Next Generation Science Level 3 - Textbook A

Science for the Next Generation

Science Gra d e T h ree

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.

gre

Charact

Fish are anim live in the oc can also be such as stre

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.

Most fish re some give b

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

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Ecologist

If you are interested in all sorts of organisms and how they interact within their environment, then maybe you’d like to be an ecologist.

A community of living things and their interactions with their environment is called an ecosystem.

An ecologist is a scientist who studies these ecosystems.

Ecologists study a wide range of interactions and relationships within a given ecosystem. They may study small parts of an ecosystem such as small bugs living in the soil. They may also study large interactions such as fish populations in the ocean or how rainforests effect the atmosphere.

Ecologists usually choose a specific environment or living thing to study. For example, an ecologist desert or ocean environments. may only study A Clos er Look They may also choose to study one type of such as weather events or how human interaction Graphing Weather impact environments. activities Scientists are constantly collect ing data about the weath They often create tables er. and environment orthem graphs to help an ecologist, which you were If seaso understand nal changes in weath er. study?

Tables and charts are would you choose to organism way to comm also a useful unicate weather inform ation to people.

133 Let’s take a look at the yearly changes in weath er for San Francisco, United States .

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

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Average Daylight Hours – San Francisco Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 10 11 12 13 14 14.5 14.5 13.5 12.5 11.5 10 9.5

Average Precipitation

120 mm

– San Francisco

100 mm 80 mm

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.

60 mm 40 mm 20 mm 0 mm

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Jan

Feb Mar Apr May Jun

Jul

Aug Sep

Oct Nov Dec

Amazing Fact!

Interesting facts to build interest and enthusiasm.

fish gills

stingray

eat white shark

Fish have body parts well-adapted to life in water. They have gills to take in oxygen from the water. They have fins and tails to

teristics of Fish

mals that live in water. Most fish cean, which is salt water. Fish found in freshwater habitats, eams, rivers and lakes.

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

A starfish has the word ‘fish’ in its name. Do you think a starfish is a fish?

Explain your answer.

help them swim.

Like reptiles and amphibians, fish are cold-blooded.

eproduce by laying eggs, but birth to live young.

Did You Know?

Think Deeply

Try This!

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

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Science Words Use the words to comp

Review

lete the sentences.

mammals metamorphosis fish insects pupa 1.

oxygen invertebrates amphibians larva chrysalis

Animals need a specia l part

of air called

2.

Animals with a backb one are

3.

Animals without a backb one

4.

vertebrates birds reptiles caterpillar

.

are called

are the only animals with

6.

are cold-blooded with

7.

Frogs and salamander s are

8.

A change in body form

.

a body covered in feathe rs.

a body covered in scales

or plates.

. They have smooth, moist

during an animal’s life

9.

live in water and have

10.

have six legs and a body

List the needs of anima ls.

List three vertebrate anima ls.

3.

List three invertebrate

4.

How are mammals differe nt from most other anima reproduction? ls in terms of

.

called

are animals with a body covered in fur.

They give birth to live young.

5.

1.

2.

cycle is called

gills to help them take

animals.

5.

List the characteristics

6.

List four kinds of reptile s.

7.

How is the life cycle of

8.

List the characteristics

9.

Describe insects in terms

of birds.

birds similar to that of

of their number of legs

10. Classify the anima ls as either

skin.

(a) .

reptiles?

of fish.

A worm-like butterfly egg.

12.

A caterpillar spins a coveri ng over its body, called a enters an inactive state called a .

, called a

and body parts. .

(b)

in oxygen.

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hatches from a

(c)

Discussion

(d)

, and

How does the weather change throughout the year in San Francisco?

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Average Maximum Temp erature – San Francisco

25oC

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

vertebrates or inverte brates

divided into three parts.

11.

AB Activity

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

20oC 15oC 10oC 5oC 0oC

AB

Jan

Feb Mar Apr May Jun

Jul

Aug Sep

Review

Oct Nov Dec

Activities 9.7 – 9.8

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

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

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Contents Unit 1 - Living Things Around Us What Are Living Things?

Needs of Living Things Classifying Living Things Review

Unit 2 - All About Plants Plant Needs Plant Parts Classifying Plants Review

Unit 3 - All About Animals Needs of Animals Classifying Animals Vertebrates Invertebrates The Circle of Life Review vi

2 4 9 13 14

16 18 20 26 35

36 38 42 44 66 75 77

Unit 4 - Inheritance and Traits Heredity and Traits Behavioral Traits Environmental Traits Natural Selection Review

Unit 5 - Adaptations for Survival What Are Adaptations?

Living in Groups Surviving Change Review

Unit 6 - Organisms of the Past Life on Earth Long Ago Fossils Review

78 80 84 86 88 91

94 96 114 122 130

136 138 142 154

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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 used 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.

Do not enter the laboratory without a teacher.

Follow your teacher’s instructions.

If you have any questions or are unsure of what to do, raise your hand and ask your teacher.

Do not eat, drink, play or run in the laboratory.

Wash your hands with soap when 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.

Wear appropriate safety gear when carrying out scientific investigations.

Safety gear includes a lab coat, safety googles and gloves. Tie long hair back and do not wear open-toed shoes.

Be careful when handling sharp tools 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 O such 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

Living Things Around Us

In this chapter you will ...

• list the characteristics of living things.

• list the needs of plants and animals.

• understand that all living things are made up of one or more cells.

• list the four main groups of organisms.

How can you tell that something is a living thing?

2

What do plants and animals need to live and grow?

Go Online!

How can we organize and classify living things?

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

3

What Are Living Things?

Try This!

Predict how much you think you will grow in one year. Measure and mark your height on a wall once a month.

How accurate was your prediction? In what other ways do you change as you grow?

There is a great diversity of things around us.

Some are living things. A living thing is called an organism. Other things are non-living.

How can we tell which things are living and which are non-living?

AB

Activity 1.1

Growth Look at a photograph of when you were one or two years old. How have you changed since you were a baby?

You are a living thing and like all living things, you grow as you get older.

A newborn kitten grows as it gets older. It gets bigger and taller. As an adult cat, it will produce new kittens of its own.

AB

A young kitten gets larger and heavier as it grows into an adult cat.

4

Activity 1.2

Sunflower seedlings get bigger and taller as they grow. As adult sunflower plants, they will develop seeds and produce new sunflower plants.

Response to Change

sunflower seedlings

Living things respond to changes around them.

Some plants bend their leaves to face the sunlight. Other plants, like the mimosa plant and Venus flytrap, close their leaves in response to touch. The leaves of an oak tree change color and fall to the ground in response to changes in seasons and the weather.

Animals respond to changes around them too.

Kangaroos may seek shade on hot days in the Australian bushland. When a meerkat senses danger, it will respond by retreating to its burrow.

AB

Activities 1.3 – 1.4

5

Movement Living things move. Animals move from place to place in search of food or to flee from danger.

Some plants move their parts in response to changes around them. The Venus flytrap closes its leaves to catch small insects.

Other plants move their stems, leaves or flowers to follow the movement of the Sun.

Think Deeply A car can move from place to place. Explain why a car is not a living thing.

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Reproduction All living things reproduce. To reproduce means to produce new young of the same kind.

An adult lion will give birth to lion cubs. An adult chicken will lay eggs from which baby chicks will hatch.

An adult tomato plant has flowers and fruits.

Under the right conditions, the seeds inside the fruits will fall to the ground and grow into new tomato plants.

Why is it important that all living things are able to reproduce?

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Did You Know?

Some living things, such as bacteria, are made up of only one cell. They are called unicellular, or one-celled organisms.

Cells All living things are made up of tiny building blocks called cells. Most cells are too small to see using only your eyes. To observe cells, scientists use a microscope. A microscope is a scientific instrument that is used to closely observe very small objects.

Most organisms are made up of many different types of cells. The different cells help the organisms in different ways.

onion skin cells

AB 8

Activity 1.5

Needs of Living Things Another way you can tell if something is a living thing is by looking at the things it needs. All living things need food, air and water. Different living things get what they need in different ways.

Food Food gives living things the energy they need to grow and carry out life processes. Plants use air, water and the energy in sunlight to make their own food. This food-making process is called photosynthesis.

Plants store the energy they make in different parts. This energy is passed to animals when they eat those plant parts.

Other animals get the energy they need by eating other animals.

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Water All living things need water. Many animals drink water. Others get water from the food they eat.

The water helps animals to break down and transport food inside their bodies.

Plants take in water through roots. The water is used in photosynthesis. It also helps to transport food, nutrients and minerals within the plant.

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Oxygen and Carbon Dioxide Air is a mixture of different gases. To make food, plants need a gas in air called carbon dioxide. They take in carbon dioxide through small openings found mostly on the underside of their leaves.

When plants make food, they also produce a gas called oxygen. The oxygen leaves the plant through the openings in the leaves.

Oxygen is the part of air needed by people and animals. Many land animals get the oxygen they need by breathing in air using lungs. Many aquatic animals, such as fish, have gills that help them take in oxygen from water.

Gases enter and exit a plant through tiny openings found mostly on the underside of leaves.

What will happen to an organism if it does not get enough food or water?

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Amazing Fact!

Every year, about 25,000 humpback whales swim thousands of miles from the icy waters of Antarctica to the much warmer waters of Queensland, Australia.

In the warmer waters, they give birth to young before making the return trip to Antarctica.

A Place to Live All organisms need a place to live. Animals need a place that provides them with all the food, water and oxygen they need. The place an animal lives also keeps them safe from danger and provides them with a safe space to raise their young. Some animals, like a frog or fish in a pond, only need a small place to live. Others, such as humpback whales and grizzly bears, need much larger places to live.

Plants need a place to live too. They need space for their roots to spread out and take in minerals and water. The need a place with enough sunlight to photosynthesize.

AB

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Activities 1.6 – 1.7

Classifying Living Things There is a great variety of living things around us. Plants fill our parks, gardens and forests.

Animals, big and small, can be found all over the Earth, underground and underwater too. There are also many living things that are too small for us to see!

Go Online!

Watch a video about how scientists classify organisms into groups on the NGScience website.

QuickCode: G8S6

To organize and learn more about different types of organisms, scientists classify them into four main groups – microorganisms, fungi, plants and animals.

AB

Microorganisms

Fungi

Plants

Animals

Activity 1.8

Make a list of some organisms found in your local area. How can you classify them into groups?

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Science Words Use the words to complete the sentences. organism respond reproduce

cells photosynthesis

carbon dioxide oxygen

1. To help them survive, organisms

to changes around them.

2. All organisms are made up of one or more

.

3. Plants make their own food through the process of

.

4. All organisms produce new young of their own, they 5. A living thing is also called an 6. Plants take in of their leaves.

.

.

through holes found mostly on the underside

7. Fish have gills that help them to take in

from water.

Review 1.

True or false. (a) Plants take in carbon dioxide and give out oxygen. (b) All organisms grow as they get older. (c) Only organisms that can move from place to place are living things.

2. List the things plants need in order to carry out photosynthesis.

3. What can you use to observe the cells that make up all organisms?

4. What must the place an organism lives have?

5. List the four main groups of organisms.

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A Closer Look

Fungi Mushrooms are similar to plants in some ways. They often grow in soil or are attached to trees, and they don’t move about like animals. In fact, up until about 150 years ago, scientists classified mushrooms as a type of plant.

Mushrooms however, are not able to photosynthesize. They get the energy they need by breaking down dead or living plants and animals. As such, scientists now classify mushrooms into a special group of organisms called fungi.

Other types of fungi include bracket fungi, puffballs and molds.

Go Online!

Discover more about fungi on the NGScience website.

QuickCode: E6G3

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2

All About Plants

In this chapter you will ...

• list the needs of plants.

• list and describe plant parts and functions.

• describe the life cycle of a flowering plant.

What are the needs of plants? How do the parts of a plant help it to get the things it needs to survive?

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

Go Online!

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

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Plant Needs Think Deeply Deep inside a cave is one place you will not find any plants. Why is this so?

Plants come in all shapes, sizes and colors. They live in all areas of the Earth – from lush, tropical rainforests to icy tundras. Plants also live on and in water. The place where a plant lives is its environment. An environment provides a plant with the sunlight, water, air and nutrients it needs to live, grow and reproduce.

Carbon Dioxide Air is a mixture of different gases. To make food, plants need a gas in air called carbon dioxide.

They take in carbon dioxide through small openings found mostly on the underside of their leaves.

When plants make food, they also produce a gas called oxygen. The oxygen leaves the plant through the openings in the leaves.

How is gas exchange different in plants and animals?

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Water and Nutrients All plants need water to survive. They take in water through their roots. The water travels from the roots, through the stem to the leaves. In the leaves, plants use water to make food.

When plants take in water, they also take in nutrients from the soil. Nutrients are substances dissolved in water. They help the plant to grow and stay healthy.

Light You have learned that plants need carbon dioxide from the air and water to make food. This process of making food is called photosynthesis.

The word ‘photo’ means light and the word ‘synthesis’ means to put together. That’s exactly what plants do! They use the energy in light to combine carbon dioxide and water to make food. Without light, plants would not be able to make food and would not live and grow.

Try This!

You know that all plants need water. What do you think happens if a plant gets too much water?

Conduct an investigation to find out.

Think Deeply A vegetable garden is an environment for plants made by people. What things do people have to do to make sure the plants grow and stay healthy?

Space to Grow All plants need a space to grow. Some plants are able to grow close together. Other plants need more space. If they grow too close together, individual plants may not get enough sunlight.

There also may not be enough water and nutrients for plants to grow.

AB

Activity 2.1

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Try This!

Make a list of the plant-based foods you eat in a week.

Group the foods by the part of the plant they come from.

Plant Parts Plants can be found in almost all areas of the Earth. They come in all shapes and sizes. So far, scientists have identified about 390,000 types of plants. Most plants have the same basic parts.

They have roots, stems and leaves.

Many plants also have flowers and fruits. Each plant part plays an important role in helping the plant get the things it needs to survive and reproduce.

How do the parts of a plant help it to get the things it needs to survive?

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Roots Roots are the plant part that usually grows down into the soil. They often branch out in all directions or grow deep underground.

The roots hold the plant firmly in the ground. Tiny structures on the surface of the roots, called root hairs, take in water and minerals from the soil.

Stems The stem is usually the part that holds up the plant. The water and minerals taken in through the roots travel through the stem to the upper parts of the plant. By holding up the plant, the stem also helps leaves to take in more sunlight.

Leaves The leaves of a plant is where the food-making process takes place. To make food, plants need the energy from sunlight. Many plants have leaves that are wide and flat. This gives them a large surface area which enables them to take in more sunlight. To make food, leaves take in carbon dioxide from the air. The food-making process produces oxygen. The oxygen leaves the plant through the leaves.

AB

Think Deeply Some plants, such as vines, are called climbers. They have stems that wrap around and cling to the trunk and branches of trees.

How does this help the plant get the things it needs?

Go Online!

Observe how water and food are transported through a plant on the NGScience website.

QuickCode: K8T5

Activities 2.2 – 2.4

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A Closer Look

Photosynthesis Plants do not eat food as animals do. To get the energy they need to survive, plants make their own food through an amazing process called photosynthesis.

Sunlight is absorbed by the leaves.

Photosynthesis usually takes place in the leaves of plants. The large surface area of leaves allows them to absorb lots of sunlight. They also take in carbon dioxide from the air. Water taken in by the roots is transported through the stem to the leaves.

The leaf now has all the things it needs to make food. Using the energy from sunlight, it converts the water and carbon dioxide into glucose. The glucose is the food the plant needs. It gives the plant the energy it needs to live, grow and reproduce.

Water and minerals are taken in through the roots.

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Small openings in the leaves take in carbon dioxide from the air.

Go Online!

Get a better understanding of photosynthesis by watching an animation on the NGScience website.

QuickCode: G6S8

Oxygen produced during photosynthesis is given off through the leaves.

During photosynthesis, plants produce oxygen. The oxygen is given off through the leaves. Oxygen is the part of air that animals and people need to survive.

AB Activity 2.5

Think Deeply Plants are able to photosynthesize in moonlight, but they cannot produce as much food as they do during the day. Why is this so?

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Flowers and Fruits Try This!

Go into your schoolyard and observe flowering plants. Make some notes about the similarities and differences between the flowers.

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Most of the plants on Earth produce flowers.

Flowers are often brightly colored or produce odors to attract insects and other animals for pollination. Once pollination occurs, a flower may develop into a fruit. A fruit holds and often protects the seeds from which new plants will grow.

The flowers, fruits and seeds of different plants can look very different. If you look very closely at a sunflower, you will notice it is made up of many smaller flowers.

Each small flower develops into a hard fruit containing the seed.

A white strawberry flower develops into a bright red fruit. The seeds are attached to the outside of the fruit.

Some plants, such as oak trees produce hard fruits. Others, such as papaya trees, produce fleshy fruits.

sunflower seeds

AB Activity 2.6 Papayas are fleshy fruits.

Strawberries have seeds on the outside of the fruit.

Acorns are hard fruits produced by oak trees.

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Classifying Plants There is a great diversity of plants around us. To organize and better understand plants, we can classify them into groups. They may be classified by their appearance, habitat or how they reproduce. Scientists classify plants into two main groups – non-flowering plants and flowering plants.

Non-flowering Plants As the name suggests, nonflowering plants do not produce flowers. Common types of nonflowering plants include mosses, ferns and conifers. cones on a conifer

fern

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moss

fern spores

Non-flowering plants reproduce in different ways. Mosses and ferns reproduce from spores. Conifers have cones that hold the seeds from which new conifers can grow.

AB Activity 2.7

Amazing Fact!

The tallest plant in the world is a type of giant conifer, the sequoia tree, found in California, USA. They can reach heights of almost 100 meters!

sequoia trees

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Flowering Plants More than 80 percent of the plants on Earth are flowering plants.

Flowering plants produce flowers and fruits. They reproduce from seeds.

Amazing Fact!

So far, scientists have named and classified more than 300,000 different kinds of flowering plants. Many more flowering plants have yet to be discovered.

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Flowers contain a sticky powder called pollen. To make seeds, pollen needs to move from one part of a flower to another. This process is called pollination. Pollination is often done by animals called pollinators.

To attract pollinators, many flowering plants produce flowers that are brightly colored, have a strong smell or contain a sweet liquid called nectar.

white daisies

Brightly colored flowers attract pollinators like bees and other insects.

Try This!

In small groups, observe the flowering plants in your schoolyard.

Identify and record the pollinators you observe.

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A Closer Look

Seed Germination Flowering plants reproduce from seeds. Inside a seed are all the things needed for the seed to grow into a new plant.

The outer covering of a seed is called a seed coat. The seed coat protects the seed and keeps it from drying out. Inside the seed coat is a tiny plant, called an embryo. A tiny root, called a radicle, is attached to the embryo. Surrounding the embryo are seed leaves.

Parts of a Seed

embryo (tiny plant) radicle (tiny root)

seed leaves

seed coat

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What does a seed need to start to grow?

Under the right conditions, a seed will start to grow or germinate. To germinate, most seeds need air, water and warmth.

The root is normally the first part to grow from the seed. It grows down to hold the seed in the soil.

Next, a shoot grows upwards. It uses the food in the seed leaves for energy. As leaves begin to develop, the seed leaves fall away and the young plant, called a seedling, begins to make food of its own.

Try This!

Do you think seeds need sunlight to germinate?

Plan and conduct an investigation to find out!

Go Online!

Watch a seed germinate on the NGScience website.

QuickCode: G3Q9

AB Activity 2.8

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Flowering Plant Life Cycle

tomato seeds

All plants have a life cycle that ensures their kind continues to survive and reproduce. All of the stages of a plant’s life make up its life cycle. The life cycles of flowering plants are similar in many ways.

The life of a flowering plant starts as a seed. Under the right conditions, the seed will germinate. Roots grow under the soil. A stem emerges from the soil and the seedling begins to develop leaves. The seedling usually gets taller and develops more leaves as it grows.

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The seedling grows into an adult plant and develops flowers. The flowers hold the seeds from which new plants will grow. After pollination, many flowers will develop fruits. The fruits protect the seeds and also help to spread the seeds to new places. Under the right conditions, the seeds will grow into new plants and the life cycle repeats.

AB

Go Online!

Observe how flowering plants grow and change throughout their life cycle on the NGScience website.

QuickCode: N2D6

Activities 2.9 – 2.10

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Science Words Use the words to complete the sentences. nutrients leaves roots life cycle flowering plants

germinate carbon dioxide non-flowering plants environment flowers

seeds photosynthesis fruits stem pollination

1. To make food, plants need a gas in air called

.

are substances dissolved in water. They help the plant to 2. grow and stay healthy.

3. A plant’s provides it with the sunlight, water, air and nutrients it needs to live, grow and reproduce.

4. Water moves from the of a plant.

, through the

to the

5. The process by which plants make food is called 6. Many plants have brightly colored

.

to attract insects.

which hold and protect the 7. Flowers develop into

from which new plants will grow.

8. is the process whereby pollen moves from one part of a flower to another.

9. When a seed gets air, water and warmth it will

.

10. All of the stages of a plant’s life make up its 11.

Plants that produce flowers are called

12.

Plants that do not produce flowers are called

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. . .

13.

Use the words to label the diagram. seed coat embryo seed leaves radicle (a)

(b)

(c)

(d)

Review 1. List the needs of plants.

2. Describe two functions of the roots of a plant.

3. Describe the main function of leaves.

4. Where does a plant get the energy it needs to make food during photosynthesis?

5. Describe the function of flowers and fruits.

6. List two types of non-flowering plants.

7. Describe the process of pollination.

8. How does a flowering plant change during its life cycle?

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3

All About Animals

In this chapter you will ...

In this chapter you will ...

• list the needs of plants.

• list the needs of animals.

• list and describe plant parts and functions.

• identify the characteristics of different animal groups.

• describe the life cycle of a flowering plant.

• develop models to describe that animals have unique and diverse life cycles.

NGSS: 3-LS1-1

What are the needs of plants? How do the parts of plant help it to get the things it needs to survive?

What are the stages in the life cycles of different animals?

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What are the needs of animals?

How do the different animals get the things they need to survive?

Go Online!

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

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Think Deeply How are the needs of animals similar to the needs of plants? How are they different?

Amazing Fact!

A panda’s diet consists almost entirely of bamboo.

Because the bamboo is low in nutrients and energy, a panda eats for about 14 hours every day and eats about 12 to 15 kilograms of bamboo!

Needs of Animals Animals live in a great variety of places on Earth. They live on land in forests, deserts and grasslands. They live in the ocean, rivers and streams. Some animals live underground too.

The place where an animal lives is called its environment. An environment provides the animal with the food, water, air and shelter it needs to survive.

Getting Food Unlike plants, animals are not able to make their own food. They get the energy they need by eating other living things.

Many animals move from place to place to get the food they need. They move in different ways using legs, wings or fins.

Different body parts help animals get the food they need in different ways. An eagle uses its large wings, sharp claws and powerful beak to catch and kill its prey.

bald eagle

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A giraffe’s long neck and tongue are adaptations to help it get food.

A giraffe has long legs and a long neck to reach leaves in treetops. Its long tongue tears the leaves from the trees.

Getting Water Animals need fresh water to help their bodies function. Water helps animals to process the food they eat. It also helps them to remove wastes and stay healthy.

Amazing Fact!

The kangaroo rat can go its entire life without drinking any water. It gets any water it needs from the seeds and grasses it eats.

Many animals drink fresh water found in puddles, lakes, rivers and streams. Some animals get the water they need from the food they eat.

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Fish have gills to get the oxygen they need from water. fish gills

Did You Know?

Plants take in carbon dioxide from the air and give off oxygen. Animals take in oxygen from the air and breathe out carbon dioxide. This movement of carbon dioxide and oxygen in the air is called the oxygen cycle.

Adult frogs have lungs to take in oxygen from the air. They can also take in oxygen through their moist skin.

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Getting Air Animals need a special part of air called oxygen.

Mammals, reptiles and birds have lungs to take in oxygen from the air.

Fish do not have lungs and cannot breathe air.

They have gills to take in oxygen from water.

Some animals, such as worms and some amphibians, are able to take in oxygen through their skin.

Seeking Shelter An animal’s environment provides it with shelter.

Shelters may provide shade for animals when it is too hot. They keep the animals warm when it is cold or wet. Shelters can also protect animals from other animals or provide them with a safe place to raise their young.

Many animals use plants for shelter. Squirrels and raccoons seek shelter in the hollows of trees. Many birds build nests in trees. Rabbits build their homes among blackberry bushes.

The sharp thorns of the blackberry bush protect them from other animals.

Non-living things provide shelter too. Logs and rocks can provide shelter for insects and other small animals. Caves and burrows provide shelter for many mammals and reptiles.

AB

Anemone fish seek shelter in sea anemones.

Activity 3.1

A blackbird feeding her chicks.

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Classifying Animals Try This!

Run your hand down the center of your back.

What do you feel?

Would you classify people as vertebrates or invertebrates?

Animals come in all shapes and sizes. To make them easier to study, understand and name, scientists classify animals into groups based on ways they are the same.

One way animals can be classified is by the presence or absence of a backbone. A backbone is a series of small bones, called vertebrae, that run down the center of an animal’s back.

Animals with a backbone are classified together as vertebrates. Animals without a backbone are classified together as invertebrates. backbone

A domestic cat has an internal skeleton of bones.

What is a main difference between vertebrate animals and invertebrate animals?

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squid

horned starfish

Most of the animals on Earth are invertebrates.

Invertebrates include small animals such as insects, spiders, worms and snails.

Sea creatures such as giant clams, squid, lobsters and starfish are invertebrates too.

tarantula earthworms

snail

honeybee

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parakeet

corn snake

eagle

Vertebrates Many of the large animals you are familiar with are vertebrates. By looking closely at the structures, body coverings and ways in which vertebrates reproduce, we can further classify them into five smaller groups – mammals, birds, reptiles, amphibians and fish. terrapin

tree frog

salamander

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stingray trevally fish

Compare the vertebrate animals on these pages. How can you tell which animal group they belong to?

AB Activity 3.2

hamster

chimpanzee

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dolphins

Characteristics of Mammals Tigers, monkeys, dolphins, squirrels and polar bears are mammals. Mammals are animals with a body covered in hair or fur. Most mammals reproduce by giving birth to live young. Female mammals produce milk which they feed their young.

hedgehog

tiger cub

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young bonobo

humpback whale

Mammals are warm-blooded animals.

They have lungs and take in oxygen when they breathe in air. Some mammals, such as dolphins, seals and whales, live in the ocean. They must come to the surface to breathe.

What are the characteristics of mammals?

squirrels

polar bear cub

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Did You Know?

The time it takes for a mammal to grow and develop inside its mother is called the gestation period. Generally, smaller mammals have shorter gestation periods than larger mammals. The gestation period for a mouse is about 20 days.

The gestation period for an elephant is 22 months.

Mammal Life Cycles All of the stages of an animal’s life - from first entering the world, to growing and changing, and reproducing young of its own, make up its life cycle.

Most vertebrates reproduce by laying eggs.

Mammals’ life cycles are different in that the unborn young, called an embryo, develops inside the mother. The mother then gives birth to live young. The young look similar to their parents.

male lion

female lion

lion cub

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Adult hippopotamuses with their young.

Adult mammals often stay and 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.

AB Activity 3.3

8-month old lion

Galapagos sea lions

Amazing Fact!

The echidna and platypus are two kinds of animals found only in Australia.

These strange-looking mammals reproduce by laying eggs.

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hornbill

Characteristics of Birds

Birds are the only animals that have bodies covered in feathers. Birds also have two wings, two feet and a beak or bill.

Most birds use their wings to fly. There are some flightless birds such as ostriches and kiwis. These birds walk and run using their legs. Penguins are also flightless birds. They use their wings as fins and rudders to help them swim.

kingfisher

kiwi

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hummingbird

emperor penguins

Like mammals, birds are warm-blooded. They have lungs and get the oxygen they need by breathing in air.

Birds reproduce by laying eggs.

mallard duck

mallard duckling

cockatoo

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sunbird feeding its young

fieldfare hatchlings

Bird Life Cycles Go Online!

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

QuickCode: W2P1

All birds reproduce by laying eggs. The eggs are often laid in a nest. The nest helps to protect the eggs. The parents sit on the eggs to keep them warm.

As a young bird develops, it gets all the things it needs from inside the egg.

Once developed, a young bird will break out of the egg, or hatch.

egg

hatchling

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robin bird feeding its chicks

goose with eggs

Many birds feed and care for their young until they are able to fly about and find food on their own.

When a young bird grows into an adult, it will reproduce young of its own.

AB Activity 3.4

chick

adult chicken

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marine iguana

banded sea snake

Characteristics of Reptiles

Alligators, snakes, turtles and lizards are reptiles.

Reptiles have lungs and get the oxygen they need by breathing in air. Most reptiles live on land, but some such as sea turtles, sea snakes, crocodiles and alligators live in water.

crocodile

terrapin

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leopard gecko

Reptiles have bodies covered in scales or hard plates. The scales and plates protect the reptiles and also keep them from drying out in hot weather. Reptiles are cold-blooded. This means their body temperature changes with the temperature of their surroundings.

In what ways are reptiles similar to birds?

Galapagos tortoise

Think Deeply Few reptiles can survive in cold environments.

Why is this so?

viper snake

Chinese water dragon

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adult corn snake

Reptile Life Cycles

The life cycle of reptiles is similar to that of birds. Let’s look at the life cycle of reptiles by looking at the life cycle of a corn snake.

A female corn snake lays eggs. The young snakes grow and develop inside the eggs.

Once developed, a young snake will hatch from each egg. The young snakes look similar to their parents.

corn snake hatching from egg

eggs

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crocodile hatchlings

turtle hatchling

Unlike mammals and birds, snakes and other reptiles do not often care for their young after they hatch.

As the young snakes grow, they get bigger in size and look more like their parents.

Once mature, they will reproduce corn snakes of their own.

AB Activity 3.5

Think Deeply Some snakes, such as the pit viper, live in cold climates and therefore do not lay eggs. Instead the eggs are kept inside the mother’s body until they hatch. How does this help the snake reproduce?

young corn snake

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caecilian

red-eyed green tree frogs

Amazing Fact!

Wallace’s flying frog, also known as a parachute frog, has wide webbed feet that help it to fly through the air.

It can glide distances more than 15 meters!

Characteristics of Amphibians Amphibians are animals that usually spend the first part of their lives in water before moving onto land. The most common type of amphibians are frogs. Other amphibians include salamanders and caecilians. salamander

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Like reptiles, amphibians are cold-blooded. Their body temperature is dependent on the temperature of the environment.

A young amphibian has gills and takes in oxygen from water. The gills develop into lungs as it gets older.

Most amphibians have smooth, moist skin.

They often live in moist places or near bodies of water such as ponds and puddles.

Why do most amphibians live in moist places or near water?

cane toad

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Go Online!

Watch a video on the fascinating life cycle of amphibians on the NGScience website.

QuickCode: U4E6

Amphibian Life Cycle The life cycle of a frog is different from other vertebrate animal life cycles in that the young do not look like their parents. As they grow and develop, their bodies change form. This change in body form is called metamorphosis.

Frog eggs are usually laid in water with many eggs usually laid at one time. A frog larva, called a tadpole, hatches from each egg. A tadpole does not look like a frog. It has a tail to help it swim and uses gills to take in oxygen. frog eggs

young frog undergoing metamorphosis frog larva (tadpole)

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A northern leopard frog in the process of metamorphosing from a tadpole to an adult.

As a tadpole grows and develops, it starts to look more like a frog. Its tail gets smaller and it begins to develop legs and feet. Its gills develop into lungs as it prepares to move onto land. As a frog grows, it moves from life in water to life mostly on land.

reticulated glass frog

adult frog

AB Activity 3.6

As a frog grows, it develops legs, feet and lungs.

How are the life cycles of amphibians similar to that of reptiles? How are they different?

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great white shark

Characteristics of Fish Fish are animals that live in water. Most fish live in the ocean, which is salt water. Fish can also be found in freshwater habitats, such as streams, rivers and lakes.

Most fish reproduce by laying eggs, but some give birth to live young.

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fish gills

stingray

Fish have body parts well-adapted to life in water. They have gills to take in oxygen from the water. They have fins and tails to help them swim.

Like reptiles and amphibians, fish are cold-blooded.

Think Deeply A starfish has the word ‘fish’ in its name. Do you think a starfish is a fish?

Explain your answer.

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Fish Life Cycles Let’s take a look at the life cycle of fish by looking at the life cycle of a salmon.

Female salmon lay eggs in water. Young fish hatch from the eggs. The young salmon have an attached yolk that they use for food.

eggs

alevin

adult salmon

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As the salmon get older, they get larger and look more like their parents. The young salmon grow into adults and will produce young of their own.

AB Activity 3.7

fry

parr smolt

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jellyfish

earthworms

Invertebrates

caterpillar

Many of the animals around us are invertebrates. An invertebrate is an animal that does not have an internal skeleton of bones or a backbone. Without bones or a backbone for support, invertebrates are generally smaller in size than vertebrates.

centipede

scorpion

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pill millipede

fiddler crab

For support and protection, many invertebrates such as insects, spiders and crabs, have a hard outer body covering. Some insects have one or two sets of wings and are able to fly.

octopus

Did You Know?

The bones inside vertebrates is called an endoskeleton.

The hard outer body covering of invertebrates is called an exoskeleton.

honeybee

praying mantis garden snail

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ladybug

dragonfly

Characteristics of Insects Insects are the most diverse animals on Earth.

So far, scientists have classified more than one million different kinds of insects, and many more are yet to be discovered.

Insects are invertebrates with a hard outer body covering. They have six legs, two antennae and a body divided into three parts. head

thorax

antenna

Go Online!

Observe the great diversity of insects on the NGScience website.

QuickCode: A4J3

leg ant

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abdomen

stag beetle

All insects reproduce by laying eggs. Some insects have one or two pairs of wings and can fly.

honeybee

How are insects similar to spiders?

How are they different?

grasshopper

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Butterfly Life Cycle Like many insects, butterflies have a four-stage life cycle that involves metamorphosis. A butterfly starts its life inside an egg. A worm-like larva, called a caterpillar, hatches from each egg. Caterpillars grow very quickly. They spend most of their time eating the leaves around them.

caterpillar (larva)

chrysalis (pupa)

When the larva reaches a certain size, it attaches itself to a leaf or branch and spins a covering, called a chrysalis, over its body. It enters an inactive state called a pupa.

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adult butterfly

Inside the chrysalis, the caterpillar’s body changes form completely.

It will emerge from the chrysalis as an adult butterfly. The butterfly will have the same body parts as its parents. It will go on to reproduce young of its own. adult butterfly emerging from chrysalis

Go Online!

Watch butterfly metamorphosis in action in a video on the NGScience website.

QuickCode: V9P5

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ladybug eggs

Ladybug Life Cycle Like a butterfly, the life cycle of a ladybug has four stages with the offspring undergoing metamorphosis.

Adult ladybugs lay eggs. The larvae that hatch from the eggs look very different from their parents.

Eggs are often laid on plants with small insects like aphids or mites for the larvae to feed on. The larvae shed their skin, or molt, several times as they grow.

adult ladybug

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ladybug larva

After a certain time, the larva attaches itself to a leaf and enters the inactive pupa stage. After a few days, it will emerge as an adult ladybug.

ladybug pupa

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Grasshopper Life Cycle The life cycle of a grasshopper is a threestage life cycle. The adult lays eggs - often underground. The young that hatch from the eggs are called nymphs. Although they look similar to adult grasshoppers, nymphs do not have wings, cannot fly and cannot reproduce. nymph

As the nymph grows, it develops wings. As an adult, it will reproduce and lay eggs of its own. eggs

adult grasshopper

AB Activity 3.8

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The Circle of Life The life cycles of living things can be different in many ways.

A small root will emerge from the germinating seed of a flowering plant. A shoot and leaves will develop. As an adult plant, it will produce flowers and fruits containing seeds. Under the right conditions, each seed will grow into a new plant.

A newborn deer looks a lot like its parents. It will grow bigger and stronger as it gets older. As an adult deer, it will produce young of its own.

Frogs and ladybugs look nothing like their parents when they hatch from eggs. Their bodies change completely as they grow and develop.

As adults, they will go on to produce young of their own.

Although there is great diversity in the life cycles of living things, they are all similar in one way – living things enter the world, they grow, develop, reproduce and die. The life cycles of living things ensure their kind continues to survive.

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Science Words Use the words to complete the sentences. mammals metamorphosis fish insects pupa

oxygen invertebrates amphibians larva chrysalis

vertebrates birds reptiles caterpillar

1. Animals need a special part of air called 2. Animals with a backbone are called

. .

3. Animals without a backbone are called

.

are animals with a body covered in fur.

4.

They give birth to live young.

5.

are the only animals with a body covered in feathers.

6.

are cold-blooded with a body covered in scales or plates.

7. Frogs and salamanders are

. They have smooth, moist skin. .

8. A change in body form during an animal’s life cycle is called 9.

live in water and have gills to help them take in oxygen.

10.

have six legs and a body divided into three parts.

11. A worm-like butterfly egg.

, called a

hatches from a

12. A caterpillar spins a covering over its body, called a enters an inactive state called a .

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, and

Review 1. List the needs of animals.

2. List three vertebrate animals.

3. List three invertebrate animals.

4. How are mammals different from most other animals in terms of reproduction?

5. List the characteristics of birds.

6. List four kinds of reptiles.

7. How is the life cycle of birds similar to that of reptiles?

8. List the characteristics of fish.

9. Describe insects in terms of their number of legs and body parts.

10. Classify the animals as either vertebrates or invertebrates. (a) (b)

(c) (d)

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4

Inheritance and Traits Why do offspring often look similar to their parents?

In this chapter you will ...

• understand that plants and animals have traits inherited from parents.

• understand that there are variations in traits within a group of similar organisms.

• provide examples of traits that can be influenced by the environment.

• explain how variations in traits of the same species may provide advantages for survival.

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How can the environment affect an animal’s appearance or behavior?

Go Online!

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

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Heredity and Traits Look at the photograph of the cheetah family. What similarities do you see between the parents and their offspring? Why are they similar?

Go Online!

Learn more about inherited traits in plants and animals on the NGScience website.

QuickCode: T4X6

Like their parents, the young cheetah cubs have the same eye color. They all have four legs and a tail. Their fur is covered in spots. These features or characteristics of the cheetahs are called traits.

Plants have traits too. The shape of a plant’s leaves and flowers or the type of fruit it produces are examples of traits.

The young cheetah cubs have inherited traits from their parents.

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fir saplings

When living things reproduce, traits are passed from parents to offspring. This process is called heredity.

The young cheetah cubs look similar to their parents because of their inherited traits.

A young fir plant will grow into a tall fir tree with thin, spiky leaves due to its inherited traits.

People inherit traits too. What are some traits you have inherited from your parents?

AB

Think Deeply firsome trees seeds Chelsea found on the ground. How can she find out which plant the seeds came from?

Activities 4.1 – 4.2

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Variation in Offspring Why don’t the kittens look exactly like their parents or their siblings?

Think Deeply Look at a family photograph.

What variation can you see between you and your siblings?

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When most living things reproduce, inherited traits are passed from both parents to the offspring. Some offspring may look more like their mother. Some may look more like their father. They may look similar to both parents, but the offspring will not look identical to their parents or identical to each other.

The differences in characteristics between individuals of the same kind is called variation.

color variation in tulips

We can see variation in the same kind of plants too. The plants above are all the same kind of tulip. They are similar in many ways. We can also see variation in the heights of the plants and the colors of the flowers.

Sometimes, variation within living things of the same kind can result in some offspring surviving and some not surviving. Certain offspring may be stronger or be able to survive longer without food or water. Variation may mean some offspring have a body covering that is better at hiding from other animals.

Think Deeply How could knowledge of inherited traits be important to crop farmers and the plants they grow?

How could color variation in the ghost mantises increase the chances of survival of an individual?

AB

Activities 4.3 – 4.5

ghost mantises

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Behavioral Traits

Instinct

Characteristics such as body coverings, body parts and eye color are physical inherited traits. Offspring can also inherit behaviors from their parents. An inherited behavior is called an instinct. An instinct is the way an animal acts that it has not learned from its parents or environment.

When young ducks hatch from eggs, they start to follow their mother.

This instinct helps the young to stay safe and learn from their mother.

Other instincts include a spider spinning a web, animals fighting and nest building.

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lioness with her cubs

squirrel monkey

Learned Traits

As young animals grow and develop, they learn new skills from their parents or from other experiences around them. Animals can also learn new skills and behaviors by playing with other animals. These newly-acquired skills and behaviors are called learned traits.

Learning to hide from animals and hunt for food are examples of learned traits. These learned traits are not passed on from parent to offspring. Learned traits must be learned by the offspring each time an animal reproduces.

AB Activity 4.6

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Environmental Traits How can changes in an environment affect the traits of the plants and animals that live there?

Think Deeply Is the shape of the tree an inherited or environmental trait? Explain your answer.

There is a great variety of environments on Earth and they are always changing. The traits of plants and animals can be influenced by the conditions in their environment. These traits are called environmental traits.

The availability of water and the amount of sunlight in an environment can affect the plants that live there. In an environment where there is plenty of water and sunlight, the plants may grow taller and have more leaves than the same plants in a drier or darker environment.

Hydrangea plants produce blue flowers in acidic soil and pink flowers in alkaline soil.

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The flowers of the hydrangea plant are either pink or blue. The color of the flowers depends on the type of soil in its environment.

Animal traits can be affected by their environment too. At times when there is plenty of food available, animals may become overweight.

When less food is available, they may become thinner again.

Changes in seasons and temperature can also affect the traits of animals. Some animals have thicker fur when the weather is cold and shed the fur when the weather gets warmer. The mountain hare has a thin layer of brown fur in the summer months and a thick layer of white fur during winter.

Think Deeply Poison dart frogs produce a deadly poison. The poison comes from their diet of ants and termites.

Why is this an example of an environmental trait?

How do environmental traits help organisms to survive?

The mountain hare has thick white fur in winter and thinner brown fur in summer.

AB Activity 4.7 87

Natural Selection

A living thing of the same kind is called a species. Although the traits of individuals within a species are very similar, there are always slight differences. Sometimes, these slight differences between individuals provide advantages in surviving, finding mates and reproducing.

Survival of the Fittest Imagine a group of giraffes living in an African savanna. One trait of all giraffes is a long neck. This helps the giraffes to reach leaves high in trees. A variation within the giraffes may be that some have longer necks than others. If shorter trees begin to produce less leaves, those giraffes with longer necks will have a greater chance of survival. They will also have a better chance of reproducing. This process by which the best suited organisms survive and pass on their traits is called natural selection.

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peppered moths

Another variation in traits that may give individuals within a species a greater chance of survival is being better camouflaged.

Camouflage is an animal’s ability to blend into its surroundings.

The peppered moth is a day-flying moth that is camouflaged on the bark of trees. In habitats where the trees are light in color, lighter-colored peppered moths have a greater chance of survival than darker moths. In these habitats, most of the peppered moths are light. In habitats where the trees are dark in color, most of the peppered moths are dark.

Finding a mate and reproducing is important for the survival of a species. Often males that are stronger, or have other desirable traits, attract more mates. This helps to ensure that the stronger traits are passed on to offspring.

AB

Activities 4.8 – 4.9 Two male gemsbok fighting to compete for a mate.

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Science Words Use the words to complete the sentences. heredity instinct species traits

environmental traits learned traits natural selection variation

1. Features or characteristics passed from parents to their offspring are called .

2.

is the passing of traits from parents to offspring.

3. Differences in characteristics between individuals of the same kind is called . is the way an animal acts that it has not learned from its 4. An parents or environment.

5. Skills and behaviors taught by parents to their offspring are 6. Traits that change as a result of changes in a living thing’s surroundings are called .

7. A

is a living thing of the same kind.

8. is the process by which the best suited organisms survive and pass on their traits.

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.

Review 1. List two traits the young monkeys inherited from their parents.

2. List two inherited traits of the pine saplings.

3. Why do offspring look similar but not identical to their parents?

4. Provide an example of animal instinct.

5. List two learned traits of the young bear cubs.

6. How can the environment affect a living thing’s traits?

7. How does natural selection help a species survive?

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A Closer Look

Attracting Mates Attracting mates is important to ensure the survival of a species. Different kinds of animals have different and very interesting ways of attracting mates.

Bird courtship displays are a fascinating example of attracting mates. During a courtship display, a bird, usually the male, behaves in a manner to ‘impress’ the female. This may include a display of colorful feathers, an elaborate dance or a song. By choosing the male with the best courtship display, the offspring will likely inherit these desirable traits and therefore have a greater chance of survival.

male frigate bird

male peacock

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Male frigate birds inflate large red pouches hanging below their throat. They extend their large wings and make sounds much like the beating of a drum. Birds with bigger and brighter pouches and louder sounds are more likely to attract a mate.

Perhaps one of the most impressive courtship displays is that of the peacock. To attract a mate, male peacocks spread out their large and brightly colored feathers. The peacocks with the larger and more impressive feathers attract more mates.

Go Online! female peacock

Watch some fascinating bird courtship displays in a video on the NGScience website.

QuickCode: Y5S8

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5

Adaptations for Survival What is an adaptation? How do adaptations help organisms survive?

In this chapter you will ...

• understand that some animals form groups to help members of the group survive.

• describe and provide examples of how organisms have adaptations to help them survive in their environment.

• describe and provide examples of how environments can change.

• describe and provide examples of how organisms are affected by changes in their environment.

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Go Online!

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

How are organisms affected by changes to their environment?

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What Are Adaptations?

Go Online!

Surviving in the freezing Antarctic is a tough job.

Find out what adaptations animals have to survive in this harsh environment on the NGScience website.

QuickCode: S9W6

The Antarctic is a region of the Earth that is so cold all year round that few animals can survive there. The animals that live in the Antarctic have adaptations that help them survive in the extreme cold. An adaptation is a trait or behavior that helps an organism survive.

Adelie penguins have adaptations that help them survive in the Antarctic. They have waterproof feathers and a thick layer of fat, called blubber, that help to keep them warm.

Their small, yet strong, wings help them to swim in search of food.

Camouflage is an adaptation that helps animals blend into their surroundings. This can help them to hide from predators or sneak up on prey.

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Plants may have spikes on their stems to stop them being eaten by animals.

Many animals have specialized body parts that help them move about, or get food and water.

Many plants and animals have adaptations to survive in places that are very hot or very cold.

Think Deeply What adaptations do polar bears have that help them to survive in an icy Arctic environment?

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Adaptations to the Environment Try This!

Visit a natural environment in your area. List the animals you spot and the adaptations they have that help them survive in the environment.

Go Online!

Discover some amazing animal adaptations to their environments on the NGScience website.

QuickCode: S1X5

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There is a great variety of different living things on Earth. There is also a great variety of habitats.

In a given habitat some organisms can survive well, some survive less well, and some cannot survive at all.

Often, a living thing can only be found in one type of habitat. This is because living things have adaptations that allow them to survive in certain environmental conditions.

A red-eyed tree frog has adaptations to survive in a tropical rainforest. You will not find a redeyed tree frog in an icy tundra or dry desert.

Similarly, you will not find tundra or desert animals living in rainforests either.

Why can’t an animal like a tree frog survive in a hot and dry desert?

Surviving in a Desert

A desert is a very dry habitat. It may only rain a few times a year. Deserts are also often hot during the day and much cooler at night.

What are some adaptations of desert organisms? How do the adaptations help them to survive?

Not many plants can live in deserts. Those plants that do have adaptations to survive with little water. Some plants have deep roots that can take in water from deep in the soil. Others have shallow roots that spread out to take in water over a large area.

Desert plants also have small leaves to help reduce water loss. In some desert plants, the leaves are in the shape of spines to keep animals away.

joshua tree

prickly pear cactus

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Desert horned lizard camouflaged on sand.

Desert viper camouflaged in sand.

Think Deeply Why do many nocturnal animals, such as owls and geckos, have large eyes?

Desert animals have adaptations to survive in hot weather with little water. Some desert animals are nocturnal. This means they sleep during the day and are active at night. Some animals also seek shelter in burrows to help them stay cool.

Some animals, such as snakes, are camouflaged or bury themselves under the sand. This helps them to hide from other animals.

Why are many desert animals active at night?

The giant ground gecko hunts for insects and other small animals at night.

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What adaptations does a camel have for surviving in deserts?

Camels are well-adapted to surviving in deserts.

They have a hump on their backs which stores fat for energy. They can also survive for many months without drinking water.

Amazing Fact!

Camels can survive for up to six months without water. When they do find water, they can drink up to 40 gallons at once!

Camels have large, flat feet that spread their weight on the sand. They have thin, narrow nostrils and two rows of eyelashes to help keep out sand.

AB

Activity 5.1

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A Closer Look

The Saguaro Cactus The saguaro cactus is a tree-like cactus found in the Sonoran Desert in Arizona, United States. The Sonoran Desert is very hot all year round and it may not rain for many months. The saguaro cactus has many adaptations which allow it to survive in this harsh environment.

Saguaro cacti are able to store large amounts of water in their thick stems. The stems are also covered in a waxy substance which helps to prevent water loss. Its leaves are in the shape of sharp spines that stop animals from getting to the precious water inside the stem.

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The saguaro has modified leaves in the shape of sharp spines.

The strong aroma of saguaro flowers attract insects. The Gila woodpecker helps pollinate the flowers when it feeds on the insects.

Saguaro cacti also have shallow roots that branch out over a large area.

When it does rain in the Sonoran Desert, the roots are able to take in a lot of water and store it in the stem.

Saguaros produce bright flowers that have a strong smell to attract pollinators. At night the flowers attract bats. During the day they attract bees, butterflies and birds. The flowers develop into fruits which can contain up to 2,000 seeds. The seeds are dispersed to new places when animals such as birds and small mammals feed on the fruits.

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Surviving in a Rainforest Go Online!

Rainforests can be divided into four different layers with each layer providing a habitat for different organisms. Learn more on the NGScience website.

QuickCode: H9W9

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Tropical rainforests are dense forests with warm weather and lots of rain all year round. They are home to millions of different kinds of organisms and are the most diverse land habitat on Earth.

With high diversity comes lots of competition for the things organisms need to survive. Trees in rainforests have tall trunks. The trunks lift the leaves high in the sky to take in sunlight. The leaves branch out in all directions.

bird’s-nest fern

With so many tall trees, very little sunlight reaches the rainforest floor. The plants there have adaptations for living in low light. Many rainforest plants have large leaves to take in more sunlight. Other plants, like bird’s-nest ferns and orchids, get more sunlight by growing on the trunks of trees. orchid

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leaf-tailed gecko

leaf insect

Rainforest animals have adaptations that help them get the things they need and stay safe in a warm and moist forest.

With such a great diversity of animals, hiding is important to stay safe. A leaf insect blends into its habitat by looking a lot like a leaf. An adaptation where an organism looks or acts like another organism is called mimicry. pit viper

Green viper snakes and tree frogs use camouflage to hide from other animals.

Javan tree frogs

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Toucans use their specialized bills to tear fruits from branches.

spider monkey

Many rainforest animals have adaptations that help them get food that other animals cannot reach. Spider monkeys live high in the rainforest canopy. They swing effortlessly from tree to tree feeding on fruits.

Rainforest birds have beaks or bills of all shapes and sizes. A toucan has a large bill that helps it to cut fruits from trees. Parrots have a strong beak to break open seeds and nuts.

Owls are nocturnal rainforest animals. They have large eyes to see at night and use their powerful wings and sharp claws to catch and kill their prey.

AB Activity 5.3

buffy fish owl

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Surviving in a Savanna

A savanna is a tropical grassland habitat. Like a tropical rainforest, it is warm all year round. Savannas are mostly dry, with seasonal rains, usually during summer.

Savannas are mostly wide open places with grasses, shrubs and scattered trees.

Many plants in savannas have long deep roots, called taproots, that reach deep underground. Some plants, such as the baobab, store water in their stems.

Baobabs store water in their stems.

Living in a wide open savanna means hiding from animals and escaping danger is important.

Animals like meerkats hide in burrows to avoid predators. Others, such as gazelles run, jump and change direction quickly to avoid getting caught by animals like cheetahs.

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Escaping a cheetah is a tough job!

A cheetah’s dark spots camouflages it in the dry vegetation allowing it to sneak up on its prey. Cheetahs are also the fastest land animals on earth. They can reach speeds of more than 60 kilometers per hour when chasing prey.

What are some other animal adaptations to living in a savanna?

AB Activity 5.4

Meerkats dig burrows to stay cool and avoid predators.

Did You Know?

The Serengeti is a vast grassland habitat in Africa.

It is home to many big predators including lions, cheetahs and leopards.

Lions in the Serengeti are often seen climbing trees.

Scientists believe this may be an adaptation to avoid getting bitten by insects on the ground.

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Surviving in a Tundra A tundra is a habitat that is very cold all year round. It is often windy and there is little water available. The organisms in a tundra have special adaptations to survive in the cold.

Leaves with a hair-like coating protect tundra plants from cold winds.

Plants are often small and live close to the ground. Many plants live close together and have a hair-like coating on their leaves. This helps to protect them from the wind. Small leaves also stop the plants from losing water.

Many tundra plants are deciduous.

Deciduous means they lose their leaves for part of the year.

Blubber and thick fur keep polar bears warm.

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Tundras have frozen soil with only the top layer suitable for plants. To survive in the soil, tundra plants have very shallow roots.

Animals adapt to the cold in different ways.

Many animals, such as polar bears, foxes and hares, have a thick fur coat and a layer of blubber to keep them warm.

During the coldest months of the year, some tundra animals go into burrows or caves to hibernate. Hibernation is like a deep sleep that allows the animals to save energy.

Reindeer migrate to warmer areas during the tundra winter.

Polar bears hibernate during the tundra winter.

AB Activity 5.5

Other animals move in large groups to warmer places for part of the year. This movement is called migration.

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A Closer Look

Surviving the Deep Ocean The deep ocean is a habitat very different from any other on Earth.

At more than 1,000 meters deep, there is no light, no plants and the water temperature is very cold. The strange animals that live there have unique adaptations to help them survive. Let’s take a look at a few deep sea creatures.

The viperfish can live at depths of more than 2,000 meters. It has large needle-like teeth and a wide mouth. In the darkness of the deep ocean, the viperfish has a light-producing organ to attract its prey.

Giant isopods use their seven pairs of legs and four sets of jaws to scavenge for food on the deep ocean floor. They can curl their segmented bodies into a ball shape for protection against predators.

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The ferocious-looking anglerfish has a fleshy, light-emitting growth on its head to attract prey. It has long, sharp teeth and a mouth so wide it can eat prey bigger than its own size!

To see in almost complete darkness, the colossal squid has the largest eyes of all known animals. The animal is believed to reach lengths of up to 15 meters and weigh over 700 kilograms.

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Living in Groups Go Online!

Discover the many advantages of animals living in groups in a video on the NGScience website.

QuickCode: Y8S7

Animals can be found in all regions of the Earth – from the icy Antarctic to the open plains of the Serengeti. To help them survive in their environment, many animals form groups.

What are some animals that form groups? How does forming a group help them survive?

Keeping Warm Think Deeply What other adaptations do emperor penguins have that help them survive in the Antarctic?

Some animals that live in cold habitats form groups to stay warm. Emperor penguins live in one of the coldest habitats on Earth – the Antarctic. Temperatures get as low as –50°C (–58°F) and there are very strong winds.

The penguins huddle together in large groups to keep warm. The penguins rotate between being on the inside of the group, where it is the warmest to the outside of the group, where it is the coldest.

Emperor penguins huddle in groups to keep warm.

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Leaf cutter ants gather food in groups. The food is taken back to the colony and shared among the group.

Finding and Sharing Food When animals form groups, they can increase their chances of finding food. It may also allow them to gather more food than they would as individuals.

Groups of insects such as ants and bees are able to search for food over a large area. When members of the group find a rich source of food, they signal to other members of the group, directing them to the food source.

When a lion pack catches and kills its prey, the food is shared with all the members of the group.

Amazing Fact!

Honeybees live in large groups. When a honeybee finds flowers with a lot of nectar, it performs a special dance, called a waggle. The waggle dance tells other bees the exact location of the flowers.

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Defense Against Predators Amazing Fact!

A group of lions living together is called a pride.

Within a pride the lionesses raise their cubs together and any cub in the pride can suckle milk from any female.

How does forming groups help animals stay safe from predators?

In the African savanna, lions often prey on elephants. In the photograph above, two lions watch on as a group of elephants walk by. While the lions may be able to catch an elephant on its own, they cannot take on the whole group. There is a greater risk of getting injured or killed by other elephants in the group. Staying in a group keeps the elephants safe.

Forming groups also gives animals a greater chance of survival during fights with other animals of the same kind.

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Different kinds of African animals often form large groups. As a large group, the animals have a better chance of spotting predators.

Another way that forming groups helps animals stay safe is by keeping a lookout for predators. As a group, the animals are able to spot predators faster and warn other group members of danger. This gives the animals in the group more time to flee or defend themselves as a group.

Think Deeply Generally, living in groups gives animals an advantage to survive.

What could be some disadvantages to animals living in groups?

Deer stay safe by keeping a lookout for predators as a group.

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Strength in Numbers Imagine a young zebra being chased by a lion.

The lion is much stronger and faster than the young zebra and it would not take much time before it’s caught. Most zebras however, move in large groups. Evading predators as a group increases each individual animal’s chance of survival. Large groups also confuse the predator and make it harder to focus on just one animal.

Many types of fish move about in large schools. They swim and change direction in coordinated movements. This makes it difficult for predators like sharks and dolphins to catch them.

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Reproducing and Raising Young Living in large groups often makes it easier for animals to find a mate and reproduce. Older members of the group can also help raise each other’s young. This allows time for different members of the group to go off in search of food, knowing their young are safe.

Living in groups also helps the young animals learn from other members of the group. They may learn to hide from predators or hunt for food. Young animals in groups often play with each other. In doing so, they develop the skills they will need to survive as adults.

Living in large colonies makes it easier for animals to find a mate.

Think Deeply What skills and behaviors can young animals learn by playing with other members of their group?

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Did You Know?

Different groups of animals have different names.

Here are just a few: Monkeys – troop Elephants – parade Lions – pride Kangaroos – mob Giraffes – tower See what other names you can find for groups of animals.

Engineer It! Use art and craft supplies to design and build a model of a bird beak. Describe how your beak is suited to the food the bird eats.

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Catching Prey Many animals hunt for prey in groups. When hunting in groups, different members of the group can take on different roles. The animals in the group may also communicate with each other to increase the chances of catching their prey.

Hunting in groups also allows animals to use the combined strength of the group to prey on animals that are much bigger or stronger.

A cheetah risks being injured if it tries to take down a wildebeest alone. Hunting in a group increases the chance of catching and killing the wildebeest. The catch is then shared among the members of the group.

Killer whales hunt in groups. They communicate with each other to find and catch prey.

Usually, an individual ant would not be able to prey upon a large beetle. As a group, ants are able to overpower the beetle and share the meal with the rest of the colony.

AB

Activities 5.6 – 5.7

By working as a group, the cheetahs are able to catch larger prey.

Ants work in groups to attack much larger animals as a source of food or for defense.

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Think Deeply Scientists have observed that human activities, such as the burning of fuels, are causing the Earth to warm up faster than usual. This process is called climate change.

Along with higher temperatures, climate change is also causing changes in rainfall patterns, rising sea levels and the melting of sea ice and glaciers. How could these changes affect organisms?

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Surviving Change What are some ways an environment can change? How do such changes affect the organisms in the environment?

Environments around the Earth are constantly changing. They may change from season to season. They may change due to a flood, drought or fire. Human activities can change environments too.

When an environment changes, the types of organisms that live there may change. Some organisms may adapt to the change and continue to survive. Some may move to new places. Organisms that are unable to adapt to the change or move to a new place, may die.

Did You Know?

Rapid, Natural Changes

A wildfire causes rapid changes to the environment.

Plants are not able to flee fires like animals can and many do not survive. Some plants in wildfire areas are able re-sprout rapidly after a fire. Others have seeds that germinate in response to the heat and smoke from the fire.

Floods and droughts are extreme weather events that can change an environment rapidly. During a flood, rivers may overflow, blocking the sunlight and air which plants need to survive. During a drought there may not be enough water for plants to make food. Some plants may be able to survive in these changed conditions. Other plants may die and regrow if the environment returns to normal.

During floods and droughts animals need to adapt to the changes in water and food.

Some may survive and continue to reproduce.

Others may flee to new areas. Some animals may not survive.

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Seasonal Changes An environment can change a lot from season to season. There are changes in temperature, rainfall and in the types of plants and animals that live there.

Some organisms are able to survive and reproduce all year round. Others may not be able to survive a very dry summer or very cold winter. monarch butterflies

Amazing Fact!

About 500,000 monarch butterflies migrate from the Eastern United States to Mexico in the fall and return in the spring. Female butterflies lay eggs part way through their return to the United States. Due to their short life cycles, no individual butterfly ever completes the full migration pattern.

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Many organisms in seasonal environments have adaptations to help them survive.

Some animals migrate to new places when conditions become unsuitable. Some animals go underground and hibernate in winter to save energy when there is little food available.

Emperor penguins have young during the Antarctic winter. Although they have adaptations to survive in the cold, many young do not survive.

fall

winter

spring

summer

How do the trees and plants change with the change of seasons? How does this help them survive?

Unlike animals, plants cannot migrate to new places as the environment changes during seasons. Some plants die when there is not enough water during summer, or it gets too cold during winter.

Think Deeply Some plants produce seeds that are inactive, or dormant, when it is too cold or too dry. How does this adaptation help the plants?

The needle-like leaves of a spruce tree.

Many plants have adaptations to survive seasonal changes. Deciduous trees lose their leaves through fall to save energy when there is less sunlight in winter. The leaves grow back in spring. Other plants are evergreens – they keep their leaves all year round. Pine trees have thin, needle-like leaves with a waxy surface.

This helps reduce water loss and stops the leaves from freezing.

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Human Changes

Go Online!

The large-scale clearing of forests by humans is called deforestation. More than half of the world’s tropical rainforests have been destroyed by deforestation.

This has caused many organisms to become extinct. Find out more about deforestation on the NGScience website.

QuickCode: T7B4

Think Deeply Cities often have higher temperatures than the natural environments they replaced. Why is this so?

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Throughout history, humans have been changing the environment in many ways.

We change the environment when we cut down trees for wood, or dig mines to take resources from under the ground. We change the environment when we clear land to make way for roads, houses and cities.

Pollution can also change the environment.

Pollution is when harmful substances are added to the air, water or land.

Human changes to the environment can affect the organisms living there in many ways. There may be changes in the availability of food, water or shelter. The types of organisms living in the environment can also change.

When humans make big changes to the environment, the organisms living there are unable to adapt and do not survive. When forests are cleared to make way for human activities, the plants die, as do many of the animals that cannot move to new areas.

Human activities can also change the natural flow of streams and rivers. This affects the plants and animals that were dependent on the water for survival.

Did You Know?

Human changes to the environment have caused many organisms to be endangered.

Endangered means the organism is in danger of disappearing forever.

Discuss the different ways humans can change the environment and the effect it has on the organisms that live there.

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The Gold Coast, Australia was built on a coastal wetland environment.

Adapting to Human Changes

All over the world, people have cleared natural environments to make way for cities and homes.

Sometimes, animals are able to adapt to living in these urban or city environments.

Australian white ibis

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The natural habitat of the Australian white ibis is a coastal wetland. When its habitat was cleared to make way for cities, the ibises survived by feeding on food scraps in trash cans.

monkeys living in an urban environment

Many monkeys and other small mammals such as rodents and squirrels have become well-adapted to urban and city environments.

Parks and gardens are often constructed in and around urban and city environments. The plants that live there are adapted to living in the environment.

AB

Activity 5.10

Think Deeply Often, changes to an environment made by people cause the animals that live there to die or move to new places. What are some things people can do so that more animals are attracted to cities and neighborhoods?

Discuss some other examples of organisms adapting to human changes to the environment.

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Science Words Use the words to complete the sentences. adaptation nocturnal mimicry 1. the day.

hibernate dormant

deciduous evergreen

animals are active during the night and sleep or rest during

2. trees lose their leaves through the fall to save energy when there is less sunlight in the winter.

3.

trees keep green leaves throughout the year.

4. A seed that is inactive and will not germinate is 5. Some animals go underground and

. during winter months.

6. An adaptation where an organism looks or acts like another organism is called .

7. An

is a trait or behavior that helps an organism survive.

Review 1. List two adaptations that help each organism survive in its environment. (a) (b)

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(c) (d)

2. List the environment each plant can be found and one adaptation that helps them to survive. (a) (b)

3. How can mimicry help an organism to survive?

4. Describe two ways that living in groups help individual animals survive.

5. List two natural changes to an environment.

6. List two ways people can change an environment.

7. What happens if organisms are not able to adapt to changes in their environment?

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In the Field

Ecologist If you are interested in all sorts of organisms and how they interact within their environment, then maybe you’d like to be an ecologist.

A community of living things and their interactions with their environment is called an ecosystem. An ecologist is a scientist who studies these ecosystems.

Ecologists study a wide range of interactions and relationships within a given ecosystem. They may study small parts of an ecosystem such as small bugs living in the soil. They may also study large interactions such as fish populations in the ocean or how rainforests effect the atmosphere.

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Ecologists usually choose a specific environment or living thing to study. For example, an ecologist may only study desert or ocean environments.

They may also choose to study one type of interaction such as weather events or how human activities impact environments.

If you were an ecologist, which environment or organism would you choose to study?

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A Closer Look

The Great Migration

One of the largest movement of animals in groups is the Great Wildebeest Migration. During this spectacular event, more than two million wildebeests, zebras and gazelles migrate in a circular pattern as they follow green pastures from the Serengeti in Tanzania to the open grasslands in Kenya. In one year, the animals move more than 800 kilometers.

Go Online!

Watch the massive movement of animals during the Great Wildebeest Migration on the NGScience website.

QuickCode: X5Z7

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During the migration, the animals pass through the habitats of predators such as lions and cross crocodile infested rivers.

Moving in such a large group increases the chance of survival of individual animals.

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6

Organisms of the Past

In this chapter you will ...

• describe how fossils provide evidence of organisms and the environments in which they lived long ago.

• identify and describe relationships in fossil data and organisms that are alive today.

• provide evidence of organisms that lived long ago but have become extinct.

What organisms lived on Earth long ago? How do we know they existed?

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Go Online!

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

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Life on Earth Long Ago

Go Online!

Take a virtual field trip to the Ice Age and discover more about fascinating woolly mammoths on the NGScience website.

QuickCode: T6V3

Woolly mammoths were large elephant-like mammals that roamed the Earth about 20,000 years ago during a period called the Ice Age. During the Ice Age, it was very cold. Most of the Earth’s land was covered in ice. Woolly mammoths were well-adapted to living in the cold. They had a body covered in fur and a thick layer of blubber.

woolly mammoth

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Over many years, the climate on Earth changed. The temperature increased and much of the ice melted. The food that woolly mammoths ate was no longer available. They were also hunted by people. Eventually they become extinct about 10,000 years ago. An organism becomes extinct when all of its kind are no longer alive.

How do scientists know about woolly mammoths if they became extinct so long ago?

We know a lot of things about woolly mammoths. We know about their size, body covering, what they ate and where they lived.

We know these things because scientists have found evidence of their existence. They have found frozen mammoths deep under the ice.

They have found skeletons, tusks and teeth.

Paintings in caves are also evidence of their existence long ago.

AB

An ancient cave painting of cavemen hunting a mammoth.

Activity 6.1

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Causes of Extinction Go Online!

Scientists have discovered that human activities, such as the burning of fuels, are causing the Earth to get warmer. It is feared that this could cause many more extinctions. Find out more on the NGScience website.

QuickCode: C9D3

Did You Know?

About 66 million years ago, three-quarters of all plants and animals on Earth became extinct.

Scientists believe this mass extinction occurred when a large asteroid hit the surface of the Earth.

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Using evidence, scientists have discovered that life first appeared on Earth over three billion years ago. Throughout this time, different kinds of living things became extinct and new kinds of living things evolved. The process of a new kind of living thing gradually developing from an existing living thing is called evolution.

Living things can become extinct for different reasons. In the case of the woolly mammoth, the slow changing of the climate, called climate change, caused the environment to become unsuitable for the woolly mammoths.

Living things can also become extinct due to more rapid changes to their environment.

Rapid changes can include things like volcanic eruptions and wildfires. Rapidly-spreading diseases can also cause extinctions.

Human activities can also lead to the extinction of living things. The thylacine was a mammal that was only found in Australia. Due to hunting by people, the thylacine became extinct about 100 years ago.

thylacine

Changes to a living thing’s habitat by people can also cause extinction. Habitats can be changed when we make way for roads, houses and cities.

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Go Online!

Watch a fossil slideshow on the NGScience website. See if you can guess the organisms that formed the fossils.

QuickCode: B7B8

Fossils

How Do Fossils Form?

Scientists can learn about the characteristics of organisms that lived millions of years ago by looking at fossils. A fossil is the preserved remains or trace of an organism.

Most of the time when an organism dies, its remains are eaten or broken down by other organisms, leaving no trace. For an organism to form a fossil, it must be buried in mud, sand or other substance soon after its death.

Amazing Fact!

To be called a fossil, a specimen must be more than 10,000 years old. The oldest fossils ever discovered are over three billion years old. That is almost as old as the Earth itself!

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Over many years, the layers of mud or sand turn to rock. Groundwater washes away the organism, leaving an imprint in the rock. The imprint is the same shape as the skeleton of the organism. Sometimes the imprint is also filled with rock.

The process of an organism becoming a fossil is called fossilization.

AB Activity 6.2

Did You Know?

Organisms from long ago can also be preserved in amber.

Amber is fossilized tree sap. By studying the organisms in the amber, scientists are able to learn about the plants and animals that made up habitats long ago.

Some amber fossils are more than 100 million years old.

What organism may have formed this fossil? How do you know?

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A Closer Look

How Fossils Are Formed Most of the time when an organism dies, its body quickly decomposes, leaving no trace it ever existed. Under certain conditions, parts of an organism such as bones, shells and teeth, can become buried in layers of sediment before being fully-decomposed. This process is called fossilization.

Let’s take a closer look at one way fossilization occurs.

AB Activity 6.3

1

An organism dies.

The soft, fleshy parts of its body begin to decompose.

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2 The skeleton of the organism gets covered in sediment, such as mud and sand. Layers of sediment form on top.

3 As more layers of form on top, the sediment around the organism’s skeleton compacts and turns to rock.

Water seeps through the rock, dissolving the skeleton.

Minerals fill the spaces in the rock where the skeleton was, leaving a fossilized replica of the skeleton.

4 The fossil is discovered by scientists during excavations or when layers of rock become exposed due to weathering and erosion. Fossils are carefully removed and taken to laboratories to be studied.

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fern-like fossil

dragonfly fossil

Learning from Fossils Think Deeply What can scientists infer if they discover a plant and an animal fossil in the same piece of rock?

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By studying fossils, scientists are able to learn about life on Earth long ago. They can learn about which types of plants grew in different environments. They can learn about animals too. A fossil of a skeleton can let scientists know an animal’s size and body parts. They can also work out how the animals moved and what food they ate.

Archaeopteryx fossil

The Archaeopteryx was a bird-like dinosaur that lived on Earth about 150 million years ago.

Scientists are able to use Archaeopteryx fossils as evidence to make predictions about how the animal looked, moved and what it ate. Wings and feathers are evidence that Archaeopteryx could fly. Sharp claws and teeth means it probably ate other animals.

Archaeopteryx

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Scientists can use fossil evidence to learn about how the Earth has changed over time. A trilobite was an animal that lived in the ocean more than 500 million years ago. When a trilobite fossil is discovered on land, scientists can infer that the area was once underwater.

When the fossils of tropical plants are discovered in the Antarctic or Arctic regions, we can infer that those areas were once much warmer.

How deep underground a fossil is discovered can also help scientists learn about the Earth in the past. Older fossils are found deeper underground than newer fossils.

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Another way scientists can learn about living things and the Earth long ago is by studying trace fossils.

A trace fossil is evidence such as a footprint, burrow, nest or eggshell that indicates the presence of life.

Fossilized dinosaur footprints are evidence that dinosaurs once walked on the land. Fossilized woolly mammoth footprints may indicate that the environment was once much colder than it is now.

AB Activity 6.4

A fossilized dinosaur footprint is trace evidence that dinosaurs lived long ago.

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A Closer Look

Dinosaurs Dinosaurs were a diverse group of animals that ruled the Earth more than 200 millions years ago. The word dinosaur comes from Greek words which mean ‘terrible lizard’. Like lizards, dinosaurs were reptiles. They were cold-blooded and reproduced by laying eggs.

Scientists have been able to learn a lot about dinosaurs from the large number of fossils and trace evidence that have been discovered all over the world. Dinosaurs varied greatly in size, body shape, where they lived and what they ate.

Go Online!

Go back to the time when dinosaurs ruled the Earth in a video on the NGScience website.

QuickCode: A8M8

Tyrannosaurus

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Stegosaurus

Argentinosaurus

Based on fossil evidence, scientists have discovered and named more than 700 different kinds of dinosaurs.

One of the most well-known dinosaurs, Tyrannosaurus, was up to 14 meters long and weighed up to 10,000 kilograms. It had a large head with sharp teeth. Tyrannosaurus was a meat-eater, feeding on other dinosaurs.

Think Deeply For how many years did dinosaurs roam the Earth?

The largest of all dinosaurs discovered was the Argentinosaurus. Fossil evidence shows that this gigantic, plant-eating dinosaur could reach lengths of more than 40 meters.

Fossils and other data collected by scientists show that the dinosaurs became extinct about 66 million years ago.

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crocodile

Learning From Organisms Most of the fossils and trace fossils discovered by scientists are from organisms that are now extinct. Usually, organisms become extinct when they are not able to adapt to changes in their environment.

Sometimes, scientists discover fossils of organisms that are still around today. These organisms have been able to adapt, survive and reproduce as the environment changed. crocodile fossil

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Fossils that are similar to organisms alive today can tell us things about the environment in the past.

horseshoe crab fossil

Crocodiles and horseshoe crabs have survived on Earth for millions of years. By looking at where these animals live, what they eat, and how they move and reproduce, we can infer things about the environment in the past.

AB

Activities 6.5 – 6.6

horseshoe crab

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Science Words Use the words to complete the sentences. extinct evolution

climate change fossil

fossilization trace fossil

1. The process of an organism becoming a fossil is called

.

2. The process of a new kind of living thing gradually developing from an existing living thing is called .

3. The slow change of the Earth’s climate is called

.

4. A is evidence such as a footprint, burrow, nest or eggshell that indicates the presence of life in the past.

5.

A

is the preserved remains or trace of an organism.

6.

An organism becomes

when all of its kind are no longer alive.

Review 1. True or false. (a) Dinosaurs are an example of extinct animals. (b) Some extinct animals live on Earth today. (c) Changes to the Earth’s climate can cause plants and animals to become extinct.

2. How have scientists been able to learn so much about animals that lived on Earth so long ago?

3. In point form, describe how fossils form.

4. What is the difference between a fossil and a trace fossil?

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5. What things can scientists learn from trace fossils?

6. Paleontologists discover trace fossil footprints and leaf fossils in the same layer of sedimentary rock. What can they infer about the environment when these organisms were alive?

7. Describe the organism that formed each fossil and its environment. (a)

(b)

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In the Field

Paleontologists If you are fascinated by the great diversity of organisms that lived on Earth millions of years ago, then maybe you’d like to be a paleontologist.

A paleontologist is a scientist who searches for and studies the fossils of all kinds of organisms all over the world!

Paleontologists are trained to use special tools to carefully remove fossils from the rocks and soil in which they are found. They study the fossils to work out how old they are and to learn about the interactions of organisms long ago.

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Fossils discovered by paleontologists are used to build models of all kinds of organisms. These are often donated to museums so that people all over the world can learn about the history of life on our amazing planet!

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This publication would not have been possible without the tireless effort of our production team.

Special thanks to: Matthew Cole, Daniel Cole, Wang Hui Guan Joseph Anderson, Halle Taylor-Pritchard, Sophie Taylor-Pritchard, Tejal Thakur Natchanuch Nakapat, Varasinun Mathanattapat, Kanungnit Pookwanmuang, Saijit Lueangsrisuk Original Illustrations: Natchanuch Nakapat, GraphicsRF, Blue Ring Media and Interact Images Royalty-free images: Shutterstock, Adobe Stock