Next Generation Science Level 4 - Textbook A by Blue Ring Media Pty Ltd

Science for the Next Generation

Science G ra d e F ou r

Textbook

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.

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.

Animal

Animals are or structures animals to s can be divid structures a

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.

External stru birds warm birds to fly m

Amazing Fact! Great white sharks are the largest of all predatory fish in the world. They can reach lengths of up to seven meters and weigh up to 3,000 kilograms!

great white sh

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

Renewable Energy Engineer

In many countries around the world, governments are closing down fossil fuel power stations and replacing them with renewable energy alternatives. These include solar farms, wind farms and new technologies that produce electricity using tidal and wave energy. Because these electricity production methods do not produce emissions, they are referred to as clean energy. If you are interested in clean energy and helping to reduce emissions, you may like to be a renewable energy engineer. A renewable energy engineer is a scientist that researches, develops and tests new technologies to produce clean energy.

To a renewable energy engineer, the production of electricity by burning fossil fuels is identified as a problem. Renewable energy engineers see the design and implementation of a renewable energy alternative as the solution.

Renewable energy engineers collect data on the availability of renewable energy in the field. They look at how energy from the Sun, moving water and wind can be used to generate electricity efficiently. In laboratories, they build models and use computers to test and evaluate the effectiveness of their designs. They also monitor and maintain renewable energy technologies once constructed. What would you work on if you were a renewable energy engineer?

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

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

A Closer Look Features of the Eart

h’s Surface

Forces such as movin g water, wind and the movement of the Earth’s tectonic plates are continually shapin g the Earth’s surface and water sources.

111

1 10

lake

plateau canyon

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

lagoon

peninsula island

ocean

Amazing Fact! Interesting facts to build interest and enthusiasm.

bald eagle

l Structures

e made up of different parts s. These structures help the survive in their environment and ded into two types – external and internal structures.

ladybug

scorpion

Did You Know?

Scorpions have pincers and a stinger to catch and kill their pray. Ladybugs have a hard outer covering that helps to protect its body and wings.

uctures such as feathers keep and their light weight help the more easily.

green palm snake

Animals such as sharks, snakes and dolphins have internal skeletons and backbones to support their bodies. Organs inside the bodies of animals also help them to get the things they need to survive, grow and reproduce. Discuss some animals you know of and the structures they have that help them survive.

hark

Try This!

sea turtle

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

dolphin

Science Words

13.

are blood vessels that carry blood high in oxyge heart to all parts of an n from the animal’s body.

14.

Most mammals have specialized hairs, called their mouth and nose.

Use the words to comp

lete the sentences.

vertebrates invertebrates exoskeleton herbivore carnivore camouflage 1. 2.

endoskeleton lungs gills arteries capillaries

veins nocturnal whiskers antennae brain

The is an internal structure that processes and interpr information and instruc ets ts the body how to respon d to change.

Insects have a pair of sense

receptors called

animals are active at night and

Animal

External Structures Body Covering

Movement

Getting Food

rest during the day.

are blood vessels that carry blood high in carbo from the cells back to n dioxide the lungs.

Arteries branch out into a fine

network of

Use a chart to describe how each animal’s extern al structures help it to survive.

is an animal that eats

, surrounding

Review 1.

(a) .

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

(b)

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

(c)

plants.

A is an animal that eats other animals. Animals without a backb ones are called hard outer covering called . Some have a an . 9. Animals with a backb one are called . They have an interna structure of bones called Descri l be the landforms and an . water sources shown in the diagram. Which of 10. An anima ability to blend these can be l’s into its surroundings is found in your area? called . 11. are internal structures used to take in oxyge AB Activities 7.3 – 7.4 n from the air. 12. are internal structures used to take in oxyge n from water. 8.

mountain

List and describe three internal structures of a dolphin that help it to survive.

Discussion

A monkey eats a sweet rose apple. Draw and label a flow chart to show how the sensory input is received by the monkey and how it is processed in the brain to help it survive.

glacier

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

hill river

Review

plain

delta beach

sand bar

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

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

Contents Unit 1 - Classification of Organisms

Characteristics of Life Cells Organism Classification Review

4 6 14 27

Unit 2 - Plant Structures and Functions Plant Structures External Structures Internal Structures Review

Unit 3 - Animal Structures and Functions Animal Structures External Structures Internal Structures Animal Senses Review

28 30 32 42 49

50 52 54 68 76 85

Unit 4 - Human Body Systems Your Amazing Body Human Senses Review

Unit 5 - Ecosystems What is an Ecosystem? Energy in Ecosystems Review

88 90 106 109

110 112 126 139

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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.

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.

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.

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?

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.

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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Classification of Organisms How can we distinguish living things from non-living things?

In this chapter you will ... • identify the needs and characteristics of living things. • understand that all organisms are made up of one or more cells. • describe how scientists classify organisms into groups. • list the six kingdoms and provide examples of organisms within each kingdom.

How can we classify the living things around us?

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

Some poison dart frogs carry their young to water.

fox with her cubs

squirrel eating

How can we classify the living things around us?

Characteristics of Life The plants and animals on these two pages are all living things. A living thing is called an organism. We can tell if something is an organism by looking at its needs and characteristics. Organisms need the same things to live and survive in their environment. Animals need water, food, nutrients and a place to live. They also need the gas oxygen. Plants are organisms that produce their own food through the process of photosynthesis. To do this, plants need sunlight and a gas called carbon dioxide.

All organisms grow as they get older. When organisms grow, they usually get taller and heavier. As organisms get older, they look more like their parents. All organisms can reproduce. This means they are able to produce young of the same kind. Organisms also respond to changes around them. When an animal senses danger, it may respond by running away. Some plants open and close their leaves or flowers in response to the change from day to night. Many plants grow or bend in the direction of sunlight. Responding to changes around them helps all organisms to meet their needs and survive in their environment.

Activities 1.1 – 1.2

Sunflower seedlings get bigger and taller as they grow.

Think Deeply A plant’s response of growing or bending in the direction of sunlight is called phototropism. How does this response help plants to live and grow?

Sunflower plants turn and bend to follow the position of the Sun throughout the day.

Cells All organisms are made of structures called cells. Cells are the smallest unit within an organism that carries out life processes – including reproduction and growth.

leaf cells

stem cells

Some organisms are made of only one cell. Many of the organisms around us, such as most plants and animals, are made up of millions of different cells.

Most plants and animals are made up of many cells. They are called multicellular organisms.

Each type of cell plays a role in helping the organisms to function. In a plant, cells in the roots take in water for the plant. Cells in the stem move water and food to different parts of the plant. In the leaves, many cells contain chloroplasts. Chloroplasts are the part of a cell that make food for the plant. Animal cells can be different in shape, size and their function. Cells in the brain of a kitten help it to send messages about its surroundings. Cells in the blood help to move oxygen to where it is needed.

brain cells

blood cells

Why do cells come in a variety of different shapes and sizes?

Activities 1. 3 – 1.4 7

Try This! Draw a Venn diagram to show the similarities and differences between a hand lens and a microscope.

microscopic chlorellas

Unicellular Organisms Most cells are very small and can only be seen using powerful microscopes. Many organisms, from tiny seedlings to giant blue whales, are made up of millions of cells. Some organisms are made of only one cell. They are called unicellular organisms or one-celled organisms. Chlorellas are unicellular green algae that are able to photosynthesize. Parameciums are unicellular organisms that, when observed under a microscope, are shaped like a shoe.

microscopic parameciums

Bacteria are simple unicellular organisms found all over the world. Some bacteria can be harmful to plants and animals. Other bacteria can be helpful. Rhizobium is a bacterium found in soil that helps a plant to get the nutrients it needs. People often use unicellular organisms in preparing food. Lactobacillus is a bacteria used to make yogurt. Yeast is a unicellular fungus used to make bread and other food and drink products.

Amazing Fact! A bacterium reproduces by dividing into two cells. Each of the two cells can then divide again to form four cells. By reproducing in this way, billions of bacteria can be produced in just one day!

Go Online!

Activity 1.5

Discover more about microorganisms in a video on the NGScience website. QuickCode: T9L6 yeast

Multicellular Organisms Most organisms are multicellular – they are made up of many different cells. The cells that make up multicellular organisms come in a great variety of shapes and sizes. The shape, size and location of the cells within an organism are suited to their function. Humans are multicellular organisms with many different types of cells. muscle cells

The shape, size and location of muscle cells help you to move different parts of your body. Bone cells give your bones strength and structure.

bone cells

Your skin cells form a protective layer around your body. Blood cells help to transport gases to and from other types of cells.

skin cells

Amazing Fact!

All of the cells within a multicellular organism work together to help the organism function as a system.

The human body is an amazing and complex system. There are about 200 different types of cells and about 30 trillion cells in all!

Activity 1.6

red blood cells

Try This! Observe some prepared slides of human cells under a light microscope. Draw and describe the cells you observe under low power and high power.

Cell Organization Humans and many of the animals you are familiar with are complex, multicellular organisms. The variety of cells that make up multicellular organisms are organized in a way that helps the organisms function as a whole system. Cells that are of the same kind and have the same function are often grouped together as tissue. Intestinal cells in your body, for example, make up your different kinds of intestinal tissues.

intestinal tissue

Two or more types of tissue that are grouped together make up an organ. Each organ has a primary function. Your small intestine is an organ that helps your body to absorb nutrients from food.

Think Deeply Why do multicellular organisms have different types of organs?

A group of organs that perform a central task is called an organ system. Your esophagus, stomach and intestines are organs that work together as your digestive system. The primary function of the digestive system is to break down food to enable your body to get the energy and nutrients it needs to carry out life processes like moving about, growing and repairing itself. All of the organ systems work together to make up an organism. How are cells organized in a multicellular organism?

Activity 1.7

intestines digestive system

Organism Classification There is a great variety of different organisms on Earth. From deep in the ocean to the top of the coldest mountains. More than one and a half million different kinds of organisms have been named by scientists and millions more are yet to be discovered.

Amazing Fact! So far, about 1.6 million different kinds of organisms have been named, described and classified. Scientists estimate there are more than 10 million different kinds of organisms yet to be discovered.

bacteria

In order to better understand each kind of organism and their differences and similarities with other organisms, scientists have classified them into groups called kingdoms. The six main kingdoms are ancient bacteria, bacteria, protists, fungi, plants and animals. To decide which kingdom an organism belongs to, scientists look at the organism’s characteristics such as how it gets food, how it reproduces and whether it is unicellular or multicellular.

Volvox are unicellular algae.

fir sapling

Why is it important to classify organisms into groups?

Activity 1.8

Did You Know? Not all bacteria are harmful. Blue cheese, Korean kimchi and soy sauce are just some of the many food made using different kinds of bacteria.

Bacteria Bacteria are the simplest organisms on Earth. They are unicellular and their cells are simpler than that of other organisms. Most bacteria break down the remains of plants and animals for food. Some bacteria get the food they need by living in or on other organisms. Other bacteria are able to photosynthesize and make their own food. Bacteria are able to reproduce rapidly by dividing. During this process, a single bacterium divides into two identical daughter bacteria. Bacteria can cause diseases and infections in plants, animals and people. Salmonella is a bacteria that can cause food poisoning in people and some animals. Bacteria can also be helpful. Many organisms need bacteria to help them get the nutrients they need. Bacteria in your stomach help you to get nutrients from the food you eat.

In what ways can bacteria be harmful? In what ways can they be helpful?

salmonella

amoeba

Protists Protists are a diverse group of organisms. Some, like amoebas and parameciums, are unicellular and can only be seen under a microscope. Others, like giant kelp, are multicellular and can reach lengths of more than 50 meters.

Think Deeply Why are kelp forests only found in shallow coastal waters and not in the deep ocean?

Some protists, like euglenas, make their own food. Others get the food they need by eating other organisms. Different protists reproduce in different ways. Some are able to reproduce by dividing. Others have more complex life cycles.

Activity 1.9

euglenas

Fungi Go Online! Discover more about fungi in a video on the NGScience website. QuickCode: Y5S7

Think Deeply Many years ago scientists classified fungi as plants. Upon closer observation, they noticed that fungi were different from plants in a number of ways. With a classmate, create a chart to show the similarities and differences between fungi and plants.

Fungi have many features in common with plants. They often grow in soil and do not move from place to place. Fungi lack the distinguishing features of plants such as stems, leaves, flowers or fruits. Fungi are also different from plants in the way they get their food. They do not make their food as plants do, but instead break down the remains of plants and animals. An organism that gets its energy in this way is called a decomposer. Decomposers play an important role in an ecosystem by helping to recycle dead organisms into nutrients in the soil. Unlike plants, fungi do not produce seeds. Most fungi reproduce by releasing microscopic spores into the air. New fungi grow from the spores. Common types of fungi include mushrooms, bracket fungi, puff balls and molds.

puff ball

mold

Like bacteria, some fungi can be harmful to other organisms by causing infections and diseases. Fungi are also important to people. Mushrooms, for example, are an important source of food. Other types of fungi, such as yeast, are used in the production of different food. Penicillium is a type of mold that is used to make penicillin.

In what ways are fungi similar to plants? In what ways are they different?

penicillium fungi

Amazing Fact! Truffles are edible fungi found underground. They only grow in certain regions of the world and are hard to find. They range in size from the size of a strawberry to the size of an apple. Some truffles can sell for thousands of dollars.

AB Activity 1.10 19

A Closer Look

The Zombie Fungus Found mostly in tropical rainforests are a type of fungi that are truly fascinating. Meet the mind-controlling cordyceps fungus, sometimes called zombie fungus. Cordyceps are parasites, which means they infect and live inside other organisms. When a cordyceps fungus infects an animal, usually an insect, it begins to take over its mind. The fungus compels the insect to leave the safety of its nest and move to a branch above the ground that is the right temperature for the cordyceps to reproduce.

Did You Know? Cordyceps fungi are used in traditional Chinese medicine. However, scientists have not found any evidence on their ability to treat human diseases.

After about a week, the insect dies and the cordyceps pushes a spore-containing growth through the insect’s head. Cordyceps fungi reproduce through spores. The spores are released into the air and land on other insects. The insects become infected and the life cycle repeats!

sequoia trees

Go Online! Plants can be different in many ways. Learn about some of Earth’s more unusual plants in a video on the NGScience website. QuickCode: L1K7

Think Deeply Hundreds of millions of years ago, plants only lived in the ocean and other aquatic environments. They eventually developed adaptations suitable for living on land. As more plants adapted to life on land, the amount of oxygen in the Earth’s atmosphere increased. Why did this occur?

Plants Plants are organisms that can be found almost everywhere on Earth and they come in a diverse range of shapes, sizes and colors. Scientists have named and classified hundreds of thousands of different kinds of plants and more plants are constantly being discovered. Plants are able to make their own food through the process of photosynthesis. During photosynthesis, plants use light energy from the Sun to transform carbon dioxide, water and minerals into food and oxygen. Scientists classify plants into smaller groups by looking closely at their external structures. Plants that produce flowers and fruits are called flowering plants. Flowering plants reproduce from seeds. Plants that do not produce flowers and fruits are called nonflowering plants. Many non-flowering plants, such as mosses and ferns, reproduce from spores.

Scientists can also classify plants by looking closely at their internal structures. Vascular plants are plants with internal structures, called xylem and phloem, to transport food and water throughout the plant. Plants without these internal structures are called non-vascular plants. What characteristics of plants make them different from fungi and animals?

Amazing Fact! The oldest living organism on Earth is a type of pine called the methuselah tree. It is found in the California mountains in the United States and is estimated to be 4,853 years old!

moss

anemone fish hiding in a sea anemone

Sally Lightfoot crab

Animals leopard

There is a great diversity of animals on Earth. They can be found in the coldest polar regions to the driest desert. They fill our rainforests and coral reefs and come in all sorts of shapes and sizes. So far, scientists have identified and named over a million different kinds of animals and many new animals are discovered every year. Scientists estimate there may be as many as eight to ten million different kinds of animals yet to be discovered, named and classified.

king penguins

jellyfish

bee

treefrog

Like plants, animals are organisms that need food, water and air. Unlike plants, animals are not able to make food. To get the energy and nutrients they need, animals feed on other organisms. Within the animal kingdom, scientists divide animals into two main groups. Animals that have a backbone are classified as vertebrates. Animals without a backbone are classified as invertebrates. About 95 percent of the animals on Earth are invertebrates.

Amazing Fact! Paedophryne amauensis is a type of frog discovered in New Guinea in 2009. At just 7.7 millimeters long, it is the smallest vertebrate on Earth! See if you can find out the largest invertebrate on Earth.

Go Online!

Activity 1.11

dwarf crocodile

Like plants, animals are a very diverse group of organisms. Discover some strange and outright weird animals in a video on the NGScience website. QuickCode: M3H1

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

cells multicellular organisms chloroplasts unicellular organisms

tissue organ organ system kingdoms

1. Organisms made of just one cell are called

2. Organisms made of more than one cell are called 3.

to changes around them.

Organisms

are the smallest unit within an organism that carries out 4. life processes. 5.

are the part of a cell that make food for the plant.

6. Cells that are of the same kind and have the same function form a . 7. All organisms can young of the same kind.

which means they are able to produce

8. Two or more types of tissue that are grouped together make up . an 9. Plants produce their own food through the process of 10. When organisms 11. A living thing is called an

, they usually get taller and heavier. . .

12. A group of organs that perform a central task is called an 13.

Organisms can be classified into six main groups called

Review 1. List the characteristics of all organisms. 2. Provide an example of how an organism responds to changes in its environment. 3.

True or false. (a) All organisms are made up of at least one cell. (b) All cells contain chloroplasts. (c) Different cells have different functions.

4. How can bacteria be harmful to people? 5. Draw a flow chart diagram to show how cells are organized in the human body. 6. List the six kingdoms and provide an example of an organism in each. 7. Copy and complete the chart below. Kingdom

Characteristics

Examples

Plant Structures and Functions What are the external and internal structures of plants?

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

In this chapter you will ... • identify and list the external structures of plants. • identify and list the internal structures of plants. • describe a plant system in terms of its components and their interactions. • construct an argument that plants have internal and external structures that function to support survival, growth and reproduction.

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

flower

Plant Structures Plants are made up of different parts or structures. Many plants, for example, have roots, stems and leaves. There are also parts inside plants, such as the tubes that transport water and nutrients around the plant.

fruit

All of the structures of a plant interact and work together as a system to support the survival, growth and reproduction of the plant. What are the functions of the tomato plant structures you can see here?

leaf

stem

roots

Each plant structure has a function that helps the plant to survive, grow and reproduce. The bright petals of flowers function to attract bees and other pollinators.

bee pollinating flower

The thorns on a blackberry bush help to protect its leaves and fruits from grazing by wildlife. If one or more plant structures are removed or do not function as they are supposed to, the survival of the whole plant system may be affected.

blackberry thorns

Discuss what would happen to a plant if all of its leaves were removed.

Activity 2.1

External Structures Structures that are observable on the outside of a plant are external structures. These include roots, stems, leaves, flowers and fruits. Roots are usually the external structures that grow down into the soil. The primary function of the roots is to take in the water and nutrients the plant needs to survive and grow. Some roots are shallow and branch out to cover a large area. These roots are called fibrous roots. Fibrous roots help the plant to take up lots of water when it rains. Growing out from the roots are microscopic root hairs. The root hairs help in absorbing water and nutrients from the soil.

Root hairs take in water from the soil.

root hairs

Tree roots branch out and hold the tree firmly in the soil.

Other plants have one main root, called a taproot, which grows deep into the soil. This helps to reach water deeper in the soil. Roots also hold plants firmly in place. This helps to prevent them from being washed away by water or blown away by wind.

Amazing Fact! The shepherd tree grows in the very dry grasslands of South Africa. It has the deepest roots of all plants – reaching depths of over 60 meters!

How are the shapes of roots suited to their function?

AB Activity 2.2

dandelion with taproot

Go Online! Observe how roots take in water and minerals in an animated video on the NGScience website. QuickCode: Y3G5

Try This! Design and construct a device that mimics the external structures of a plant to produce electricity using solar cells.

Many plants have a stem. Stems can be different in many ways, but they usually perform two important functions for the plant. Plants need the energy from sunlight in order to make food through the process of photosynthesis – a process that takes place in the leaves. One function of the stems in many plants is to hold up the plant. This allows the leaves to absorb more sunlight. Stems also hold up the plant’s reproductive structures – flowers and fruits. Some plants have stems that are soft and can bend easily. They are called herbaceous plants. Herbaceous stems grow quickly.

Other plants, such as trees, have stiff, strong stems. They are called woody plants. The strong stems of woody plants grow thicker and taller each year. This allows the plants to reach high into the sky where the leaves can trap the sunlight they need to photosynthesize. For protection against animals, some plants have coverings on their stems. Trees have an outer layer of bark. Some plants like roses and bougainvilleas have stems with thorns for protection against animals.

Try This! With your classmates, visit a place in your area that has lots of plants. Classify the plants you spot into groups. Draw a diagram or create a chart to show how you classified the plants.

AB Activity 2.3

maple leaves

Amazing Fact! The bryophyllum plant can reproduce from its leaves. Small plantlets with roots develop along the edges of the leaves. The plantlets can grow into new plants when they fall to the ground.

eucalyptus leaves

How is the shape of leaves suited to their primary function? Plants are organisms that absorb the energy in sunlight to make food through the process of photosynthesis. In most plants, photosynthesis takes place in the leaves. To take in lots of sunlight, leaves are external structures that are often flat and branch out to cover a large area. The key to making food is what lies inside the leaf. We’ll take a look at that in more detail later.

Victoria lily pads

Leaves have a large surface area for absorbing sunlight, but this can also lead to water loss. To reduce water loss, many leaves have a waxy outer covering called a cuticle. Some plants in hot and dry environments like deserts store water in their leaves. They have a thick cuticle to prevent water loss.

Think Deeply The leaves of a cactus are modified into sharp spines and do not contain chloroplasts. How is a cactus able to photosynthesize?

What is the function of the cuticle on a plant’s leaves?

AB Activity 2.4

longhorn beetle covered in pollen

Go Online! Watch the process of pollination in an animated video on the NGScience website. QuickCode: E1V7

hummingbird feeding on nectar

Flowers are external structures found on flowering plants. Their primary function is to help the plants reproduce. The sepals are often at the base of a flower. Their function is to protect the flower as it develops. For most flowering plants to reproduce, pollination needs to occur. Pollination is the transfer of pollen from the male part of the flower, the stamen, to the female part of the flower, the pistil. The petals are often the brightly-colored part of a flower that surround the reproductive parts. The petals help to attract pollinators, such as insects and birds, which transfer pollen between flowers and other plants.

dandelion fruit

Flowers develop into fruits which help to protect the seeds from which flowering plants reproduce. Fruits can also help plants to reproduce by spreading seeds to new places.

Think Deeply Many plants produce seeds that are dispersed to new places by wind. What characteristic would you expect these seeds to share?

By spreading seeds to new places, the seeds are able to grow in areas away from the parent plant where there is less chance of competition for water, sunlight and nutrients.

AB Activity 2.5

A Closer Look

Seed Dispersal Most flowering plants reproduce from seeds. For seeds to germinate and grow, they often need to be scattered in areas away from the parent plant where there is less competition for the water, nutrients and sunlight the new plants need to survive. This process of scattering seeds to new places is called seed dispersal.

milkweed seeds

Flowering plants have different adaptations to disperse their seeds in different ways. Some plants have fruits that burst open and throw the seeds into the air. Seeds can also be dispersed by wind and water.

Go Online! Learn all about seed dispersal in a video on the NGScience website. QuickCode: E7X1

coconut floating on water

Many flowering plants develop fruits and seeds that are moved to new places by the animals they attract. Seeds can be dispersed when animals that feed on the fruits move or drop the seeds. Seeds may stick to the fur or feathers of animals and are moved to new places when they fall off. Seeds can also be dispersed when they are eaten. They are moved to new places in the animal’s waste.

Engineer It! Design and build a seed that can be dispersed by wind. Test and evaluate your design with your classmates.

How does seed dispersal help plants survive?

young wombat with seeds stuck to its fur

AB Activities 2.6 – 2.7 squirrel holding an acorn fruit from an oak tree

Internal Structures

The roots, stem, leaves and flowers are external structures that each play a role in helping the plant function as a whole system. There are structures inside a plant too. They are called internal structures. Like external structures, each internal structure has an important role in helping the plant function as a whole system. One important internal structure is called vascular tissue. Vascular tissue is a series of tubes that transports water, nutrients and food throughout the plant. There are two main structures within the vascular system – xylem and phloem.

Amazing Fact!

xylem

phloem

Mosses are non-vascular plants. They don’t have xylem to transport water. In fact, they don’t have roots at all. They absorb water and nutrients directly into their bodies. They have root-like rhizoids which help to hold them in place.

root section

root hair

Xylem are tubes that transport water and nutrients from the roots, through the stem to the leaves. Phloem are tubes that transport food in the form of sugar from the leaves to all parts of the plant. The vascular tissue in the roots, stem and leaves is arranged in different ways to help the plant function and meet its needs. xylem phloem

Go Online! Observe how water, food and nutrients are transported through the stem in an animated video on the NGScience website. QuickCode: P6Z5

AB Activity 2.8 stem section

What are the primary functions of the xylem and phloem in vascular plants?

A Closer Look

Internal Leaf Structures The leaves of the plant are where the food-making process of photosynthesis takes place. In order to photosynthesize, the external and internal structures in the leaves work together as a system. Let’s take a closer look! Water and nutrients travel in the xylem from the roots through the stem to the cells in the leaves. Tiny holes, mostly on the underside of the leaves, called stomata, open and close to take in the air the plant needs.

phloem

leaf section

xylem stoma

vascular tissue in leaf

cells on underside of leaf

stoma

chloroplast

Inside the cells of a leaf are special structures called chloroplasts. Chloroplasts are the part of the cell where photosynthesis takes place. In chloroplasts, the energy from sunlight is used to convert carbon dioxide and water into food for the plant. The food is transported from the leaves to the rest of the plant in phloem tubes.

AB Activities 2.9 – 2.10

Think Deeply Would you expect to find chloroplasts in animals cells? Explain your answer.

Go Online! Observe how water and food are transported within leaves in an animated video on the NGScience website. QuickCode: X9Y7

We have learned that flowers are the external reproductive structures of flowering plants. Internal structures within the flower also play an important function in reproduction.

anther

When pollination occurs, pollen grains, which are male sex cells, move from the stamen to the pistil. The pollen grains move down a pollen tube to the ovary. The ovary holds the eggs – the female sex cells.

stamen

pistil

Fertilization occurs when the male sex cell joins with the female sex cell. The fertilized egg cell then develops into a seed. The petals and reproductive parts of the flower fall away and the ovary develops into a fruit. Once developed and under the right conditions, the seeds will be dispersed and grow to become new plants.

Once fertilized, the ovary in a tomato flower develops into a protective fruit.

Think Deeply What is the difference between pollination and fertilization?

A Closer Look

Parts of a Flower petal

stigma

style anther

pollen tube

stamen

pistil

filament ovule ovary sepal

AB Activities 2.11 – 2.14 47

Science Words Use the words to complete the sentences. fibrous roots taproot herbaceous plants woody plants cuticle sepals

pollination stamen pistil petals seed dispersal

vascular tissue xylem phloem stomata fertilization

is the scattering of seeds to new places.

are roots that are shallow and branch out.

3. The series of tubes that transport water, nutrients and food through a plant is called . 4. transports water and nutrients from the roots to the upper parts of the plant. 5.

transports food from the leaves to all parts of the plant.

are openings in the leaf that take in air.

7. the

is the transfer of pollen from the male part of the flower, , to the female part of the flower, the .

8. Many leaves have a waxy outer covering called a

9. When a male sex cell joins with a female sex cell,

occurs.

10. The are often brightly-colored and surround the reproductive parts of a flower. 11. are often at the base of a flower and help to protect the flower as it develops.

12.

have stems that are soft and bend easily.

13. Some plants have one main root called a into the soil. 14.

that grows deep

have stiff strong stems often covered in bark.

Review 1. Copy and complete the chart below. External Structure

Functions

roots stem leaves 2. What is the primary function of root hairs? 3. How can you distinguish between herbaceous plants and woody plants? 4. On leaves, what is the primary function of the cuticle? 5. Draw a diagram to show the process of pollination. 6. List two ways plants disperse their seeds. 7 Copy and complete the chart below. Internal Structure

Functions

xylem phloem chloroplasts 8. Describe the process of fertilization.

Animal Structures and Functions What are the external and internal structures of animals?

In this chapter you will ... • identify and list some of the external structures of animals. • identify and list some of the internal structures of animals. • describe an animal system in terms of its components and their interactions. • construct an argument that animals have internal and external structures that function to support survival, growth, behavior and reproduction.

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

How do an animal’s structures support its survival, growth, behavior and reproduction?

bald eagle

Animal Structures Animals are made up of different parts or structures. These structures help the animals to survive in their environment and can be divided into two types – external structures and internal structures.

Amazing Fact!

External structures such as feathers keep birds warm and their light weight help the birds to fly more easily.

Great white sharks are the largest of all predatory fish in the world. They can reach lengths of up to seven meters and weigh up to 3,000 kilograms!

great white shark

scorpion

ladybug

Scorpions have pincers and a stinger to catch and kill their prey. Ladybugs have a hard outer covering that helps to protect their body and wings.

green palm snake

sea turtle

dolphin

Go Online! Watch how elephants use their different external structures in a video on the NGScience website. QuickCode: H7S6

External Structures Animals have parts on the outside of their bodies that help them to survive and get the things they need to grow and reproduce. Let’s look at the external features of elephants.

Wrinkly skin helps to trap moisture between the cracks. This helps to reduce water loss and keep the elephant cool in its often hot and dry environment.

Elephants have a tail with a hairy tip. They use their tails to swish away insects and other small biting animals.

Like most land mammals, elephants use their legs and feet to move from place to place in search of food or when evading predators.

Elephants have big ears with a large surface area. Blood vessels are close to the surface. Flapping their ears helps them to stay cool.

Tusks are modified teeth. They are used to dig, gather food and for protection against predators.

Elephants are well known for their impressive trunks. The trunk is actually a nose. It’s used to smell, breathe and shovel food and water into the elephant’s mouth.

Movement Try This! With a classmate, compare an aquatic mammal with a land mammal. Create a chart to show the differences in their external structures for movement.

springbok

Animals are organisms that eat other organisms for food. To get the food they need, most animals need to move from place to place. Moving from place to place is also helpful for escaping danger. Different animals have different external structures to help them move. Legs are external structures that help many land animals to walk, run and crawl. Cheetahs, the fastest land animals, can run at speeds as fast as a car.

tiger shark

spider monkey

Animals like spider monkeys, have long legs and arms and a tail to help them swing effortlessly through forests. Sharks and other aquatic animals have fins and a tail which help them to move and change direction underwater. Birds, bats and flying insects have wings and move about by flying.

AB bullfrog

Amazing Fact! Wandering albatrosses have the largest wingspans of all birds, measuring almost 12 feet from end to end. They can fly thousands of kilometers without needing to flap their wings!

Activity 3.1 wandering albatross

Amazing Fact! Spiky fur is not the only unique feature of echidnas. They are also one of just two mammals that reproduce by laying eggs. The other is the platypus. Both of these egglaying mammals, called monotremes, can only be found in the wild in Australia.

Body Coverings Animal body coverings are external structures that help them to survive in their environment. Mammals have fur. Birds have feathers. Reptiles and fish have scales. A tiger’s fur helps to keep it warm. It also helps it to blend into its environment when sneaking up on prey. Like tigers, echidnas are mammals with fur too. Rather than keeping it warm, an echidna’s fur is in the form of sharp spikes. This helps to protect it from predators.

king penguin

tiger

freshwater carp

Feathers keep many birds warm and help them to fly. Penguins are flightless birds. Their waterproof feathers help them to stay warm and swim. Scales provide fish and many reptiles with an outer layer of protection. Turtles are reptiles with modified scales called plates. When a turtle senses danger it retreats into its plate-covered shell.

Smooth and hard scales provide fish with an outer layer of protection.

In what ways do animal body coverings support their survival in their environment?

AB Activity 3.2

cobra

echidna

A Closer Look

Animal Body Armour – Exoskeleton Many of the animals we are familiar with are vertebrates. Vertebrates are animals with a backbone and an internal skeleton of bones. Mammals, birds, reptiles, amphibians and fish are all vertebrates. The skeleton provides vertebrates with structure and support. It also protects vital organs like the heart, lungs and brain. Most of the animals on Earth don’t have a backbone or internal skeleton. They’re called invertebrates. While some invertebrates like worms, jellyfish and octopus have soft bodies, many have a hard outer covering called an exoskeleton. It’s like a skeleton on the outside of their bodies.

Insects, like ants, bees and beetles, have exoskeletons made of a substance called chitin. Like the internal skeleton of vertebrates, the exoskeleton gives the insects shape, helps them move and provides protection. It also helps to prevent water loss. Lobsters, crabs, scorpions and spiders are other animals with an exoskeleton made of chitin.

Think Deeply As animals grow, they break out of their exoskeletons and build a new one in a process called molting. Explain why a molting animal may be more vulnerable to predators.

chameleon

Catching Prey When predators catch up with their prey, the fight for a meal isn’t over. They need to hold on to it too. Predators have external structures to do just that. A chameleon has a tongue that is twice the length of its body. It extends its tongue to reach its prey. Sticky saliva on the tip of the tongue holds the prey in place as the tongue is pulled back to the mouth.

Eagles and other birds of prey have sharp beaks and large claws, called talons, to catch and kill prey. bald eagle

Grizzly bears have large and sharp teeth for catching and killing their prey.

Teeth are external structures that help animals get the food they need. The shape and size of teeth are always suited to the types of food an animal eats. Animals that eat plants, called herbivores, often have strong and flat teeth for grinding grasses and leaves. Animals that feed on other animals are called carnivores. They often have large canine teeth for catching and holding prey.

Amazing Fact! Crocodiles are fierce predators. They have powerful jaws lined with sharp teeth. When a crocodile catches its prey, it dives underwater and rolls rapidly in a behavior known as the `death roll’.

West African slender-snouted crocodile

monarch caterpillar

monarch butterfly

Defense Against Predators

frilled-necked lizard

Many animals have external structures for defense against other animals. The monarch butterfly caterpillar has bright yellow, black, and white stripes that scare away predators. Adult butterflies are also brightly colored to let predators know they are poisonous. When a frilled-necked lizard senses danger, it expands its neck making it appear larger and scarier to potential predators. When threatened, a millipede responds by curling into a tight ball for protection. millipede

A common gray treefrog on bark.

A common gray treefrog on a leaf.

Many animals are camouflaged which means they are able to blend into their surroundings, making them hard to spot. The color of a gray treefrog changes in response to its environment. It takes on a gray color when on bark and a green color when on leaves. Stick insects, as their name implies, have external structures that make them look a lot like sticks. This makes them almost impossible for predators to spot.

Engineer It! In a small group, design and build an object that will be camouflaged in your school garden. Test the effectiveness of your design by getting other groups to act as predators and try to spot your object.

Activities 3.3 – 3.4

How does being camouflaged help prey survive in their environment? How could it help predators?

A Closer Look

The World’s Fastest Animal Peregrine falcons have many external structures that allow them to live in a range of different environments and climates. From icy tundras to hot and dry deserts. With a light and sleek body and large wings, peregrine falcons are the fastest animals on Earth. They can dive through the sky at speeds of up to 320 kilometers an hour. They have excellent vision too, using their large eyes to spot prey from high in the sky.

Specialized external structures help the peregrine falcon to catch, hold on to and kill its prey. They have sharp claws called talons and a hooked beak for tearing the flesh of their prey.

Did You Know? Peregrine falcons have excellent vision. Scientists believe they are able to see eight times better than humans. They are able to spot prey from more than three kilometers away.

Go Online! Watch the amazing peregrine falcon in action in a video on the NGScience website. QuickCode: S5H7

AB Activity 3.5 67

Internal Structures

Try This! With a partner, take turns in naming some of your internal structures. Discuss the function of each structure.

Most animals are complex organisms. Along with external structures to help them survive, animals also have many internal structures that work together to help the animal get the things it needs to stay alive, grow and reproduce. A cow has muscles and bones that work together to help it move. Lungs help it to get oxygen from the air and pass it to the blood. Its heart pumps the oxygenated blood throughout its body. It has four stomachs that work together with its intestines to get energy from the grass it eats. All of the internal structures work together to help the cow function as a whole system.

How do the internal structures of a cow help it to survive, grow and reproduce?

leopard

Support and Movement Vertebrate animals – mammals, birds, reptiles, amphibians and fish – have an internal structure of connected bones that forms an internal skeleton, called an endoskeleton. The bones are hard and rigid and provide the animals with support. The endoskeleton also gives their bodies shape and protects vital organs like the brain, heart and lungs.

leopard skeleton

Muscles are internal structures found throughout the bodies of vertebrate animals. Many muscles are attached to bones. When these muscles contract, they pull on the bones. This allows the animal to move. Muscles help invertebrates move too. An earthworm moves by contracting its muscles in waves. Insects have muscles attached to the inner surface of the exoskeleton. Insects move their legs and wings by contracting and relaxing these muscles.

muscles

orangutan

grasshopper

Gas Exchange Animals have internal structures to help them get the oxygen they need from their surroundings. The same structures also get rid of the carbon dioxide which animals produce. Mammals, birds and reptiles have lungs to take in oxygen from the air when they breathe in. In the lungs, the oxygen passes into the blood. Carbon dioxide passes from the blood and is removed from the body when the animal breathes out. Along with having lungs, some amphibians are able to take in oxygen through their moist skin. Aquatic mammals and reptiles also have lungs. To take in oxygen and remove carbon dioxide, they must come to the surface to breathe in air.

seagull lung

air sac

Amazing Fact! Dolphins are marine mammals that must come to the surface about every eight to ten minutes to breathe. Another marine mammal, Cuvier’s beaked whale, can stay underwater for more than two hours before needing to breathe at the surface. blowhole

dolphin

lung

Fish and many aquatic invertebrates like crabs, squid and clams do not have lungs. Taking in oxygen and removing carbon dioxide takes place in an organ called gills. When water washes over the gills, oxygen moves into the blood and carbon dioxide moves from the blood to the water.

Go Online! Watch how fish use gills to take in oxygen and give out carbon dioxide in an animated video on the NGScience website. QuickCode: A1Z2

What is the primary function of gills and lungs?

Blood Circulation All vertebrates and some invertebrates have internal structures to move blood throughout their bodies. Central to these structures is the heart. The heart is an organ made mostly of muscle. When the muscle in the walls of the heart contract, blood is pumped through the heart and around the body.

Did You Know? The hearts of different animals beat at different rates. The heart of a turtle beats about 10 times per minute. The heart of the world’s smallest mammal, the Etruscan shrew, beats about 1,500 times a minute!

Branching out from the heart is a network of fine tubes called blood vessels. Arteries are blood vessels that carry blood high in oxygen from the heart to all parts of the animal’s body. The arteries branch out into a fine network of blood vessels called capillaries. In the capillaries, oxygen and nutrients move from the blood to the cells. Carbon dioxide moves from the cells to the blood. Veins are blood vessels that carry blood high in carbon dioxide from the cells back to the lungs.

turtle heart

What is the primary function of an animal’s heart and blood vessels?

AB Activity 3.6

internal anatomy of the painted wood turtle

A Closer Look

An Internal System The various internal structures of an animal have specific functions. These internal structures work together to allow the animal to function as a whole system.

When a tiger breathes in, air moves to the lungs where the oxygen needed passes to the blood. When the tiger breathes out, carbon dioxide is removed.

The heart pumps blood through arteries to capillaries where oxygen and nutrients are exchanged for carbon dioxide. Veins carry the carbon dioxide back to the lungs.

Food broken down into small pieces in the mouth is sent to the stomach. The stomach further breaks down food and sends it to the intestines where nutrients are absorbed.

An internal network of bones helps to protect vital organs such as the brain, heart and lungs. Joints allow the tiger to move its limbs and other body parts when bones are pulled by muscles.

Muscles pull on bones to help the tiger move. Muscles also provide protection for other internal organs. The heart is an organ made mostly of muscle.

AB Activity 3.7 75

Amazing Fact! The Australian platypus has a very poor sense of sight and often closes its eyes when hunting. To find food, it uses its bill which is filled with electro-receptors that pick up electrical signals given off by its prey.

platypus

Animal Senses Humans have five senses to take in information about the world around them. Our five senses are sight, smell, hearing, taste and touch. Animals also have senses. They use their senses to gather information about their environment. Processing and responding to this information help them to survive, grow and reproduce.

Sense Organs Animals have a variety of different sense organs. Like humans, many animals have eyes, ears and a nose. Other animals have specialized structures and systems for gathering specific information about their surroundings. long-eared owl

grey long-eared bat

Owls are nocturnal. This means they are active at night and rest during the day. To sense their prey at night, owls have large eyes that allow them to see well in low light. They also have a keen sense of hearing which they use to sense small prey as they rustle in leaves in trees or on the ground. Like owls, bats are also nocturnal. Most bats have a very poor sense of sight. To ‘see’ in the dark, bats use a special technique called echolocation. Bats let out a very high-pitched sound through their mouth which is too high for humans to hear. The sound travels away from the bat, but is reflected back when it hits other objects. Bats use their sensitive ears to receive these echoes which allow them to determine how far away and how big the object is.

Go Online! Bats are great listeners! They can use their sense of hearing to ‘see’ in the dark. Find out more about echolocation on the NGScience website. QuickCode: P1T3

Dolphins and shrews also use echolocation to sense their surroundings.

Many animals rely on a strong sense of smell to help them find food or escape nearby predators. The African elephant takes in smells through nostrils located at the tip of its trunk. Its keen sense of smell can detect sources of water up to 20 kilometers away. You may have noticed that snakes regularly flick their tongues out. It looks like they are using their tongue to taste the air. In fact, their tongue functions more like a nose to smell the air. Their tongue collects particles in the air and brings them to a special body part inside their mouth for examination.

African elephants

pit viper

African lion

Imagine trying to make your way from your desk to the classroom door in complete darkness. What would you use to sense the objects around you? Similar to humans using their fingers and skin to feel the things around them, most mammals have whiskers to help in sensing their surroundings. A whisker is a specialized hair attached to the animal’s skin and is surrounded by many nerve cells at the base of the hair. Whiskers are often located around the mouth and nose. Sea lions use whiskers to detect vibrations in the water caused by fish. Nocturnal hunters, like lions and cheetahs, use whiskers to sense and catch prey.

Australian sea lion

Did You Know? Cockroaches have two antennae which are used mostly for smell. They also have legs covered in many hair-like structures that are highly sensitive touch organs. They can detect even the slightest movement in the air.

Insects have a pair of sense receptors called antennae attached to their heads. Many insects use their antennae to smell. Others use their antennae for touch, to detect sounds or to taste.

American cockroach

The Brain An animal’s sense organs are constantly gathering information about the world around them. This information travels along a network of nerves to the brain. The brain is an internal structure that processes and interprets the information and instructs the body how to respond to change. Such changes may include sound, light, odor or temperature. Information sent to the brain can be processed immediately as perception of the environment. It can also be stored as memories to enable animals to engage in appropriate behaviors in the future.

Go Online! Chimpanzees are one of just a few animals that are able to use tools. Find out what other animals use tools on the NGScience website. QuickCode: K9N5

Using its sense organs, a chimpanzee detects termites in a mound. It uses a stick to catch and feed on the termites. After a successful meal, it stores the memories in its brain and will return to the mound next time it is hungry.

chimpanzee

Imagine an animal that sees a brown, rotten fruit and also smells bad odor. This sensory information is processed in the brain and stored as memories. The animal uses this stored information to identify other fruits that appear to be rotting and makes decisions about whether or not to eat them. In a rainforest, toucans use their eyes to spot fruit. A toucan may spot a green papaya and an orange papaya and eat them both. In doing so, the toucan learns that the unripe green fruit tastes bitter and the ripe orange fruit tastes sweet. It can use this sensory information, perceived and stored as memories, to guide its fruit choice next time it is hungry. Sensory input, the brain, and behavioral output are all parts of a system that allow animals to engage in appropriate behaviors.

AB Activity 3.8 toucan

A Closer Look

Senses and Behavior Let’s use the example of a barn owl spotting its prey to provide an explanation that animals receive different types of information through their senses, process the information in their brain and respond to the information in different ways.

Using its eyes, which are its sense organ for sight, the barn owl spots a mouse.

2 The image of the mouse is sent to the barn owl’s brain where the information is processed.

The brain recognizes the mouse as a source of food and instructs the barn owl to attack. 4

The barn owl attacks, catches and eats the mouse.

The experience is stored in the barn owl’s brain as memories. The memories will guide its actions in the future.

Science Words Use the words to complete the sentences. vertebrates invertebrates exoskeleton herbivore carnivore camouflage

endoskeleton lungs gills arteries capillaries

veins nocturnal whiskers antennae brain

is an internal structure that processes and interprets 1. The information and instructs the body how to respond to change. 2. Insects have a pair of sense receptors called 3.

animals are active at night and rest during the day.

are blood vessels that carry blood high in carbon dioxide 4. from the cells back to the lungs. 5. Arteries branch out into a fine network of

6. A

is an animal that eats plants.

7. A

is an animal that eats other animals.

8. Animals without a backbones are called hard outer covering called an . 9. Animals with a backbone are called structure of bones called an

. Some have a . They have an internal

10. An animal’s ability to blend into its surroundings is called

11.

are internal structures used to take in oxygen from the air.

12.

are internal structures used to take in oxygen from water.

13. are blood vessels that carry blood high in oxygen from the heart to all parts of an animal’s body. 14. Most mammals have specialized hairs, called their mouth and nose.

, surrounding

Review 1. Use a chart to describe how each animal’s external structures help it to survive. External Structures Animal

Body Covering

Movement

Getting Food

(a) (b) (c)

2. List and describe three internal structures of a dolphin that help it to survive.

3. A monkey eats a sweet rose apple. Draw and label a flow chart to show how the sensory input is received by the monkey and how it is processed in the brain to help it survive.

In the Field

Sniffer Dogs All animals have senses that collect information about the world around them. Some animals have more heightened senses than others. Compared to people and most other animals, dogs have a very heightened sense of smell. They are able to detect and interpret smells that we cannot. This makes them great companions for doing all sorts of jobs. Dogs are trained by people to identify certain smells. By rewarding dogs when they find a certain smell, the dogs form memories and are then able to search for the smell in the future.

At airports and stations, dogs are used by law enforcement officers to search for and locate drugs, weapons or explosives. This helps to keep people safe. Dogs can also be used in search and rescue operations. In the case of a natural disaster such as an earthquake or hurricane, dogs can assist in locating survivors by identifying the smell of human breath amongst the rubble. By smelling a piece of clothing belonging to a missing person, dogs are able to use their sense of smell to find the smell again. This can lead people to the missing person. Imagine you had the sense of smell of a dog. What things do you think you could smell?

Human Body Systems

What are the primary functions of the human body systems?

How do the human body systems work together?

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

What are the human sense organs? What sensory information do they provide?

In this chapter you will ... • list and describe the organs and systems that make up the human body. • describe the ways in which body systems work together to help the human body function as a whole system.. • list the human sense organs and describe their function.

Your Amazing Body Think Deeply What body parts and internal body systems do sprinters use when they run a race?

The human body is an amazing machine that can do all sorts of things. It is made up of many internal body systems that all work together to help your body to get the things it needs to stay healthy and grow.

muscle

Each body system consists of a group of organs that work together to perform a specific function. Your nose, mouth, windpipe and lungs form a system that helps you to get the oxygen you need from the air.

In order for your body to function properly, all of the body systems must interact and work together. When oxygen enters your lungs, it passes into your blood. Your blood, heart and blood vessels are another body system. It delivers the oxygen to all of your cells.

brain

If an organ that makes up a body system is not functioning properly, the body as a whole can be affected.

bone

heart

Activity 4.1

lung

What are some body systems in the human body? How do they work with other body systems?

Amazing Fact! When you were born, your skeleton was made up of 300 different bones. As you grow, some bones fuse together. By the time you are an adult, you’ll have just 206 bones.

The Skeletal System Take your hand and squeeze your forearm, wrist and fingers. What do you feel? The hard parts you feel are bones. Just like the internal skeleton in vertebrate animals, humans also have bones that make up our skeletal system. One main function of the skeletal system is to provide the body with support and give it structure. If it were not for bones, we would not be able to stand or move about. Another function of the skeletal system to is protect our internal organs. The rib cage is a series of bones that protects the heart, lungs and other organs. The skull surrounds and protects the brain. Bones are hard, strong and not flexible. How are you able to do things like bend your elbow, stand up or clench your fingers to form a fist? The place where two or more bones meet are called joints. Our bones, joints and muscles all work together to help us move. Your elbow joint allows you to move your forearms. Your hip and knee joints allow you to move your legs. Look at the skeletal system on the next page. Which bones protect our internal organs? Which bones and joints help us to move?

AB Activity 4.2 92

skull

humerus ribs elbow spine pelvis

femur

knee tibia fibula

skeletal system

The Muscular System For you to move different parts of your body, your skeletal system needs to work together with another body system – the muscular system. The muscular system consists of all the muscles in your body.

There are three main types of muscle – smooth muscle, cardiac muscle and skeletal muscle. Smooth muscles are layers of muscles in your internal organs. Smooth muscles in your stomach and intestines, for example, help you to digest food. Cardiac muscles are the muscles that make up your heart. They work together to pump blood all around your body. Smooth muscle and cardiac muscle are involuntary muscles. This means they cannot be controlled. They work on their own.

muscular system

Intestines

Heart

Skeletal Muscle

smooth muscle cells

cardiac muscle cells

skeletal muscle cells

Skeletal muscles are the muscles that connect to your bones. They are voluntary muscles. These are the muscles you use when you throw a ball, go for a run and chew your food.

Try This! Bend different parts of your body. Identify which muscles contract and which muscles relax.

Muscles can only pull on bones, not push. When you bend your arm, the muscles on top contract and get shorter. At the same time, the muscles on the bottom relax and get longer. The opposite happens when you straighten your arm.

biceps contract

triceps relax

biceps relax

triceps contract

AB Activity 4.3 95

The Circulatory System Try This! The number of times your heart beats per minute while you are relaxed is called your resting heart rate. The best time to record your resting heart rate is the moment you wake up. Measure your resting heart rate. How does it compare to your classmates’ resting heart rates?

Think Deeply Your heart beats about 80 times in one minute. With a classmate, work out how many times your heart beats in one hour, one day and one week.

Place your hand over the left side of your chest. Can you feel your heart beating?

Your heart is a organ made mostly of muscle that pumps blood throughout the body. Blood travels to and from the heart through a network of tubes called blood vessels. The heart, blood vessels and blood work together in a system called the circulatory system. The primary function of the circulatory system is to deliver the oxygen, food and nutrients to all parts of the body. It also helps to remove wastes.

Blood vessels that carry blood away from the heart are called arteries. Blood in arteries carries the oxygen needed by all of the cells in your body.

heart blood vessels

Amazing Fact! If all of your blood vessels were laid out in one straight line, they would stretch for about 100,000 kilometers (about 62,000 mi).

circulatory system

Blood vessels that carry blood back to your heart are called veins. Blood in veins is low in oxygen, but high in the waste gas carbon dioxide. The carbon dioxide moves from the heart to the lungs where it is removed from the body. What are the parts and primary functions of the circulatory system?

AB Activities 4.4 – 4.5 97

The Respiratory System Think Deeply When you exercise, your heart rate and breathing rate increase. Why does this occur?

Air is a mixture of different gases. It contains nitrogen, oxygen, carbon dioxide and water vapor. The respiratory system is the body system that delivers and removes different gases from your body. The respiratory system is made up of your nose and mouth, windpipe, lungs and diaphragm. When you breathe in, or inhale, air enters through your nose and mouth. It moves down a tube, called the windpipe, and into your lungs.

windpipe

lung

diaphragm

respiratory system

In the lungs, the oxygen is passed to your blood and moves through blood vessels to all parts of your body. Your body uses the oxygen to get the energy from food. When energy is produced, the waste gas carbon dioxide is also produced. The unwanted carbon dioxide passes into the blood and is transported back to the lungs. The carbon dioxide is removed from the body when you breathe out, or exhale. What are the parts and primary functions of the respiratory system?

Try This! With a classmate, calculate how many times you inhale and exhale in one full day. Share your calculation with others in your class.

AB Activity 4.6

A Closer Look

Inhalation and Exhalation Inhalation and exhalation occur when a muscle below the lungs, called the diaphragm, contacts and relaxes. When you inhale, your diaphragm contracts and pulls downward. The space in the lungs increases, drawing air in. When you exhale, the diaphragm relaxes and pushes upwards. The space in the lungs decreases and air is forced out. Inhalation rib cage gets bigger

diaphragm contracts

Exhalation rib cage gets smaller

diaphragm relaxes

The Digestive System Your body gets all of the energy it needs to grow and carry out life processes from the food you eat. In order to get energy from food, it first needs to be broken down into pieces that are small enough to be absorbed into the blood. The process by which food is broken down and absorbed into the blood is called digestion. It is the primary function of your digestive system. Digestion begins in the mouth where teeth begin to cut, grind and tear food. A digestive juice, called saliva, also helps to break down food.

Go Online! Take a journey through the digestive system in an animated video on the NGScience website. QuickCode: X8W4

Try This! Take a piece of fruit and put it in your mouth. Describe what happens to the fruit as you chew it and swallow.

AB Activity 4.7

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The tongue helps to push the food down a tube called the esophagus. Muscles in the wall of the esophagus push the food into the stomach. The stomach works like a concrete mixer. Food is churned and mixed with acids and other digestive juices to form a soupy liquid. Food moves from the stomach into the small intestine. Here, food is further broken down by digestive juices into substances that are absorbed into the blood. Any undigested food then moves to the large intestine where water is removed. The unused food is then stored in the rectum before leaving the body as waste through the anus. What are the parts and primary functions of the digestive system?

mouth

esophagus

liver

stomach

pancreas small intestine

large intestine

rectum anus

digestive system

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The Excretory System Your body is an amazing system that can do all sorts of things. In carrying out life processes, your body also produces wastes. Wastes are substances the body produces that it does not need. To stay healthy, wastes need to be removed from the body regularly. The removal of wastes from the body is the primary function of the excretory system. Parts of the excretory system include the liver, kidneys and bladder.

liver kidney

The liver is an organ that filters waste from the blood. The waste, called urea, is sent to two beanshaped organs called kidneys. Kidneys further filter the urea to produce urine.

ureter bladder

Urine moves through two tubes, called ureters to the bladder. The bladder stores urine until it leaves the body through another tube called the urethra. Why can your lungs be considered part of your excretory system? What waste do they remove from your body?

AB Activity 4.8

excretory system

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The Nervous System Your body’s sense organs are constantly gathering information about the world around you. This information travels through your spinal cord in a network of cells called nerves to your brain. Your brain interprets the messages and instructs the body on how to respond. All of your nerves, spinal cord and brain function together as your nervous system. Its primary function is to control and communicate information throughout the body. There are two main types of nerves – sensory nerves and motor nerves. Sensory nerves send messages from your sense organs to your spinal cord and brain. Motor nerves send messages from your spinal cord and brain to all parts of your body.

brain

spinal cord

nerves

When you smell a rotten apple, information about the smell is sent from your nose to your brain. Your brain interprets the information and instructs you not to eat the rotten food. Some nerves control the organs inside the body. They regulate breathing, heartbeat, body temperature, the digestive system and other activities.

AB Activity 4.9 nervous system

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The Immune System

thymus

spleen

lymph nodes

Our amazing bodies do a great job of keeping us healthy, but sometimes germs can cause us to get sick. If too many germs get into your body, they can cause infections or diseases. Luckily, our bodies have a number of ways of stopping germs from getting into our bodies. If germs do get inside, our bodies are able to find and kill the germs before we get too sick. All of the cells, tissues and organs that protect you from getting sick and help you get well make up your immune system. Your skin is part of the immune system. It provides a layer of protection around all of the internal parts of the body. Your saliva, nostril hairs, eyes lashes and tears are parts of the immune system too. All of these parts of your body stop or kill germs before they get inside the body. Sometimes germs can get into your body through your mouth, nose, eyes or a cut in your skin. White blood cells, which are found in blood and lymph nodes, are special germ-fighting cells. They are able to locate and kill germs. They are also able to ‘remember’ the types of germs they fight and kill, so that they can fight them more effectively the next time these germs enter the body. Why is it important to maintain a healthy immune system?

immune system

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A Closer Look

Viruses Viruses are tiny germs that can only be seen using very powerful microscopes. Viruses can cause us to get sick if they get inside our bodies. The common cold and influenza (flu) are illnesses caused by viruses. Viruses are not living organisms as they are only able to replicate inside a host organism. Once inside your body, the virus enters a cell and takes over its function. The cell is forced to replicate the virus which then damages or kills the cell. This causes infections within the body. The buildup of mucus in the throat and nose, skin rashes and fever occur as your immune system fights the virus. Medicine can help you feel better if you have a cold or the flu, but to get rid of the virus for good, it’s up to your immune system. That’s why it is important to keep your body in top shape so it can fight the viruses on its own.

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Human Senses People have five senses that take in information about the world around them. The information is sent along nerves to the brain where it is interpreted and processed. The brain uses the processed information to instruct the body how to respond. The five senses are sight, smell, hearing, taste and touch.

Eyes are the sense organs for the sense of sight. Light passes into the eyes and travels as electrical signals in nerves to the brain. The brain interprets the signals as images.

Ears are the sense organs for the sense of hearing. Sound waves enter the ears causing parts in the ear to vibrate. The vibrations travel as electrical signals along nerves to the brain. The brain interprets the signals as sounds of different volumes and pitch.

Skin is the sense organ for the sense of touch. When skin comes in contact with an object, signals travel along nerves to the brain. The brain interprets the information and responds.

1 06

The brain is the control center of the body. It constantly receives, processes and interprets information from the sense organs and controls the body’s response. The brain controls movement and the regulation of body systems.

The nose is the sense organ for the sense of smell. Receptors in the nose detect odors and send the information along nerves to the brain. The brain interprets the information as smells.

The tongue and mouth are the sense organs for the sense of taste. Special cells on the tongue, called taste buds, respond to different types of taste. Information about taste travels along nerves to the brain where they are interpreted as sweet, salty, bitter, sour and umami tastes.

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Science Words Use the words to complete the sentences. skeletal system joints muscular system blood vessels circulatory system 1. The

respiratory system inhale exhale diaphragm digestion

digestive system excretory system nervous system immune system

delivers and removes different gases from the body.

2. The internal network of bones make up the

3. The cells, tissues and organs that protect you from getting sick and help you get well make up your . 4. The removal of wastes from the body is the primary function of the . 5. The process by which food is broken down and absorbed into the blood is called . It is the primary function of your . 6. When you breathe in, you you .

. When you breathe out,

7. Inhalation and exhalation occurs when a muscle below the lungs, called the , contracts and relaxes. 8. The

consists of all the muscles in your body.

9. Bones meet at points called different parts of our bodies.

which allow us to bend

10. are a network of tubes through which blood flows. These, along with blood and the heart make up the . 11. Your nerves, spinal cord and brain make up your

108

Review 1. What characteristics of bones make them suited to their function? 2. Use the chart to describe the function of each body system when you compete in a bicycle race. Body System

Function

skeletal muscular respiratory digestive 3. What is the primary function of the heart? 4. Describe two functions of the respiratory system. 5. Name and describe the function of each organ. List the body system it belongs to. (a) (b) (c)

(d) (e) (f)

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Ecosystems

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

110

How do organisms in an ecosystem interact with each other and their surroundings?

How does energy flow through ecosystems?

In this chapter you will ... • describe and provide examples of different types of ecosystems. • describe how ecosystems are organized and the interactions that take place within them. • describe how energy flows through different ecosystems. • use models to describe how energy in animals’ food (used for body repair, growth, motion and to maintain body warmth) was once energy from the Sun.

111

What Is an Ecosystem? In a rainforest, there is a great diversity of organisms. There are many different kinds of plants, from tiny mosses to giant trees. Hiding amongst the plants you’ll find many different kinds of animals. There’s also fungi growing on the forest floor or attached to logs and tree trunks.

Did You Know? All of the living things in an ecosystem are called biotic factors. All of the non-living things are called abiotic factors.

112

There are also many non-living things in a rainforest, such as air, water, rocks and soil. All of the organisms and non-living things in a rainforest along with the interactions between them, make up a rainforest ecosystem. An ecosystem is group of organisms that live and interact with each other and with the non-living things in a specific environment.

Think Deeply What organisms can you spot in the rainforest? How do the organisms interact with each other and their environment?

The organisms in a given ecosystem live in different places. In a rainforest, there are leeches and insects crawling on the moist rainforest floor. Fish and frogs can be found in and around streams. Monkeys and birds move from tree to tree high up in the canopy. The place where an organism lives within an ecosystem is called a habitat. An organism’s habitat provides it with all of the things it needs to survive.

Activities 5.1 – 5.2 113

Ecosystem Interactions All ecosystems have living and non-living components that interact with each other so that the system functions as a whole. Frogs are organisms found in a pond ecosystem. The frogs interact with the insects and other small animals they eat for food. They interact with plants when they use them for shelter from predators. Birds and snakes preying on frogs are interactions too.

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Frogs also interact with the non-living parts of the pond ecosystem. They take in oxygen from the air through their lungs and skin. The water in the pond provides the frogs with a place to live and reproduce. The interactions between the components in an ecosystem keep the whole system in balance. When a component of an ecosystem changes, the ecosystem as a whole can be affected. If the water in a pond was to dry up, there would be no place for frogs to live and reproduce. With no frogs, there would be fewer snakes and birds.

Think Deeply Discuss how the components in a pond ecosystem would be affected if the water becomes polluted.

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A Closer Look

Ecosystem Organization To study different parts of an ecosystem and to better understand the interactions between organisms and the environment, scientists organize ecosystems into different levels. The simplest level is a single organism, called an individual. In an African grassland, a single antelope is an example of an individual. All of the organisms of the same kind within an ecosystem are called a population. All of the same kind of antelope in the African grassland make up a population. Organisms within a population interact and reproduce together.

116

In the African grassland, there are populations of many other organisms. There are populations of acacia trees, termites, zebras, lions and many others. All of the populations in an ecosystem make up a community. The community and the interactions with the non-living components of their surroundings make up the ecosystem. The interactions between the gazelles, zebras, lions and other organisms with the air, soil, water and other non-living things make up the African grassland ecosystem.

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Wetland Ecosystems Did You Know? Wetlands are often located between a source of water and dry land. They help to maintain the level of water while also protecting the land from flooding.

A wetland ecosystem is an area of land that is covered in water for part or all of the year. Wetlands can contain fresh water or salt water and are often found in low-lying areas near lakes and rivers. The water-covered soil in a wetland is often rich in minerals which helps plants grow. Wetlands have a rich diversity of plants growing in and around the edges of the water. Wetlands are important habitats for many kinds of vertebrates. A great variety of birds can be found in wetlands which provide them with food, a safe place to reproduce and a place to rest during migration.

spoonbill

118

moose

Fish, amphibians and snakes are also common wetland animals. As the amount of water in a wetland changes from season to season, the type and diversity of organisms can change. When the wetland is at its driest, plants may die and there are fewer animals. During the wet season, plants grow back and animal diversity also increases.

Why does the diversity of organisms in a wetland often change throughout the year?

freshwater carp

Go Online! Head to the NGScience website to watch a video about wetlands. QuickCode: Y6Y6 red-eared turtle

AB Activity 5.3

119

macaw

Tropical Rainforest Ecosystems Forests are ecosystems with tall trees and an undergrowth. Tropical rainforests are dense forests close to the Earth’s equator. They are warm and moist all year round and receive lots of sunlight – although much of the sunlight is blocked by a thick canopy. In tropical rainforests, there are usually only two seasons – a wet season and a drier season. Plants have green leaves all year round. Tropical rainforests are the most diverse of all land ecosystems. The single largest rainforest in the world, the Amazon, is home to about 10 percent of all known organisms.

red-eyed treefrogs

Why are rainforest ecosystems home to such a variety of organisms?

120

Tropical rainforests have a great diversity of plants. Tall trees form a dense canopy that blocks much of the light from reaching the forest floor. Under the canopy is a layer of shorter trees and shrubs. Mosses, ferns and orchids can often be found attached to trees. A warm, moist environment with a great variety of plants makes rainforests the perfect ecosystem for many different kinds of animals. There are spiders, leeches and all kinds of insects. There’s a great variety of mammals, birds, reptiles, amphibians and fish too. spider monkey

Go Online! Head to the NGScience website to watch a video about rainforests. QuickCode: Q4E3

Amazing Fact! Leopards are the only big cats that can be found in dry deserts and moist tropical rainforests. They spend most of the day resting, camouflaged in trees and are active predators at night.

AB Activity 5.4 leopard

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great horned owl

Go Online! Head to the NGScience website to watch a video about temperate forests. QuickCode: Y4Y8

Temperate Forest Ecosystems Temperate forests are ecosystems with enough rainfall and sunlight for tall trees to grow. They also have a diverse layer of grass, shrubs, ferns and mosses on the forest floor. Temperate forests are generally cooler than tropical rainforests. Temperate forests usually have four distinct seasons – summer, fall, winter and spring. The changes in weather from season to season affects the organisms in the ecosystem. In fall, the weather begins to cool. To conserve energy, the leaves of some trees change color and fall to the ground. They grow back when the weather warms as spring approaches. During winter, some animals leave the ecosystem and return in the spring.

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Temperate forests are home to a wide variety of mammals, including bears, squirrels, deer and rodents. The high branches and hollows in trees provide a safe place for many birds to live and raise young. There’s also a variety of invertebrates including snails, spiders, cicadas and beetles.

squirrel

In what ways are a temperate forest different from a tropical rainforest? In what ways are they similar?

AB Activity 5.5 grizzly bear

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hawksbill sea turtle

Amazing Fact! Some animals in coral reef ecosystems have venom to kill prey. The blue-ringed octopus is less than 20 centimeters in length, but contains enough venom to kill 25 adults. The blue rings on its body glow brightly before it bites and injects venom into its prey.

Coral Reef Ecosystems The ocean is a large body of salt water that covers more than 70 percent of the Earth’s surface and gives the Earth its deep blue color. Within the ocean are a range of different ecosystems. The average depth of the ocean is over 3.5 kilometers. Most organisms can be found at depths of less than 100 meters. At this depth, sunlight can reach plants like seagrasses so they can photosynthesize.

moray eel

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seagrass

grey reef shark

anemone fish

The most diverse ecosystems in the ocean are coral reefs. Corals are small animals that stay in one place throughout their adult lives. They usually live together in groups called colonies. The colonies form large reefs. Coral reefs provide many places for animals to seek shelter and find food. They are home to a great variety of fish, from tiny anemone fish to giant reef sharks and rays. There are lobsters, clams and jellyfish. There are marine reptiles like sea turtles and sea snakes. Why are coral reef ecosystems home to such a variety of animals?

AB Activity 5.6

Go Online! Go to the NGScience website and take a virtual field trip to the world’s largest coral reef – the Great Barrier Reef in Queensland, Australia. QuickCode: U6A9

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Energy in Ecosystems All of the organisms in an ecosystem need energy. Some make food through photosynthesis. Some eat other organisms. Others break down the remains of dead plants and animals. How an organism gets its energy determines the role it plays in the ecosystem.

Producers, Consumers and Decomposers An organism that makes food through photosynthesis is called a producer. In most ecosystems, plants are the main producers. They use light energy from the Sun, carbon dioxide from the air and water to produce food in the form of sugar.

Think Deeply In most ecosystems, all of the energy can be traced back to the Sun. Why is this so?

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An organism that gets energy by eating other organisms is called a consumer. All animals are consumers. They get the energy they need by feeding on other organisms in the ecosystem.

Some organisms meet their energy requirements by breaking down, or decomposing, the remains of dead plants and animals. They feed on the broken down material. These organisms are called decomposers. Bacteria and fungi are decomposers. Decomposing releases nutrients back into the ecosystem.

Go Online! Check out the ‘All About Fungi’ video on the NGScience website. QuickCode: R7D5

AB Activity 5.7

What role do decomposers play in an ecosystem?

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Types of Consumers Consumers can be classified into three main groups based on the organisms they eat. Animals that eat only plants or the products of plants are called herbivores. Grasshoppers, squirrels, horses, antelope, giraffes and elephants are herbivores. Butterflies feed on the nectar produced by flowers, so butterflies are herbivores too. Animals that eat other animals are called carnivores. Big cats like lions, tigers and cheetahs are carnivores. Spiders, sharks, snakes and eagles are carnivores too.

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Some animals eat both plants and other animals. They are called omnivores. Omnivores can eat algae and fungi too. Many birds are omnivores. Ostriches eat plants and grasses. They also eat small insects and lizards. Bears are omnivores too. In some months they hunt for salmon and deer. At other times they eat leaves, berries and mushrooms. Some reptiles are omnivores. Box turtles eat fish, frogs and other small animals. They also eat berries and flowers.

Think Deeply Mosquitoes feed on different things at different stages of their life cycle. Mosquito larva feed on microorganisms in water. Many adult mosquitoes feed on flower nectar. Adult female mosquitoes feed on the blood of animals to help them produce eggs. As a class, discuss how you would classify mosquitoes as consumers.

Activities 5.8 – 5.9 129

Food Chains All of the organisms in an ecosystem need energy from food. This energy can be traced back to the Sun when producers use its light energy to photosynthesize. The energy is passed to herbivores and omnivores when they eat the producers. Energy passes to carnivores when they feed on other animals. Decomposers get energy when they break down the remains of other organisms.

The acacia tree is a producer.

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The giraffe is a herbivore.

This energy pathway from the Sun to producers to consumers and decomposers is called a food chain. There are usually many food chains in an ecosystem. In a food chain diagram, arrows are used to show the direction of the flow of energy. In an African savanna food chain, acacia trees use the energy from the Sun to make food. Energy is passed to giraffes when they use their long necks to feed on the leaves of the acacia trees. Energy is passed to lions when they prey on the giraffes.

AB Activity 5.10

Go Online! Learn about the food chains in other ecosystems on the NGScience website. QuickCode: R4W4

What are some other food chains in an African savanna ecosystem?

The lion is a carnivore.

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Food Webs A food chain shows one energy pathway in an ecosystem from the Sun, to a producer and to a consumer. In all ecosystems, there are many overlapping food chains. A food web shows how all of the food chains in an ecosystem are connected. As in a food chain, the arrows in a food web show the direction of the flow of energy.

giraffe

gazelle

acacia

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lion

cheetah

zebra

wildebeest

Think Deeply What other animals can be found in an African savanna? Where would they fit in the food chain?

grass

AB Activity 5.11 133

A Closer Look

An Arctic Food Web Not many plants are able to grow in the cold, and often dark, Arctic ocean water. Producers in this ecosystem are tiny single-celled, photosynthesizing organisms called phytoplankton.

seagull

leopard seal

silverfish

Arctic cod

baleen whale

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These organisms provide food for a great diversity of animals. From tiny zooplankton to giant whales. Energy is passed on to other Arctic ocean predators when they feed on other animals. polar bear

walrus

orca

krill phytoplankton

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In the Field

Ecologists If you love plants, animals and the great outdoors, you’ll love being an ecologist. An ecologist is a scientist that studies the relationships between all of the organisms in an ecosystem and their interactions with the non-living things around them. Ecologists measure many aspects of an ecosystem such as the number of organisms in each population. They measure the non-living things too, such as air and water temperature and the condition of the soil. An important role of an ecologist is to observe the impacts of changes to the ecosystem on the organisms that live there. Such changes may include climate, natural disasters or the addition or removal of a population within the ecosystem’s community.

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Science Words Use the words to complete the sentences. ecosystem habitat individual population community 1. A

producer consumer decomposer herbivore

carnivore omnivore food chain food web

is an animal that eats only plants or the products of plants.

2. All of the populations in an ecosystem make up a

3. All of the organisms of the same kind in an ecosystem form a . 4. A model that shows one energy pathway from the Sun to producers to consumers and decomposers is called a . is a model that shows how all of the food chains in an 5. A ecosystem are connected. 6. A

is an animal thats eats other animals.

7. An

eats both plants and other animals.

8. A breaks down the remains of organisms and feeds on the broken down material. 9. A is an organism that makes its own food through photosynthesis. 10. A is an organism that gets energy by eating other organisms.

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11. The place where an organism lives within an ecosystem is called . its 12. A single organism in an ecosystem is an

is a group of organisms that live and interact with each 13. other and with the non-living things in a specific environment.

Review 1. Provide an example of an individual, population and community in a forest ecosystem. 2. What is the difference between a community and an ecosystem? 3. Copy and complete the chart. In the last row, add an ecosystem in your local area. Ecosystem

Characteristics

Organisms

Wetland Tropical Rainforest Temperate Forest Coral Reef

4. Provide an example of a producer, consumer and decomposer in a temperate forest ecosystem. 5. Use the Sun and organisms below to make a food chain diagram.

lion

grass

zebra

Sun

6. What is the difference between a food chain and a food web?

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Next Generation Science Level 4 - Textbook A

Articles inside

Unit 1 - Classification of Organisms

Unit 2 - Plant Structures and Functions