This activity demonstrates this by asking a participant to locate sounds in the environment without the use of visual clues. Sound clues directly in front of or behind the participant will be the hardest to discern, because they will have little to no ITD, whereas sounds exactly to the right or left of the participant will elicit the greatest ITDs and be the easiest to distinguish. Plugging one ear will greatly diminish the accuracy of localizing any sound. It doesn’t go away completely because some sound will still filter through to the plugged ear.

Materials Needed • 1 blindfold • 16 new #2 pencils • 8 Post-its • 1 earplug Procedures 1. Recruit 10 volunteers from the class.

2. Blindfold one student and place him or her in the middle of the front of the classroom.

3. Give two pencils and one Post-it with a number from 1 to 8 on it to eight of the students, then arrange them in a circle around the blindfolded student according to the Scoring Sheet Template. Have each student stick the Post-it to the front of his or her shirt for the scorer to see.

4. The ninth student will score the accuracy of the responses by the blindfolded student.

5. Instruct the eight noisemakers to tap their pencils together firmly, twice in quick succession, whenever the instructor points at them. Tell them to try to keep the taps as uniform as possible around the circle.

6. Whenever a noisemaker taps his or her pencils, the blindfolded student should point to the direction from which he or she perceives the sound to be coming. The blindfolded student should keep his or her head still and pointed forward throughout the activity.

7. The instructor should randomly select noisemakers until each position has been selected two or three times.

The scorer should mark a + for a correct response and a – for an incorrect response at the corresponding place on the sheet. Tally up the hits and misses and tell the class which was the most accurate and which was the most inaccurate position. The most misses will occur when trying to locate sound directly in front of or behind the blindfolded person.

8. Now have the blindfolded student repeat the activity with one ear plugged. Have the scorer use a different-colored pen to record accuracy under this circumstance.

Assessment Suggestions Use the following questions to initiate and direct a post-activity discussion: 1. Based on the huge difference in accuracy between the no-ears-blocked and the one-ear-blocked states, what information about the incoming sound do you think the nervous system is using to locate sound in the horizontal plane?

(Because the nervous system needs both ears to be accurate, it is comparing when the sound arrives at the two ears to determine which ear is closer to the sound source.)

2. Why is the accuracy poorer for sounds directly in front of or behind the student even when neither ear is blocked?

(Those sounds will arrive at both ears at approximately the same time.)

3. Barn owls use sound localization for hunting at night when they can’t see as well. We are about as good as they are at localizing sounds in the horizontal plane, but they are much better at discriminating sounds in the vertical plane. From an evolutionary standpoint, why do you think this is?

(We are terrestrial and thus don’t need to be that good at locating sounds in the vertical plane, whereas owls are aerial and go after prey on the ground (a good distance beneath themselves). Thus, their environment requires that they must be able to locate sounds very well [even better than in the horizontal plane] in the vertical plane.) .

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Instructor Guide Biology: Life on Earth Speculate on what physical features might allow the owls to localize sounds in the vertical plane.

(If horizontal displacement of the ears helps localize sounds in the vertical plane, then vertical displacement of the ears should help to localize sounds in the vertical plane. [Point both index fingers at the bottoms of your ears and show the class that we also have a slight vertical displacement of our ears. There is no evidence that I know of that we use this offset to locate sounds in the vertical plane.] Owls, in fact, do have vertical displacement of their ears in addition to asymmetries in the feathers around the face and ears that further enhance differences in sound signals from the top or bottom of the animal.)

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 39.2 Handout—Response Accuracy Scoring Sheet

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Lecture Activity 39.3: Olfaction Contributes to Taste Perception Estimated Time to Complete: 5 minutes Section Reference 39.6 How Are Chemicals Sensed?

Introduction Olfaction and gustation are two very important chemical senses. Gustation, or taste, is detection of molecules dissolved in water, whereas olfaction, or smell, is the detection of airborne molecules. The five major taste receptors are (1) sweet, (2) salty, (3) sour, (4) bitter, and the more recent addition, (5) umami (Japanese for “delicious”).

With only five taste receptors, how do we perceive so many different flavors? In part, this is due to combinations of these five tastes, but the majority of our sense of flavors comes from olfaction. Aromatics from the food we are eating diffuse into the nasal cavity and contribute most of the complexity and nuance to our sense of taste. This activity demonstrates the distinct contribution from both gustation and olfaction to our perception of flavors.

Materials Needed • 1 blindfold • 1 pair of nose plugs • Different-flavored candies or jellybeans Procedures 1. Recruit a volunteer from the class.

2. Blindfold the student and offer substances of different flavors (jellybeans, candies, and pieces of fruit or vegetables could all work; candies might be the safest in terms of avoiding any food allergy problems) and have the student name the flavors.

3. Repeat while the student either holds his or her nose or uses nose plugs.

Assessment Suggestions Use the following questions to initiate and direct a post-activity discussion: 1. Relate the results of this experiment to what happens when you get a cold.

(The loss of ability to smell when you have a head cold is what causes the loss of ability to taste anything other than the five basic tastes [sour, sweet, bitter, salty, umami].)

2. Speculate on how much of a role other cues, visual or tactile, play in our experience of taste.

(The presence of something in your mouth plays a role in taste, because smell alone, when you have nothing in your mouth, doesn’t typically elicit sensations of taste. Visual cues, especially color, can influence taste. Many sodas, candies, and popsicles have colors that go along with their flavors. How many of these might taste indiscriminately sweet without that visual cue? This activity could be expanded to include a taste test of different sodas, using a few that are colored and only sweet, or flavored and clear.)

3. How much does recent experience or anticipation have on the experience of flavors? Have the students volunteer incidents where experience or anticipation has greatly changed the flavor of something.

(For example, consider orange juice after toothpaste, or salty when you are expecting sweet. This could lead into a discussion of receptor adaptation and why the first drink of V-8 juice might seem salty, but after eating a handful of salty potato chips, the second drink doesn’t seem salty.)

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CHAPTER 40 ACTION AND SUPPORT: THE MUSCLES AND SKELETON LECTURE OUTLINE Case Study: Muscles of Gold 40.1 How Do Muscles Contract?

A. Muscles Are Tissues That Produce Movement by Contracting B. Vertebrates Have Three Types of Muscles 1. The three types of muscle tissue are skeletal, cardiac, and smooth C. Vertebrate Skeletal Muscles Have Highly Organized, Repeating Structures 1. Skeletal muscles move the skeleton and appear striated 2. This type of muscle tissue consists of a series of nested, repeating parts (Figure 40-1) a. Muscles are encased in connective tissue sheaths called tendons b. Muscle fibers are individual cells found within the sheath c. Muscle fibers contain myofibrils encased in the sarcoplasmic reticulum (Figure 40-2a) d. Each myofibril consists of repeating elements called sarcomeres, which contain the protein filaments that make up muscles (Figure 40-2b) i. The filaments of myofibrils are made of myosin and actin, each of which interacts with the other to contract the muscle fiber (Figure 40-2c) D. Muscle Fibers Contract Through Interactions Between Thin and Thick Filaments 1. The sliding-filament mechanism describes how thick and thin filaments slide over each other, shortening muscle length (Figure 40-3) a. Each spherical actin molecule has a myosin binding site i. Myosin binding sites are blocked by tropomyosin b. During contraction, tropomyosin moves aside and exposes the myosin binding sites i. The myosin heads bind to actin ii. The myosin heads pull the thin filaments toward the sarcomere center, sliding over the thick filaments (Figure 40-4) 2. Muscle contraction uses the energy of ATP a. Energy from ATP is used to extend the head on the myosin filament so it can flex the thin filament toward the center of the sarcomere b. A skeletal muscle’s reserves of ATP are used up quickly c. Muscle cells carry creatine phosphate i. These molecules in muscle tissue quickly resynthesize ATP from ADP, but only last a few seconds d. Glycolysis can provide some ATP for short activities e. Cellular respiration provides ATP for prolonged activity i. Glucose and fatty acids are used to form ATP ii. An oxygen source is required for efficient ATP formation â Case Study Continued: Muscles of Gold E. The Nervous System Controls the Contraction of Skeletal Muscles 1. Motor neurons excite skeletal muscle fibers at neuromuscular junctions (Figure 40-5) a. Motor neurons release neurotransmitters that diffuse across the synaptic cleft to receptors on the muscle fiber, triggering an action potential b. The action potential travels along the muscle fiber cell membrane and passes down T tubules, causing the sarcoplasmic reticulum to release calcium ions into the myofibril cytoplasm i. Calcium ions bind to troponin accessory proteins ii. Calcium-troponin binding causes tropomyosin to shift position, exposing myosin binding sites on actin iii.Myosin heads bind to actin .

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Instructor Guide Biology: Life on Earth iv. The actin filaments slide past the myosin filaments, shortening the muscle fiber c. When the action potential is over, calcium is actively transported back into the sarcoplasmic reticulum i. Calcium is removed from the accessory proteins that block the actin binding sites, and the muscle relaxes 2. The size of motor units and the frequency of action potentials determine the force of muscle contraction a. A motor unit is one branched motor neuron synapsing with many muscle fibers i. The size of a motor unit regulates the type of movement it can generate b. The nervous system controls the strength of muscle contractions by varying the number of muscle fibers stimulated and the frequency of action potentials to each fiber â Lecture Activity 40.1: Muscle Contraction Class Activity F. Fast-Twitch and Slow-Twitch Muscle Fibers Are Specialized for Different Types of Activity 1. Muscle fibers come in two basic types, slow-twitch and fast-twitch a. Slow-twitch fibers contract with less power than fast-twitch b. Fast-twitch fibers contract powerfully but fatigue more quickly â Case Study Continued: Muscles of Gold

40.2 How Do Cardiac and Smooth Muscles Differ from Skeletal Muscle?

A. The Three Muscle Types Differ from Each Other Structurally and Functionally (Table 40-1) B. Cardiac Muscle Powers the Heart 1. The structure and contraction mechanism is similar to that of skeletal muscle a. One main difference is that cardiac muscle fibers are connected to each other by intercalated discs 2. Unlike skeletal muscle, cardiac muscle can generate its own contractions a. The heart’s pacemaker does this b. Gap junctions allow for the synchronization of contractions by allowing action potentials to travel from muscle cell to muscle cell C. Smooth Muscle Produces Slow, Involuntary Contractions 1. Smooth muscle surrounds blood vessels and most hollow organs 2. Smooth muscle cells are not striated because the thin and thick filaments are scattered throughout the cell (Table 40-1) 3. Contractions are initiated by stretch, hormones, or the nervous system and are slow and sustained

40.3 How Do Muscles and Skeletons Work Together to Provide Movement?

A. The Actions of Antagonistic Muscles on Skeletons Move Animal Bodies 1. Three different types of skeletons are seen in the animal kingdom 2. Coordinated movement of an animal’s body is produced by alternating contractions of antagonistic muscles (Figure 40-6) 3. Worms, cnidarians, and many mollusks have a hydrostatic skeleton made of fluid and muscle (Figure 40-6a) a. Muscles around fluid cause shape changes and locomotion 4. The bodies of arthropods are encased by rigid exoskeletons (Figure 40-6b) a. Movement occurs at joints and is based on antagonistic muscles b. Arthropods must molt periodically in order to grow (Figure 40-7) 5. Endoskeletons are rigid structures found inside echinoderms and chordates a. Movement occurs at joints and is facilitated by antagonistic muscles (Figure 40-6c) B. The Vertebrate Endoskeleton Serves Multiple Functions 1. It supports the body and protects internal organs 2. It allows locomotion in many different forms 3. It participates in sensory function in the middle ear 4. Bones produce blood cells 5. Bones store calcium and phosphorus 6. The vertebrate skeleton consists of two parts (Figure 40-8) a. The axial skeleton includes the head, vertebral column, and rib cage b. The appendicular skeleton includes the pectoral and pelvic girdle and the appendages attached to them C. The Vertebrate Skeleton Is Composed of Cartilage, Ligaments, and Bone .

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1. Cartilage provides flexible support and connections a. During embryonic development, most of the skeleton is composed of cartilage, which is later replaced by bone (Figure 40-9) b. Cartilage covers the ends of bones and provides flexible support to other parts of the body (Figure 40-10) c. The living cells of cartilage are called chondrocytes i. They secrete the collagen matrix ii. Cartilage lacks blood vessels, and is slow to heal 2. Ligaments connect bone to bone in joints 3. Bone provides a strong, rigid framework for the body a. Bone consists of a hard outer shell of compact bone that encloses spongy bone in its interior (Figure 40-10) i. Compact bone is arranged in osteons, in which collagen and calcium phosphate surround a central canal containing blood vessels ii. Spongy bone is lightweight, rich in blood vessels, and porous b. There are three types of bone cells i. Osteoclasts break down bone ii. Osteoblasts are bone-forming cells iii. Osteocytes are mature bone cells 4. Bone remodeling allows skeletal repair a. Bone remodeling occurs through the coordinated activity of osteoblasts and osteoclasts i. Bones become thicker and larger as a person grows b. Bone remodeling varies with age â Health Watch: Osteoporosis—When Bones Become Brittle (Figure E40-1) c. The ultimate bone remodeling occurs after a fracture (Figure 40-11) i. Healing begins when a cartilage callus forms at the break site ii. The cartilage is replaced by bone â Lecture Activity 40.2: A Demonstration of Bone Composition â Lecture Activity 40.3: A Demonstrative Comparison of the Human Male and Female Pelvis D. Antagonistic Muscles Move Joints in the Vertebrate Skeleton (Figure 40-12) 1. Joints are held together by ligaments, which are strong and flexible a. Tendons hold muscles to bones 2. The origin of any joint is where muscle is attached to the immovable bone on one side of a joint a. Movement occurs in antagonistic muscle pairs when one muscle flexes while the other is passively extended b. The insertion is where muscle is attached to the movable bone on one side of a joint 3. Hinge joints move in two dimensions (Figure 40-13a) 4. Ball-and-socket joints allow movement in many planes (Figure 40-13b) â Lecture Activity 40.4: A Group Discussion of the Benefits and Potential Harm of Intense Exercise

Case Study Revisited: Muscles of Gold

KEY TERMS actin antagonistic muscles appendicular skeleton axial skeleton ball-and-socket joint bone cardiac muscle cartilage chondrocyte compact bone endoskeleton exoskeleton

hinge joint hydrostatic skeleton intercalated disc joint ligament motor unit muscle fiber myofibril myosin myosin head neuromuscular junction osteoblast .

osteoporosis sarcomere sarcoplasmic reticulum (SR) skeletal muscle skeleton smooth muscle spongy bone T tubule tendon thick filament thin filament Z line

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extensor flexor

osteoclast osteocyte

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LECTURE ACTIVITIES Lecture Activity 40.1: Muscle Contraction Class Activity Estimated Time to Complete: 10 minutes Section Reference 40.1 How Do Muscles Contract?

Introduction Students benefit from problem-solving exercises when attempting to learn complex physiological concepts such as the sliding filament mechanism. In the following activity, the students work as a class, or in small groups, to assemble a sequence of events that accurately describes the sliding filament mechanism. In doing this, the students are required to consider both the anatomical structures as well as the physiological processes that are involved.

Materials Needed • 11 sheets of paper, each representing a physiological “event” (see Procedures section) Procedures 1. Tape to the board 11 sheets of paper, each representing a physiological event that occurs during sarcomere contraction (DO NOT PLACE THEM IN ORDER, and assign a random identifying letter to each): a. an action potential travels down a motor neuron b. the skeletal muscle fiber is activated at the neuromuscular junction c. an action potential travels down the muscle cell membrane d. the action potential enters T-tubules e. an action potential stimulates the sarcoplasmic reticulum f. calcium ions are released into the muscle cell cytoplasm g. calcium ions bind to troponin h. tropomyosin exposes myosin binding sites on actin i. myosin cross-bridges bind to actin j. myosin cross-bridges bend k. thin filaments are pulled toward sarcomere center, and muscle fiber shortens 2. Work with the class, or have the class work in small groups, to assemble the above 11 physiological events in order, WITHOUT using their notes or the text. You may wish to project an image of Figures 40-4 through 407 as a guide to the anatomical parts involved in the process. It is important that you do not give them any answers, but feel free to give them hints to help them figure out the sequence on their own.

3. This process may need to be repeated several times, but by then the students should feel much more comfortable with the process and should be able to work through the basics on their own.

4. As a spin-off of this activity, have the students identify which steps need to be removed for muscle relaxation to occur. Although there is some room for interpretation, technically this would be steps (b) and (f).

Assessment Suggestions Assessment by lecture exam or weekly quiz should suffice.

Lecture Activity 40.2: A Demonstration of Bone Composition Estimated Time to Complete: Preparation: 3 days; presentation: 10 minutes Section Reference 40.3 How Do Muscles and Skeletons Work Together to Provide Movement?

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Introduction Although students usually have little difficulty appreciating the support functions of bone, they often do not understand that these functions are due to the characteristics of the substances that make them up. This demonstration will show the students how the supportive function of bone is affected when certain tissue components are removed, specifically, inorganic calcium salts and collagen protein fibers. When inorganic calcium salts are removed, bone becomes extremely flexible and rubbery, whereas when the proteins are removed, the bone becomes extremely brittle. In either case, the bone will not adequately support the body unless both proteins and inorganic salts are present.

Materials Needed • 3 chicken drumsticks (easily acquired at the butcher or the local chicken-oriented fast food restaurant) • 1 bottle of vinegar • 1 500-ml beaker • Oven • Disposable gloves • Plastic wrap • A pair of thick gloves Procedures Preparation: 1. Remove the meat from the three chicken drumsticks and keep the bones that remain.

2. Place one bone in a 500-ml beaker and pour vinegar into the beaker until the bone is covered. Let the bonebeaker preparation sit for at least 3 days. After 3 days, remove the bone from the vinegar-filled beaker (using disposable rubber gloves), rinse it, and place it in plastic wrap until needed.

3. Place one bone in an oven preheated to 250°F for 2 hours. Remove it after 2 hours and let it cool. Place it in plastic wrap until needed.

4. Wrap one untreated chicken bone in plastic wrap and place it in the refrigerator until needed.

5. Once all three chicken bones have been prepared (vinegar-treated, heat-treated, and untreated), you are ready to use this demonstration in lecture.

Presentation: 1. Explain to your students that two of the more significant bone components are collagen fibers and calcium salts. Collagen protein fibers provide strong, but flexible support, whereas inorganic calcium salts provide rigid support. It is the interplay between the proteins and inorganic salts that gives bone its structural characteristics.

2. Explain to the students that, to drive this point home, you have brought three chicken bones of differing composition: a. The first bone was immersed in vinegar for 3 days, which has the effect of removing its inorganic salts.

This results in a limp, flexible bone that is primarily composed of collagen and other proteins. The spaghetti-like consistency of the bone is not conducive to carrying loads, however. Demonstrate by twisting the bone (try to tie it into a knot!). b. The second bone, which was heat-treated in an oven, had its protein (e.g., collagen) composition removed.

The result is a brittle bone composed almost entirely of inorganic salts. This bone is extremely intolerant to bending. Demonstrate by breaking the bone with your bare hands, provided you are wearing thick gloves. Bone fragments can be sharp! c. The last bone, which was untreated, retains its rigid, supportive properties, but can withstand bending forces as well. This is because both the collagen and the inorganic salt components of bone are both intact.

Assessment Suggestions One or two short questions on an exam or weekly quiz should suffice to demonstrate the concepts of this activity.

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Lecture Activity 40.3: A Demonstrative Comparison of the Human Male and Female Pelvis Estimated Time to Complete: 10 minutes Section Reference 40.3 How Do Muscles and Skeletons Work Together to Provide Movement?

Introduction Time permitting, it can be an engaging exercise to compare the sex-related differences in the human pelvis.

Although a variety of structural differences could be depicted, for sake of lecture time (and the assumed lack of anatomical expertise by the students) only the major differences will be described.

In females, the pelvis is generally more adapted for childbirth than weight loading, whereas the opposite is true for males.

Specifically, the female pelvis is generally tilted more forward and has a wider pelvic opening than the male pelvis to accommodate the head/body of the infant. Also, the coccyx (tailbone) of females is straighter than that of males (which curves inward toward the front of the pelvis). This reduces tailbone interference with the birth of the infant on its way through the pelvic opening.

In contrast, the male pelvis is heavier and thicker, with more prominent markings for muscle attachment.

Also, the hip sockets of males are closer together (and larger) to allow better weight support.

Last, it is also possible to distinguish between a male and female pelvis by examining the pubic arch at the base of the front of the pelvis. Females generally have a pubic arch that is more rounded, at an angle of around 85°, whereas males have a pubic arch that is less rounded, with a more acute angle (around 55°).

Materials Needed • Images and/or models of a male and female pelvis • Internet resources for pelvis images. An Internet search using “male and female pelvis” as search terms will assist in finding images.

Procedures 1. Gather appropriate visual aids (see Materials Needed section) so the students can understand what you are trying to explain.

2. Show the female and male pelvises in turn, making sure to explain how the structural differences relate to their function. Alternatively, you can have the students examine the anatomical differences between the pelvis types and ask them to predict the possible functions of these differences as a critical thinking exercise.

Assessment Suggestions One or two short questions on an exam or weekly quiz should suffice to demonstrate the concepts of this demonstration.

Lecture Activity 40.4: A Group Discussion of the Benefits and Potential Harm of Intense Exercise Estimated Time to Complete: 10 minutes Section References 40.1 How Do Muscles Contract?

40.3 How Do Muscles and Skeletons Work Together to Provide Movement?

Introduction Many of your students are probably involved with some sort of regular physical activity, either through association with college athletic teams and clubs, a personal exercise program, or job-related physical exertion.

This degree of involvement makes it easy to lead students in a discussion on musculoskeletal exercise, simply because it is directly relevant to their lives. .

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Ask the class to discuss the reasons why exercises such as swimming and power walking are beneficial to musculoskeletal development. Write these ideas on the board for greater effect.

After this is accomplished, ask the class whether there are any exercises that could be potentially harmful.

If the class is stumped for ideas, suggest an exercise that involves intense bouts of repetitive activity, such as sprinting, tennis, or basketball.

If students do not explore the idea on their own, direct the discussion so that the class considers how chronic overexertion may damage musculoskeletal structures that are involved with body movement (e.g., cartilage, tendons, ligaments, etc.).

If time permits, you can discuss some of the more common injuries associated with these activities (such as tendonitis, torn ligaments and muscles, and ruptured tendons), and ways to minimize the possibility of injury (through training, proper stretching, etc.).

Materials Needed • Instructor background information on sports-related injuries: Perform an Internet search using “sports injuries” as the search terms.

Procedures Nothing specific is needed, other than traditional discussion techniques.

Assessment Suggestions One or two short questions on an exam or weekly quiz should suffice to demonstrate knowledge of these concepts.

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CHAPTER 41 ANIMAL REPRODUCTION LECTURE OUTLINE Case Study: To Breed a Rhino 41.1 How Do Animals Reproduce?

A. Animals Reproduce Either Sexually or Asexually 1. In asexual reproduction, a single individual produces offspring a. The offspring are genetically identical to the parent 2. In sexual reproduction, organs called gonads produce sperm or eggs in the parents a. These cells fuse, producing offspring that are genetically different from the parents B. In Asexual Reproduction, an Organism Reproduces Without Mating 1. Budding produces a miniature version of the adult (Figure 41-1) a. Many sponges and cnidarians reproduce this way 2. Fission followed by regeneration can produce a new individual a. Some animals can divide into two or more pieces that regenerate missing parts and become whole organisms 3. During parthenogenesis, eggs develop without fertilization (Figures 41-2 and 41-3) a. In this process, eggs develop into viable offspring without being fertilized b. Some offspring are haploid and some are diploid C. In Sexual Reproduction, an Organism Reproduces via the Union of Sperm and Egg 1. Sexual reproduction produces genetically unique offspring 2. The ovaries in females produce eggs and the testes in males produce sperm a. Fertilization is the union of sperm and egg that produces a diploid zygote 3. Some animals are hermaphrodites, producing both sperm and egg (Figure 41-4) 4. Successful reproduction requires sperm and egg from different individuals to be brought together 5. External fertilization occurs outside the parents’ bodies a. In a process called spawning, sperm and eggs are released into water (Figure 41-5) b. Some fish perform a courtship ritual during which sperm and egg are released in the same location (Figure 41-6) c. Frogs and toads assume a mating pose that stimulates the female to release eggs (Figure 41-7) 6. Internal fertilization occurs within the female’s body a. The transmission of male gametes into a female occurs through copulation or spermatophore use (Figure 41-8) b. In most animals, sperm and egg do not live very long i. Consequently, ovulation, the release of an egg from the ovary, must occur shortly before or soon after sperm are deposited inside the female â Lecture Activity 41.1: “Why Is There Sex?” â Case Study Continued: To Breed a Rhino

41.2 What Are the Structures and Functions of Human Reproductive Systems?

A. The Ability to Reproduce Begins at Puberty 1. Puberty is a stage of development characterized by rapid growth and the appearance of secondary sexual characteristics a. In both sexes, brain maturation causes the hypothalamus to release GnRH i. GnRH stimulates LH and FSH release from the anterior pituitary ii. LH and FHS stimulate gamete, testosterone, and estrogen production iii. Secondary sexual characteristics also develop iv. In males, the penis, which deposits semen in the female reproductive tract, and the testes enlarge v. In females, the breasts develop, and menstruation begins 406

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B. The Male Reproductive System Includes the Testes and Accessory Structures (Figure 41-9 and Table 41-1) 1. Sperm are produced in the testes a. They are located in the scrotum, which keeps the testes at a slightly lower temperature, promoting sperm development b. The testes produce sperm in seminiferous tubules via spermatogenesis (Figure 41-10a) i. Interstitial cells produce testosterone (Figure 41-10b) c. The development of sperm follows a specific sequence (Figure 41-11) i. Sertoli cells nourish developing sperm d. Sperm have various structures (Figure 41-12) i. The head contains the nucleus (a haploid set of chromosomes) ii. The acrosome is also part of the head and is the enzymatic drill that allows penetration of the egg iii. The midpiece contains mitochondria and produces energy for sperm movement iv. The tail is a flagellum that provides swimming movements 2. Hormones from the anterior pituitary and testes regulate spermatogenesis a. The hypothalamus secretes GnRH, which stimulates the anterior pituitary to secrete LH and FSH i. LH stimulates interstitial cells in the testes and causes them to produce testosterone (Figure 41-13) ii. Testosterone and FSH stimulate Sertoli cells and promote spermatogenesis b. Testicular function is regulated by negative feedback 3. Accessory structures contribute to semen and conduct the sperm outside the body a. The epididymis leads into the vas deferens, a tube that provides passage from the testes to the urethra i. The urethra conducts urine and sperm out of the body b. Accessory structures produce secretions to aid sperm called semen i. Seminal vesicles produce fructose for energy and alkaline fluid to neutralize any acidic urine and vaginal acidity ii. The prostate gland produces basic fluids that allow the sperm to swim more freely iii. Bulbourethral glands produce alkaline mucus, neutralizing any remaining vaginal acidity C. The Female Reproductive System Includes the Ovaries and Accessory Structures (Figure 41-14 and Table 41-2) 1. Egg development in the ovaries begins before birth a. The ovaries produce the female gametes via oogenesis (Figure 41-15) i. Oogenesis starts with the formation of the oogonia, which will differentiate into primary oocytes 2. The ovary produces eggs, estrogen, and progesterone during the menstrual cycle a. The follicle is a structure that contains an oocyte and supportive cells within the ovary i. The follicle undergoes a series of changes during the menstrual cycle, which is directed by various hormones and ultimately produces an oocyte or egg (Figure 41-16) b. The egg leaves the ovary during ovulation i. The corpus luteum remains in the ovary and produces estrogen and progesterone, which prevent the development of new follicles â In Greater Depth: Hormonal Control of the Menstrual Cycle (Figure E41-1) 3. Accessory structures include the uterine tubes, uterus, and vagina a. The uterine tubes, also called oviducts, transport the egg to the uterus using cilia in their lining i. They are also the site of fertilization b. The uterus is a muscular organ where embryo development occurs i. The endometrium is the inner uterine lining supplied with blood vessels, and will form the placenta during pregnancy ii. The myometrium is a thick smooth muscle layer that contracts during childbirth c. The cervix is a ring of connective tissue that forms the opening to the uterus d. The vagina serves as the receptacle for the penis and sperm during intercourse, and also as the birth canal e. If an egg is fertilized, it will find a rich environment for growth i. If the egg is not fertilized, it and the growing endometrium are squeezed out during menstruation .

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Instructor Guide Biology: Life on Earth â Case Study Continued: To Breed a Rhino 4. The embryo sustains its own pregnancy a. If fertilization occurs, the developing embryo secretes chorionic gonadotropin (CG) into the female bloodstream i. CG maintains the corpus luteum ii. High estrogen and progesterone levels maintain a thick endometrium (for the developing embryo) D. During Copulation, Sperm Are Deposited in the Vagina 1. Sexual arousal in males causes an erection, the swelling of the penis in which dilation of penis arterioles and constriction of penis veins inflates the penis tissues with blood (Figure 41-17) 2. Ejaculation is the forceful ejection of semen during intercourse 3. In females, sexual arousal causes an increase in blood flow to the vagina and clitoris â Health Watch: Sexually Transmitted Diseases (Figure E41-2) â Lecture Activity 41.2: Reproductive Health—How Much Do You Really Know? â Lecture Activity 41.3: The Spread of Sexually Transmitted Diseases â Lecture Activity 41.4: A “Rogue’s Gallery” of Sexually Transmitted Diseases E. During Fertilization, the Sperm and Egg Nuclei Unite 1. This typically occurs in the uterine tubes a. The egg is surrounded by the corona radiata and zona pellucida (Figure 41-18a) b. Hundreds of sperm reach the egg and surround the corona radiata (Figure 41-18b) c. Each sperm has enzymes that weaken the corona radiata and the zona pellucida i. Burrowing sperm stimulates the second division of meiosis in the egg and sperm/egg nuclei fuse â Health Watch: High-Tech Reproduction (Figures E41-3 and E41-4)

41.3 How Can People Prevent Pregnancy?

A. Contraception Is the Prevention of Pregnancy B. Sterilization Provides Permanent Contraception 1. In sterilization, the pathways that sperm and egg travel are blocked (Figure 41-19) a. In a vasectomy, each vas deferens is severed b. In tubal ligation, the oviducts are severed C. Temporary Birth Control Methods Are Readily Reversible (Table 41-3) 1. Synthetic hormones prevent ovulation a. Birth control pills provide high doses of estrogen/progesterone to prevent ovulation 2. Fertilization cannot occur if sperm cannot contact the egg a. Condoms (male and female) provide a barrier that interrupts sperm travel b. Spermicide chemicals kill sperm before fertilization c. The rhythm method (natural family planning) is where no intercourse occurs during days when an egg could be fertilized, but is unreliable 3. Some birth control methods work through multiple mechanisms, including preventing implantation a. The intrauterine device (IUD) is a plastic/metal device that interferes with sperm motility and can prevent embryo implantation b. The “morning after” pill delays or prevents ovulation 4. Male birth control methods are under development a. Options include reversible plugs placed in the vas deferens and drugs that prevent sperm production

Case Study Revisited: To Breed a Rhino (Figure 41-21)

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KEY TERMS acquired immune deficiency syndrome (AIDS) acrosome asexual reproduction budding bulbourethral gland cervix chlamydia chorionic gonadotropin (CG) clitoris contraception copulation corona radiata corpus luteum crab lice egg embryo endometrium epididymis estrogen external fertilization fertilization fission follicle follicle-stimulating hormone (FSH) genital herpes gonad

gonadotropin-releasing hormone (GnRH) gonorrhea hermaphrodite human papillomavirus (HPV) internal fertilization interstitial cell labium (plural, labia) luteinizing hormone (LH) menstrual cycle menstruation oogenesis oogonium (plural, oogonia) ovary ovulation parthenogenesis penis placenta polar body primary oocyte primary spermatocyte progesterone prostate gland puberty regeneration scrotum secondary oocyte secondary spermatocyte

semen seminal vesicle seminiferous tubule Sertoli cells sexual reproduction sexually transmitted disease (STD) spawning sperm spermatid spermatogenesis spermatogonium (plural, spermatogonia) sterilization syphilis testis (plural, testes) testosterone trichomoniasis urethra uterine tube uterus vagina vas deferens zona pellucida zygote

LECTURE ACTIVITIES Lecture Activity 41.1: “Why Is There Sex?” Estimated Time to Complete: 10–15 minutes during two class periods, or an entire class period (if desired) Section Reference 41.1 How Do Animals Reproduce?

Introduction The president of the National Academy of Sciences has chosen you (the students) to serve on a panel that will try to answer the question “Why is there sex?” The panel will meet next week, so form groups of four students to develop a possible explanation. The problem each group faces is this: Sexual reproduction is inefficient.

To illustrate this, imagine a population of 20 insects (10 male, 10 female) in which each female can produce two offspring in her lifetime. The females in this population, however, are of two types. Five females reproduce asexually, giving birth only to more females. The other five reproduce sexually and give birth to males and females in equal proportions. After five generations, how many females of each type will be in the population?

Through asexual methods, assuming no deaths, 155 females will be produced. Through sexual methods, assuming no deaths, only 25 females will be produced. Clearly, sexual reproduction puts individuals at a severe disadvantage in the contest to reproduce.

Although it’s true that sexual recombination of genes can have advantages over the very long term, the theory of natural selection suggests that a trait can persist only if it helps individuals survive and reproduce in the short .

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term. So we’re faced with a mystery: What direct advantage was gained by the first sexually reproducing organisms? Was a series of intermediate steps required? Were particular environmental conditions required? Did sex originally arise for a purpose other than reproduction?

The Academy is expecting each group to produce a plausible scenario for the origin of sex, so consult with your group for critical discussion, and submit your hypothesis.

Materials Needed None, other than paper for each group to write its responses Procedures 1. Break the class into groups of four, give them their “assignment,” and present the hypothetical insect population scenario.

2. Explain to the students (on the board) how after five generations (with no deaths) the asexual females produce a total female population of 155, whereas the females that rely on sex produce only 25.

3. Present the dilemma of this situation (that natural selection allows a trait to persist only if it is useful in the short term) and ask each group to prepare a written explanation for the possible origin of sex. Have them discuss this among themselves for no more than 5 minutes, as this assignment could take much of the class!

Instead, have group members meet outside of class to work this out on their own, with their write-ups to be submitted at a later date. Encourage each group to do some basic library or Internet research to help with the assignment.

4. During a future class, have the groups submit their responses and have each group briefly describe its rationale for the origin of sex. (Note: Discussion may not be possible for classes larger than 30 students.)

Assessment Suggestions The written submission is the most obvious assessment method. Also, assessment by lecture exam or weekly quiz would also work well.

Lecture Activity 41.2: Reproductive Health—How Much Do You Really Know?

Estimated Time to Complete: 10–20 minutes, depending on the depth of the class discussion Section Reference 41.2 What Are the Structures and Functions of Human Reproductive Systems?

Introduction Although your students would like to think that they are informed about topics such as sex, pregnancy, and sexually transmitted disease, the truth is that there has been quite a bit of misinformation circulated in the media about these important issues. To emphasize this point, have your class collectively take one of the many safe sex/STD quizzes that can be found on the Internet and discuss the results. Your students may be surprised that they do not perform as well as they thought!

This exercise will provide a sense of urgency and interest in the students toward the topics of reproductive physiology and health.

Materials Needed • A classroom with computer projection capabilities and Internet access • In order to find quizzes, perform an Internet search using “safe sex quiz” and “reproductive health” as search terms. Go through a few and choose the one that you think is most appropriate.

• For information on sexually transmitted diseases, perform an Internet search using “sexually transmitted disease quiz” as search terms. Go through a few and choose the one that you think is most appropriate.

Procedures 1. Before lecture, examine one of several online quizzes (from the previous search) on safe sex and reproductive health. These quizzes vary in length, so select one that best fits your time frame and lecture emphasis.

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Answer each question as a group and discuss the implications of the correct answers in turn. If the class is sensitive about appearing ignorant about issues of sex and reproductive health, record all of the questions prior to class, present them to your students (taking a poll on which answers are most popular), and then proceed to answer the online quiz using the most popular responses as answers (after all the questions have been answered). This way, the students will not be directly put on the spot for giving incorrect answers.

Assessment Suggestions Assessment by lecture exam or weekly quiz would work well.

Lecture Activity 41.3: The Spread of Sexually Transmitted Diseases Estimated Time to Complete: 10–15 minutes (more for a class larger than 30 students) Section Reference 41.2 What Are the Structures and Functions of Human Reproductive Systems?

Introduction Students often feel that they would never catch an STD; however, the following activity should make it clear that catching an STD may be much more possible than they think.

To simulate the spread of STDs among the students in the class, use colored paper strips to represent different STD conditions, with each color representing an STD condition (STD or no STD). The total number of strips of paper should equal the number of students in your class and the frequency of the colored strips should represent the frequency of each STD in the U.S. population (see Procedures section for practical examples).

Hand one strip of paper to each student, but do not tell them what it signifies. During the activity, the students exchange pieces of their colored strips. This exchange is analogous to the exchange of body fluids during sexual reproduction. Have the students share their paper strip with four different classmates. For the first exchange, each student should give half of the strip to a classmate while retaining the other half. For all subsequent exchanges, students should give half of EACH STRIP THEY POSSESS to their partners while retaining the remaining halves. Once four exchanges have been completed, tell the students what the colors represent so they can see what STDs they have contracted.

Discuss the results and emphasize how quickly an STD can spread by having those who initially were given a paper strip for a particular STD raise their hands, followed by those who contracted that STD from them. Ask how many contracted more than one STD. Materials Needed • 6-inch paper strips of three different colors (each representing a different STD status): white, red, and green.

The total number of paper strips must equal the number of students in the class.

Procedures 1. Hand a strip of paper to each student in the class. Paper strips of different colors should be handed out according to the frequency of specific STDs in the U.S. population. For the sake of simplicity, try three different colors, each representing a different STD status: (a) WHITE = no STD, (b) RED = herpes, and (c) GREEN = genital warts. Red and green strips should be handed out according to their prevalence in the U.S. population. Specifically, herpes (RED) infects 1 in 5 adults and genital warts (GREEN) infect 1 in 14 adults. All other students (no STDs) should receive a white strip.

2. Once the paper strips are distributed among the class, ask each student to make four “exchanges” (each representing a sexual encounter) with other students. During an exchange, students should tear EACH STRIP IN THEIR POSSESSION in half and give one set of halves to the other student (after the first exchange, students will be giving multiple strips to their “partners”).

3. After the exchanges have taken place, survey the students to see how many red and green paper strips (STDs) have distributed themselves throughout the class. Inform them what the different color strips represent and see how many students have contracted multiple STDs. Assessment Assessment by lecture exam or weekly quiz would work well. .

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Lecture Activity 41.4: A “Rogue’s Gallery” of Sexually Transmitted Diseases Estimated Time to Complete: 10–20 minutes, depending on the level of detail you present Section Reference 41.2 What Are the Structures and Functions of Human Reproductive Systems?

Introduction Although the facts of many STDs are listed in the text, the severity of these diseases often does not register with students until they observe the symptoms of these conditions in infected adults. In particular, students seem to appreciate fairly graphic medical images of these diseases and their symptoms, although you may wish to warn your students that some of these disease images are graphic. This demonstration is easily conducted in conjunction with a lecture on STDs, and will have even greater impact if it occurs after conducting Lecture Activity 41.3: The Spread of Sexually Transmitted Diseases.

Materials Needed • A classroom with computer projection capabilities and Internet access Procedures Either as a separate topic or integrated in lecture, discuss the health impact of the major STDs that are common among adults. In particular, it is effective to project symptomatic images of the diseases you choose to cover, which can be located on the Internet through a search using “sexually transmitted diseases” as search terms.

Assessment Suggestions Assessment by lecture exam or weekly quiz would work well.

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CHAPTER 42 ANIMAL DEVELOPMENT LECTURE OUTLINE Case Study: Rerunning the Program of Development 42.1 What Are the Principles of Animal Development?

A. Development Is the Process by Which a Multicellular Organism Grows and Increases in Organization and Complexity 1. Three principal processes contribute to development a. Individual cells multiply b. Daughter cells differentiate c. As cells differentiate, they become organized into multicellular structures

42.2 How Do Indirect and Direct Development Differ?

A. In Direct Development, Offspring Are Miniature Versions of the Adult 1. During indirect development, the newborn has a very different body structure than the adult B. During Indirect Development, Animals Undergo a Radical Change in Body Form 1. Indirect development occurs in amphibians, such as frogs and toads, and most invertebrates a. Large numbers of eggs are produced that have a small yolk b. An immature larva emerges from the egg (Figure 42-1) c. Metamorphosis produces a sexually mature adult C. Newborn Animals That Undergo Direct Development Resemble Small Adults 1. Direct development occurs in reptiles, birds, mammals, and some invertebrates (Figure 42-2) a. The newborns are typically larger than indirectly developing species b. Few offspring are produced, but they are more developed i. They also require more nourishment

42.3 How Does Animal Development Proceed?

A. Most of the Processes of Development Are Fundamentally Similar in All Animals B. Cleavage of the Zygote Begins Development 1. Cleavage is a series of mitotic cell divisions of the fertilized egg, or zygote (Figure 42-3a) a. The zygote divides via mitosis without any cell growth b. Eventually, a solid round ball of cells called the morula is formed (Figure 42-3b) c. The morula develops an internal cavity and becomes the blastula (Figure 42-3c) C. Gastrulation Forms Three Tissue Layers 1. Gastrulation is the formation of the three tissue layers a. A dimple, called the blastopore, forms on one side of the blastula and cells fold inward (Figure 42-3d) b. Folding blastula cells migrate to form three embryonic cell layers in what is now called the gastrula (Figure 42-3e and Table 42-1) i. Endoderm (cells of inner cell layer) forms the digestive/respiratory tracts ii. Ectoderm (cells of outer cell layer) forms the skin and nervous system iii. Mesoderm (cells of middle layer) forms the muscles, skeleton, and circulatory system D. The Major Body Parts Develop During Organogenesis 1. Organs form from the three embryonic layers in a process called organogenesis a. Organogenesis proceeds by two major processes i. A series of “master” genes turns on to signal the development of a particular organ ii. Cells that are not needed are pruned away â Lecture Activity 42.1: “Animal Development Gone Wrong: Environmental Influences” Class Demonstration and Discussion

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Instructor Guide Biology: Life on Earth E. Development in Reptiles and Mammals Depends on Extraembryonic Membranes 1. Reptiles, birds, and mammals produce amniotic eggs a. Reptiles, birds, and mammals produce similar extraembryonic membranes i. The embryo is encased in a protective shell and liquid-filled space ii. It acts as a private pond b. Amniotic eggs contain four extraembryonic membranes (Table 42-2) i. Chorion lines the shell, and is involved with O2/CO2 exchange with the environment ii. Amnion encloses the embryo in a watery environment iii. Allantois surrounds and isolates wastes iv. The yolk sac contains stored food in the form of yolk c. In placental mammals, the embryo develops inside the mother’s body until birth

42.4 How Is Development Controlled?

A. Each Cell in an Organism Contains the Entire Set of Genes for the Organism 1. Every cell has the entire genetic blueprint for an animal a. A cell’s characteristics will be reflected only by the genes that are expressed b. Developmental biologists have discovered many of the genes and proteins that control development â Science in Action: Unraveling the Mechanisms of Animal Development (Figures E42-1 and E42-2) â Lecture Activity 42.2: Fetal Stem Cell Research Class Discussion B. Molecules Positioned in the Egg and Produced by Nearby Cells Control Gene Expression During Embryonic Development 1. The differentiation of cells and development of entire structures are driven by one or both of two processes a. The actions of gene-regulating substances inherited from the mother in her egg b. Chemical communication between the cells of the embryo 2. Maternal molecules in the egg may direct early embryonic differentiation a. Some proteins in the egg are transcription factors that regulate which genes are turned on or off i. The positioning of these molecules in some eggs strongly controls development so that the egg can be mapped according to what structures will be produced by daughter cells (Figure 42-4) 3. Chemical communication between cells regulates most embryonic development a. During induction, certain cells release chemical messengers that alter the development of other nearby cells i. Some of these messengers are proteins that interact with other molecules to affect gene expression 4. Homeobox genes regulate the development of entire segments of the body a. Homeobox genes are short sequences of DNA found within larger genes that are involved in development by acting on other genes i. Mutations in homeobox genes can cause significant developmental changes (Figure 42-5a) ii. They are arranged on chromosomes in a head-to-tail order (Figure 42-5b) â Lecture Activity 42.3: Gene Control of Body Form Class Activity â Case Study Continued: Rerunning the Program of Development

42.5 How Do Humans Develop?

A. Human Development Is Controlled by the Same Mechanisms That Control the Development of Other Animals B. Differentiation and Embryonic Growth Are Rapid During the First Two Months 1. The egg is typically fertilized in the oviduct on the way to the uterus a. It undergoes several cleavage divisions (Figure 42-6) 2. After about 5 days, a blastocyst is formed (Figure 42-7a) a. A blastocyst is a hollow ball of cells with an inner cell mass on one side 3. The outer cell layer adheres to the uterus and burrows into the endometrium in a process called implantation (Figure 42-7a, b) a. The outer cell layer becomes the chorion b. The inner cell mass becomes the embryo i. The inner cell mass forms the other three embryonic membranes â Health Watch: The Promise of Stem Cells (Figure E42-3) .

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4. After implantation, two cavities form and gastrulation occurs a. The inner cell mass splits, forming two fluid-filled sacs separated by the embryonic disc i. One sac is continuous with the yolk sac ii. The second sac is continuous with the amniotic cavity iii. Gastrulation begins near the end of the second week after fertilization 5. Organogenesis begins during weeks Three to Eight a. During the third week, the embryo begins to form the spinal cord and brain b. The embryonic heart forms and begins to beat c. During the fourth week, the embryo bulges into the uterine cavity (Figure 42-8) d. The yolk stalk connects the yolk sac and the embryonic digestive tract i. The umbilical cord is formed from the merger of yolk stalk and body stalk e. During the fourth and fifth weeks, the embryo develops a tail and pharyngeal grooves (gills) (Figure 42-11) i. These will disappear later in development f. By the seventh week, rudimentary eyes and a brain develop and the webbing between the fingers and toes begins to disappear 6. After 2 months, the embryo is recognizably human a. By end of the second month, most major organs have formed b. After 2 months of development, the embryo is now called a fetus (Figure 42-10) C. Growth and Development Continue During the Last Seven Months (Figure 42-11) 1. The brain and spinal cord develop rapidly, generating fetal responses to stimuli after 3 months 2. Many organs needed outside the uterus become functional 3. A fetus can survive outside the womb after 32 weeks D. The Placenta Exchanges Materials Between Mother and Embryo 1. The placenta forms from interlocking structures produced by the embryo and endometrium (Figure 42-12) a. The outer layer of the blastocyst grows chorionic villi that connect to blood vessels in the umbilical cord b. The placenta regulates exchange of material between the mother and the fetus i. Many small molecules can be exchanged between the fetus and the mother, including O2, CO2, nutrients, and fetal urea ii. Large proteins and most cells are blocked by the chorionic villi â Health Watch: The Placenta—Barrier or Open Door? (Figure E42-4) â Lecture Activity 42.4: Prenatal Care Class Discussion E. Pregnancy Culminates in Labor and Delivery 1. In the final months of pregnancy, the fetus is positioned head-downward on the cervix 2. Near the end of the ninth month, childbirth begins (Figure 42-13) a. Uterine stretching occurs b. Fetal and maternal hormones trigger labor c. Labor involves the uterine contractions that produce birth d. Uterine stretching and fetal stimulation of maternal estrogen/prostaglandin release cause the uterus to contract i. The baby’s head pushes against the cervix, stretching it ii. Cervix dilation stimulates oxytocin release, causing stronger uterine contractions iii. Positive feedback ceases when the baby emerges from the birth canal e. Contractions resume, resulting in placental detachment and expulsion from the body F. Milk Secretion Is Stimulated by the Hormones of Pregnancy 1. Elevated estrogen and progesterone stimulate mammary gland growth 2. Mammary glands each have a duct that leads to the nipple (Figure 42-14) 3. Lactation (milk production) is stimulated by prolactin a. Suckling of the baby stimulates prolactin and oxytocin release i. Oxytocin causes muscles surrounding the mammary glands to contract, leading to milk ejection from the nipples 4. Colostrum is released for several days after birth a. It is high in proteins and antibodies that help the newborn fight infection b. High-lactose/high-fat mature milk is produced afterward

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42.6 Is Aging the Final Stage of Human Development?

A. Aging Is the Gradual Accumulation of Damage to Essential Biological Molecules over Time (Figure 42-15) 1. It reduces the ability of the body to repair cell/tissue damage 2. Several evolutionary hypotheses suggest that aging is inevitable

Case Study Revisited: Rerunning the Program of Development

KEY TERMS adult stem cell (ASC) aging allantois amnion amniotic egg blastocyst blastopore blastula chorion chorionic villus (plural, chorionic villi) cleavage colostrum development differentiation direct development

ectoderm embryonic disc embryonic stem cell (ESC) endoderm extraembryonic membrane fetal alcohol syndrome (FAS) fetus gastrula gastrulation homeobox gene implantation indirect development induced pluripotent stem cell (iPSC) induction inner cell mass

labor lactation larva (plural, larvae) mammary glands mesoderm metamorphosis morula organogenesis placenta stem cell yolk yolk sac zygote

LECTURE ACTIVITIES Lecture Activity 42.1: “Animal Development Gone Wrong: Environmental Influences” Class Demonstration and Discussion Estimated Time to Complete: 10–30 minutes, depending on the enthusiasm of the class and the needs of the instructor.

Section Reference 42.3 How Does Animal Development Proceed?

Introduction Although students seem to have an innate understanding that exposure to certain chemicals, natural or otherwise, can have profound effects on animal development, this appreciation tends to be exclusively from a human perspective. In fact, other vertebrate animals, especially aquatic ones, may be at much greater risk than we are due to the presence of chemicals in the environment. As part of a lecture on Sections 42.3D and 42.3E, you may wish to include images and information that demonstrate that poor environmental stewardship can cause major developmental problems for some animals, and perhaps, ultimately, ourselves. Two especially topical examples of this are (1) the increasing prevalence of malformed amphibians and (2) the feminization of some aquatic animals due to the introduction of environmental estrogens (chemicals that have estrogen-like properties).

• Malformed Amphibians: In 1995, some Minnesota students found populations of frogs with terrible malformations, including having as many as five hind legs, large tumors, unusual toe webbing, and missing limbs and eyes. Although a baseline level of malformations is expected for metamorphosing amphibians, the numbers found were much greater than the norm. Since then, malformed amphibians have been located in at least 46 U.S. states and 4 Canadian provinces. A variety of causes have been suggested that may explain why these developmental malformations are becoming more prevalent, including the presence of excess UV-B light .

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and various chemical agents that have been released into the environment. Ultimately, these malformations have been suggested as one possible cause (of probably many) of the current global decline in amphibian populations.

• Environmental Estrogens: The abnormal environmental presence of chemicals that either mimic the effects of estrogen in the body or block the ability of hormones to bind to their proper cell receptors have been shown to affect proper development in many aquatic animals. For example, it has been found that (1) male Florida alligators that were exposed to DDT (a pesticide) in the environment had reduced male reproductive structures, increased estrogen, and reduced testosterone levels (i.e., feminization) that limit their ability to reproduce; (2) male fish exposed to alkylphenols (a chemical by-product of plastic and detergent breakdown) had both male and female characteristics; and (3) male frogs exposed to atrazine (a common herbicide) exhibited progressive feminization from the front to rear of their bodies, to the point where the testes of males actually produced eggs. Given the effects of environmental estrogens on these, and other, animals, it has been suggested that humans need to be wary of these chemicals too. It has been speculated that they may cause a variety of cancers of the reproductive system, low sperm counts, and a variety of other possible reproductive conditions.

• An Internet search using “effect of pollution on amphibian development” will provide background information and examples.

Materials Needed • Computer with Internet connection and projector for presentation of Web sites.

Procedures While presenting this material to the class, ask questions such as: 1. Why do you think amphibian malformations are so prevalent compared to other vertebrate groups?

(Possible responses: Responses should be centered around [a] the fact that amphibians have extremely permeable skin that allows chemicals to diffuse directly into their bodies, and [b] amphibian eggs have clear, permeable membranes that allow chemical influx [as above] and expose developing embryos to UV light [a mutagen].)

2. How do you think amphibian malformations may be caused?

(Possible responses: A variety of responses are possible, including UV light exposure, exposure to pesticides/herbicides, and parasite disruption of amphibian development.)

3. If feminization is occurring in some aquatic animals, what might be the short- and long-term effects on their populations?

(Possible responses: Generally speaking, responses should center around the failing reproductive ability of males, and whole populations having less favorable male/female ratios than normal.)

4. Should steps be taken to minimize the release of environmental estrogens into the environment?

If so, how?

(Possible responses: Many answers are possible, as students are likely to have many opinions on the subject.)

5. Such steps could affect the everyday lives of many people, as several environmental estrogens are found in common pesticides, herbicides, and detergents. Would reducing environmental estrogens be worth the potential impact on lifestyles and industry (such as agriculture)?

(Possible responses: Many answers are possible, as students are likely to have many opinions on the subject.)

Assessment Suggestions Integration of questions into a lecture exam, weekly quiz, or as an extra-credit essay works well.

Lecture Activity 42.2: Fetal Stem Cell Research Class Discussion Estimated Time to Complete: 10–30 minutes, depending on the enthusiasm of the class and the needs of the instructor.

Section Reference 42.4 How Is Development Controlled?

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Introduction Stem cell research is a controversial issue in the United States. Many scientists argue that advances in the treatments of many diseases could be realized by conducting fetal stem cell research. For example, repair of nervous system damage using fetal neural stem cells has been successful in an animal model system. However, many political, religious, and public interest groups are against the use of human stem cells in research because, in effect, human blastocysts must be harvested (usually from abortion clinics) to produce a sufficient quantity of cells. In small groups, compare the medical benefits with the ethical problems this issue presents. Under what situations does your group feel that fetal stem cell research is justified? Under what conditions does your group feel that the use of fetal stem cells should be denied? Discuss!

Materials Needed None, other than a basic understanding of the use of stem cells in research Procedures 1. Break the class into groups of four, give groups their discussion “assignment,” and have them talk among themselves for 5–10 minutes (in a respectful fashion!).

2. After time has expired, the instructor should lead the entire class in a discussion that considers the pros and cons of stem cell research. These discussion points should be compiled on the blackboard. It is important for the instructor to stay impartial during the discussion, and emphasize that both sides have legitimate views that need to be expressed.

Assessment Suggestions Assessment by lecture exam, weekly quiz, or extra credit essay would work well.

Lecture Activity 42.3: Gene Control of Body Form Class Activity Estimated Time to Complete: 15–50 minutes, depending on the enthusiasm of the class and the needs of the instructor. This activity works best in a class of fewer than 30 students (for larger classes, you can use teaching assistants to help mediate group discussion).

Section Reference 42.4 How Is Development Controlled?

Note: The class should have covered the topics of cell fate and the control of body form by homeobox genes prior to this activity.

Introduction Your research team at the Institute for Animal Development has been presented with some fascinating new information. Other researchers working on insect development discovered that a gene called DII is active during the development of legs. If DII fails to turn on during development, an insect will develop no legs, only stumps.

Intriguingly, DII is also present in vertebrates, and it switches on during vertebrate leg development. What’s more, DII is also present in a diverse array of invertebrates, including sea urchins, sea squirts, and velvet worms.

Your team has been asked to answer some key questions about these findings: (1) How can the same gene control the development of structures as different as an insect leg and vertebrate leg? (2) What is the most likely function of the protein encoded by DII (that is, what does the protein do)? (3) Why has DII remained, virtually unchanged, in the genomes of all these different animals whose common ancestor lived hundreds of millions of years ago? The class should break up into groups of four to propose logical, detailed answers.

Materials Needed None

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Procedures 1. Break the class into groups of four and give them their “assignment,” making sure to write the questions for discussion on the blackboard.

2. Give the groups at least 7–10 minutes to discuss the scenario and answer the questions.

3. Discuss the answers that different groups came up with, either as an entire class or broken into sections with teaching assistants moderating each discussion.

Assessment Suggestions Assessment by lecture exam or weekly quiz works well.

Handouts or Display See the following page.

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Chapter 42 Animal Development Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

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Group Members’ Names: ________________________________________________________________

Group Recorder: _________________________

Date: _________________________

Lecture Activity 42.3 Handout—Gene Control of Body Form Background Your research team at the Institute for Animal Development has been presented with some fascinating new information. Other researchers working on insect development discovered that a gene called DII is active during the development of legs. If DII fails to turn on during development, an insect will develop no legs, only stumps.

Intriguingly, DII is also present in vertebrates, and it switches on during vertebrate leg development. What’s more, DII is also present in a diverse array of invertebrates, including sea urchins, sea squirts, and velvet worms.

Your team has been asked to answer some key questions about these findings: (1) How can the same gene control the development of structures as different as an insect leg and vertebrate leg? (2) What is the most likely function of the protein encoded by DII (that is, what does the protein do)? (3) Why has DII remained, virtually unchanged, in the genomes of all these different animals whose common ancestor lived hundreds of millions of years ago?

The class should break up into groups of four to propose logical, detailed answers.

1.

How can the same gene control the development of structures as different as an insect leg and vertebrate leg?

Student Response:

2.

What is the most likely function of the protein encoded by DII (that is, what does the protein do)?

Student Response:

3.

Why has DII remained, virtually unchanged, in the genomes of all these different animals whose common ancestor lived hundreds of millions of years ago?

Student Response:

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Lecture Activity 42.4: Prenatal Care Class Discussion Estimated Time to Complete: 10–30 minutes, depending on the enthusiasm of the class and the needs of the instructor.

Section Reference 42.5 How Do Humans Develop?

Introduction It can be an intellectually and emotionally engaging exercise to discuss ethical dilemmas brought up by our knowledge of biological systems, particularly when it directly affects humans. With this in mind, have your class break up into small groups (if greater than 30 students) to consider the following statement: Many children are born with birth defects and/or a variety of behavioral and emotional disorders as a result of smoking and drug/alcohol consumption during pregnancy. Some individuals have suggested that legislation should be passed to hold mothers criminally responsible for the consequences of their actions during pregnancy. What do you think?

The class should discuss both the pros and cons of legislation of this type, with the instructor acting as an intermediary and “devil’s advocate” to further discussion. The instructor should be prepared to provide a number of counterarguments to the class sentiments, making sure the students examine all sides of the argument. For example, consider the following provocative statements: 1. If a woman became addicted to drugs/alcohol before she became pregnant, should she be held responsible if she claims her addictions kept her from stopping? Should cigarette and pharmaceutical companies be liable?

2. If a mother is held responsible for her actions during pregnancy, what of the father? Secondhand smoke has been shown to have adverse effects on human development; if the father is a chain smoker and refuses to stop smoking around the mother, what then?

3. Is this scenario any different than what may occur when a person kills another when he or she drinks and drives?

4. Would legislation of this type be just another case of “big brother” trying to control our lives? Is this justified or not? Why? Materials Needed None Procedures Nothing specific, other than traditional discussion techniques Assessment Suggestions A bonus question on an exam or quiz, or an extra-credit essay, is appropriate.

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CHAPTER 43 PLANT ANATOMY AND NUTRIENT TRANSPORT LECTURE OUTLINE Case Study: Autumn in Vermont 43.1 How Are Plant Bodies Organized?

A. The Bodies of Flowering Plants Consist of Two Systems, a Root System and a Shoot System (Figure 43-1) 1. Roots are generally embedded in the soil and serve six major functions a. Anchor the plant b. Absorb water and minerals from the soil c. Transport water, minerals, sugars, and hormones to and from shoot d. Store surplus food e. Produce hormones f. Interact with soil fungi and bacteria that help provide nutrients to the plant 2. The shoot system is usually aboveground and is composed of leaves, buds, flowers, and fruits, borne on various parts of stems 3. Functions of shoots include a. Capture sunlight energy and synthesize sugars during photosynthesis b. Transportation of materials among leaves, flowers, fruits, and roots c. Store surplus sugars and starches d. Reproduction e. Hormone synthesis B. Flowering Plants Can Be Divided into Two Groups 1. Two broad groups of plants are called monocots and dicots (Figure 43-2) a. Cotyledons, parts of the plant embryo, are what distinguish the two groups i. Monocots have long thin leaves, and bushy fibrous roots ii. Dicots have broad leaves and thick taproots iii. Monocots have a single cotyledon, whereas dicots have two â Lecture Activity 43.1: Two Major Groups of Flowering Plants: Differentiating Between Monocots and Dicots

43.2 How Do Plants Grow?

A. Animals and Plants Develop in Very Different Ways B. During Plant Growth, Meristem Cells Give Rise to Differentiated Cells 1. Plants consist of two categories of cells a. Meristem cells are like the stem cells of animals and can divide by mitosis b. Differentiated cells are specialized in structure and function 2. Apical meristems (“tip meristems”) are located at tips of shoots and roots (Figure 43-3) a. They produce primary growth, which increases the length of the plant and affects the development of specialized plant structures 3. Increases in diameter occur from cell division in lateral meristems (“side meristems” or cambia) a. These are located as a continuous cylinder the length of the root and shoot system b. These produce secondary growth (woody) in some mature shoots and roots

43.3 What Are the Tissues and Cell Types of Plants? â Lecture Activity 43.2: Tissue/Cell Types and Functions A. The Plant Body Consists of Three Different Tissue Systems (Table 43-1) B. The Dermal Tissue System Covers the Plant Body 422

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1. Epidermal tissue forms the epidermis, which covers the leaves, stems, roots of all young plants, and new growth in older plants a. It also covers flowers, seeds, and fruit b. It secretes a cuticle (waxy, waterproof material), which helps conserve water 2. Periderm replaces epidermal tissue on the stems and roots of woody plants as they age C. The Ground Tissue System Makes Up Most of the Young Plant Body 1. This tissue includes everything that is not epidermis or vascular and is composed of parenchyma, collenchyma, and sclerenchyma 2. Parenchyma tissue is the most abundant type of ground tissue (Figure 43-4a) a. Thin-walled cells b. Usually involved in metabolic activity such as photosynthesis, storage of starch or sugars, or secretion of hormones, depending on location 3. Collenchyma is more rigid, but still flexible (Figure 43-4b) a. Elongated cells b. Strong, provide support to leaf stalks and young stems 4. Sclerenchyma is composed of cells with thick, hardened cell walls (Figure 43-4c) a. Thick secondary cell walls provide additional support in woody stems b. Found in portions of the veins, seed coverings, pear fruit, and wood D. The Vascular Tissue System Transports Water and Nutrients 1. This system is composed of xylem and phloem 2. Xylem transports water and dissolved minerals from the roots to the rest of the plant a. It is composed of tracheids and vessel elements (Figure 43-5) b. Tracheids are thin, tube-like cells, with overlapping slanted ends that have pits c. Vessel elements are larger in diameter, and form pipelines called vessels 3. Phloem transports sugars and other organic molecules throughout the plant body a. It is composed mainly of sieve tubes (Figure 43-6) b. Perforated sieve plates are found at adjoining ends c. Nourished by adjacent companion cells through plasmodesmata

43.4 What Are the Structures and Functions of Leaves?

A. Leaves Are the Principal Photosynthetic Structures of Most Plants (Figure 43-7) 1. Leaves are composed of two major parts, the blade and petiole a. The petiole orients the blade to intercept sunlight, and has a continuous connection of vascular tissue from stem to blade B. The Epidermis Regulates the Movement of Gases into and out of a Leaf 1. The cuticle on the epidermis reduces evaporation 2. Stomata pierce the epidermis and the cuticle a. Guard cells (specialized epidermal cells) control the size of the stomata that regulate diffusion of CO2, oxygen, and water in and out of the leaf C. Photosynthesis Occurs in Mesophyll Cells 1. Air spaces between them allow mesophyll cells access to CO2 D. Veins Transport Water and Nutrients Throughout the Leaf 1. Vascular bundles containing xylem and phloem conduct materials between the leaf and the rest of the plant body â Case Study Continued: Autumn in Vermont E. Many Plants Produce Specialized Leaves 1. Temperature and the availability of water and nutrients have exerted strong selection pressure on leaves a. Consequently, leaves have adapted into many different forms (Figure 43-8)

43.5 What Are the Structures and Functions of Stems?

A. The Stems of a Plant Support and Separate the Leaves, Lifting Them into the Sunlight and Air 1. Stems have a variety of functions and structures B. Primary Growth Produces the Structures of a Young Stem 1. At the tip of a newly developing shoot is the terminal bud a. This structure consists of apical meristem cells surrounded by leaf primordia (Figure 43-9) i. During growth, the meristem cells divide, producing specialized structures .

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Instructor Guide Biology: Life on Earth 2. Nodes and internodes are found below the terminal bud a. The node is the site of attachment of the petiole of the leaf b. The internode is the part of the stem between nodes c. Lateral buds, clusters of meristem cells, are usually left at the nodes d. During the reproductive season, meristem cells form flower buds 3. The epidermis of the stem reduces water loss while allowing carbon dioxide to enter a. Like the leaf epidermis, the stem epidermis secretes cuticle to decrease water loss b. It also has stomata for gas exchange 4. The cortex and pith support the stem, store food, and may photosynthesize a. The cortex is located between the epidermis and vascular tissues b. The pith is located at the center of the stem c. These structures have three major functions i. Support of the young stem ii. Storage of starch iii. Photosynthesis 5. Vascular tissues in the stem transport water, dissolved nutrients, and hormones a. Vascular tissue is organized into bundles (Figure 43-9b) b. Each bundel consists of primary xylem and primary phloem (Figure 43-9c) C. Secondary Growth Produces Thicker, Stronger Stems 1. Vascular cambium produces secondary xylem and secondary phloem a. Daughter cells of the vascular cambium differentiate into secondary xylem and phloem (Figure 43-9c) b. Sapwood, the youngest secondary xylem, transports water and minerals (Figure 43-10) c. Heartwood, older secondary xylem at the center of the trunk, provides support d. Annual rings are formed from alternating rings of large cells (formed in spring with abundance of water) and small cells (formed in summer when water is limiting) â Lecture Activity 43.3: Secondary Growth of Stems e. Annual rings can be used in variety of ways i. Approximate age of trees ii. Reconstruct past climates 2. Cork cambium replaces the epidermis with cork a. Cork cambium forms from cells in the epidermis, cortex, or phloem, stimulated by hormones b. Cork cambium produces cork cells, which are tough, waterproof, and protective (Figure 43-11a) i. Cork sloughs off and is re-formed as the xylem expands the diameter of the trunk ii. Cork can be harvested for many uses without harming the tree (Figure 43-11b) c. Bark includes all tissues outside the vascular cambium i. Stripping the bark removes the sugar transport to roots and eventually kills the tree D. Many Plants Produce Specialized Stems or Branches 1. Flowering plants have evolved a variety of stem specializations (Figure 43-12) a. Some function in water and nutrient storage b. Some are for protection or reproduction, as well as other functions

43.6 What Are the Structures and Functions of Roots?

A. Dicots and Monocots Have Different Root Structures 1. Dicots have taproot systems consisting of a central root and many smaller roots that grow from its sides (Figure 43-13a) 2. Monocots have fibrous root systems with many roots of approximately equal size (Figure 43-12b) 3. Both young taproots and fibrous roots have four distinct regions (Figure 43-14) B. The Root Cap Shields the Apical Meristem 1. Root cap cells have thick cell walls and secrete a slimy lubricant that helps the root move through soils C. The Epidermis of the Root Is Permeable to Water and Minerals 1. The crucial function of the root is to absorb water and minerals from the soil a. Root hairs increase the surface area for water and mineral absorption (Figure 43-15) D. The Cortex Stores Food and Controls the Absorption of Water and Minerals into the Root 1. The cortex occupies a majority of the inside of a young root located between the epidermis and vascular cylinder (Figure 43-15) a. This consists of a large mass of parenchyma cells .

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b. Sugars are converted to starch here for food storage (Figure 43-16) 2. The endodermis is a layer of closely packed cells around the vascular cylinder, containing waterproof material called the Casparian strip E. The Vascular Cylinder Contains Conducting Tissues and Forms Branch Roots 1. The vascular cylinder contains the conducting tissues of xylem and phloem a. The pericycle is the outermost layer of the vascular cylinder and works with endodermal cells to regulate the movement of water and minerals into the xylem b. The pericycle is also the source of branch roots (Figure 43-17) F. Roots May Undergo Secondary Growth 1. The roots of woody plants become thicker and stronger through secondary growth

43.7 How Do Plants Acquire Nutrients?

A. Plants Require a Variety of Nutrients (Table 43-2) 1. These nutrients are obtained from the air or the soil a. Water is used to transport many nutrients, including minerals, throughout a plant B. Roots Transport Minerals from the Soil into the Xylem of the Vascular Cylinder (Figure 43-18) 1. The young root is made up of living cells, extracellular space, and tracheids and vessel elements of xylem a. Cells in the roots are porous, allowing the diffusion of water and minerals into the root b. The Casparian strip provides a barrier for the diffusion of water and minerals c. Minerals go through a three-step process to get into the root (Figure 43-18a) i. From soil or water into a living cell outside the Casparian strip ii. Through plasmodesmata interconnecting living cells iii. Into the extracellular space within the vascular cylinder 2. The Casparian strip prevents the loss of minerals from the vascular cylinder C. Roots Take Up Water from the Soil by Osmosis 1. The inside of the tracheids and vessel elements have a high mineral concentration a. Water travels into the roots through osmosis, following the minerals 2. In some plants, this movement of water creates root pressure, which moves fluid up the shoot (Figure 43-19) a. Usually, the evaporation of water out of the leaves causes the water to move up the shoot D. Symbiotic Relationships Help Plants Acquire Nutrients â Lecture Activity 43.4: Function of Symbiotic Microbes in Reestablishing Plant Life After a Severe Fire 1. Some plants live with fungi that aid absorption 2. Other plants, such as legumes, have bacteria that aid in the conversion of nitrogen into usable ammonium 3. Fungal mycorrhizae help most plants to acquire minerals a. Fungal strands grow in between root cells and extend into the soil (Figure 43-20) b. This is mutually beneficial: plants receive minerals, and the fungus obtains sugars, amino acids, and vitamins from the plant c. The relationship increases the range of both the fungus and plant, allowing them to grow in less optimum environments 4. Nitrogen-fixing bacteria help legumes acquire nitrogen a. Nitrogen in the air (N2) is not a usable form of nitrogen for plants b. Nitrogen-fixing bacteria live in soils, have the ability to fix nitrogen, but don’t convert large amounts because it requires high cost in ATP c. Legumes and a few other plants form mutual symbioses with nitrogen-fixing bacteria d. Plants provide the bacteria with space within root nodules and sugars (Figure 43-21) e. Bacteria use the sugars for additional energy to fix nitrogen into a usable form

43.8 How Do Plants Move Water and Minerals from Roots to Leaves?

A. Transpiration Drives the Movement of Water from the Roots Upward Through the Plant Body B. The Cohesion–Tension Mechanism Explains Water Movement in Xylem 1. This mechanisms involves two essential processes (Figure 43-22) a. Cohesion, the attraction among water molecules that holds the water together b. Tension produced by water evaporating from the leaves causes it to move up the xylem 2. Hydrogen bonds between water molecules produce cohesion .

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3. Transpiration produces the tension that pulls water upward a. Water is pulled up the xylem by the evaporative force of transpiration b. Water moves from nearby xylem into mesophyll cells by osmosis 4. Cohesion and tension work together to move water up the xylem a. The pulling force caused by the evaporation of water is enough to help pull water up the xylem â Earth Watch: The Surprising Impacts of Forests on Climate and Growth of Their Own Trees (Figure E43-1) â Case Study Continued: Autumn in Vermont C. Minerals Move Up the Xylem Dissolved in Water D. Stomata Control the Rate of Transpiration 1. A plant must regulate its stomata to maintain a balance of drawing up water and allowing CO 2 entry, and minimizing water loss â Lecture Activity 43.5: Environmental Control of Stomata 2. Guard cells regulate opening and closing of stomata a. Stomata are openings surrounded by guard cells (Figure 43-23) b. Stomata are open when guard cells take in water and elongate, and close when the guard cells lose water and shrink (Figure 43-24a) i. Potassium is actively pumped into guard cells during the day (Figure 43-24b) ii. Water follows by osmosis c. Three important factors regulate potassium concentration inside guard cells i. Light reception causes a reaction series that results in potassium entering guard cells, opening the stomata ii. Low carbon dioxide concentrations make stomata open iii. Water loss causes the release of the hormone abscisic acid, which inhibits transport of potassium into guard cells, and stomata close

43.9 How Do Plants Transport Sugars?

A. Botanists Studied Phloem Using Aphids to Understand Sugar Transport (Figure 43-25) B. The Pressure-Flow Mechanism Explains Sugar Movement in Phloem 1. Differences in water pressure drive the flow of fluid through the sieve tubes a. Sugars move from mature leaves carrying out photosynthesis, a sugar source, to structures that use the sugar, such as a developing fruit (sink) b. Sugar produced by a source cell is transported into a phloem sieve tube (Figure 43-26) c. Water follows the sugar by osmosis d. Water pressure drives the fluid through the sieve tubes e. Cells of the sugar sink actively transport sugar out of the phloem

Case Study Revisited: Autumn in Vermont

KEY TERMS annual ring apical meristem bark blade branch root bud Casparian strip cohesion cohesion–tension mechanism collenchyma companion cell cork cambium cork cell cortex

dermal tissue system dicot differentiated cell endodermis epidermis fibrous root system flower bud ground tissue system guard cell heartwood internode lateral bud lateral meristem leaf .

legume meristem cell mesophyll mineral monocot mycorrhizae nitrogen fixation nitrogen-fixing bacterium node nodule nutrient parenchyma pericycle periderm

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cuticle phloem pit pith plasmodesma (plural, plasmodesmata) pressure-flow mechanism primary growth root root cap root hair root pressure root system sapwood

leaf primordium (plural, primordia) sclerenchyma secondary growth shoot system sieve plate sieve-tube element sink source stem stoma (plural, stomata) taproot system terminal bud tissue

petiole tissue system tracheid transpiration vascular bundle vascular cambium vascular cylinder vascular tissue system vein vessel vessel element xylem

LECTURE ACTIVITIES Lecture Activity 43.1: Two Major Groups of Flowering Plants: Differentiating Between Monocots and Dicots Estimated Time to Complete: 15–20 minutes (depending on the number of samples) Section Reference 43.1 How Are Plant Bodies Organized?

Introduction There are two major groups of flowering plants—monocots and dicots. The names are based on the number of cotyledons (seed leaves) for the plants. In addition to the number of cotyledons, the similarities of the plants within each group are far reaching and include same number of flower parts, leaf vein pattern, root system, and vascular bundle arrangement (Figure 43-2). If the plant has any one of the characteristics for the group, it will also have the others. There is no need to see all characteristics to accurately place a flowering plant into the correct group, enabling one to deduce information about the sample plant that may not have been present at the time the sample was harvested.

Materials Needed • A variety of monocot and dicot plants at different stages of development. Examples of easily accessible plant/plant parts include: monocots: lilies, Austrumaria, Zebrina (wandering Jew), grasses, soaked corn kernels; and dicots: any tree branches with leaves, geraniums, dandelion, vegetable plants, roses, soaked pea or bean seeds. Each sample should be clearly labeled.

• Figure 43-2 Procedures Have the students work in groups of three to five. They should examine each sample and put it into the appropriate group on the tally sheet based on the characteristics listed in Figure 43-2.

Assessment Suggestions After 15 minutes, have a group discussion and reach consensus on the samples and discuss what the students can tell about the characteristics that are not actually present in the particular sample but will appear at some point in the development of that plant.

Handouts or Display See the following page.

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Name: ________________________

Date: _________________________

Instructor: _____________________

Course Section: _________________

Lecture Activity 43.1 Handout—Two Major Groups of Flowering Plants: Differentiating Between Monocots and Dicots Tally sheet Monocots

Flower parts in 3’s or multiples of 3

Parallel veins

Vascular bundles scattered through stem

Fibrous root system

One cotyledon

Dicots

Flower parts in 4’s, 5’s, or multiples of 4 or 5

Netlike veins

Vascular bundles in ring around stem

Taproot system

Two cotyledons

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Lecture Activity 43.2: Tissue/Cell Types and Functions Estimated Time to Complete: 20 minutes Section Reference 43.3 What Are the Tissues and Cell Types of Plants?

Introduction Plants are composed of three tissue types throughout the body: epidermal, vascular, and ground tissue. The epidermis protects underlying tissues, the vascular tissue provides transport, and the ground tissue serves in storage or metabolic functions. Part I demonstrates vascular function, illustrating that vascular tissue alone is responsible for liquid transport. Part II demonstrates that starch storage in roots and seeds is limited to the ground tissue and not the epidermis or the vascular tissue.

Materials Needed Part I • Stem with easily visible vascular tissue—celery, carnation, daisy, mums • 5% eosin stain (or any water-soluble stain) • Single-edged razor • 150-ml beaker or glass • Dissecting microscope, document camera with zoom, or overhead projector Procedures Place a freshly cut stem into stain that is 2–3 inches deep in a glass or beaker. Allow the stain to be drawn up in the vascular tissues of the stem. This will take a few minutes and will be easily visible. Remove the stem from the stain and make a cross-section slightly above the region where the stain is visible on the outside of the stem.

First, make a few thin cross-sections of stem in this region to observe the vertical transport of the stain. Place the cross-sections on a dissecting scope, document camera with zoom capability, or overhead projector. Even though the stain is not visible from the outside of the stem, the students will observe that the stain is present and limited to the veins.

Second, take a few cross-sections from the stem below the area cut previously. This is the stem that will look visibly stained from the outside, indicating that the stain has been transported laterally to tissues surrounding the veins.

Materials Needed Part II • Root, tuber, and/or seeds that function in starch storage—radish, Irish potato, soaked rice (soaked overnight to allow softening) • Single-edged razor • Iodine stain Procedures Slice the storage structures and allow the students to observe the unstained sample. Explain that the iodine stain will turn dark purple/black when it encounters starch. Ask them to predict which areas of the sample will turn black (i.e., which areas contain starch: the ground tissues and not the epidermis or vascular tissue). Apply a few drops of the stain and observe.

Assessment Suggestions Have the students answer the following questions on paper or in group discussions.

Which tissue type transports liquids? Is the transport vertical, lateral, or both? Explain. Did the stain indicate starch in the expected tissues? What is the function of starch storage for plants? How do we use these structures?

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Lecture Activity 43.3: Secondary Growth of Stems Estimated Time to Complete: 20 minutes Section Reference 43.5 What are the Structures and Functions of Stems?

Introduction Secondary growth provides increased strength in stems, storage of waste materials, and transport for the plant.

Darker areas of dense-walled secondary xylem growth occur during the summer when the xylem cells have less water available and expand less. In contrast, cells have much more water available in the spring and expand more; this provides a lighter-colored appearance. Annual rings are visible from this contrast between the dark summerwood of the previous year adjacent to the spring growth of the next year. We can estimate the age of secondary growth by counting the annual rings. There is a relationship between the width of the rings and the rainfall. Years with more rainfall have wider spring-wood.

Materials Needed • Cross-section slices from young trees that have a variation in the growth rings • OR photos of these cross-sections Procedures Have groups of students count the growth rings and reach a consensus about the age of the tree. Also, have them mark any rings that are noticeably narrower or wider than the others.

Assessment Suggestions Answer the following questions as a group or as a separate written assignment.

Approximately how old was the tree? How many dry (approximately 1/2 the width of the average year annual ring) years occurred during the lifetime of the tree? Do you expect trees that grow in a tropical rain forest to have growth rings? What about trees in tropical seasonal forests (forests that have a rainy and a dry season)?

Lecture Activity 43.4: Function of Symbiotic Microbes in Reestablishing Plant Life After a Severe Fire Estimated Time to Complete: 15 minutes Section Reference 43.7 How Do Plants Acquire Nutrients?

Introduction Certain soil microbes are beneficial to plants and assist the plant in obtaining nutrients. Mycorrhizae are fungi that live in close association with roots and increase uptake of phosphorus and other nutrients. These fungi have a wide host range and are found in association with most plants, especially those growing in nutrient-poor soils.

Nitrogen-fixing bacteria convert into a biologically useful form, NH3. These bacteria are limited to legume plants (certain trees, especially common in the tropics; and crop plants such as peas, clover, and soybeans). Nitrogenfixing bacteria are found more commonly in nitrogen-poor soils. Some fires become so hot that they burn up not only the plants above the ground, but also the roots and organic layer of the soil.

Materials Needed None Procedures Ask each student to write the name of a beneficial microbe that will need to be reintroduced to assist in establishing plants after a severe fire. Have them pass it to the student next to them. Now, list a different type of

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Chapter 43 Plant Anatomy and Nutrient Transport beneficial microbe. Have the students converse with the person on their right and decide which of the listed microbe(s) should be included in reforestation efforts after a severe forest fire.

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Assessment Suggestions Have the pairs of students submit a brief rationale for their answers.

Lecture Activity 43.5: Environmental Control of Stomata Estimated Time to Complete: 20 minutes Section Reference 43.8 How Do Plants Move Water and Minerals from Roots to Leaves?

Introduction Stomata are pores in leaves and herbaceous stems that open and close to regulate CO 2 and water content within the plant. Pores are opened and closed by the guard cells that surround them. Guard cells swell with the uptake of water by osmosis, opening the pore. Guard cells contract with water loss, closing the pore. Osmosis of water is controlled by changes in potassium concentrations in the guard cells. Movement of potassium into and out of guard cells is stimulated by several environmental factors. One of these factors is daylight. Increases in potassium levels result in a lower water concentration. Water responds by entering the guard cells by osmosis and causes the stomata to open.

Materials Needed • Epidermal peels (from Zebrina or any plant with thick epidermis) of leaves taken from plants that were exposed to daylight for at least 1 hour and from leaves that were covered with aluminum foil for 1–2 hours (or overnight) • Glass cover slip and slide • Water • Dissecting microscope or document camera with zoom Procedures Make the epidermal peel by snapping the leaf in half and drawing one edge across the other to peel back the epidermis. It will look like an uneven tear. Place it on a glass slide with several drops of water and put a cover slip over top. Stomata are easily visible in the green sectors of Zebrina leaves. Use a dissecting microscope or a doc cam with zoom to compare the epidermal peel from plants exposed to light to those kept in the dark.

Assessment Suggestions Encourage group discussion about the role of light, CO2 levels, and water availability in stomata control.

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CHAPTER 44 PLANT REPRODUCTION AND DEVELOPMENT LECTURE OUTLINE Case Study: Some Like It Hot—and Stinky!

44.1 How Do Plants Reproduce?

A. Plants Can Reproduce Sexually or Asexually 1. Asexual reproduction produces new plants by mitosis a. The offspring are genetically identical to the parent B. The Plant Sexual Life Cycle Alternates Between Diploid and Haploid Stages 1. Plants exhibit an alternation of generations between two distinct forms: diploid sporophytes and haploid gametophytes (Figure 44-1) a. The sporophyte produces spores that undergo mitosis and form the gametophyte, which produces gametes b. In mosses, the gametophyte is an independent plant that dominates the life cycle c. Ferns also have an independent gametophyte i. The reproductive cells of the sporophyte are found on the underside of the fronds (Figure 44-2) d. In gymnosperms and angiosperms, sporophytes are the dominant form of the plant and the gametophyte is never an independent plant e. The life cycle of angiosperms goes through multiple stages (Figure 44-3) i. The male gametophyte produced is pollen, whereas the female gametophyte is the egg

44.2 What Are the Functions and Structures of Flowers?

A. Most Flowers Lure Animals That Pollinate Them 1. Wind pollination is an inefficient process 2. The evolution of flowers set the stage for the evolution of symbiotic relationships between animals and the plants they pollinate â Health Watch: Are You Allergic to Pollen? (Figure E44-1) B. Flowers Are the Reproductive Structures of Angiosperms 1. Complete flowers have four sets of modified leaves (Figure 44-4) a. Sepals, at base of the flower, protect the flower bud during development i. These are different in monocots and dicots (Figure 44-4a, b) b. Petals, just above the sepals, attract pollinators c. Stamens, just above the petals, are the male reproductive structures i. The filament is a slender stalk ii. The anther produces pollen d. Carpels, in the center of the flower, are the female reproductive structure i. The stigma is at the top, and is sticky so pollen adheres to this structure ii. The style is an elongated tube connecting stigma to ovary iii. The ovary, at the base of carpel, contains one or more ovules, where the female gametophyte develops iv. The mature ovule becomes a seed and the ovary develops into fruit enclosing the seeds 2. Incomplete flowers lack one or more of the four floral parts a. Grasses lack petals and sepals b. Zucchini have imperfect flowers, which lack either the male stamens or the female carpels (Figure 44-5) â Lecture Activity 44.1: Flower Parts and the Corresponding Fruit/Seed Structures â Case Study Continued: Some Like It Hot—And Stinky!

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C. The Pollen Grain Is the Male Gametophyte (Figure 44-6) 1. Each anther has four pollen sacs with many diploid microspore mother cells 2. Meiosis occurs in each microspore mother cell, forming four haploid microspores 3. Each microspore undergoes mitosis, forming two cells a. The tube cell guides formation of the pollen tube b. The generative cell undergoes mitosis at maturity to form two sperm cells, which often develop a tough shell 4. When the pollen has matured, the pollen sacs split open a. In wind-pollinated flowers, the pollen grains spill out and are distributed by wind currents (Figure 44-8) b. In animal-pollinated flowers, the pollen grains adhere to the pollinator and are distributed by them D. The Female Gametophyte Forms Within the Ovule (Figure 44-9) 1. Each ovule contains a diploid megaspore mother cell surrounded by protective integuments 2. Meiosis of the megaspore mother cell produces four haploid cells, called megaspores a. Only one megaspore survives 3. Mitosis of the megaspore occurs three times, producing eight haploid nuclei a. Seven cells are formed by the plasma membrane b. There are three small cells at each end, each with one nucleus, and one large central cell with two nuclei c. The egg cell is one of the three at the lower end E. Pollination of the Flower Leads to Fertilization (Figure 44-10) 1. Pollination occurs when a pollen grain lands on the stigma of a flower of the same species, triggering a series of events a. The pollen grain absorbs water from the stigma b. The tube cell elongates, burrowing into the style, producing a tube that will conduct sperm into an ovule in the ovary c. The pollen tube ruptures when it breaks into the embryo sac, releasing sperm 2. Double fertilization occurs a. One sperm fuses with the egg (fertilization) to form the diploid zygote i. The zygote develops by mitosis into the embryo and eventually into the sporophyte generation b. One sperm fuses with the two nuclei already present, forming an endosperm (food storage tissue in the seed) â Lecture Activity 44.2: Pollen and Pollen Tube Formation

44.3 How Do Fruits and Seeds Develop?

A. The Fruit Develops from the Ovary (Figure 44-11) 1. Fruits may be fleshy and edible, but some are hard, winged, sharp, or spiked a. The various shapes and textures aid in seed dispersal B. The Seed Develops from the Ovule 1. Three developmental processes occur to produce the seed (Figure 44-12a) a. The integuments of the ovule thicken, harden, and become the seed coat b. The triploid central cell divides rapidly and the resulting daughter cells absorb nutrients from the parent plant, forming the endosperm c. The zygote develops into the embryo 2. As the seed matures, the embryo begins to differentiate into shoot and root (Figure 44-12b) a. The shoot portion includes one or two cotyledons, or seed leaves, which absorb food from the endosperm and distribute it to other parts of the embryo i. Monocots have a single cotyledon, whereas dicots have two â Lecture Activity 44.3: Is It the Seed That Grows? Hey, There’s a Baby Plant in There

44.4 How Do Seeds Germinate and Grow?

A. Germination Occurs When the Embryonic Plant Within a Seed Grows, Breaks Out of the Seed, and Forms a Seedling 1. Some seeds do not germinate immediately, so they enter a period of dormancy during which they will not sprout

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Instructor Guide Biology: Life on Earth B. Seed Dormancy Helps Ensure Germination at an Appropriate Time 1. Adequate temperature and moisture are almost always prerequisites for germination 2. Depending on the environment, seeds may require three conditions for germination a. Drying prevents the seed from germinating while still inside the fruit b. Cold ensures that seeds in temperate and arctic plants germinate during the spring c. Seed coat disruption—for example, in desert plants, by sufficient water to weather seed coat or wash inhibitory chemicals—ensures enough water will be present for the plant to complete its life cycle C. During Germination, the Root Emerges First, Followed by the Shoot 1. The embryo absorbs water, swells, and bursts the seed coat 2. The root usually emerges first, and absorbs water and minerals, which are transported to the shoot (Figure 44-13) a. In monocots, the coleoptile protects the shoot tip as it pushes up through the soil (Figure 44-13a) 3. The embryonic shoot of the dicot consists of the hypocotyl and the epicotyl (Figure 44-13b) a. The hypocotyl makes a path through the soil for the shoot tip to follow 4. Cotyledons nourish the sprouting seed (Figure 44-14) â Lecture Activity 44.4: How Do Seeds Germinate and Grow?

44.5 How Do Plants and Their Pollinators Interact?

A. Plants and Their Pollinators Have Coevolved B. Some Flowers Provide Food for Pollinators 1. Bees perceive a different range of light than humans (Figure 44-15) a. Many flowers that bees pollinate have markings that reflect UV light b. The flowers are also structured so that pollen rubs off on the bee and can pollinate other flowers (Figure 44-16) 2. Fused, tube-shaped flowers accommodate the long tongues of butterflies and moths 3. Scavenging insects are attracted to foul-smelling flowers â Earth Watch: Pollinators, Seed Dispersers, and Ecosystem Tinkering (Figure E44-3) â Case Study Continued: Some Like It Hot—and Stinky!

4. Red and orange tubular flowers without much scent attract hummingbirds and other mammals (Figure 44-17) C. Some Flowers Are Mating Decoys 1. Many orchids are shaped and smell like female wasps, and males transfer pollen while attempting to mate with the orchid (Figure 44-18) D. Some Flowers Provide Nurseries for Pollinators 1. Yucca moths cross-pollinate yucca flowers and then lay eggs (Figure 44-19) a. Offspring are ensured a food source, but do not eat all the seeds

44.6 How Do Fruits Help to Disperse Seeds?

A. Explosive Fruits Shoot Out Seeds 1. Mistletoe can shoot seeds more than 60 feet B. Lightweight Fruits May Be Carried by the Wind 1. Dandelions, milkweeds, elms, and maples produce lightweight fruits that can be carried by the wind (Figure 44-20) C. Floating Fruits Allow Water Dispersal 1. Coconuts may be carried long distance (Figure 44-21) D. Clingy or Edible Fruits Are Dispersed by Animals 1. Clingy fruits stick to fur and are brushed or picked off at a distance from the parent plant (Figure 44-22) 2. Edible fruits benefit both the plant and the animal disperser (Figure 44-22) a. Some have large seeds that aren’t eaten by animals b. Some have small seeds that survive passage through the animal’s gut

Case Study Revisited: Some Like It Hot—and Stinky! (Figure 44-23)

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KEY TERMS alternation of generations anther carpel coleoptile complete flower cotyledon dormancy double fertilization egg endosperm epicotyl filament flower fruit

gametophyte generative cell germination hypocotyl imperfect flower incomplete flower integument megaspore megaspore mother cell microspore microspore mother cell ovary ovule petal

pollen grain pollination seed seed coat sepal spore sporophyte stamen stigma style tube cell zygote

LECTURE ACTIVITIES Lecture Activity 44.1: Flower Parts and the Corresponding Fruit/Seed Structures Estimated Time to Complete: 20 minutes Section Reference 44.2 What Are the Structures and Functions of Flowers?

Introduction The activity is divided into two parts. The first part allows the students to dissect common flowers and identify the different parts and their functions. This portion of the activity can stand alone or be followed up by the second half. The second half of the activity compares the flowers (or photos of them) to the fruits (or photos) that develop from the floral parts.

Part I Complete flowers have four major parts (Figure 44-4). Sepals are located in a ring at the base of the flower and protect the flower bud during development. Often the sepals are green and leaf-like in appearance, although some of the more primitive (developed early in evolution of flowering plants) have sepals that are similar in appearance to the petals. Austrumaria (a common lily used in fresh flower arrangements) is an example of such a flower. Petals occur just above the sepals and attract pollinators to the flower. In general, petals are more colorful than sepals and often appear quite differently to insect eyes than they do to our sight. (For images of different flowers, perform an Internet search using “flowers and pollinators” as search terms.) Petals are instrumental in attracting pollinators to flowers of the same species at the appropriate time for successful pollination. Stamens occur above the petals. Each stamen has a slender stalk, the filament, which holds the anther. Anthers are fourlobed structures that produce pollen (the male gametophyte). The female structure, the carpel, is found at the center of the flower. This flask-shaped structure has a sticky stigma at the top to which pollen adheres. The style connects the stigma to the ovary at the base of the carpel. The ovary contains one or more ovules, which will develop into female gametophyte(s).

Part II After successful pollination, the flower petals wilt and are shed. They have served their purpose, and plants no longer put resources into maintaining the petals. The ovary swells and forms the fruit, and integuments form a protective seed coat around the seed. Inside the seed is the developing embryo.

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Materials Needed • Assortment of simple, complete flowers: for example, rose, lily, austrumaria, daffodil, tulip, impatiens, African violets Part I Impatiens and African violets are readily available as houseplants. Often, florists are willing to donate flowers in the list above that are getting older and won’t be usable for quality arrangements. These easily serve the purpose for student dissection. To allow students to become proficient with the basic structures, this activity avoids use of daisy or mum types of flowers that have disk and ray flowers. If imperfect flowers (male and female) are available, they provide a good contrast to the complete flowers. Examples of imperfect flowers include ash, willow, holly trees, and begonias.

Part II Pollinate some of the flowers from the list several weeks prior to using the flowers in class, or harvest the fruits of flowers in gardens. Examples of easily accessible fruits include rose hips, the swollen tips of impatiens, tulips and daffodils after the petals have dropped off, and fruits/vegetables developing in gardens or from the produce department that still contain the stem and sepals.

Procedures Part I Compare the sample flowers to the stylized drawings and photos in the textbook (Figure 44-2). Identify the four structures and their functions.

Part II Find the sepals at the base of the fruit. Slice open the fruit and determine how many ovules were inside the ovary of the flower that produced this fruit (one or more than one).

Assessment Suggestions Have groups of students work on different flowers (and fruits, if Part II is included) and present their findings to the class.

Have each student draw one of the flowers with parts labeled.

Lecture Activity 44.2: Pollen and Pollen Tube Formation Estimated Time to Complete: This activity is supported by Figure 44-8 and the corresponding portion of the text and allows students to use the scientific method during a 75-minute class period. Approximately 20 minutes will be needed for introduction, followed by observations interspersed every 15 minutes during the class and discussion.

This activity/demonstration helps clarify the role of pollen as a male gametophyte—not a gamete. If done during class it can provide breaks and renew attention spans during long lecture periods. If the class period is short, start the slides 30 minutes before class, so there will be growth during class. Try it out ahead of time with your pollen source— times for pollen tube formation will vary with pollen source.

Section Reference 44.2 What Are the Structures and Functions of Flowers?

Introduction Pollen tubes must form to provide the connection between the sperm in the pollen and the egg and polar bodies in the ovary (Figure 44-10). The pollen is the male gametophyte that produces, protects, and transports the sperm to another flower. When the pollen is transported to another flower of the same species (by wind or animal pollinator), it absorbs moisture from the stigma and the tube nucleus directs formation of a pollen tube. The pollen tube grows through the style tissue to the base of the ovary, where it bursts and releases two sperm. One of the sperm fuses with the egg to form the zygote, which will become the embryo. The other sperm fuses with the two polar bodies to form the endosperm.

Pose the question: Does the pollen have enough stored food to grow a tube or does it need an energy source?

Have the students develop a hypothesis (basically, yes or no).

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Materials Needed • Anthers with pollen—florists routinely snip the anthers off the large lilies to avoid pollen staining tablecloths when it is shed from the flowers in arrangements. Check with a local florist ahead of time and use them within 1–2 days. (Dicot pollen is not as easily available but does make a nice comparison, allowing students to see the characteristic three pores of dicot pollen in comparison to one pore in monocot pollen.)

• 1% and 10% sugar solutions • Tap water • Distilled or deionized water • 4 glass slides • A doc cam with a zoom lens works well for this demo for a large group. It also works with dissecting scopes with zoom lenses or on an overhead projector if you can get it far enough away from the wall for magnification.

Procedures Test the hypothesis.

Use pollen from monocots easily available from florists (lily or austrumaria). Place large drops of distilled water, tap water, 1% sucrose, and 10% sucrose on separate glass slides. Tap the anthers over the drops to add pollen and make initial observation of pollen without tubes.

Make observations every 15 minutes.

1. Which tubes grew the most?

(10% sugar) 2. Is the hypothesis supported or not? (depends on their hypothesis) 3. Where could the pollen grain be getting energy from in nature? (from the stigma and style tissue) Assessment Suggestions You could have a class discussion of questions 1–3.

Alternatively, you may prefer to have individuals answer questions 1–3 in writing.

Lecture Activity 44.3: Is It the Seed That Grows? Hey, There’s a Baby Plant in There Estimated Time to Complete: 5 minutes prep time the day before; 10 minutes of class time Section Reference 44.3 How Do Fruits and Seeds Develop?

Introduction Most commonly, we say that seeds grow. What part of the seed is actually the new plant? By looking inside a large, mature seed, we can see the embryo that will grow and become the seedling when the seed germinates.

Materials Needed • Large dried lima beans (grocery store) soaked overnight (about 18 hours) in water (put in enough water to cover the beans by 3–4 inches) • Document camera with zoom or dissecting microscope, if this is to be done as a demonstration • Enough seeds for each student to have a few, if students are doing it at their desks • Methylene blue (or food coloring will also do the same thing) to accentuate the veins of the embryonic leaves Procedures Soak several bean seeds overnight. Remove the paper-thin seed coat from the softened seed. Split the seed lengthwise with your fingernail. The embryo will adhere to one of the cotyledons (see Figure 44-10c). Note the location of the root, hypocotyl, and embryonic leaves. The entire plant is present in this embryo within the seed.

Use a drop of coloring provided by the instructor to accentuate the veins of the embryonic leaves. The leaves in Figure 44-10c are green to emphasize the function they will have when the seedling breaks through the soil. Why are the embryonic leaves of the seed white instead of green? .

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Assessment Suggestions You could have a group discussion on the function of the structures of the seed and embryo. Alternatively, you could have the students answer the following questions in group discussion or as a written assignment: 1. Which part of the seed will actually emerge and grow into the seedling? (the embryo) 2. Why are the embryonic leaves of the seed white instead of green?

(They haven’t been exposed to light yet. Light is needed for development of chloroplasts.)

3. What is a potential reason that the embryonic root does not have any root hairs?

(The root hairs develop in the region of maturation, which hasn’t developed yet. If root hairs were present in the embryonic root, they would be damaged as the root emerged and pushed between soil particles.)

Lecture Activity 44.4: How Do Seeds Germinate and Grow?

Estimated Time to Complete: This can be done as a demonstration or as an individual experiment that each student takes home to complete. A few minutes will be needed to prepare the seeds for germination. Growth observations must be noted over a period of several weeks.

Section Reference 44.4 How Do Seeds Germinate and Grow?

Introduction At the start of seed germination, the embryo absorbs water, swells, and bursts the seed coat. The root usually emerges first. This allows it to absorb water and minerals and transport them to the developing shoot. The shoot lengthens as cells elongate. As the shoot is pushed up through the soil, it is essential that the apical meristem (source of all new cells) is protected. In monocots this is accomplished by the coleoptile—a tough sheath that pushes aside soil particles. In dicots, the apical meristem is protected by the hypocotyl or epicotyl hook. The hook is a curvature of a portion of the stem that pushes through the soil first, and drags the apical meristem to the surface through a tunnel made by the passage of the hook. To visualize and document this process, monocot and dicot seeds will be germinated, planted, and observed.

Materials Needed • Bean seeds (dicot)—amount depends on if demonstration or hands-on activity • Corn seeds (monocot)—amount depends on if demonstration or hands-on activity • Potting soil • Plastic cups with drainage hole or 3-inch pots • Paper towels • Foil • OR a demonstration pot made as a box with Plexiglas side to view germinating seeds and seedling growth.

Many biology departments have these available, or they can be made by constructing a box that is at least 3″ × 6″ and 6″ deep, with one side of Plexiglas.

Procedures If the demonstration pot is available, fill it to within 1 inch of the top with potting soil. Plant several bean and corn seeds about ½ inch deep along the Plexiglas side of the box. Water the seeds and keep the soil moist for the next several weeks.

If the students are doing the activity as a hands-on experience, they each need two cups/pots filled with potting soil, six bean seeds, six corn seeds, paper towels, and foil. Plant three of the corn seeds in one cup and three of the beans in the other cup. They should be well covered with soil, but not deeper than ½ inch. Keep them well watered. Observe growth daily. Because the cups or pots are not clear, the remaining seeds should be germinated by wrapping them in damp paper towels. Seal the seeds in a zip-lock bag, “Tupperware”-type container, or foil to maintain a moist environment. Check the seeds once a day to note progress and record observations of germinating seeds.

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Discuss the following questions: 1. Even though all of the seeds were planted at the same time, did they all germinate at the same time? (probably not) 2. What could explain this? (individual variation, potential variation in microenvironment) 3. What part of the seedling emerged from the seed first?

4. How many days after germination did the coleoptile (for monocots) and hypocotyl hook (for dicots) break through the soil?

5. Where are the cotyledons located (above- or belowground) for monocots and dicots?

6. Did shoots always grow up and roots always grow down?

7. Are cotyledons always photosynthetic?

8. Where do root hairs appear as the root grows? What is the function of the root hairs?

Assessment Suggestions You might have group discussion of the results or have students hand in written answers to the above questions.

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CHAPTER 45 PLANT RESPONSES TO THE ENVIRONMENT LECTURE OUTLINE Case Study: Predatory Plants 45.1 What Are Some Major Plant Hormones?

A. Plants Hormones Are Secreted by Specific Cells and Transported to Other Parts of the Plant Body 1. Different hormones have specific effect(s) a. The effect may vary depending on the target cell, the stage in the life cycle, the concentration of the hormone, the presence of other hormones, and the species of the plant B. Six Different Hormones Are Found in Plants (Table 45-1) 1. Auxins promote or inhibit elongation in different target cells a. They can cause the shoot to bend toward light and the root to grow toward the pull of gravity b. They inhibit the growth of lateral buds, but stimulate lateral root branching c. In mature plants, they stimulate fruit development d. uxins are produced primarily in the shoot apical meristem â Science in Action: How Were Plant Hormones Discovered? (Figures E45-2 through E45-6) â Lecture Activity 45.1: Phototropism â Lecture Activity 45.2: Gravitropism in Shoots 2. Gibberellins also stimulate cell elongation a. They are involved in fruit production and development, and seed germination b. hey are produced in the shoot apical meristem, young leaves, and plant embryos 3. Cytokinins promote cell division a. These are produced primarily in root apical meristems b. hey inhibit the formation of branches in roots, but stimulate this in shoots c. Some are used to keep cut flowers fresh 4. Ethylene is a gas at environmental temperatures a. It stimulates adaptive change in plant tissues in response to stress b. t also stimulates the formation of abscission layers, which allow leaf, flower, and fruit drop to occur at the right time c. It causes fruit ripening and is often used commercially for this purpose 5. Abscisic acid causes stomata closure during times of water limitation a. It promotes root growth and helps maintain dormancy of seeds until environmental conditions are good for growth 6. Florigens are hormones synthesized in leaves that control the timing of flowering in response to environmental cues

45.2 How Do Hormones Regulate Plant Life Cycles?

A. Each Plant Life Cycle Begins with a Seed 1. Abscisic acid maintains seed dormancy a. The environment affects abscisic acid concentration, which allows germination at the appropriate time i. Cold temperatures induce destruction of abscisic acid, so seeds in temperate/northern climates germinate after winter ii. In deserts, germination doesn’t occur until large amounts of rain wash away the abscisic acid (Figure 45-1) â Earth Watch: Where There’s Smoke, There’s Germination (Figure E45-1) 2. Gibberellin stimulates seed germination a. Gibberellins stimulate enzymes that break down starch for seedling growth 440

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B. Auxin Controls the Orientation of the Sprouting Seedling â Lecture Activity 45.3: Is It Possible to Plant a Seed Upside Down?

1. Plants use tropisms, growth toward or away from stimuli, to respond to cues such as light and gravity 2. Auxin stimulates shoot elongation away from gravity and toward light a. Auxin causes gravitropism and phototropism b. When the stem is vertical, auxin distribution is even and the stem grows straight up (Figure 45-2a) c. When the stem is horizontal, the stem bends and grows upward, called negative gravitropism (Figure 45-2b) i. Even in the dark, plants exhibit negative gravitropism (Figure 45-2c) d. Light causes auxin to accumulate on the shaded side of a stem, causing bending toward light by cell elongation, called positive phototropism (Figure 45-3) 3. Auxin stimulates root elongation toward gravity a. Gravity is sensed in the root cap, which causes accumulation of auxin on the lower side b. Increased auxin concentration in roots causes inhibition of cell elongation (opposite effect of auxin in stem cells) i. This causes the bending of root tips downward 4. How do plants sense gravity? a. Specialized cells in stems and root caps have starch-filled plastids called statoliths b. These plastids “sink” to the other side of the cell when the orientation of the plant is changed (Figure 45-4) i. The statoliths may then cause auxin to accumulate on the same side of the cell C. The Growing Plant Emerges and Reaches Upward 1. After a seed germinates, different hormones cause a variety of changes in the plant, both in development and growth 2. Plants called vines display thigmotropism, a directional movement or change in growth in response to touch (Figure 45-5) D. Auxin and Cytokinin Control Stem and Root Branching 1. Branching in stems is inhibited by auxin and stimulated by cytokinin a. Apical dominance is the suppression of lateral buds by auxin produced in the shoot tip i. Auxin levels decrease with distance from the shoot tip, so lower lateral buds are more likely to branch (Figure 45-6) b. Cytokinin stimulates the development of lateral stem buds into branches 2. Branching in roots is stimulated by auxin and inhibited by cytokinin a. Auxin stimulates cell division in the pericycle b. Auxins are included in commercial rooting mixtures to produce new plants from plant stem/leaf cuttings c. Gradients of auxin and cytokinin create a balance between root and shoot systems i. The exact ratio of auxin (produced in shoot tip) and cytokinin (produced in root tip) varies along the length of the plant (Figure 45-7) E. Plants Sense and Respond to Light and Darkness 1. Timing of flowering and seed production must correspond with favorable environmental conditions 2. Day length is the most reliable cue for determining season 3. Three categories of plants in respect to time of flowering have been observed (Figure 45-8) a. Day-neutral plants flower as soon as they reach a sufficient stage of development and are not affected by day length b. Long-day (short-night) plant flowering depends on uninterrupted darkness shorter than a given time period (amount of time is species specific) c. Short-day (long-night) plant flowering depends on uninterrupted darkness longer than a given period of time (amount of time is species specific) 4. Photopigments called phytochromes detect light a. Photopigments absorb light and cause biochemical changes that lead to responses in plants b. Plants have an internal biological clock that relies on complex biochemical reactions to measure the duration of darkness c. Often light can reset the clock d. Phytochrome occurs in two similar forms: Pr absorbs red light and Pfr absorbs far-red light (Table 45-2) i. In general, Pfr is the active form that stimulates or inhibits physiological processes .

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Instructor Guide Biology: Life on Earth ii. When either of the pigments absorbs light of the proper wavelength, it is converted into the other form e. Plants use the phytochrome system to detect uninterrupted periods of darkness and regulate flowering 5. Phytochrome influences many plant responses a. Examples include inhibition of shoot elongation, leaf growth, and chlorophyll synthesis 6. Florigen stimulates flowering in response to light cues a. Leaves produce florigen when exposed to light for certain periods of time F. Hormones Coordinate the Development of Seeds and Fruit 1. Auxin or gibberellin stimulates ovary development into fruit a. Both are used commercially to stimulate fruit ripening (Figure 45-9) 2. As fruits ripen, chlorophyll is broken down in them, causing them to change color and look more palatable to animals (Figure 45-10) 3. Fruit ripening is also stimulated by ethylene G. Senescence and Dormancy Prepare the Plant for Winter 1. Senescence is a genetically programmed series of events that prepares a plant for winter a. Starches and chlorophyll in the leaves are broken down for transport to roots for food storage 2. Ethylene is involved in the formation of an abscission layer at the base of the petiole and release of leaves and fruit (Figure 45-11)

45.3 How Do Plants Communicate, Defend Themselves, and Capture Prey?

A. Plants May Summon Insect “Bodyguards” When Attacked 1. When chewed on by insects, many plants release volatile chemicals into the air, like a “cry for help” a. These chemicals often attract other insects that feed on the ones eating the plant (Figure 45-12) â Case Study Continued: Predatory Plants B. Attacked Plants Defend Themselves 1. Leaf damage from insects causes many plants to produce a signaling molecule that may stimulate responses that make the plant less palatable or more toxic 2. Plants also have a type of immune response that helps defend against infectious microorganisms C. Wounded Plants Warn Their Neighbors 1. Several studies indicate that plants near injured plants may be detecting volatile compounds and have an increased resistance to the pests 2. This is not always species specific a. Plants of one species can detect and respond to the defense compounds produced by a different species D. Sensitive Plants React to Touch 1. Mimosa leaves “wilt” rapidly and close in response to touch due to electrical signals causing “motor cells” to increase potassium flow (Figure 45-13) E. Carnivorous Sundews and Bladderworts Respond Rapidly to Prey 1. Sundew leaves attract and trap insects with red hairs that secrete gluey globules (Figure 45-14) a. Movements of insects stimulate the leaves to curl and trap them 2. The aquatic bladderwort is the fastest of the predatory plants (Figure 45-16)

Case Study Revisited: Predatory Plants (Figure 45-16)

KEY TERMS abscisic acid abscission layer apical dominance auxin biological clock cytokinin day-neutral plant

ethylene florigen gibberellin gravitropism hormone long-day plant phototropism

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phytochrome plant hormone senescence short-day plant thigmotropism

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LECTURE ACTIVITIES Lecture Activity 45.1: Phototropism Estimated Time to Complete: Approximately 10 minutes will be needed for observation and discussion during class. A few days are needed prior to class to prepare the plants.

Section Reference 45.1 What Are Some Major Plant Hormones?

Introduction Although plants do not move from place to place, they are not completely without motion. Sunlight must be intercepted by the shoot system to fuel photosynthesis. Auxin accumulates on the shaded side of stems, causing the cells there to elongate. Because the corresponding cells on the side of the plant facing the light don’t elongate, the stem bends toward the sun. (Silly Putty, modeling clay, or a plastic straw can be used to get a quick visual of what happens when one side of a “stem” lengthens and the other side doesn’t.)

Materials Needed • Two houseplants with slender, upright stems work well for this demonstration (such as coleus or impatiens).

Procedures One of the plants should be turned every other day to allow even arrangement of the leaves and an upright growth. The other plant should not be turned or have any significant light source other than the window. If the class is large and/or without windows, assign this as an at-home experiment. Many students have houseplants or could be supplied with small, inexpensive houseplants. Clippings from Zebrina (wandering Jew), Impatiens, or ivys in water also illustrate phototropism in addition to adventitious root formation. If your department has a greenhouse, you may be able to supply the students with clippings for the experiment in place of plants.

Assessment Suggestions Questions for class discussion or written assignment: 1. Which hormone is responsible for the bending of the plant toward the light? (auxin) 2. What is causing the stem to bend?

(Increased auxin levels cause cells to elongate on the shaded side of the plant.)

3. Why doesn’t the plant that was turned have any curvature in the stem?

(The auxin concentrations don’t accumulate on one side because the plant was turned regularly.)

Lecture Activity 45.2: Gravitropism in Shoots Estimated Time to Complete: 45 to 75 minutes (The plant is lying on its side for most of this time. If there is not adequate time during class, start the process before class begins.)

Section Reference 45.1 What Are Some Major Plant Hormones?

Introduction The saying goes “As the tree is bent, so it grows.” This is true if the physical pressure is continuous. But if the young sapling is bent (let’s say, by another tree falling over the supple trunk) and the top of the tree is not damaged, growth at the tip of the tree will be toward the sky (not parallel to the ground). Many of us have seen an unusual tree with an extreme angle in the trunk. Although trees in this situation are responding to both light and gravity, this classroom demonstration allows students to visualize the effect of gravity alone on stems.

Materials Needed • 4 three- to four-week-old bean plants • Cardboard box, large enough to cover two of the plants lying on their sides .

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Procedures At the beginning of class (or before, if there will not be time for the response to occur during class), lay two of the plants on their sides, measure how many millimeters the apical meristem is from the tabletop, and record the distance. Then place the box over them so no light reaches the plants. Do the same thing with the other two plants but don’t place a box over them. This allows a comparison between any movement due to light. If the plants are left undisturbed for a few days, the bending is very striking. The plants can then be placed upright and will form another bend upward.

Ask the students to predict what will happen.

Every 10 to 15 minutes, measure the distance between the tabletop and the apical meristem.

Assessment Suggestions Follow up on predictions. Did the expected outcome occur? What was the probable mechanism involved?

Lecture Activity 45.3: Is It Possible to Plant a Seed Upside Down?

Estimated Time to Complete: 10 minutes to set up, 3–4 days to see the results Section Reference 45.2 How Do Hormones Regulate Plant Life Cycles?

Introduction Often, novice gardeners think that seeds that don’t grow may have been placed or settled into the ground upside down, with shoots emerging from the seed facing away from the soil surface. In actuality, seeds that don’t produce seedlings were most likely inviable or were planted too deeply. The emerging shoots and roots are affected oppositely by the same hormone, auxin. In response to gravity, auxin accumulates on the lower side (side closest to the pull of gravity) of the embryonic shoot and root. The shoot responds to the auxin by cells elongating. The root senses gravity in the root cap and responds oppositely, and cell elongation on the underside of the root is inhibited, causing it to bend down into the soil.

Materials Needed • Seeds of various types—corn, wheat, rye, and beans are examples that work well. The seeds have distinct shapes that allow easy distinction of different orientations.

• Cheesecloth or soft paper towels • Foil Procedures Dampen the cheesecloth or paper towels completely. Arrange seeds in different orientations, snaring them in the cloth to prevent them from dropping out. Lay another damp cloth over them and enclose the seed “sandwich” in foil. Place this upright, not flat (leaned against a wall or on a bookshelf). Allow the seeds to germinate for 3–4 days.

This can be done as a classroom demonstration, but also works very well if students or student groups are given a quick demonstration about setting up the germination, and are then allowed to use the materials to set up their own experiment.

Assessment Suggestions Discuss the following as a class: Did the roots always grow down and shoots always grow up? What was the hormone involved?

If there is time, use a razor blade to cut off just the tip of some of the roots (the root cap), and mark the location with ink on the cheesecloth. Replace everything in the foil and turn the packet 90°. Allow it to sit that way for 2 more days and check the orientation of the cut versus the uncut roots. What happened?

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QUICK REFERENCE GUIDE INSTRUCTOR MEDIA On DVDs and at www.masteringbiology.com in the Instructor Resources area: PowerPoint Lecture Tools • Lecture presentations (including Label Edit images from the text, animations, videos) • Art and photos • Clicker questions • Scientific American Current Issues presentations Jpegs of Art and Photos • Labeled images (art, photos, tables) • Unlabeled images (art, photos, tables) • Transparency acetate images Animation and Videos • BioFlix™ 3-D animations plus PowerPoint labeled slideshows (see grid) • Animations (see grid) • BLAST animations (see grid) Instructor Guide • Instructor Guide in Word format • Answers to LabBench in Word format • Quick Reference Guide in Word format Test Bank CD-ROM • Test Bank provided in TestGen and in Word format

STUDENT MEDIA At www.masteringbiology.com in the Study Area: BioFlix 3-D animations, Web animations, BLAST animations, and eText; also includes Pre-Tests, Post-Tests, Word Study Tools (Flashcards, Word Roots, Key Terms, Audio Glossary), Current Events (In the News, Current Events, Scientific American Podcasts), Lab Resources (Biology Labs On-Line, LabBench, and Graphit!), Cumulative Test, Tutor Services, and more.

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Chapter 1 An Introduction to Life on Earth Web/Author Animation • Hypothesis Formation and Testing • Spontaneous Generation • Defining Life

Chapter 2 Atoms, Molecules, and Life Web/Author Animation • Atomic Structure and Chemical Bonding • Introducing Water’s Properties • Specific Heat of Water BLAST Animation • Covalent Bonds • Hydrogen Bonds in Water

Chapter 3 Biological Molecules Web/Author Animation • Dehydration Synthesis and Hydrolysis • Carbohydrate Structure and Function • Lipid Structure and Function • Protein Structure BLAST Animation • Alpha Helix • Protein Primary Structure • Protein Secondary Structure • Protein Tertiary and Quaternary Structure

Chapter 4 Cell Structure and Function BioFlix 3-D Animation • Tour of an Animal Cell • Tour of a Plant Cell BLAST Animation • Animal Cell Overview • Plant Cell Wall • Mitochondrion • Prokaryotic Cell Size • Vacuole • Vesicle Transport Along Microtubules

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Quick Reference Guide

Chapter 5 Cell Membrane Structure and Function BioFlix 3-D Animation • Membrane Transport Web/Author Animation • Plasma Membrane Structure and Transport • Osmosis and Diffusion BLAST Animations • Active Transport: Sodium-Potassium Pump • Diffusion • Endocytosis and Exocytosis • Passive Diffusion Across a Membrane

Chapter 6 Energy Flow in the Life of a Cell Web/Author Animation • Energy and Coupled Reactions • Enzymes BLAST Animation • Structure of ATP • ATP/ADP Cycle

Chapter 7 Capturing Solar Energy: Photosynthesis BioFlix 3-D Animation • Photosynthesis Web/Author Animation • Photosynthesis BLAST Animation • Photosynthesis: Light-Independent Reactions

Chapter 8 Harvesting Energy: Glycolysis and Cellular Respiration BioFlix 3-D Animation • Cellular Respiration Web/Author Animation • Cellular Respiration in Mitochondria • Overview of Glucose Metabolism • Glycolysis and Fermentation BLAST Animation • Harvesting Energy: Krebs Cycle .

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Chapter 9 The Continuity of Life: Cellular Reproduction ABC News Video • Henrietta Lacks Cells • The Effect of Exercise on Cells BioFlix 3-D Animation • Meiosis • Mitosis Web/Author Animation • Meiosis • Mitosis • Comparing Mitosis and Meiosis • The Human Life Cycle BLAST Animation • Genetic Variation: Fusion of Gametes • Genetic Variation: Independent Assortment • Cytokinesis in Plant Cells

Chapter 10 Patterns of Inheritance INSTRUCTOR MEDIA ABC News Video • The Genetics of Short Sleepers Web/Author Animation • Self- and Cross-Pollination of Pea Plants • The Inheritance of Single Traits • The Inheritance of Multiple Traits BLAST Animation • Single-Trait Crosses • Two-Trait Crosses

Chapter 11 DNA: The Molecule of Heredity BioFlix 3-D Animation • DNA Replication Web/Author Animation • DNA Structure • DNA Replication BLAST Animation • Structure of DNA Double Helix • Hydrogen Bonds in DNA • Genetic Recombination in Bacteria • Hydrogen Bonds in DNA .

Quick Reference Guide

Chapter 12 Gene Expression and Regulation INSTRUCTOR MEDIA BioFlix 3-D Animation • Protein Synthesis Web/Author Animation • Transcription • Translation BLAST Animation • Transcription • Translation

Chapter 13 Biotechnology INSTRUCTOR MEDIA ABC News Video • Genetically Altered Salmon Web/Author Animation • Polymerase Chain Reaction (PCR) • Manufacturing Human Growth Hormone BLAST Animation • DNA Fingerprinting • Gel Electrophoresis • Stem Cells

Chapter 14 Principles of Evolution ABC News Video • Exploring Evolution in the Solomon Islands • Protecting the Galapagos Islands Web/Author Animation • Natural Selection for Antibiotic Resistance BLAST Animation • Evidence for Evolution: Antibiotic Resistance in Bacteria • Evidence for Evolution: Homologous Limbs • Natural Selection

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Chapter 15 How Populations Evolve ABC News Video • Herbicide-resistant Pigweed BioFlix 3-D Animation • Mechanisms of Evolution Web/Author Animation • The Bottleneck Effect • Three Modes of Natural Selection BLAST Animation • Population Dynamics

Chapter 16 The Origin of Species Web/Author Animation • The Process of Speciation • Allopatric Speciation • Speciation by Polyploidy

Chapter 17 The History of Life ABC News Video • Modern Humans and Neanderthal DNA Web/Author Animation • The Endosymbiont Hypothesis • Continental Drift from Plate Tectonics

Chapter 18 Systematics: Seeking Order Amid Diversity INSTRUCTOR MEDIA Web/Author Animation • Taxonomic Classification • The Tree of Life

Chapter 19 The Diversity of Prokaryotes and Viruses Web/Author Animation • Bacterial Conjugation • Retrovirus Replication • Herpes Virus Replication

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Quick Reference Guide

Chapter 20 The Diversity of Protists ABC News Video • Turning Algae into Biofuel Author Animation • The Life Cycle of the Malaria Parasite

Chapter 21 The Diversity of Plants Web/Author Animation • Adaptations in Plant Evolution • Life Cycle of a Fern

Chapter 23 Animal Diversity I: Invertebrates Web/Author Animation • The Architecture of Animals

Chapter 25 Animal Behavior ABC News Video • Eating Behavior in Monkeys • The Cuttlefish Web/Author Animation • Communication in Honeybees

Chapter 26 Population Growth and Regulation INSTRUCTOR MEDIA BioFlix 3-D Animation • Population Ecology Web/Author Animation • Population Growth and Regulation • Human Population Growth

Chapter 27 Community Interactions Web/Author Animation • Competitive Exclusion and Resource Partitioning

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Chapter 28 Energy Flow and Nutrient Cycling in Ecosystems ABC News Video • Ocean Acidification BioFlix 3-D Animation • Carbon Cycle Web/Author Animation • Energy Flow and Food Webs • The Carbon Cycle and Global Warming • The Nitrogen Cycle • The Hydrologic Cycle BLAST Animation • Carbon Cycle • Energy Flow • Nitrogen Cycle

Chapter 29 Earth’s Diverse Ecosystems Web/Author Animation • Atmospheric Circulation and Global Climate

Chapter 30 Conserving Earth’s Biodiversity Web/Author Animation • Habitat Destruction and Fragmentation

Chapter 31 Homeostasis and the Organization of the Animal Body Web/Author Animation • Homeostasis BLAST Animation • Negative Feedback: Body Temperature

Chapter 32 Circulation Web/Author Animation • Circulatory Systems • Two-Chambered Hearts • Three-Chambered Hearts • The Human Cardiovascular System • Blood Pressure BLAST Animation • Anatomy of the Heart .

Quick Reference Guide

Chapter 33 Respiration INSTRUCTOR MEDIA BioFlix 3-D Animation • Gas Exchange Web/Author Animation • The Human Respiratory System

Chapter 34 Nutrition and Digestion Web/Author Animation • The Digestion and Absorption of Food

Chapter 35 The Urinary System Web/Author Animation • The Mammalian Kidney BLAST Animation • Anatomy of the Kidney • How the Kidney Works

Chapter 36 Defenses Against Disease Author Animation • The Inflammatory Response • Humoral Versus Cell-Mediated Immunity • Memory B Cells and the Immune Response • HIV: The AIDS Virus BLAST Animation • Adaptive Immunity • AIDS Treatment Strategies • HIV Structure • Inflammation • Innate Immunity

Chapter 37 Chemical Control of the Animal Body: The Endocrine System INSTRUCTOR MEDIA BioFlix 3-D Animation • Homeostasis: Regulating Blood Sugar

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Web/Author Animation • Hypothalamic Control of the Pituitary • How Hormones Influence Target Cells

Chapter 38 The Nervous System INSTRUCTOR MEDIA BioFlix 3-D Animation • How Neurons Work • How Synapses Work Web/Author Animation • Electrical Signals in Neurons • The Synapse • Reflex Arcs • The Human Brain BLAST Animation • Action Potential • Signal Amplification in Neurons • Signal Transmission at Synapses

Chapter 39 The Senses Web/Author Animation • The Human Ear • The Human Eye

Chapter 40 Action and Support: The Muscles and Skeleton Web/Author Animation • Muscle Structure • Muscle Contraction BLAST Animation • Anatomy of Muscle

Chapter 41 Animal Reproduction Web/Author Animation • The Male Reproductive System • The Female Reproductive System

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Quick Reference Guide

Chapter 42 Animal Development Web/Author Animation • Overview of Animal Development

Chapter 43 Plant Anatomy and Nutrient Transport BioFlix 3-D Animation • Water Transport in Plants Web/Author Animation • Primary and Secondary Growth • Plant Transport Mechanisms

Chapter 44 Plant Reproduction and Development Web/Author Animation • Reproduction in Flowering Plants Blast Animation • Alternation of Generations • Flower Structure • Flowering Plant Life Cycle • Pollination and Fertilization

Chapter 45 Plant Responses to the Environment Web/Author Animation • Plant Hormones • The Light-Sensitive Pigment Phytochrome • Plant Responses to Stimuli

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