Next Generation Science Level 5 - Textbook A

Science for the Next Generation

Science Gra d e F i ve

Textbook

A

The 5E Model – Guided Inquiry The Next Generation Science series is based on the Biological Sciences Curriculum Study (BSCS) 5E teaching and learning instructional model.

The 5E model is centered on the idea that students understand science concepts best by using prior knowledge to pose questions and find answers through guided inquiry.

This hands-on approach, integrated with engineering and design skills, has students learn science by doing science. Teachers guide the learning process and are able to assess student performance by evaluating student explanations and the application of newly acquired knowledge and skills.

Engage

The Engage phase of the 5E model provides students with the opportunity to demonstrate their prior knowledge and understanding of the topic or concept. Students are presented with an activity or question which serves to motivate and engage students as they begin the lesson. Teachers identify and correct any misconceptions and gather data from students which will guide informed teaching and learning.

Essential to stimulating and engaging students is the use of mixed media such as colorful photos, illustrations and diagrams found throughout the textbooks and activity books. Next Generation Science also includes extensive digital resources such as narrated videos, interactive lessons, virtual labs, slideshows and more.

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Explore

This phase encourages exploration of concepts and skills through handson activities and investigations. Students are encouraged to work together and apply various process skills while gaining concrete, shared learning experiences. These experiences provide a foundation for which students can refer to while building their knowledge of new concepts. This studentcentered phase comes before formal explanations and definitions of the concept are presented by the teacher.

Explain

This phase follows the exploration phase and is more teacher-directed.

Students are initially encouraged to draw on their learning experiences and demonstrate their understanding of the concept through explanations and discussion. After the students have had the opportunity to demonstrate their understanding of the concept, the teacher then introduces formal definitions and scientific explanations. The teacher also clarifies any misconceptions that may have emerged during the Explore phase.

Elaborate

In the Elaborate phase, students refine and consolidate their acquired knowledge and skills. Opportunities are provided for students to further apply their knowledge and skills to new situations in order to broaden and deepen their understanding of the concept. Students may conduct additional investigations, share information and ideas, or apply their knowledge and skills to other disciplines.

Evaluate

This final phase includes both formal and informal assessments. These can include concept maps, physical models, journals as well as more traditional forms of summative assessment such as quizzes or writing assessments.

Students are encouraged to review and reflect on their own learning, and on their newly acquired knowledge, understanding and skills.

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Next Generation Science Next Generation Science is based on the United States Next Generation Science Standards (NGSS). The series consists of full-color textbooks and full-color activity books for Grades K to 6.

Wallac

Amphibians

The word amphib term which mean to their unique life amphibians, begin land. Amphibians fertilization, and h

Next Generation Science engages students with a highly visual presentation of the disciplinary core ideas in the textbooks and places an emphasis on applying scientific knowledge using NGSS practices through numerous scientific investigations. Next Generation Science sees engineering as an essential element of science education and as such is tightly integrated into both the textbooks and activity books.

There are three m Frogs are amphib They often have s legs for moving a Toads are similar often have drier a

European tree frog

The Next Generation Science textbooks include the following features:

Think Deeply Topic-related questions for group discussion aimed at deepening students’ understanding of the topic.

In the Field

Sir Alexander Fleming

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“One sometimes finds what one is not looking for. When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer. But I suppose that was exactly what I did.“ – Sir Alexander Fleming.

Sir Alexander Fleming was a Scottish physician and microbiologist, best known for discovering the drug penicillin – the first effective antibiotic used to kill bacteria.

In his laboratory in 1928, Fleming was investigating the properties of the bacteria Staphylococci. On returning from a family holiday, Fleming noticed that bacteria growing in a petri dish were being killed by the fungus Penicillium, a type of mold.

He observed that the bacteria immediately surrounding the fungus had been killed, and that the bacteria farther away were normal. “That’s funny” he famously remarked to his assistant.

Fleming’s discovery led to the development of the antibiotic penicillin. The discovery was a medical breakthrough for the treatment of many illnesses caused by bacteria. Today, modern antibiotics are still tested using a method similar to how Fleming discovered penicillin.

Engineer It! Goes beyond inquiry by encouraging students to design, model and build to engineer solutions to defined problems.

moor frog with eggs

Fleming received many awards A Closer Look for his hard work and scientific Nobel Prize discoveries including the Arth ropod Life Cycles in Physiology or Medicine in 1945.

After hatching, most arthro pods do not resemble their parents. The young, called larvae, go through a series of chang es in a process called metamorphosis.

During metamorphosis, a larva goes into an inactive pupa stage. When an arthropod emerges has all of the characterist from the pupa, it ics of its parent.

31 The life cycle of a mosqu ito goes through four distinct phases – egg, larva, pupa and adult. The organism looks, feeds and moves differently in each stage.

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raft of eggs

egg

In the Field Inspirational sciencerelated professions to stir interest in sciencerelated careers.

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A Closer Look Invokes enthusiasm in science by presenting interesting topics beyond the syllabus.

aquatic larva

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Amazing Fact!

Interesting facts to build interest and enthusiasm.

ce’s flying frog

Did You Know?

tadpoles

s

bian comes from a Greek ns ‘double life’. This is due e cycle which, for many ns in water and moves on to reproduce sexually by external hatch from eggs.

Salamanders are amphibians that are similar in appearance to lizards. They have long, slender bodies with a tail. Caecilians are limbless, worm-like amphibians. Most live underground. spotted salamander

Most amphibians get the oxygen they need using lungs to breathe in air. Many amphibians are also able to take in oxygen through their moist skin.

main groups of amphibians. bians we are most familiar with. short bodies with powerful hind about on land and in water. in appearance to frogs, but and rougher skin.

Extra information to build students’ knowledge base of the current topic.

Try This!

Optional hands-on activities to be conducted in groups or at home.

Some poison dart frogs carry their young on their backs to a source of water.

What are the characteristics of amphibians?

AB Activity 3.12 85

Science Words

12.

Use the words to comp

lete the sentences.

biotic factors abiotic factors individual population community

producer consumer primary consumer secondary consumer tertiary consumer

13.

decomposers food chain food web energy pyramid

14.

An animal that feeds

on a producer is a

.

on primary consumers

is a

.

An is a model that shows how much energy is availa each level in an ecosy ble at stem.

Review

1.

break down organic mater ial and absorb the broken down remains.

1.

2.

List three biotic factor s you would expect to find in a tropical rainforest ecosystem.

A is an organism that gets energy by eating other organisms.

2.

List three abiotic factor s you would expect to find in a tropical rainforest ecosystem.

3.

A

4.

An animal that feeds

is an organism that make s food through photosynthe sis. on secondary consumers is a .

5. A single organism in an ecosystem is called an .

6. All of the organisms in an ecosystem are called .

7. All of the non-living things in an ecosystem are called .

8. All of the organisms of the same kind that interact and reproduce within an ecosystem make up a .

9.

An animal that feeds

A is a model used to show the interconnected food in an ecosystem. chains

10. A is a simple and often graphical model that energy and nutrients shows how flow through an ecosy stem.

Think Deeply 11. A consists of all of the interac Mosqu itoes are within ting popula insects that an ecosystem. tions can spread

diseases to humans. Female Anophe les mosquitoes can spread the disease malaria which infects more than 200 million people every year. How can learning about the life cycle of Anopheles mosquitoes help control the spread of malaria?

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3.

Draw and label a simple diagram to show an individ and a community in a ual, a population grassland ecosystem.

4.

What role does each

(a) hawk

organism play in a desert

(b) rattlesnake

5.

What does a food web

6.

How is an energy pyram

(c) brittlebrush

(d) wood rat

web?

7.

Explain how all of the food within an Arctic Ocean ecosystem can be traced back to the energ y in sunlight.

8.

Riley thinks most of the material for plant growt h comes from the soil.

Do you think Riley is correc t? Explain your answe r.

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A female Anopheles mosqu ito feeding on human blood.

emerging adult

aquatic pupa

Go Online!

Watch a video about the life cycle of a mosquito on the NGScience website.

QuickCode: V1J4

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Links students to the Next Generation Science Activity Book at the appropriate juncture.

ecosystem?

show? id different from a food

AB Activity

Review Topical questions at the end of each chapter for formative assessment.

Discussion Topic-related questions and situations for class discussion to build a deeper understanding of topics.

Science Words Lists the essential science vocabulary covered in each chapter.

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Contents

Unit 1 - Diversity of Life What Are Organisms?

Classifying Organisms Kingdoms What’s Inside Cells?

Cell Organization Review

Unit 2 - Plants Classification of Plants Plant Structures Plant Life Cycles Review

Unit 3 - Animal Classification Classification of Animals Invertebrates Vertebrates Review

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2 4 10 15 24 27 29

32 34 40 48 59

60 62 63 78 93

Unit 4 - Energy in Ecosystems What Is an Ecosystem?

Energy in Ecosystems Matter in Ecosystems Review

Unit 5 - Earth’s Land and Water Structure of the Earth Earth’s Landforms The Hydrosphere Review

94 96 100 110 113

114 116 120 126 140

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Science Skills Scientists ask questions about the world around them. To find the answer to these questions, scientists use special skills to collect, analyze and interpret data. They communicate the things they find out.

Let’s look at how you can use these skills so you can be a scientist too.

Observing You make observations when you gather information about something using your senses. You can observe how something looks, feels, sounds, smells or tastes.

Scientists often use tools and instruments that allow them to observe things closely. Such tools include hand lenses, microscopes and telescopes.

It is important to accurately record your observations in a way that can be easily understood by others. You can make notes, and create charts and tables. You can also draw and label diagrams.

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Comparing and Classifying Scientists compare the things they observe.

To compare means to observe the properties or characteristics of two or more things and identify their similarities and differences.

Classification is the process of placing things into groups based on similarities in their properties or characteristics. Objects around us can be classified by the properties of the materials they are made of. Organisms can be classified by their features, such as the presence or absence of a backbone.

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Measure Measuring is an important science skill. It allows you to quantify your observations.

Distance, time, volume, mass and temperature are some quantities that can be measured.

To measure accurately, you often need to use tools such as rulers, beakers, thermometers and stopwatches.

Make a Model Scientists often construct models to predict, test and observe real-life phenomena.

Models can be physical objects, such a model of a miniature wind turbine to simulate electricity generation or a model of the Earth’s surface to simulate weathering and erosion.

Models can also be in the form of diagrams. A food web diagram is a model that shows the flow of energy in an ecosystem. A map is a diagrammatic model of an area of land or water.

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Infer You infer when you make a guess about something based on what you know or what you observe.

If you see footprints in the snow, you can infer that an animal has passed by after the last snowfall.

If you discover an animal jaw bone with large canine teeth, you can infer that the animal likely ate other animals.

Communicate You communicate when you show or tell other people what you find out.

Communication can be in the form of a written report, visual displays or an oral presentation.

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Scientific Method Scientists ask questions based on observations of the world around them. To find the answers to their questions, they carry out tests and investigations following the scientific method.

Why is it useful for scientists to follow the same scientific method?

The scientific method is a logical set of steps that is followed to help guide an investigation. It also helps to ensure the investigation is carried out fairly and in a manner that can be understood and repeated by other scientists.

Make Observations The scientific method begins by making observations about the world around you.

You may observe that plants in one area grow faster and taller than plants in other areas.

You may notice that you feel hotter in a darker-colored shirt than a lighter-colored shirt.

You may observe that ice melts faster in a cup made of one material than a cup made of another material.

Such observations lead you to ask questions about why these things occur.

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Ask Questions Before a science investigation begins, it’s important to ask questions about what you would like to find out.

Asking questions helps you to define the investigation. Your investigation should be designed to find the answer to your questions.

You can also use prior knowledge and experiences to provide possible answers to your questions.

Why does warm water cool faster in a metal cup than in a foam cup?

Do plants grow taller when fertilizer is added to soil?

Why do amphibians live near water?

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Make a Prediction Once you have asked questions based on your observations, it’s time to make a prediction and form a hypothesis. A hypothesis is a statement about what you think your investigation will show.

A hypothesis is more than just a guess.

It is a statement based on knowledge you already have or things you have observed in the past.

Based on past gardening experience, you may predict that plants will grow faster and taller in humus-rich potting soil than in sandy soil.

Based on a previous investigation, you may already know that metal is a better conductor of heat compared to wood or plastic. These past experiences can help you predict the results of an investigation.

Why is it important to write a procedure that can be easily followed by others?

Plan and Carry Out an Investigation Once you have stated your hypothesis, it’s time to plan and conduct an investigation that will test your prediction. In planning your investigation, you should include all the materials you will need and a procedure that clearly shows the steps you will take to conduct the investigation.

Your materials and procedure should be written in a way that allows the investigation to be easily followed and repeated by others. In your procedure, include the data you will collect and the way it will be recorded.

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Variables An important part in a science investigation are variables. A variable is any factor that can be controlled or changed during the investigation. There are three main variables – the independent variable, the dependent variables and the controlled variables.

The independent variable is the one condition in the investigation that you can change. Usually it is the thing that is being tested. If you were investigating which materials are good conductors of heat, the independent variable would be the type of material.

The dependent variable is the factor that you measure or observe. The dependent variable should change due to changes in the independent variable.

In an investigation on materials that are good conductors of heat, the dependent variable could be temperature of water in a cup. You would expect the temperature of the water to change as you change the independent variable – the type of material the cup is made of.

Imagine conducting an investigation about the growth rates of different seedlings.

What would be the independent variable?

What would be the dependent variable?

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Imagine you were carrying out an investigation into the effect of temperature on plant growth. What would be your controlled variables?

The controlled variables are variables that do not change during the investigation.

Controlled variables could include the type and size of a container, the source and temperature of water and the types of instruments used to take measurements.

The purpose of the controlled variables is to ensure that the only influence on changes in your observations is due to the independent variable.

Collecting and Recording Data Make observations and collect data as stated in your procedure. The data should be recorded in an organized way that can be read and understood by others.

Often, data is recorded in a visual manner, such as charts, graphs and diagrams. Data can also be entered into computer software which can make it easier to analyze and present the data.

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Analyze and Interpret Data Once your observations have been accurately recorded, it’s time to analyze and interpret the data to see if your hypothesis is supported.

You analyze when you look closely at recorded data. You look for patterns to help explain your results. A pattern is when data repeats in a predictable way.

You interpret when you understand and explain what the data means. In interpreting data, you use your prior knowledge, experience, and skills to explain patterns and trends identified in the analysis of the data.

An important part of analyzing and interpreting is to check the accuracy of the data collected. If there are inaccuracies or inconsistencies in the data, you may need to adjust your procedure and repeat the investigation.

Draw a Conclusion By analyzing and interpreting your data, you reach a conclusion. Your conclusion is a summary of the data collected. Your conclusion should indicate the accuracy of your prediction.

Your conclusion should state whether your hypothesis was supported or not supported.

If your hypothesis was not supported, you may decide to form a new hypothesis and plan and conduct a new investigation. If your hypothesis was supported, you may wish to do further investigations to confirm the results or improve the accuracy of the data collected.

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Communicate The final step in a science investigation is to communicate your findings to others.

This allows you to share what you have discovered and also allows others to assess the accuracy of your investigation.

The people you communicate your results with may wish to conduct a similar investigation and compare results. They may also wish to conduct further investigations to find out more.

If they do, they’ll also communicate their results so others can learn from their investigations too.

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Scientific Method Flowchart Make Observations

Ask Questions

Construct Hypothesis Plan and Conduct Investigation Analyze and Interpret Data Form a Conclusion Hypothesis Not Supported

Hypothesis Supported

Communicate Results

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Science Safety In the Laboratory

Follow these safety rules when in your science laboratory or when carrying out any science investigation. o not enter the laboratory without D a teacher. ollow your teacher’s instructions.

F If you have any questions or are unsure of what to do, raise your hand and ask your teacher. o not eat, drink, play or run in D the laboratory. ash your hands with soap when W entering and before leaving the laboratory. Dry your hands properly, especially if you will be working with electrical equipment. If any chemical or hazardous material gets on your hands, inform your teacher immediately. ear appropriate safety gear when W carrying out scientific investigations.

Safety gear includes a lab coat, safety goggles and gloves. Tie long hair back and do not wear open-toed shoes. e careful when handling sharp tools B or working with burners and hot substances.

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o not panic if an accident occurs.

D Be aware of eyewash stations, fire extinguishers, exit doors and other safety equipment and procedures in case of an emergency. eep your workspace clean and K organized. Report any spills or breakages to your teacher. Clean up any spills straight away and dispose of the cleaning products safely. hen cleaning up, ensure all W materials and substances go into the correct bin or container. Do not pour any liquid down the sink unless your teacher has instructed you to do so. ook after the equipment you use and L return it to its proper location in the same condition you received it. Wipe your workstation down after use.

In the Field ake sure you are accompanied by an M adult when on field trips or doing other activities outside of the schoolyard. n long trips, make sure you take O enough water and food. Bring insect repellent if necessary. n sunny days, take Sun protection such O as a long-sleeved shirt, hat and sunscreen.

Try This!

Create a poster of the rules to be followed in your science laboratory or classroom.

Display the poster in a place for everyone to see.

o not touch plants, animals or other D organisms unless instructed to do so by your teacher.

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1

Diversity of Life How do scientists determine if something is an organism?

In this chapter you will ...

• identify the needs and characteristics of all organisms.

• describe and provide examples of organisms in the six kingdoms.

• describe cells and list cell organelles.

• explain how cells are organized.

How do scientists classify organisms into groups?

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What parts can be found inside a cell? What are their functions?

Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

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What Are Organisms?

Classification is an important part of science. It is the process of observing and placing things into groups based on characteristics they share. One way scientists classify things is as living things and non-living things. A living thing is an organism.

In order for something to be classified as an organism, scientists look closely at its characteristics and functions.

All organisms: • are made of one or more cells.

• obtain and use energy.

• reproduce.

• respond to changes.

• grow.

What characteristics and functions of the deer let scientists know it is a living thing?

AB

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Activity 1.1

blue whale

Cells Organisms come in a great variety of shapes and sizes, and can be found in all areas of the Earth. Some, like microscopic amoebas, are so small, we need to use a microscope to see them. Others, like the blue whale, can reach lengths of over 25 meters – that’s about as long as a basketball court!

From microscopic amoebas to giant blue whales, all organisms are made of cells. Cells are the smallest units within an organism that can carry out life processes. They are often referred to as the ‘building blocks of life’.

Some organisms, like parameciums, diatoms and bacteria, are made up of only a single cell.

They are unicellular organisms. Others, like most of the plants and animals you are familiar with, are made up of many cells. They are called multicellular organisms.

amoeba

Did You Know?

Cells were first discovered in 1665 by the English scientist Robert Hooke. When observing cork under a microscope, he noticed a series of small boxes which he called ‘cells’.

Humans are multicellular organisms. Scientists estimate that our bodies are made up of trillions of different cells that all play a role in helping our bodies function.

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Activities 1.2 – 1.3 5

Goshawk feeding on a Eurasian magpie.

Plants are organisms that use the energy in sunlight to produce food.

House Sparrows feeding on a raspberry cane.

Obtaining and Using Energy All organisms need energy to carry out life processes. Life processes include growth, reproduction and the repair and maintenance of structures. Some organisms, like many animals, use energy to move their body parts or to move from place to place.

Different organisms obtain energy in different ways. Plants are organisms that photosynthesize – they capture light energy from the Sun and convert it into food. The food is distributed throughout the plant.

Animals obtain energy by eating other organisms. Fungi obtain energy by breaking down and absorbing the remains of dead organisms.

AB

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Activity 1.4

Reproduction All organisms are able to reproduce. This means they are able to make more of their own kind. There are two main types of reproduction – sexual reproduction and asexual reproduction.

Sexual reproduction involves two parents. Each parent produces a special reproductive cell which join together to form a single cell. This process is called fertilization. The offspring that develops from the fertilized cell will have characteristics from both parents.

Asexual reproduction involves only one parent.

The offspring are genetically identical to the parent. Most unicellular organisms reproduce asexually. Bacteria and many other unicellular organisms reproduce by dividing into two identical daughter cells.

AB

Activity 1.5

Parameciums reproduce by dividing into two identical daughter cells.

Go Online!

Some simple organisms, such as yeast and freshwater hydra, reproduce asexually by budding. Find out more on the NGScience website.

QuickCode: D6S9

Lions and other mammals reproduce sexually.

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Growth and Development Organisms grow and develop as they get older. All of the stages in an organism’s life – from first entering the world, growing larger and developing new parts, to reproducing young of its own make up its life cycle.

When the sex cells from a flowering plant are fertilized, the fertilized cell develops into a seed. Under the right conditions, the seed will germinate and start to grow. It will grow leaves and start to make its own food. It will eventually develop flowers and fruits and go on to produce new plants of the same kind.

When multicellular organisms grow, they usually change in size and shape.

The number of cells that makes up their bodies increases.

Unicellular organisms also grow and change shape as they get older.

They usually get larger in size before reproducing by dividing.

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When an eagle spots prey, it responds by diving and catching it.

Response to Change An eagle flies high in the sky. It uses its keen sense of sight to search for fish in the lake below. When it spots a fish, it dives down and catches it in its sharp talons.

Spotting the fish in its environment is an example of a stimulus. The way the eagle acted when it spotted the fish is a response.

All organisms respond to stimuli in their environment.

A stimulus is any change that causes an organism to act in a certain way.

The way an organism reacts to the stimulus is called a response. Generally, an organism will respond in a way that increases its chances of survival.

Amazing Fact!

Pea plants have specialized stems, called tendrils, that curl and twine around the objects they touch as they grow. How does this response help the pea plant survive?

tendril

pea plant

A stimulus could be a change in light, temperature, sound, chemical changes to an environment or contact with other organisms.

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Activity 1.6 9

Classifying Organisms Earth is home to a great diversity of organisms. To organize and gain a better understanding of organisms, scientists classify them into groups based on the features they share. The process of naming and classifying organisms is called taxonomy.

Scientists around the world use the same system of classification. This allows scientists to describe organisms in a precise way. This enables them to easily share their knowledge and discoveries.

How is classifying organisms useful?

AB

Activity 1.7

The broadest and most general group of organisms are called kingdoms. There are six kingdoms recognized by scientists: • • • • • •

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ancient bacteria bacteria protists fungi plants animals

All of the organisms in each kingdom share basic characteristics or traits. The chart below shows some shared characteristics of the organisms within each kingdom.

The Six Kingdoms of Life Ancient Bacteria

• unicellular • no nucleus • decomposers • can move from place to place

Fungi

• unicellular and multicellular • nucleus • decomposers • cannot move from place to place

Bacteria

• unicellular • no nucleus • decomposers • can move from place to place

Plants

• multicellular • nucleus • producers • cannot move from place to place

Protists

• unicellular and multicellular • nucleus • producers and consumers • some can move from place to place

Animals

• multicellular • nucleus • consumers • can move from place to place

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By looking closely at the characteristics of organisms, scientists are able to classify them into smaller and smaller groups. Let’s take a look at this classification system by looking at how a tiger is classified.

Kingdom – Animalia

Phylum – Chordata

Class – Mammalia

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Order – Carnivora

Family – Felidae

Genus – Panthera

Species – Panthera tigris

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Think Deeply Occasionally tigers are born with white fur instead of orange. How could scientists tell if they belong to the species Panthera tigris?

Tigers belong to the kingdom Animalia which includes all animals. At the next classification level for tigers is the phylum Chordata. All of the animals in this phylum have a backbone – they’re all vertebrates.

Below a phylum is the class Mammalia.

All animals in the class Mammalia are mammals. Mammals that get their energy by eating mostly other animals are carnivores. They are classified together as the order Carnivora.

Within the class Carnivora is the family Felidae. All members of this family are cats – tigers, lions, lynx and domestic cats too. Within the cat family are the big cats – tigers, lions and leopards.

These animals belong to the genus Panthera.

The smallest unit of classification is a species. A species is a group of similar organisms that are able to reproduce young of the same species.

All species are given a two-part scientific name. The first part of the name is the organism’s genus. The second part of the name is called the specific name. The scientific name for tigers is Panthera tigris.

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Kingdoms Bacteria Bacteria (singular bacterium) are amongst the simplest and oldest organisms on Earth.

All bacteria are unicellular microorganisms and most can only be seen using powerful microscopes. Bacterial cells do not have a nucleus.

Bacteria are divided into two kingdoms – eubacteria and archaebacteria.

escherichia bacteria

Eubacteria can be found in all natural environments – in the air, in water and soil and even in the bodies of other organisms, including humans. Archaebacteria live in extreme environments such as the deep ocean floor, volcanic vents and hot springs.

Bacteria reproduce asexually whereby an individual bacterium divides to form two identical daughter bacteria. Reproducing in this way allows bacteria to reproduce rapidly.

Bacteria can cause diseases and infections in plants, animals and people. Salmonella and E. coli are bacteria that can cause food poisoning in people and some animals.

Bacteria can also be helpful. Many organisms need bacteria to help them get the nutrients they need. Bacteria in your stomach help you to get nutrients from the food you eat.

streptococcus bacteria

Bacteria are often classified by the shapes of their unicellular bodies such as rods, spirals and spheres. spirilla bacteria

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Kelp are multicellular protists. They can grow to lengths of over 50 meters.

Vorticella are unicellular aquatic organisms often found attached to plants and rocks.

Did You Know?

Protists do not have many characteristics in common.

They are classified together as they do not fit clearly into any of the other kingdoms.

Slime molds are decomposers. They breakdown dead organic matter and absorb the remains.

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Protists Protists are organisms that belong to the kingdom Protista. They come in a diverse range of shapes and sizes. Most protists, like diatoms, euglenas and vorticellas, are unicellular. There are also multicellular protists, such as the giant kelp and slime molds.

Some protists are plant-like, such as diatoms and euglenas, and are able to photosynthesize.

Others are animal-like and obtain energy by feeding on other organisms or by absorbing nutrients from their environment. Amoebas are unicellular protists that engulf and feed on other organisms such as algae and bacteria.

Most protists reproduce asexually. But some multicellular protists have more complex life cycles.

AB

Activity 1.8

Fungi Fungi (singular fungus) include organisms such as mushrooms, puffballs and molds.

Most fungi are multicellular and reproduce by releasing microscopic spores into the air. New fungi grow from the spores. Yeasts are unicellular and reproduce asexually by budding whereby a small bud forms and splits to form a new daughter cell.

Fungi are decomposers – they get the energy they need by breaking down the remains of other organisms and absorbing the organic matter. In doing so, they play an important role in ecosystems by returning nutrients to the soil.

Some fungi can cause diseases in plants, animals and people. Fungi can also be helpful to people in many ways. Many mushrooms are important food sources. Yeast is used in the preparation of bread and cheese.

The medicine penicillin, an important antibiotic, is obtained from the fungus Penicillium notatum.

What are the characteristics of fungi?

fly agaric mushroom growing on the forest floor

Go Online!

Mycorrhizae are microscopic fungi found in soil. They play an important role in helping plants take in water and nutrients. Discover more about mycorrhizal fungi on the NGScience website.

QuickCode: X2T6

AB

Activity 1.9

bracket fungus growing on a log

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A Closer Look

What Is a Virus?

You might know of viruses as the microscopic germs that can cause us to get sick. Unlike microscopic organisms such as bacteria, viruses are not alive. They are not made of cells, they cannot obtain or store energy and they can only replicate when inside the cells of other organisms.

A virus is a strand of genetic material surrounded by an outer covering. It can invade and take over the cells of all types of organisms, from animals and plants to microorganisms including bacteria. The cell that is invaded by a virus is called a host cell.

Once inside a host cell, the virus releases its genetic material and instructs the host cell to replicate it many times. Host cells can replicate millions of copies of a virus in just a few hours. Once replicated, the host cell bursts open and the newly replicated virus is released. Each new virus can go on to invade other host cells.

AB

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Activity 1.10

Most viruses are harmless to people, but some can cause us to get sick. Viruses can cause illnesses such as the common cold, the flu, cold sores and chicken pox.

We get sick from a virus when it infects or kills many of our cells, causing an immune response from our bodies. Often, the virus will infect cells in certain parts of the body. The common cold, for example, is caused by a rhinovirus that affects the nose and throat. The runny nose and sore throat you get when you have a cold is your body’s immune system fighting the infection.

Many viruses can only replicate at specific temperatures. A fever is your immune system’s response to fight the virus by increasing your body temperature.

Think Deeply What things did people do to slow the spread of Covid-19?

Why were these measures necessary?

In 2020, there was a global spread of a virus called Covid-19. This virus infected the lower airways and lungs. People infected with Covid-19 had symptoms such as a dry cough, difficulty breathing and mucus in the lungs.

envelope

genetic material

An artist’s impression of the coronavirus that causes Covid-19.

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Plants From tiny mosquito ferns to giant sequoia trees, plants can be found in all shapes, sizes and colors. Plants can be found in all areas of the Earth – in icy tundras, dry deserts and in fresh and salt water too.

Plants are multicellular organisms that get the energy they need by photosynthesizing. Photosynthesis is the process by which light energy, water and carbon dioxide are used to produce stored chemical energy in the form of glucose. The glucose is stored by the plant and used to carry out life processes. As primary producers in all ecosystems, plants are important food sources for many other organisms.

Amazing Fact!

The tallest trees on Earth are a type of sequoia called coast redwoods. They can reach heights of up to 115 meters (377 ft). With the thickest bark of all trees, they are also immune to most diseases.

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Flowering plants and conifers are vascular plants.

Plants can be classified in different ways.

One way scientists classify plants is by the presence or absence of vascular tissue.

Vascular tissue are internal tube-like structures in the roots, stem and leaves that transport water, nutrients and food around the plant.

Think Deeply Imagine you discover a new species of plant in a forest.

How could you determine if it is a vascular plant or a nonvascular plant?

Plants with vascular tissue are called vascular plants. Flowering plants, conifers and ferns are vascular plants.

Plants without vascular tissue are called non-vascular plants. Without structures to transport water, nutrients and food, nonvascular plants are usually smaller in size than vascular plants. Mosses, liverworts and hornworts are non-vascular plants.

liverwort

What are the characteristics of plants? mosses growing on rocks in a stream

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macaw

rock lobster

Animals Millions of different kinds of animals live on Earth. They can be found in the freezing poles to the hottest deserts. They can be found in bodies of fresh and salt water and underground too. They come in a great diversity of shapes and sizes. meerkat

Unlike plants, which get the energy they need by photosynthesizing, animals feed on other organisms to get the energy they need.

Most animals have body parts that enable them to move from place to place. Animals also have sense organs to take in information about the world around them. Their sense organs allow them to move in response to changes around them. Animals also move about in search of food, to escape from danger or to find a mate. blue pit viper red-eyed tree frog

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jellyfish

African elephant

Within the animal kingdom, scientists divide animals into two main groups based on the presence or absence of a backbone.

Animals that have a backbone are classified as vertebrates. Many of the animals we are most familiar with, like mammals, birds, reptiles, amphibians and fish are vertebrates.

Animals without a backbone are classified as invertebrates. They account for about 95 percent of the animals on Earth. Some invertebrates, like worms and jellyfish, have soft bodies. Others, like insects and crustaceans, have a hard outer covering called an exoskeleton. The exoskeleton provides protection and often helps to prevent water loss.

Without a backbone or internal skeleton of bones, invertebrates are generally smaller in size than vertebrates.

What are the characteristics of animals? locust

AB

Activity 1.11 23

What’s Inside Cells?

Did You Know?

The English scientist, Robert Hooke, was the first person to observe cells. He did so in 1665, when looking at a slice of cork under a microscope he made.

Shortly after, Antonie Philips van Leeuwenhoek, a selftaught scientist, made a more powerful microscope and became the first person to observe unicellular organisms.

Amazing Fact!

The human body is made up of trillions of cells of which there are about 200 different kinds. Cells are continuously reproducing.

Every day, billions of cells die and are replaced by new cells.

Plants and animals are multicellular organisms.

They are made up of cells of many different kinds and come in a variety of shapes and sizes.

The shape and size of a cell is often suited to the function it performs for the organism.

Most plant and animal cells have the same internal parts, called organelles. Each organelle has a specific role in helping the cell to function as a whole system. Let’s take a look at the parts of an animal cell.

Animal Cells The outermost part of an animal cell is the cell membrane – a thin layer that surrounds the cell.

The main function of the cell membrane is to regulate the interactions that occur between the cell and its external environment. It controls the substances that go in and out of the cell.

Inside the cell is the cytoplasm. The cytoplasm is a watery substance that holds the cell organelles except for the cell nucleus. It helps to protect the organelles and also gives the cell its shape.

The nucleus is often referred to as the control center of the cell. It controls all of the internal cell activities and processes such as growth and metabolism. At the center of the nucleus is the nucleolus which is where ribosomes are made.

Mitochondria (singular mitochondrion) are often referred to as the powerhouses of the cell. They release the energy from digested foods.

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The Golgi apparatus is the organelle that packages and transports proteins for delivery to different destinations within the cell.

Did You Know?

The endoplasmic reticulum (ER) is an organelle attached to the nucleus. Its main function is to produce proteins for the rest of the cell. The protein is made in ribosomes, which are small, round organelles on the surface of the ER.

Animal cells are generally smaller than plant cells. As they lack a cell wall, they are also irregular in shape compared to plant cells.

Vacuoles are storage spaces for water, wastes and other cellular material. nucleus

nucleolus cell membrane vacuole Golgi apparatus

endoplasmic reticulum (with ribosomes)

mitochondrion

cytoplasm

What organelles can be found in animal cells? What are their functions?

25

Plant Cells Like animal cells, plant cells have a cell membrane, nucleus, mitochondria, ER and ribosomes. Plant cells also have vacuoles, but they are usually larger than the vacuoles in animal cells. Like animal cells, the organelles in plant cells float in the cytoplasm.

plant cells with chloroplasts

Think Deeply Halle viewed unicellular protists under a microscope and noticed they contained chloroplasts. What can she infer about how they obtain the energy they need?

Plant cells are different from animal cells in that they have a cell wall – a rigid structure that surrounds the cell membrane. The main function of the cell wall is to provide support and protection.

Many plant cells also contain chloroplasts.

Photosynthesis takes place in the chloroplasts.

Chloroplasts contain chlorophyll which is a green pigment that captures the energy from sunlight.

AB chloroplast

Activities 1.12 – 1.13 nucleolus

vacuole

nucleus

cell wall

cell membrane mitochondrion

cytoplasm

Golgi apparatus

endoplasmic reticulum (with ribosomes)

In what ways are plant cells similar to animal cells? How are they different?

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Cell Organization Multicellular organisms are made up of many different kinds of cells. The cells are organized in a way that allows them to work together to perform specific functions.

A group of similar cells that work together to perform the same function forms tissue. Muscle is an example of tissue. Muscle is made of groups of muscle cells.

muscle cell

Tissues work together too. A group of tissues that work together to perform a specific function forms an organ. The heart is an organ made up of different tissues. The function of the heart is to pump blood around the body.

Organs working together to perform a specific function form an organ system. The circulatory system is comprised of the heart and blood vessels.

muscle tissue

All of the organ systems working together make an organism. Within a tiger the skeletal system, muscular system, circulatory system, respiratory system and other systems all work together to help the tiger move about and carry out life processes.

AB

Activity 1.14

body systems of a tiger

heart (organ)

27

Science Words Use the words to complete the sentences. organism cells unicellular organism multicellular organism sexual reproduction asexual reproduction virus

vascular plants non-vascular plants vertebrates invertebrates organelles photosynthesis

1. Plants produce their own food through the process of 2.

are animals with a backbone.

3.

are animals without a backbone.

4. An organism made of just one cell is a

.

5. An organism made of more than one cell is a 6. A over cells.

.

.

is a strand of genetic material that can invade and take

7. are the smallest units within an organism that can carry out life processes.

8. A living thing is called an

.

9.

do not contain vascular tissue.

10.

contain vascular tissue.

11.

Reproduction that involves fertilization is called

12.

Reproduction involving just one parent is called

13.

The parts of a cell are called

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.

. .

Review 1. List five characteristics of organisms.

2.

True or false. (a) Animals are unicellular organisms. (b) Animals cells do not have a cell wall. (c) Photosynthesis takes place in the nucleus of a cell. (d) Ferns and mosses belong to the same kingdom.

3. What is a virus?

4. Describe and provide an example of a decomposer.

5. Copy and complete the tables. (a)

Plant Classification Type of Plant

Description

Examples

Vascular Plants Non-vascular Plants (b)

Animal Classification Type of Animal

Description

Examples

Vertebrates Invertebrates 6. What is chlorophyll? Where is it found?

7. Draw a labeled diagram to show how cells are organized within a vertebrate animal.

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In the Field

Sir Alexander Fleming “One sometimes finds what one is not looking for. When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer. But I suppose that was exactly what I did.“ – Sir Alexander Fleming.

Sir Alexander Fleming was a Scottish physician and microbiologist, best known for discovering the drug penicillin – the first effective antibiotic used to kill bacteria.

In his laboratory in 1928, Fleming was investigating the properties of the bacteria Staphylococci. On returning from a family holiday, Fleming noticed that bacteria growing in a petri dish were being killed by the fungus Penicillium, a type of mold.

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He observed that the bacteria immediately surrounding the fungus had been killed, and that the bacteria farther away were normal. “That’s funny” he famously remarked to his assistant.

Fleming’s discovery led to the development of the antibiotic penicillin. The discovery was a medical breakthrough for the treatment of many illnesses caused by bacteria. Today, modern antibiotics are still tested using a method similar to how Fleming discovered penicillin.

Fleming received many awards for his hard work and scientific discoveries including the Nobel Prize in Physiology or Medicine in 1945.

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2

Plants

In this chapter you will ...

• describe some ways in which plants can be classified.

• construct an argument that plants have internal and external structures that function to support survival, growth, behavior and reproduction.

• describe and compare the life cycles of flowering plants, mosses and ferns.

What characteristics do scientists observe to classify plants?

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How do a plant’s internal and external structures support its survival, growth and reproduction?

Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

What are the stages in the life cycle of a flowering plant?

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Classification of Plants Try This!

One way scientists classify plants is by the shape and edges of their leaves.

In small groups, use a hand lens to observe and classify the plants in your schoolyard by the shape and edges of leaves.

Scientists have discovered, named and classified about 400,000 different kinds of plants. Each year, about 2,000 new plant species are discovered. To organize and better understand plant structures and the relationships between plants, scientists classify them into groups. One way plants are classified is as vascular plants or non-vascular plants.

Vascular plants have vascular tissue – internal, tube-like structures to transport water, minerals and food throughout the plant. Non-vascular plants do not have vascular tissue.

Why is it important to classify and name plants?

Go Online!

Discover more about the classification of plants on the NGScience website.

QuickCode: W8S9

AB

Activity 2.1

Plant Kingdom Non-vascular Plants

Mosses

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Liverworts

Hornworts

Moss spores are held in capsules.

Plants can also be classified by how they reproduce. Non-vascular plants and ferns do not produce seeds – they are seedless plants. They reproduce from spores. The spores are typically made of just one cell. Each spore is capable of developing into a new organism. In mosses, spores are contained in a capsule. In ferns, spores are usually located on the underside of the fronds in clusters called sori.

Gymnosperms, such as conifers and firs, are cone-bearing plants. They reproduce from seeds held in cones. Angiosperms are flowering plants.

They reproduce from seeds that develop in flowers and are held in fruits.

fern sori

AB Activity 2.2

Vascular Plants

Ferns

Gymnosperms

Angiosperms

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Non-vascular Plants Non-vascular plants do not have vascular tissue – xylem and phloem, to transport substances throughout the plant. They also lack roots, stems and leaves.

liverwort

To survive without vascular tissue, non-vascular plants are small and live close to the ground. They absorb the water and nutrients they need from their environment. The water then travels within the plant by moving from one cell to the next.

Mosses, liverworts and hornworts are non-vascular plants.

Non-vascular plants have root-like structures called rhizoids that anchor them in place. They can often be seen carpeting the moist forest floor, clinging to rocks near streams and growing on tree trunks.

moss

36

Mosses and liverworts have tiny leaf-like parts called leaflets which are just one cell thick.

Most photosynthesis occurs in the leaflets.

Did You Know?

Non-vascular plants are seedless plants.

They reproduce from single-celled microscopic spores held in a part called the capsule.

When the capsule opens, the spores are spread by water and wind to new places. Under the right conditions, new plants will grow from the spores.

Non-vascular plants were the first plants to grow on land.

Scientists have discovered fossil evidence of liverworts growing on land 473 million years ago.

AB Activity 2.3

What are the characteristics of non-vascular plants?

A Closer Look

Parts of a Moss Plant

capsule sporophyte

seta

foot

leaflets

gametophyte

rhizoids

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Vascular Plants Vascular plants are plants that have tube-like vascular tissue to transport substances throughout the plant. There are two main types of vascular tissue – xylem and phloem.

Xylem transports water and nutrients, usually from the roots to the upper regions of the plant. Phloem transports food from the leaves to all parts of the plant.

The cells in vascular tissue are rigid and provide plants with support, allowing them to grow taller than non-vascular plants.

Vascular plants can be further classified based on whether they produce seeds and where the seeds form.

bracken ferns

Think Deeply

Ferns and horsetails are seedless vascular plants.

They reproduce from spores.

What are the primary functions of xylem and phloem?

Many ferns are able to grow in low-light environments.

What adaptation allows them to do this?

Vascular Plants Seedless Plants

Ferns

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Horsetails

Plants that reproduce from seeds are called seed plants. The two main types of seed plants are gymnosperms and angiosperms.

Gymnosperms are non-flowering plants. They reproduce from seeds, but do not produce flowers or fruits. The seeds are usually held in reproductive structures called cones.

Common gymnosperms include conifers, cycads and ginkgos.

Angiosperms are flowering plants. They produce seeds that are held in the ovaries of flowers. As the seed develops, the ovary forms a protective fruit around the seeds. Angiosperms are the most diverse group of plants. More than 300,000 different species have been named and classified. All grains, fruits and vegetable plants are angiosperms. As are tulips, sunflowers, oaks and maples.

What are the characteristics of vascular plants?

Gymnosperms reproduce from seeds held in cones.

Did You Know?

The term ‘gymnosperm’ comes from Greek words meaning ‘naked seeds’ as the seeds are not enclosed in ovaries.

Go Online!

Seed Plants

Gymnosperms

Angiosperms

Learn about the life cycle of gymnosperms in a video on the NGScience website.

QuickCode: R2Y5

AB Activity 2.4

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Plant Structures

vascular tissue

Roots Find a weed in your garden and try to pull it from the soil. You’ll notice that it takes a lot of force. If the weed is big enough, you may not be able to pull it out at all. Holding the weed firmly in the ground are roots. All of the roots of a plant make up the root system. In most vascular plants, the root system is underground. The root system has three main functions: • take in water and minerals from the soil.

• hold the plant in the soil.

• store food.

root hair

epidermis

root cap

root hair

The outer layer of a root is called the epidermis.

Attached to the epidermis are tiny roots hairs which are just one cell thick. The root hairs absorb water and minerals which are transported from the root to the upper parts of the plant.

At the tip of a root is a root cap. It helps to protect the root as it grows down into the soil.

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In the center of a root is vascular tissue. Xylem vessels transport water and minerals to the upper parts of the plant, called the shoot system. Food is transported to all parts of the plant, including the roots, in phloem vessels. phloem

xylem

root hair

epidermis root section

Plants can have different roots that help them in different ways. Some roots are shallow and branch out to cover a large area. These roots, called fibrous roots, help the plant to take up lots of water when it rains.

Other plants have one main root, called a taproot, which grows deep into the soil. This helps to reach water deeper in the soil.

Some plants have roots that grow above ground, called aerial roots. An epiphyte is a plant that grows on another plant, often on the trunks of trees. Many ferns and orchids are epiphytes. Their aerial roots take in rainwater and water vapor from the air. Some epiphytes are also able to take in moisture through their leaves.

What are the primary functions of roots?

AB

Activities 2.5 – 2.6 41

A Closer Look

Mangroves Mangroves are plants that grow in intertidal regions in coastal areas. An intertidal region is submerged with salt water during high tides and exposed to the air during low tides. Mangroves have a number of adaptations that allow them to survive in this ever-changing environment.

The soil in which mangroves grow is soft and low in oxygen. To survive in such soil, many mangroves have stilt roots that prop up the plant and prevent the shoot system from being submerged during high tides.

Go Online!

Learn more about mangrove adaptations to intertidal environments and their importance to ecosystems in a video on the NGScience website.

QuickCode: F5Q2

AB Activity 2.7

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Plant cells, including those in underground roots, require oxygen. Normally, oxygen can be taken in through pockets of air in the soil.

However, the soil where mangroves often grow has insufficient spaces for air and is very low in oxygen. To adapt to this low-oxygen environment, some mangroves have specialized root structures called pneumatophores. These vertical structures stick up out of the soil and enable the mangrove root system to take up oxygen from the atmosphere.

Another unique adaptation of mangroves can be seen in their life cycle. The seeds of many mangroves germinate and begin to grow while still attached to the parent plants. Once developed, the seedlings fall away. The seedlings float and are dispersed to new places by the tidal flow of water.

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Trees have strong and thick woody stems.

Stems The stem is usually the part of the plant that connects the root system to the upper portions of the plant.

One function of the stem is to provide support and hold up the leaves. This allows the leaves to spread out and take in more sunlight.

A tomato plant has a green and flexible soft stem.

Some plants have green stems that are thin and can bend more easily than others. They are called herbaceous stems. Herbaceous stems get their green color from chloroplasts in the cells. Vegetable plants such as tomatoes, beans, peppers and herbs have soft stems.

A soft stem would not be able to support the weight of the extensive shoot system of a tree. Trees are plants with thick, strong stems covered in protective bark. They do not bend easily. These stems are called woody stems.

Many shrubs also have woody stems. Woody stems are usually brown in color. The cells in woody stems do not contain chloroplasts.

What are the differences between herbaceous stems and woody stems?

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Stems contain vascular tissue that transports substances throughout the plant. Xylem vessels transport water and minerals from the root system to the leaves. Phloem vessels transport food from the leaves to all parts of the plant. xylem

epidermis

phloem

stem section

Some plants use their stems for storage.

Bamboo and sugarcane store food in their stems. Many cacti store water in their stems.

What are the main functions of the stem?

AB

Activities 2.8 – 2.9 45

Leaves Leaves, together with the stem, form the shoot system of a plant. Leaves are the food factories for the plant. They are highly specialized to carry out photosynthesis. They are often flat, broad and branch out in all directions. This enables them to absorb as much sunlight as possible, which is the essential source of energy needed to produce food. cuticle

epidermis palisade layer

vein

stoma

Think Deeply Generally, stomata open during the day and close at night. What could be a reason for this?

day

46

night

phloem

xylem

leaf anatomy

Running through the center of the leaf is a vein containing xylem and phloem.

The top of a leaf is a layer of cells called the epidermis. A waxy covering on the epidermis, called the cuticle, helps to prevent water loss due to evaporation.

On the underside of a leaf are many tiny openings called stomata (singular stoma).

Air, including the carbon dioxide needed for photosynthesis, enters the leaf through the stomata.

Below the epidermis is a layer of cells called the palisade layer. Cells in this part of the leaf contain many chloroplasts. Photosynthesis takes place in chloroplasts.

Inside the chloroplasts, light energy absorbed by the green pigment chlorophyll combines carbon dioxide and water to produce sugar and oxygen.

The sugar provides the plant with the energy it needs to carry out life processes. The sugar is transported from the leaf to all parts of the plant through phloem vessels.

The oxygen produced during photosynthesis is released into the air through the stomata.

AB

Go Online!

Observe how substances move into and out of leaves in an animated video on the NGScience website.

QuickCode: P8Q1

Think Deeply What energy transformation takes place during the process of photosynthesis?

Activities 2.10 – 2.12

sunlight

water

sugar

oxygen carbon dioxide

During photosynthesis, plants use the energy in sunlight to convert water and carbon dioxide into sugar and oxygen.

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Plant Life Cycles Pollen grains sticking to the body of a bee.

Like all organisms, plants produce young of their own kind – they reproduce. Different types of plants reproduce in different ways. Let’s take a look at the life cycles of angiosperms, ferns and mosses.

Angiosperm Life Cycle Angiosperms are flowering plants. They reproduce by sexual reproduction. This means a male sex cell needs to unite with a female sex cell. Male sex cells are called sperms. They are located in pollen grains on the anther of a flower. Female sex cells are eggs which are stored in the ovary of a flower.

Did You Know?

Animals that help to pollinate flowers are called pollinators.

They play a vital role in the production of many of the crops humans rely on for food. Common pollinators include insects such as honeybees, butterflies, beetles and hoverflies. Many bird and bat species are also pollinators.

For an angiosperm to reproduce, pollen grains from the anther need to be transferred to the stigma of a flower – a process called pollination.

This can occur within the same flower, and also between two flowers of the same kind.

When a pollen grain lands on the stigma, it produces a tube, called a pollen tube. The pollen tube grows from the stigma, through the style to the ovary. Inside the ovary are ovules. Each ovule contains an egg cell.

A sperm cell moves from the pollen grain on the stigma, through the pollen tube to the ovary.

When the sperm cell reaches an ovule, it fuses with the egg cell. This joining of the sex cells is called fertilization.

What are some ways pollen can move from flower to flower?

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Following fertilization, the flower petals fall away and the ovule begins to develop into a seed. The ovary of the flower swells to form a protective fruit. Once developed, the seeds need to be dispersed to new places. This can occur when animals feed on fruits or when seeds and fruits stick to their bodies. Fruits and seeds can also fall away and are carried to new places by wind or water.

In its new location and under the right conditions, the seed will germinate and grow into an adult plant.

What are the stages in the life cycle of an angiosperm?

AB Activity 2.13

petal

As seeds develop, the ovary of the flower swells to form a protective fruit.

stigma

style anther

pollen tube

stamen

pistil

filament ovule ovary sepal

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A Closer Look

Angiosperm Life Cycle 1

The filament and anther make up the stamen. The filament produces pollen grains.

2

Pollen is released into the air or carried away by pollinators such as birds and insects.

3

Pollen lands on the surface of the stigma.

Each pollen grain grows a pollen tube which extends down into the style.

4

Male reproductive cells, called sperm cells, are guided down the pollen tube, through the style to the ovary.

5

Fertilization occurs when a sperm cell unites with a female sex cell, called an egg cell.

1

50

2

3

4

5 6

The fertilized cell begins to develop into a seed as the ovary swells to form a protective fruit.

7

Once developed, the seeds are spread to new places and will grow into new plants.

6

7

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Fern Life Cycle Ferns are seedless plants that reproduce from spores. Their life cycle is also different from seed plants in that it involves two distinct phases – an asexual phase and a sexual phase.

In the asexual phase, spores form in clusters on the underside of mature fern fronds. The spores are held in cases called sporangia.

Once the spores are developed, the sporangia breaks open and the spores are dispersed by wind and moving water. fern spores in sporangia

sporangia

sporophyte

mature sporophyte

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Under the right conditions, a single spore will germinate and grow into a heart-shaped plant called a gametophyte. Root-like rhizoids anchor the gametophyte to the ground. The gametophyte has both male and female parts.

Sperm cells make their way from the male part to the female part and fuse with female egg cells. The fertilized egg cell develops into an embryo. It eventually grows larger than the gametophyte and becomes a sporophyte. The sporophyte produces spores and the two-phase life cycle repeats.

spores released gametophyte

fertilization

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Moss Life Cycle Like ferns, mosses are seedless plants with a life cycle that involves both asexual and sexual reproduction.

In the asexual phase, spores are produced and held in a capsule. When the capsule breaks open, the spores are released into the air. They are spread to new places by wind or moving water. Under the right conditions, a single spore will germinate and grow into a leafy gametophyte. moss capsules

spores released

sporophyte

54

The gametophyte has male and female parts. Fertilization occurs when a sperm cell from the male part fuses with an egg cell in the female part. The fertilized egg will develop into a new moss sporophyte. The sporophyte will produce spores held in capsules and the life cycle continues.

In what ways is the life cycle of mosses similar to the life cycle of ferns?

Go Online!

Learn more about the life cycle of mosses and other non-flowering plants on the NGScience website.

QuickCode: L4H9

AB Activity 2.14

leafy gametophyte

germinating spore

fertilization

55

A Closer Look

Vegetative Reproduction Some plants are able to produce new plants from a fragment of the parent plant or a specialized reproductive structure.

This process is called vegetative reproduction. Vegetative reproduction is an asexual process and the offspring are genetically identical to the parents.

Strawberries have flowers and can reproduce sexually. They can also produce new plants from modified stems called runners. Runners grow out from the strawberry plant, usually just beneath the surface of the soil.

They eventually develop their own roots and begin to grow.

The roots hold the new plant in the soil and the runner dries up and breaks away.

How is vegetative reproduction different from sexual reproduction?

56

potato plant growing from tuber

Potatoes can also reproduce vegetatively. The part of a potato plant we eat is a modified stem called a tuber. New plants develop from buds on the sides of the tuber. As they grow, they use the starch stored in the potato for energy.

Bryophyllum is a plant that can reproduce from plantlets on its leaves. Plantlets are tiny structures growing on the edges of the leaves. The plantlets grow roots while still attached to the parent plant.

Eventually the plantlets drop to the ground and grow into new plants.

plantlets growing on the leaf of a bryophyllum plant

Think Deeply The offspring produced through vegetative reproduction are genetically identical to the parent plant.

How could this be useful in agriculture?

AB Activity 2.15

57

Science Words Use the words to complete the sentences. xylem phloem gymnosperms angiosperms fibrous roots 1.

taproot aerial roots herbaceous stem woody stem vegetative reproduction are shallow roots that branch out to cover a large area. .

2. A single main root that grows deep into the soil is called a 3. A green stem that can bend is a called a 4. The thick, strong stem of a tree is called a 5. Asexual reproduction from part of a plant is called

. . .

6.

are above ground roots.

7.

are cone-bearing plants that reproduce from seeds.

8.

are plants that produce flowers.

9. Vascular tissue that transports water and nutrients from the roots to the upper regions of the plant is called .

10. Vascular tissue that transports food from the leaves to all parts of the plant is called .

58

Review 1. List two kinds of seedless plants.

2. Why are non-vascular plants usually shorter in size compared to vascular plants?

3. How are gymnosperms similar to angiosperms in terms of how they reproduce? How are they different?

4. List two kinds of gymnosperms.

5. List two kinds of angiosperms.

6. Chelsea observed a small plant under a microscope and noticed it did not have vascular tissue. What can she infer about how the plant reproduces?

7. In a forest, Wyatt spots a tall plant with spores on the underside of its fronds. What type of plant did Wyatt spot?

8.

True or false. (a) Phloem transports water from the roots to the leaves. (b) In most plants, photosynthesis mainly takes place in the leaves. (c) Ferns and gymnosperms reproduce from seeds. (d) Most trees have woody stems.

9. What do plants need to photosynthesize?

10. What gas is released into the air during photosynthesis?

11. List two ways moss spores are dispersed to new places.

12. Draw a simple labeled diagram to show the process of pollination.

13. Describe what occurs when an egg cell in the ovule of a plant is fertilized.

14. Describe two functions of fruits.

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3

Animal Classification What characteristics do scientists look at when they classify animals?

What are the main groups of invertebrates?

In this chapter you will ...

• list and describe the characteristics of simple invertebrates.

• list and describe the characteristics of complex invertebrates.

• list and describe the characteristics of vertebrates.

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What are the main groups of vertebrates?

Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

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Classification of Animals Scientists classify animals into two main groups.

Many of the larger animals you are most familiar with are vertebrates. Vertebrates are animals with a backbone. Fish, amphibians, reptiles, birds and mammals are vertebrates. Humans are vertebrates too – we’re mammals.

Most of the animals on Earth, about 95 percent, are invertebrates. Invertebrates are animals that do not have a backbone. Sponges, jellyfish, sea stars, snails and insects are invertebrates.

Animal Kingdom Vertebrates

Invertebrates

What is the main difference between vertebrates and invertebrates?

AB 62

Activity 3.1

Invertebrates Invertebrates are the largest group of animals.

They have no backbone or internal skeleton.

Without the support and protection of bones, many invertebrates are smaller in size than vertebrates, although many large invertebrates can be found in the ocean.

Many invertebrates have soft, flexible bodies with a tough outer covering for protection and to reduce water loss. Most invertebrates reproduce sexually with the young hatching from eggs. The young often look very different from their parents. Some invertebrates, particularly arthropods, undergo changes in body form as they grow – a process called metamorphosis.

Sponges

Cnidarians

Go Online!

Discover the great diversity of invertebrate animals in a video on the NGScience website.

QuickCode: W5E4

Think Deeply Why are many invertebrates in the ocean much larger in size than invertebrates on land?

AB

Activity 3.2

Worms

Invertebrates Echinoderms

Mollusks

Arthropods

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Sponges Sponges are some of the world’s oldest and simplest animals. They are multicellular organisms, but do not have body parts, tissues or organs. Their asymmetrical bodies consist of one or more tubes with an opening at the top.

An asymmetrical body does not have any lines of symmetry. Most sponges live in the ocean, but some live in fresh water environments.

barrel sponge

Sponges are filter-feeders. They pump sea water through the holes in their bodies called pores. As water moves through the pores, bacteria and tiny particles are taken up from the water as food. Sponges do not move about and rely on a continual flow of water through their bodies to obtain food and oxygen and to remove wastes. pore

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Collar cells help to move water through the sponge and take in food.

Sponges usually reproduce sexually, but some reproduce asexually by budding. Budding is the process in which a new organism develops from an outgrowth on the body of the parent organism. Once developed, the offspring detaches as a new organism that is genetically identical to its parent.

Go Online!

Watch a video on the life cycle of sponges on the NGScience website.

QuickCode: E1K7

Did You Know?

A scientist that specializes in the study of animals is called a zoologist. A zoologist that specializes in the study of sponges is called a spongologist.

AB

Activity 3.3

tube sponge

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brain coral

fan coral

Cnidarians Amazing Fact!

Jellyfish range in size from just a few centimeters to several meters in length. The largest of all jellyfish is the lion’s mane jellyfish, or the giant jellyfish. It has a bell with a diameter of up to two meters (6.5 ft) and tentacles that can stretch for more than 30 meters (98 ft).

Cnidarians are animals that live in aquatic environments. Most can be found in the ocean, but some also live in fresh water. Jellyfish are cnidarians with soft jelly-like bodies. They spend the early stages of their life cycle attached to the sea floor and are free-swimming as adults. Jellyfish have tentacles that are used to catch prey.

jellyfish

Corals are cnidarians that spend their lives attached to the ocean floor or other underwater surfaces. Some corals get the energy they need from algae living within their tissue. Others have a series of tentacles that are used to catch small organisms floating by their anchored bodies.

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soft coral

sea anemone

Most cnidarians reproduce sexually, whereby sex cells are released and are fertilized in water. Some corals are also able to reproduce asexually by budding. Unlike sponges, cnidarians have radial symmetry. This means their bodies are arranged around a central point with more than one line of symmetry.

A unique characteristic of cnidarians are stinging cells called cnidocytes. Cnidocytes contain a toxin and are used to stun and capture prey. They are also used for defense against predators. Some jellyfish produce toxins that are harmful to people.

What are the characteristics of cnidarians?

cnidocyte

AB

Activity 3.4 67

Worms Worm is the general name given to animals from three different groups – flatworms, roundworms and segmented worms. Worms are multicellular and typically have a long tube-like body and no limbs. All worms have bilateral symmetry. Organisms with bilateral symmetry have a body with a single plane of symmetry which divides it into two mirror images.

Most worms reproduce sexually, although some can reproduce asexually.

Fuchsia flatworm

Amazing Fact!

Nematodes are considered to be the most abundant animals on earth. About four out of every five animals on Earth is a nematode!

They range in size from microscopic parasites to giant marine ribbon worms which can reach lengths of over 50 meters.

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Flatworms, also called platyhelminths, are simple worms with a soft, flat body.

They can be found in salt water, fresh water, and damp land environments. Many flatworms are parasitic. A parasitic organism lives in or on another organism. Most flatworms have a body cavity with only one opening. Food enters the body opening and waste leaves through the same opening.

Roundworms, also called nematodes, are more advanced than flatworms. They have a tubular digestive systems with openings at both ends. Roundworms live in a range of different environments. Many are parasitic and can cause illnesses and diseases in other organisms. microscopic roundworms

Earthworms live in moist soil.

Segmented worms, also called annelids, are the most advanced of the three worm groups. They get their name from their bodies which are divided into segments. Segmented worms have organ systems including circulatory, digestive and nervous systems.

Segmented worms can be found in most wet environments, including underground and in the ocean. Common segmented worms include earthworms, leeches and bristle worms.

bristle worms

leech

In what ways are flatworms, roundworms and segmented worms similar? In what ways are they different?

AB

Activity 3.5

Did You Know?

Many leeches are hematophagous which means they feed on the blood of other animals.

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sea cucumber

Echinoderms sea urchins

Amazing Fact!

When injured, some species of sea stars and brittle stars are able to regrow parts of their body. This process is called regeneration. Some species can even regrow their entire body from just one severed limb!

Go Online!

Discover the fascinating world of echinoderms in a video on the NGScience website.

QuickCode: T8C8

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Sea stars, brittle stars, sea urchins and sea cucumbers are echinoderms. All echinoderms live in the ocean, from warm tropical reefs to the icy arctic poles. Most echinoderms have radial symmetry and reproduce sexually.

However, some can also reproduce asexually.

Sea stars and many other echinoderms have five-part radial symmetry.

brittle star

Echinoderms produce a hard internal structure called an endoskeleton which gives their outer covering a rough, spiny appearance.

sea star tube feet

Echinoderms move about using a system of tube feet. This allows them to crawl slowly on the ocean floor.

What are the characteristics of echinoderms?

AB

Activity 3.6

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Mollusks Mollusks are animals with soft bodies, often with a hard outer covering called a mantle.

Most mollusks live in the ocean, with some living on land or in fresh water. Common mollusks include octopus, squid, clams, snails and slugs.

blue dragon nudibranch

Did You Know?

Nudibranchs are a diverse group of soft-bodied sea slugs. They are well-known for their bright colors and are often given fancy names such as dancers, clowns and dragons. About 3,000 different nudibranchs have been named and classified.

The soft body of mollusks contains tissues and organs to carry out life processes. They have digestive, respiratory and circulatory systems.

Most mollusks have a specialized mouth structure called a radula which is a series of tiny teeth used for scraping food particles into the mouth.

Mollusks also have a muscular organ, called a foot, which is used to move about. eye upper tentacle (ocular) shell lower tentacle (olfactory) mouth

tail

foot

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parts of a garden snail

A common characteristic of mollusks is a mantle in the form of a shell. Snails and limpets are examples of mollusks with one shell. Clams and scallops have two shells which are hinged on one side. This allows the shell to open and close. All mollusks have bilateral symmetry.

All mollusks reproduce sexually which involves the fertilization of male and female sex cells.

What are the characteristics of mollusks? giant clam

squid

Go Online!

octopus

Cephalopods are a group of mollusks that includes octopuses, squid and cuttlefish. The animals in this group are thought to be the most intelligent of all invertebrates. Their large and well-developed brain makes them very efficient predators. They are known to use tools and have demonstrated advanced learning and problemsolving abilities in laboratory environments. Watch a video about these fascinating creatures to find out just how smart they are!

QuickCode: U6G2

AB

Activity 3.7 73

blue swimmer crab

blue crayfish

Arthropods Amazing Fact!

Some arthropods have specialized internal structures that produce venom. The venom is a type of poison that is injected by a bite or sting into other animals.

It can be used to kill prey or for protection against predators. Wasps, bees, spiders and scorpions are often venomous.

eastern lubber grasshopper

Arthropods are the most diverse and numerous group of animals. They make up over 80 percent of all known species of animals on Earth. They live in all areas of the Earth – from the deep ocean to hot, dry deserts and moist tropical rainforests.

Common aquatic arthropods include crustaceans such as crabs, shrimp and lobsters.

Terrestrial arthropods include insects, spiders, ticks and millipedes.

honeybee

Arthropods have a hard outer body covering called an exoskeleton. Made of chitin, the exoskeleton supports and protects the animal’s body and can also help reduce water loss.

Arthropods have paired limbs on each side of their segmented bodies. Some arthropods have modified limbs in the form of claws or wings.

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giant hairy scorpion

tick

An exoskeleton does not bend easily. To move about, arthropods have many joints which allow them to bend parts of their bodies.

Without an internal skeleton to support their bodies, arthropods are usually small in size.

Aquatic arthropods, such as crabs and lobsters, are often larger than land arthropods as they are able to use the surrounding water for support.

Arthropods have organs and body systems for digestion, breathing, circulation and reproduction.

They also have a variety of different sense organs, such as eyes and antennae.

All arthropods have bilateral symmetry and reproduce by sexual reproduction.

European garden spider

Try This!

Use a hand lens to observe insects in your schoolyard.

Describe the structures each insect has. Discuss the function of the structures with your classmates.

What characteristics do all arthropods share? In what ways are they different?

AB

Activities 3.8 – 3.9 giant millipede

pill bug

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A Closer Look

Arthropod Life Cycles After hatching, most arthropods do not resemble their parents. The young, called larvae, go through a series of changes in a process called metamorphosis. During metamorphosis, a larva goes into an inactive pupa stage. When an arthropod emerges from the pupa, it has all of the characteristics of its parent.

The life cycle of a mosquito goes through four distinct phases – egg, larva, pupa and adult. The organism looks, feeds and moves differently in each stage.

raft of eggs

egg

aquatic larva

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Think Deeply Mosquitoes are insects that can spread diseases to humans. Female Anopheles mosquitoes can spread the disease malaria which infects more than 200 million people every year. How can learning about the life cycle of Anopheles mosquitoes help control the spread of malaria?

A female Anopheles mosquito feeding on human blood.

emerging adult

Go Online! aquatic pupa

Watch a video about the life cycle of a mosquito on the NGScience website.

QuickCode: V1J4

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surgeonfish

Fish

Vertebrates hammerhead shark

Did You Know?

Scientists have classified and named about 70,000 different species of vertebrates. Here’s how many are in each of the main vertebrate groups: fish – 30,000 species amphibians – 9,000 reptiles – 13,000 birds – 11,000 mammals – 7,000

Vertebrates are animals that have a backbone and an internal skeleton, usually made of bone.

The skeleton helps to protect vital organs such as the brain, heart and lungs. It also provides support and structure which allows vertebrates to reach sizes much larger than most invertebrates.

All vertebrates have bilateral symmetry.

Vertebrates are classified into five main groups – fish, amphibians, reptiles, birds and mammals.

Amphibians

green tree frog

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fire salamander

common box turtle

Chinese water dragon

Reptiles

Birds Vertebrates blue tit oriole

Mammals tiger cub

AB Activity 3.10

gray long-eared bat

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lampreys

A school of trevally.

Fish Fish are cold-blooded animals that live in water. Cold-blooded means their body temperature is not regulated and varies with the temperature of the environment. Fish range in size from just a few millimeters to several meters. Most fish reproduce sexually by external fertilization whereby eggs and sperms are released into and fertilized in the water.

There are three main groups of fish – jawless fish, cartilaginous fish and bony fish.

great white shark

Jawless fish are the oldest and simplest group of fish that include lampreys and hagfish. They do not have jaws and feed by sucking their food. They have long cylindrical bodies and a skeleton made of cartilage.

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A variety of bony fish inhabit coral reefs.

Cartilaginous fish include sharks, rays and skates. They have an internal skeleton made of cartilage. Cartilage is strong and flexible. It provides support and protection and enables many cartilaginous fish to grow larger than other types of fish.

Bony fish have an internal skeleton made of bone. They include many of the fish you are most familiar with including salmon, tuna and swordfish. Sea dragons and eels are also bony fish.

The body of fish is well-adapted to life in water.

They have a streamlined shape, fins and a tail that allows them to move about and change direction easily. Bony fish usually have a body covered in scales which also helps them glide through water. Scales also provide protection.

moray eel

Amazing Fact!

Leafy sea dragons have leaf-like appendages that allow them to achieve almost perfect camouflage amongst the seaweed in which they live. They have no known predators and spend all day sucking up prey using their long pipe-like snout.

Fish have a specialized respiratory system with gills. As water flows over the gills, they take in oxygen which passes into the bloodstream.

What are the characteristics of fish?

AB

Activity 3.11

Southern stingray

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A Closer Look

How Do Gills Work?

Fish and many other aquatic animals have special internal structures called gills. Gills allow animals to take in the oxygen they need from water. They also remove carbon dioxide and release it back into the water. This process of taking in and removing gases is called gas exchange.

Gills are soft, branching organs, usually located on the side of a fish’s head and protected under gill covers.

Gas exchange occurs when water enters a fish’s mouth and moves through the gills.

direction of water flow

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blood vessels

Gills are made of soft tissue called filaments. As water enters the gills, it washes over the filaments.

Each filament contains a network of tiny blood vessels called capillaries. As water washes over the capillaries, dissolved oxygen is taken into the blood and carbon dioxide is removed from the blood and released back into the water.

gill filament

oxygen-rich blood capillaries

direction of water flow

oxygen-poor blood

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Wallace’s flying frog

Amphibians The word amphibian comes from a Greek term which means ‘double life’. This is due to their unique life cycle which, for many amphibians, begins in water and moves on to land. Amphibians reproduce sexually by external fertilization, and hatch from eggs.

There are three main groups of amphibians.

Frogs are amphibians we are most familiar with.

They often have short bodies with powerful hind legs for moving about on land and in water.

Toads are similar in appearance to frogs, but often have drier and rougher skin.

European tree frog

moor frog with eggs

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tadpoles

Salamanders are amphibians that are similar in appearance to lizards. They have long, slender bodies with a tail. Caecilians are limbless, worm-like amphibians. Most live underground.

Most amphibians get the oxygen they need using lungs to breathe in air. Many amphibians are also able to take in oxygen through their moist skin.

spotted salamander

Some poison dart frogs carry their young on their backs to a source of water.

What are the characteristics of amphibians?

AB Activity 3.12 85

Nile crocodile

Reptiles

A Nile crocodile hatching from its egg.

Reptiles are cold-blooded animals with bodies covered in scales or plates. Most reptiles live on land, but some live in the ocean and fresh water habitats. All reptiles get the oxygen they need from air using lungs.

Reptiles are classified into three main groups:

Did You Know?

Most reptiles are oviparous – they reproduce by laying eggs. Some snakes, including many vipers are viviparous – they give birth to live young.

• crocodiles and alligators.

• snakes and lizards.

• turtles.

blue viper snake

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Reptiles have bodies covered in scales or plates.

chameleon

Reptiles reproduce sexually and have internal fertilization. This means the eggs are fertilized inside the body of the female. Most reptiles lay eggs from which young hatch.

Many reptiles, such as crocodiles and snakes, are fierce predators. Crocodiles and alligators have large teeth and powerful jaws to catch and kill prey. Many snakes have large fangs which can inject powerful venom into their prey.

What are the characteristics of reptiles?

Amazing Fact!

Reptiles have some of the longest life-spans in the animal kingdom. Some large tortoises can live for over 200 years. Accurately verifying the age of a giant tortoise can be difficult as they often outlive the scientists studying them.

AB Activity 3.13

green sea turtle

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great gray owl

Birds osprey feeding its young

great tit

Birds are animals with bodies covered in feathers. All birds also have two wings, two feet and a beak or bill.

With light bodies and powerful muscles, many birds use their wings to fly. There are flightless birds, like emus and cassowaries, that move about by walking and running. Penguins are also flightless birds that use their wings as fins and rudders to swim.

turkey chicken hatchling

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macaw

adelie penguins

Try This!

All birds are warm-blooded, which means they regulate their own body temperature. Birds reproduce by internal fertilization whereby the egg cells are fertilized inside the female bird. Hardshelled eggs then develop and are laid in a nest. The eggs are kept warm and are cared for by the parents until the young hatch from each egg.

Take a set of binoculars and go bird-watching with your classmates. Describe and try to name the birds you spot.

Once hatched, most birds care for their young. They provide them with warmth, food and protection from predators.

What are the characteristics of birds?

AB Activity 3.14

common magpie

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Mammals Bats, sea lions, koalas and many of the animals we keep as pets are mammals. Mammals are warm-blooded animals with a body covered in hair or fur.

Lyle’s flying fox

Another characteristic of mammals is the way in which they reproduce. Mammals reproduce by internal fertilization. Rather than laying eggs, the young develops within its mother. Once mature, the mother gives birth to live young. The mother nurses the newborn with milk until it is able to feed on its own.

Some mammals, like kangaroos and koalas, are marsupials. Marsupials are mammals that give birth to partially developed young. The newborn is then cared for in a pouch attached to the female parent.

Platypuses and spiny anteaters are unique types of egg-laying mammals called monotremes.

These mammals can only be found in Australia and New Guinea.

A female kangaroo cares for its young, called a joey, in its pouch.

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platypus koalas

Californian sea lion

Mammals have lungs and take in oxygen when they breathe in air. Aquatic mammals, such as dolphins, sea lions and whales, must come to the surface to breathe.

Most mammals reproduce by giving birth to live young.

Adult mammals often care for their young until they are old enough to survive on their own. They may teach their young how to find food or hunt. They may also teach them how to stay safe from other animals.

What are the characteristics of mammals?

AB

Activities 3.15 – 3.16

kitten

young deer brown rat

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Science Words Use the words to complete the sentences. asymmetrical radial symmetry bilateral symmetry endoskeleton

exoskeleton cold-blooded metamorphosis

external fertilization internal fertilization warm-blooded

1. An

is a hard internal body structure.

2. An

is a hard outer body covering.

3. Fertilization that takes place inside the female is called 4. Fertilization that takes place outside the female is called

. .

5. Animals with have bodies that are arranged around a central point with more than one line of symmetry.

6. Animals with have a body with a single plane of symmetry which divides it into two mirror images.

7.

animals have bodies with no lines of symmetry.

8. The temperature of their environment.

animals is regulated by

9. Animals that are able to regulate their own body temperature are .

10. is the process by which the body of a larva changes in form as it develops into an adult.

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Review 1. How do sponges get the food they need?

2. What are cnidocytes? Into what group do animals with cnidocytes belong?

3. Of the three main types of worms, which are the most advanced?

4. Which group of invertebrates can only be found in the ocean?

5. Ethan spotted an invertebrate under a log and noticed it has pairs of jointed legs. To which invertebrate group does the animal belong?

6. While snorkeling, Halle spotted an animal with radial symmetry and a rough, spiny body. What animal did Halle spot? Into which invertebrate group can she classify the animal?

7. List the three main types of fish.

8. List two invertebrates that undergo metamorphosis during their life cycle.

9. Copy and complete the table.

Vertebrate Classification Type of Animal

Description

Examples

Fish Amphibians Reptiles Birds Mammals

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4

Energy in Ecosystems

In this chapter you will ...

• describe an ecosystem in terms of its biotic and abiotic factors.

• describe the way organisms in ecosystems are organized.

• describe and provide examples of food chains, food webs and energy pyramids for a given ecosystem.

• use models to describe that energy in animals’ food was once energy from the Sun. • support an argument that plants get the materials they need for growth chiefly from air and water.

• develop a model to describe the movement of matter among plants, animals, decomposers and the environment.

How does energy flow through ecosystems? Where does the energy come from?

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What are the different roles of organisms in an ecosystem?

Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

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What Is an Ecosystem?

A system is something that is made up of different parts that work together to perform a common function. Ecosystems are examples of systems in nature. All of the organisms in an ecosystem are called biotic factors. Biotic factors include all of the plants, animals, fungi and microorganisms.

The biotic factors interact with each other in many ways. They also interact with non-living things. The non-living things in an ecosystem are called abiotic factors. Abiotic factors include sunlight, heat, air, water, nutrients, rocks and soil.

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An ecosystem consists of all of the biotic and abiotic factors and the interactions between them. The factors in an ecosystem are dependent on each other. When a change occurs to a biotic or abiotic factor, the other factors within the system can be affected.

In a pond ecosystem, the water in the pond is an abiotic factor. If the water dries up or becomes polluted, the plants and animals dependent on the water may die or move out of the ecosystem.

The algae in the pond are a biotic factor. If the population of algae increases, the amount of oxygen in the water can change which can affect other organisms in the ecosystem.

What are the biotic and abiotic factors in a coral reef ecosystem?

Go Online!

Scientists organize the ecosystems on Earth into regions called biomes. A biome is defined by its climate and the types of organisms that live there.

Discover more in a video on the NGScience website.

QuickCode: S9T3

Think Deeply The main diet of the green sea turtle is sea grass. During floods, sediment in the water can prevent sunlight from reaching the sea floor. How could this affect the green sea turtle population?

AB

Activity 4.1

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Ecosystem Organization To study different biotic factors in an ecosystem and to better understand the interactions between biotic and abiotic factors, scientists organize ecosystems into different levels.

A single organism is called an individual. In a rainforest ecosystem, a tree fern is an example of an individual. A red-eyed green tree frog is another individual in a rainforest ecosystem.

All of the organisms of the same kind that interact and reproduce within an ecosystem make up a population.

All of the tree ferns in a rainforest form a population. All of the red-eyed green tree frogs form another population. The individuals within the same population interact when they compete for food, water, mates, space and other resources. How the population interacts and uses the biotic and abiotic factors in the ecosystem can determine its size.

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In most ecosystems there are many different populations that interact and depend on each other for survival. The interacting populations within an ecosystem form a community. In a rainforest, there are thousands of different populations of plants, animals, fungi and other decomposers that interact and form the rainforest community.

The final level of ecosystem organization is the ecosystem itself. An ecosystem includes the interacting community along with the abiotic factors that affect it.

Collecting data on individuals, populations and community interactions help scientists predict the effects of changes to the ecosystem as a whole system.

How is it useful to organize the organisms in ecosystems?

AB

Activity 4.2

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Energy in Ecosystems Producers to Decomposers The organisms in an ecosystem get the energy they need in different ways. Some make food through photosynthesis. Some eat other organisms. Others break down the remains of dead plants and animals.

Organisms within an ecosystem can be classified by how they obtain the energy they need to carry out life processes.

An organism that makes food through photosynthesis is called a producer. In most land ecosystems, plants are the main producers. In aquatic ecosystems, microscopic algae called phytoplankton are the main producers. Plants and phytoplankton use light energy from the Sun, carbon dioxide and water to produce food in the form of sugar and oxygen. They obtain the energy they need from the sugar that is produced.

What producers can be found in a pond ecosystem? How do the producers obtain the energy they need?

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An organism that gets energy by eating other organisms is called a consumer.

All animals are consumers. They get the energy they need by feeding on other organisms in the ecosystem.

Animals that eat plants are herbivores. They are primary consumers. They obtain their energy from the plant matter they eat.

What are some examples of consumers in a grassland? How do they obtain the energy they need?

1 01

Animals that eat other animals are carnivores.

They are also called secondary consumers.

They obtain their energy from the tissues in the animals they feed on.

A bee-eater is a secondary consumer.

Organisms that feed on secondary consumers are called tertiary consumers. They are often referred to as top predators and are not usually prey to other animals in the ecosystem.

A short-toed snake eagle is a tertiary consumer.

1 02

Some organisms meet their energy requirements by decomposing organic matter – the remains of dead plants and animals.

They feed on the broken down material. These organisms are called decomposers. The process of decomposing organic matter releases nutrients back into the ecosystem. Bacteria and fungi are decomposers, as are some small invertebrates such as earthworms, termites and millipedes.

What role do decomposers play in an ecosystem?

AB

Activity 4.3

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The energy in a food chain enters an ecosystem as light energy from the Sun.

Food Chains Animals get the energy they need by eating other organisms.

The energy from food is used for body repair, growth, movement and to maintain body warmth. The energy released from food was once energy from the Sun that was captured by plants during photosynthesis.

A food chain is a simple and often graphical model that shows how energy and nutrients flow through an ecosystem.

Arrows are used to show the direction of energy flow.

Marsh grass gets the energy it needs by using the energy in sunlight to photosynthesize.

Energy flows from producers to primary consumers when a vole feeds on marsh grass.

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Producers are at the bottom of the food chain, followed by primary, secondary and tertiary consumers. Decomposers play a continual role in recycling nutrients in the ecosystem.

By following the energy path in a food chain, from producers to primary and secondary consumers and decomposers, we can see that most of the energy in an ecosystem can be traced back to the light energy from the Sun. Explain why most of the energy in an ecosystem can be traced back to the Sun.

AB

Activity 4.4 Energy flows from secondary consumers to tertiary consumers when a marsh harrier eats a garter snake.

Energy flows from primary consumers to secondary consumers when a garter snake eats a vole.

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Food Webs A food chain shows how energy moves from one organism to another. However, in an ecosystem, consumers get the energy they need by eating more than one type of organism. Consumers are also eaten by more than one type of consumer. So, in an ecosystem, there are many interconnected food chains. elf owl

A food web is a model used to show these interconnected food chains. It shows the many paths energy can take as it flows from one level to the next.

AB

Activity 4.5 mantid

antelope squirrel

fluff grass

1 06

wood rat

harvester ant

prickly pear cactus Sonoran Desert food web

How is a food web different from a food chain?

red-tailed hawk

diamondback rattlesnake

collard lizard grasshopper mouse

pallid-winged grasshopper

brittlebrush

gila woodpecker

saguaro cactus

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Energy Pyramids

Think Deeply In a rainforest ecosystem, would the number of organisms in a frog population be fewer or greater than the number of organisms in a leopard population?

Explain your answer.

AB

Activity 4.6

Organisms use the energy they obtain to survive.

Approximately 90 percent of the energy at each level in an ecosystem is used to carry out life processes like body repair, respiration, digestion, motion, and in warm-blooded animals, to maintain body warmth. Only about 10 percent is stored in the tissues of the organisms and is available to the organisms in the next level.

An energy pyramid is a model that shows how much energy is available at each level in an ecosystem and the number of organisms each level can support. Because less energy is available at each level as you go up a food chain, the number of organisms that can survive at each level decreases too.

tertiary consumers

energy pyramid for a grassland ecosystem

secondary consumers

primary consumers

producers energy in

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energy passed to next level

energy used or lost

In any healthy and balanced ecosystem, the number of producers is greater than the number of primary consumers. The number of primary consumers is greater than the number of secondary consumers. Only a small amount of the energy remains to support the top predators.

Scientists use energy pyramids to determine if an ecosystem is balanced. If the model does not resemble a pyramid shape, it may indicate the ecosystem is unstable, unhealthy or is undergoing change.

What do energy pyramids show?

How are they useful?

Think Deeply Imagine an ecosystem with four levels in a food chain. If the producers capture 10,000 units of energy from the Sun, work out how much energy will be available to tertiary consumers.

AB

Activity 4.7

energy pyramid for an Arctic Ocean ecosystem

energy in

energy passed to next level

energy used or lost

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Think Deeply Wyatt placed a tomato seed in a pot containing 500 grams of soil. He added 50 ml of water to the pot every other day for one month. He then removed the plant from the soil and measured the mass of the plant and the mass of the soil. The mass of the plant was 20 g. The mass of the soil was 495 g. What can Wyatt infer about where the plant acquired the materials it needed for growth?

Try This!

In small groups, plan and conduct an investigation to demonstrate that plants acquire the materials they need for growth chiefly from air and water.

The matter that makes up the young oak tree came primarily from the matter in water and the air.

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Matter in Ecosystems Just as energy flows through an ecosystem, so too does matter.

Consider a growing plant in an ecosystem.

Each day, week and month that passes, the plant grows and increases in mass. Plants acquire the material they need to grow primarily from air and water. Through the process of photosynthesis, plants convert the air, water and nutrients from the soil into matter that is food in the form of sugar.

Matter moves through an ecosystem when animals consume plants and other animals, drink water and breathe in air.

Did You Know?

Matter moves through the ecosystem as primary consumers eat plants, drink water and excrete wastes.

As matter cycles within an ecosystem, the weight of soil does not change significantly.

Soil only provides a small amount of material for plant growth. Scientists are able to grow some plants without the need for soil. This method of growing plants is called hydroponics.

Secondary and tertiary consumers take in matter as they eat other animals and also take in air, water and excrete wastes.

When these organisms die, they are consumed by decomposers. The decomposers transform the organic matter into inorganic nutrients that can be recycled back into the ecosystem.

How does matter move through ecosystems? Where does the matter come from?

Engineer It! Design and build a hydroponics system to grow a tomato plant as tall as possible. Compare your system to those of your classmates. How could your system be improved?

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Science Words Use the words to complete the sentences. biotic factors abiotic factors individual population community

producer consumer primary consumer secondary consumer tertiary consumer

decomposers food chain food web energy pyramid

break down organic material and absorb the broken 1. down remains. is an organism that gets energy by eating 2. A other organisms.

3. A

is an organism that makes food through photosynthesis.

4. An animal that feeds on secondary consumers is a 5. A single organism in an ecosystem is called an 6. All of the organisms in an ecosystem are called

. . .

7. All of the non-living things in an ecosystem are called

.

8. All of the organisms of the same kind that interact and reproduce within an ecosystem make up a .

9. A is a model used to show the interconnected food chains in an ecosystem.

10. A is a simple and often graphical model that shows how energy and nutrients flow through an ecosystem.

11. A consists of all of the interacting populations within an ecosystem.

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12. An animal that feeds on a producer is a 13.

. .

An animal that feeds on primary consumers is a

14. An is a model that shows how much energy is available at each level in an ecosystem.

Review 1. List three biotic factors you would expect to find in a tropical rainforest ecosystem.

2. List three abiotic factors you would expect to find in a tropical rainforest ecosystem.

3. Draw and label a simple diagram to show an individual, a population and a community in a grassland ecosystem.

4. What role does each organism play in a desert ecosystem?

(a) hawk

(b) rattlesnake

(c) brittlebrush

(d) wood rat

5. What does a food web show?

6. How is an energy pyramid different from a food web?

7. Explain how all of the food within an Arctic Ocean ecosystem can be traced back to the energy in sunlight.

8. Riley thinks most of the material for plant growth comes from the soil.

Do you think Riley is correct? Explain your answer.

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5

Earth’s Land and Water

In this chapter you will ...

• describe the structure of the Earth and the movement of the Earth’s tectonic plates.

• list and describe the Earth’s main landforms and water sources.

• explain the importance of clean, fresh water and describe the ways in which it is used by people.

What processes shape the surface of the Earth?

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What makes up the Earth’s hydrosphere?

Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

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Structure of the Earth Amazing Fact!

The temperature of the Earth generally increases with depth. Where the crust meets the mantle, the temperature is about 1,000oC. Where the mantle meets the outer core, the temperature is about 3,500oC. The temperature of the inner core is about 5,200oC.

Evidence from earthquakes, volcanoes and other natural hazards has enabled scientists to support the claim that the Earth is composed of four layers, with each layer having unique properties. The interactions between the Earth’s layers affect the processes that shape the Earth’s surface.

The outermost layer, the Earth’s rocky surface, is called the crust. The crust is the thinnest layer with a thickness of between 6 to 70 kilometers.

The Earth is composed of four distinct layers, each with unique properties.

crust

mantle

outer core

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Beneath the crust lies the mantle, which extends from the crust to a depth of 2,890 kilometers. The mantle is made up of hot solid and molten rock.

The central part of the Earth is the core. At a depth of 2,890 to 5,150 kilometers is the outer core, which is made mostly of molten rock. Below the outer core lies the inner core stretching from 5,150 to 6,370 kilometers. The inner core is solid.

Discuss and describe the characteristics and properties of the different layers of the Earth.

Try This!

Use modeling clay of different colors to make a model of the Earth. Carefully cut the model in half to reveal its layers.

Go Online!

Head to the NGScience website to learn more about the Earth’s layers and their properties.

QuickCode: V2T2

inner core

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Plate Tectonics Go Online!

There are three kinds of tectonic plate boundaries – divergent, convergent and transform plate boundaries.

Discover how each type of boundary shapes the surface of the Earth in different ways in a video on the NGScience website.

QuickCode: Z9P6

The Himalayas were formed by the movement of tectonic plates towards each other.

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By observing patterns in the movement of continents and fossil evidence, scientists developed a model of the structure of the Earth’s crust, called plate tectonics. The model explains that tectonic plates lie on top of a flowing region of molten rock in the upper part of the Earth’s mantle.

The tectonic plates float and move slowly on the molten rock. As they do, they bump, slide and grind against each other.

The Thingvallavatn valley in Iceland was formed by tectonic plates moving away from each other.

Forces from these tectonic plate interactions can cause the Earth’s crust to buckle and bend over many years. These interactions can result in the release of large amounts of energy in the form of earthquakes and volcanic eruptions.

Along with weathering and erosion, the movement and interactions between tectonic plates are the main processes that continually change the surface of the Earth – on land and in the ocean.

AB

Amazing Fact!

The slow movement of the Earth’s continents on tectonic plates, along with extensive fossil evidence, has led scientists to believe that long ago the Earth consisted of a giant supercontinent called Pangaea. It began assembling about 335 million years ago and began to break up about 175 million years ago.

Activity 5.1

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What are some landforms on the Earth’s surface? How did they form?

Earth’s Landforms Shaping the Earth’s Surface

Grand Canyon

Go Online!

Take a virtual field trip to the Grand Canyon and discover its many fascinating landforms.

QuickCode: B3G4

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Over millions of years, forces and processes have been continually shaping the surface of the Earth and they continue to do so today.

Some processes occur too slowly for us to notice from day to day. The Grand Canyon in the United States has been forming over millions of years by the weathering, erosion and deposition caused by the Colorado River running through it.

Denali, the highest mountain peak in the USA, has also been forming over millions of years.

It rises above the ground around it due to the pressure caused by the movement of tectonic plates beneath it.

Denali is the highest mountain in North America.

Other forces and processes, like a volcanic eruption or earthquake, change the Earth’s surface almost instantly.

Try This!

The combination of these rapid and slow changes have shaped the Earth’s surface into physical features called landforms. Mountains, plains, valleys, canyons and plateaus are some examples of landforms.

In small groups, discuss the different landforms in your area. Create a chart to classify the landforms by how they formed.

Denali was formed by the movement of tectonic plates towards each other.

North American Plate

Pacific Plate

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A mountain is a landform that rises above the surrounding land. A mountain is taller than a hill and usually has steep slopes and a sharp or rounded peak. There are three main types of mountains that differ in how they formed.

Volcanic mountains are formed when magma pushes up from beneath the Earth’s surface. When the magma reaches the surface, it creates a volcanic mountain. The mountains can get larger and taller when larva cools during volcanic eruptions. Mount Fuji in Japan is an example of a volcanic mountain.

A photograph of Olympus Mons taken by the unmanned Viking 1 spacecraft.

Amazing Fact!

Other planets in our solar system have mountains too. The tallest mountain, Olympus Mons, can be found on Mars. It is a volcanic mountain with a height of about 21 kilometers (13.6 miles). That’s about two and a half times taller than Earth’s tallest mountain, Mount Everest.

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Mount Fuji

Sierra Nevada mountains

Fold mountains are created when two or more of Earth’s tectonic plates are pressed together.

The force pushes sedimentary rock upwards into a series of bends and folds. The tallest mountain range on the Earth, the Himalayas, are an example of fold mountains.

Block mountains are formed by the movement of the Earth’s crust along cracks called faults. The movement causes the Earth to pull apart and break into large chunks of rock. Some rocks are pushed upwards, forming mountains. The Sierra Nevada mountain range in the Western United States are block mountains.

Mount Everest in the Himalayan mountain range is the tallest mountain on Earth.

What are the different ways in which mountains are formed?

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Did You Know?

A plain adjacent to a source of water such as a lake or river can be flooded when the water level is high. Called floodplains, these landforms are rich in diversity. Many organisms are attracted to floodplains when water releases nutrients into the soil.

At the base of many mountains are plains and valleys. Plains are wide, flat expanses of land with little change in elevation. Plains are generally in low-lying areas, but can also form on plateaus. Plains that extend from land to the ocean are called coastal plains. The size of plains can vary between a few hectares to hundreds of thousands of square kilometers. Being wide and flat also make plains suitable for agriculture and livestock farming. Many plains were formed over time by the erosion of the land from nearby hills or mountains. Other plains were formed by deposition of sediment by water or wind.

Like plains, valleys are low-lying areas, often between mountains or hills. Water may flow through a valley as streams or rivers. Some valleys are caused by the weathering and erosion of glaciers and have a u-shape. Others are formed by running water such as a river or stream and have a sharper v-shape. valley between two hills

The Great Plains are a broad expanse of flat land in the United States. They cover an area of more than 2.5 million square kilometers.

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Canyons, also called gorges, are deep, narrow channels that run between steep mountains or cliffs. Canyons are created by weathering and erosion of uplifted sedimentary rock caused by a river running through it. The formation of canyons usually takes millions of years. Scientists believe the Grand Canyon in the United States took between five to six million years to form.

A plateau, also called a high plain or tableland, is flat terrain that elevates sharply from the surrounding land on at least one edge.

Plateaus are often formed by the erosion of the surrounding area, leaving part of the terrain above ground surrounded by steep ledges.

Plateaus can also be formed by volcanic activity.

The Tibetan Plateau in the Himalayas is Earth’s highest and largest plateau. It covers an area of 2.5 million kilometers (970,000 sq mi) and has an average elevation of about 4,500 meters (14,800 ft).

The view from the Tibetan plateau to the Himalayan mountains.

Colca Canyon

Amazing Fact!

The Colca Canyon in southern Peru is formed by the erosion of volcanic rock caused by the Colca River. With a depth of over 3,270 meters (10,730 ft), it is one of the deepest canyons on Earth.

AB

Activity 5.2

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The Hydrosphere Amazing Fact!

Scientists and engineers have discovered several ways to turn salt water in the ocean into fresh water suitable for human use – a process called desalination.

Desalination is used extensively in the Middle East, particularly in Saudi Arabia.

Engineer It! As a class, design and build a device that uses heat to desalinate salt water. Test the effectiveness of the design.

Suggest and test how it could be improved.

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The hydrosphere is the combined mass of all of the water on Earth. It includes water in the atmosphere, oceans, lakes and rivers. It also includes groundwater and water in the form of ice at the poles and in glaciers.

The water sources in the hydrosphere can be divided into two main groups based on the amount of dissolved salts they contain.

Water that contains a lot of dissolved salts is called salt water. Due to the high level of salts, people cannot drink salt water.

Water that contains little dissolved salts is called fresh water. Clean, fresh water is suitable for people to drink and use for various purposes.

The vast majority of water on Earth, about 97.5%, is salt water held in the ocean. About 2.5% of the water in the hydrosphere is fresh water.

Much of the Earth’s fresh water is frozen at the poles or in glaciers. Only a small amount, about 0.5%, is available for people to use.

The Ocean The ocean covers more than three-quarters of the Earth’s surface. The ocean gives the Earth its blue appearance when viewed from space. The ocean is a diverse environment stretching from warm shallow coral reefs to the cold and dark deep ocean where no sunlight reaches the ocean floor.

The high amount of dissolved salts in the ocean means the water cannot be used for drinking or the many other ways people use fresh water.

The ocean is home to a great diversity of organisms that are adapted to living in salt water.

Think Deeply The process of desalinizing salt water often requires large amounts of electricity. How could a hot, dry and sunny country like Saudi Arabia produce large amounts of fresh water using renewable energy sources?

Why is the salt water in the ocean not suitable for most human uses?

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low tide

high tide

high tide Earth

moon

low tide Tides are caused by the gravitational interactions between the Earth and its moon. The gravitational pull of the Sun also influences tides.

The water in the ocean is constantly moving. Waves form as wind blows across the surface of the ocean. This causes the water to move in a circular motion. Waves can slow down and stop as they lose energy or break when they reach shallow water or the shoreline.

The gravitational pull of the Earth’s moon causes tides. Tides are the rise and fall in the level of water in the ocean and other bodies of water connected to the ocean.

Another way water in the ocean moves is in currents. An ocean current is the continual movement of water usually in one direction. Currents close to the surface of the ocean, called surface currents, are caused by wind.

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Water deep in the ocean moves too.

Deep ocean currents are caused by differences in water temperature and salinity.

Salinity is the amount of salts dissolved in water.

Currents move in large circular patterns.

Usually currents move in clockwise spirals in the Northern Hemisphere and in counter-clockwise spirals in the Southern Hemisphere.

Ocean currents play a critical role in regulating the Earth’s climate. Currents continually move warm water from the equator towards the poles and cold water from the poles back to the tropics.

Currents are of vital importance to many organisms. Currents help to move nutrients from the deep ocean to the surface. Many marine organisms are also dependent on ocean currents for reproduction.

Ocean currents play an important role in the migration patterns of whales and many other marine organisms.

Think Deeply In what job and professions would it be useful to know about the movement of water in ocean currents?

Discuss with your classmates.

surface current deep ocean current

map of surface and deep ocean currents

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The Ocean Floor

Try This!

Use modeling clay and a clear plastic container to build an ocean basin. Fill the container with water to show the different depths at which different features are found.

The ocean basin is a depression of the Earth’s surface in which the ocean lies. It fills the areas between continents. Just as plate movements and other processes shape the Earth’s land, they also shape the floor of the ocean basin.

The continental shelf is where continents meet the ocean. This is the shallowest underwater part of the ocean basin that gradually slopes down.

At the end of the continental shelf at a depth of about 200 meters is a sharp drop-off called the continental slope.

The continental slope leads to the abyssal plain.

Similar to plains on land, the abyssal plain is a large open flat area of the ocean floor. At depths of between three to six kilometers, sunlight does not reach the ocean floor of abyssal plains. The few organisms that live at these depths have special adaptations for surviving in the dark and island cold ecosystem.

continent

abyssal plain

seamount

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Scattering the vast abyssal plain are underwater landforms caused by the movement of tectonic plates and volcanic activity. There are hills, valleys and underwater mountains called seamounts. A seamount that reaches the surface of the ocean forms an island.

Where tectonic plates meet underwater lies the mid-ocean ridge – an underwater mountain range that stretches for over 65,000 kilometers (40,000 mi).

At the deepest part of the ocean floor lie ocean trenches – long and narrow depressions in the ocean floor. Ocean trenches occur at places where one tectonic plate slides under another.

How are the formations on the ocean floor similar to Earth’s landforms?

Go Online!

Through a combination of tectonic plate boundary interactions and volcanic activity, new oceanic crust is continually forming along mid-ocean ridges. The oceanic crust slowly moves away from the ridge, creating new areas of ocean floor.

Discover more in a video on the NGScience website.

QuickCode: G4P1

AB

Activity 5.3

continental shelf

mid-ocean ridge

ocean trench

continental slope

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Try This!

Distribute 1,000 milliliters of water between different containers to show the different amounts of salt and fresh water in the hydrosphere. Create a pie chart to present the data.

Go Online!

Head to the NGScience website to discover how glaciers have been shaping the Earth’s surface for millions of years.

QuickCode: L7W9

Glaciers and Ice Caps The majority of water in the hydrosphere is salt water held in the ocean. This salt water is not suitable for human consumption and cannot be used by many land plants and animals.

Only a small amount, about three percent, of the water in the hydrosphere is fresh water.

Most of the fresh water in the hydrosphere, about 68 to 70 percent, is in the form of solid ice sheets at or near the Earth’s North and South Poles. Some fresh water ice is held in glaciers and icebergs.

A glacier is a large, usually elevated, body of frozen water that slowly moves downwards towards the ocean or lake. Icebergs are chunks of ice that break off of ice shelves or glaciers and float freely into the ocean.

The frozen water at the poles, in glaciers and icebergs cannot be accessed by people for drinking and other purposes.

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Groundwater Most of the fresh water in the hydrosphere that is in liquid form is underground. This water, called groundwater, seeps into cracks and spaces in soil, sand and rock. The water is stored in large bodies of rock called aquifers.

Groundwater that is close to the surface of the Earth can be extracted by drilling or digging wells. The extracted fresh water can then be used by people.

Think Deeply What human activities can cause groundwater to become polluted and no longer suitable for use?

aquifer

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Lake Superior is the largest lake in the United States.

Rivers, Lakes and Streams A very small amount of the water on Earth, about 0.3 percent, is held in lakes or flow in rivers and streams. These sources of water are essential parts of terrestrial ecosystems and can be used by people.

The meandering river provides a source of fresh water for the residents of the town.

AB

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Activity 5.4

People often build cities and towns near lakes and rivers. The fresh water is often cleaned and filtered in treatment plants before being distributed to homes, farms and businesses where it is used in a variety of different ways.

Storing Water The amount of precipitation in a region changes throughout the year. This results in changes to the amount of fresh water available for people to use. To help make water available year-round, people often store water in reservoirs. A reservoir, also called a dam, is an artificial lake used to store water.

Reservoirs allow people to control the amount of water that is sent to homes, farms and businesses. They help to ensure that fresh water is available all year round.

Many reservoirs can also be used to generate electricity using hydroelectric power stations.

Go Online!

Learn how hydroelectric power stations use flowing water to generate electricity on the NGScience website.

QuickCode: W5V5

Think Deeply In what ways can storing water in reservoirs harm the environment and the organisms that live there?

What are some reasons people store water? How is the water used?

People use reservoirs to store and control the flow of water.

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Using Water Did You Know?

Many devices and appliances in our homes are designed to reduce the amount of water they use.

Examples include watersaving shower heads, halfflush toilets and washing machines with reduced wash times. What are some other examples?

Fresh water is used by people in a variety of different ways. Drinking clean, fresh water is essential for our bodies to carry out life processes. We need water to digest food, remove wastes and transport food and oxygen around our bodies. All of the cells in our bodies need fresh water to function.

Fresh water is used in our homes in many ways. Often, water is distributed from a reservoir to our homes by a water company.

The amount of water used by each house is measured and people pay the water company for the amount they use.

In our homes, fresh water is used for activities such as cooking, cleaning and washing. Fresh water is used to maintain lawns and gardens.

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Fresh water is essential to farming. It is used to grow crops and raise animals.

Clean, fresh water is used to process food and beverages and to produce medicines, cosmetics and cleaning products.

Businesses and factories use fresh water in manufacturing, cleaning, cooling and electricity production. As the water is not consumed by people or other organisms, it is often not as clean as drinking water. Salt water can also be used in manufacturing and cooling.

In some regions, the amount of fresh water available for human use changes throughout the year. Fresh water can also become polluted, making it unsuitable for use. It is important to conserve the amount of water we use and ensure that our fresh water sources are kept clean.

AB

Activity 5.5

Water is often used for cooling during manufacturing and electricity production.

Try This!

Create a chart to show the ways you use water from day to day. Estimate the liters of water used. In small groups, discuss some ways you can reduce the amount of water you use.

Why is it important to conserve fresh water and keep it free of pollutants?

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In the Field

Seismologist A seismologist is an Earth scientist that specializes in the study of seismic waves.

Seismic waves are waves of energy that travel through the Earth’s crust, usually as the result of tectonic plate interactions or volcanic activity.

Events that produce seismic waves are called seismic activities.

To measure the size of seismic waves, seismologists use an instrument called a seismograph. They are usually secured to rock in permanent positions on the ground. They record even the slightest vibrations in the Earth’s crust and allow seismologists to determine the size of an earthquake or volcanic eruption.

The Richter scale was developed in 1935 by Charles F. Richter.

Seismologists often work in the field. They may use portable seismographs to obtain accurate information about seismic activity.

Special computer software is used to analyze and interpret the data they collect. A scale, called the Richter scale, is used to determine the size of a seismic event. The higher the number on the Richter scale, the more powerful and destructive the seismic event.

Moderate Light Minor

5.0

6.0

Strong 7.0

Major

4.0 8.0 Great

3.0

9.0 Micro

2.0 1.0

10 the Richter scale

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Science Words Use the words to complete the sentences. plate tectonics tectonic plates mountain plain valley canyon

plateau hydrosphere salt water fresh water tides surface currents

deep ocean currents ocean basin glacier groundwater reservoir

1. Currents close to the surface of the ocean are called 2. A 3.

.

is an artificial lake used to store water. are the rise and fall in the level of water in the ocean.

are deep, underwater currents caused by differences in 4. water temperature and salinity.

5. Fresh water stored in underground aquifers is called

.

6. The combined mass of all of the water on Earth makes up the .

7. A is a landform that rises above the surrounding land and usually has steep slopes and a peak.

8. A is a large, usually elevated, body of frozen water that slowly moves downwards towards the ocean or lake.

9. Water that contains a lot of dissolved salts is called 10. Water that contains little dissolved salts is called

. .

11. The Earth’s crust is made up of large, moving pieces called

.

12. A is a low-lying area, often between mountains or hills. It may have a u-shape or v-shape.

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13. A in elevation.

is a wide, flat expanse of land with little change

14. is a model based on the idea that the Earth’s crust is made up of large, moving pieces. is a deep, narrow channel that runs between steep 15. A mountains or cliffs.

16. The ocean lies.

is a depression of the Earth’s surface in which the

17. A is flat terrain that elevates sharply from the surrounding land on at least one edge.

Review 1. Copy and complete the table.

Feature of Earth’s Surface

Description

Canyon Plateau Abyssal Plain Mid-ocean Ridge Ocean Trench 2. List the three main types of mountains and describe how they form.

3. Draw a labeled diagram that shows the features of the ocean floor.

4. Describe the ways in which water moves in the ocean.

5. What percentage of fresh water on Earth is available for people to use?

Where is the remaining fresh water?

6. Why is it important to conserve fresh water and keep available fresh water sources clean?

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