Living things. What are plants and animals?

Transcription

1 Living things Part 2 What are plants and animals?

2 Acknowledgments The Centre for Learning Innovation gratefully acknowledges the following owners of copyright material for permission to reproduce their work. COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the Centre for Learning Innovation, DET, pursuant to Part VB of the Copyright Act 1968 (the Act) The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice. All reasonable efforts have been made to obtain copyright permissions. All claims will be settled in good faith. Writer Julie Haeusler Revisions 1999 Rhonda Caddy Revisions 2004 Jane West Editor Ric Morante Illustrator Barbara Gurney, Thomas Brown Desktop publisher Alide Schimke Audio engineer Greg Parke Voice performers Rhonda Caddy, Julie Haeusler Version date 29 November 2004 Produced by the Centre for Learning Innovation, 51 Wentworth Rd, Strathfield NSW Telephone: ; Fax: Copyright of this material is reserved to the Crown in the right of the State of New South Wales. Reproduction or transmittal in whole, or in part, other than in accordance with provisions of the Copyright Act 1968 is prohibited without the written authority of the Centre for Learning Innovation. State of New South Wales, Department of Education and Training 2004.

3 Contents Part 2 Contents Part Introduction Part Lesson 6 Classifying living things... 5 Why classify?...5 How do you classify?...9 How do biologists classify plants and animals?...16 What did you achieve?...17 Lesson 7 Photosynthesis What is photosynthesis?...19 What did you achieve?...28 Lesson 8 What do animals eat? Consumers...29 What did you achieve?...36 Lesson 9 Feeding relationships Food chains...37 What did you achieve?...41 Lesson 10 The mangroves The mangrove environment...43 The excursion...43 What did you achieve?...50 Suggested answers Part Exercises Part Part 2 What are plants and animals? 1

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5 Introduction Part 2 Previously, you have classified things in our environment as living or non-living. You also investigated the characteristics of living things and learned that they are used by scientists to define living and non-living. Mosaic from ancient Delphi Source: Barbara Gurney Scientific ideas of living and non-living have developed from an understanding that is common to many cultures. Like you, many cultures distinguish between living and non-living things and between living and dead things in a scientific way. Ideas from these cultures have helped produce scientific ideas for classifying living and non-living things. This does not mean that other, non-scientific ways to classify are wrong. Different cultures can have different, non-scientific ways to look at and explain the world too. Part 2 What are plants and animals? 3

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7 Lesson 6 Classifying living things Classifying means sorting, or organising into groups. So far, you have classified, or sorted, things into two groups living and non-living. You looked at how living things were similar; that is, what living things have in common. These common features are the characteristics of life that you and biologists use to group things. In this set, you are going to classify living things into two groups plants and animals. You will examine the characteristics that scientists use to separate plants from animals. That is, you will learn about what makes a plant different from an animal. Why classify? A study of living things allows you to better understand yourself and how you fit into your environment. To make this understanding possible, it helps if we sort out, or classify, living things into groups. Classifying all the living things is a bit like when you get dressed in the morning it's much quicker if all the things you wear are already sorted into groups. Your socks, undies, shirts, jeans and shoes are grouped together so you can find them easily, rather than all being in one big box. Imagine how long it would take you to get dressed in the morning if all your clothes were in one big pile? You'd probably feel just like Laura does, in the following drawing. Part 2 What are plants and animals? 5

8 Sorting out clothes State of New South Wales, Department of Education and Training, 2004 Scientists would feel pretty confused when they tried to study living things if they were in just one big group. Classifying in our daily lives What other things in your daily life do you classify? Classification systems are not only used in science but in everybody s daily life as well. The following diagram is another example of how things are classified in the home. 6 Living things

9 Classifying in the kitchen State of New South Wales, Department of Education and Training, 2004 This makes it a lot easier to find the things you are looking for and to communicate with other people in your family. Activity: Why classify? Make a list of things in your daily life that you classify. Well done! You have realised how important classification is. You will probably agree that classifying things makes it easier to find them. Part 2 What are plants and animals? 7

10 Are there any other reasons to classify? There are also other reasons for classifying things. Classifying makes it easier to communicate. For example, when you say knife you mean a tool for cutting, with a handle and a long, sharp metal blade. It is easier to say knife than go into a long description of the object. This is the same in biology. When you say that a cat is a mammal you mean that the animal is covered with fur, is warm-blooded and suckles its young on milk. Once again, one word has saved a lengthy explanation. Classifying also makes it easier to identify or name unfamiliar objects. For example, can you identify the object in the drawing below? Unknown object State of New South Wales, Department of Education and Training, 2004 Even if you have never seen this object before, you can classify it as a type of knife from its features, or characteristics. You could also predict that it can be used for cutting. In fact, it is a scalpel used by doctors for operating. You have just read about the three benefits of classifying objects. Activity: Are there any other reasons to classify? List the three benefits of classifying objects. Check your response by going to the suggested answers section. When you classify, you put things into groups. How do you do this? 8 Living things

11 How do you classify? First you need to carefully observe the things that you want to classify. Then you can compare them. When you compare things, you are looking for similarities and differences. Things that are similar are put into the same group. A B Two groups of living things State of New South Wales, Department of Education and Training, 2004 The living things in Group A are a pine tree and a gum tree. What are the similarities? Part 2 What are plants and animals? 9

12 Activity: How do you classify? List how the living things in Group A are alike. They both have a trunk, leaves, branches, roots and seeds. The living things in Group B are a snail and a gibbon. A snail is more like a gibbon than a gum tree. Snails and gibbons both move around a lot, need to breathe in oxygen and eat food. Gum trees are rooted to the spot and make their own food. These are reasons why a snail is in the same group as a gibbon but in a different group from a gum tree. Once you have established your groups and the reasons for grouping in that way, you have built a classification system. Classifying plants and animals Look at the following diagrams and decide whether they are plants or animals. Wheat Caribou State of New South Wales, Department of Education and Training, Living things

13 Butterfly Dandelion Grass Bee Gum tree Pine Cockroach Sea urchin State of New South Wales, Department of Education and Training, 2004 Part 2 What are plants and animals? 11

14 Look closely at the diagrams and then do the activity. Activity: Classifying plants and animals Classify the things in the photographs as plants or animals. Plants Animals Check your response by going to the suggested answers section. You probably had no trouble deciding that a dandelion is a plant and a caribou is an animal. But what are your reasons for classifying in this way? How is a plant different from an animal? You have probably noticed that it is not that easy to say why plants and animals are different. This is especially true when you investigate some of the weird and wonderful living things that exist on the Earth. For example, is a green praying mantis a plant or an animal? What about a Venus fly trap that eats insects? 12 Living things

15 Venus flytrap praying mantis Plant or animal? State of New South Wales, Department of Education and Training, 2004 These living things are not easily recognisable as plants or animals. A praying mantis is an animal. A Venus flytrap is a plant. Activity: How is a plant different from an animal? What do you think makes plants different from animals? You may have thought of things like: plants don t move as much as animals do; plants are green; plants have leaves and animals don t; plants don t feel things like animals do. Take a look at two of these ideas and see how useful they are for classifying plants and animals. Animals move more than plants When animals respond to changes in their environment, it is often obvious immediately. Animals usually move away from things like heat whereas plants don t move much at all. Plant movement is usually only fairly slow growth. Animals may move from place to place whereas plants may not. Is this really true? Part 2 What are plants and animals? 13

16 Sea anemones, sponges, oysters and barnacles are examples of animals that are unable to move their entire bodies. They are fixed to a particular place. barnacle mussel sea anemone Three fixed animals State of New South Wales, Department of Education and Training, 2004 But you can say that most animals are able to move from place to place. But what about plants? In the ocean, there are tiny plants called phytoplankton. This word comes from the Greek language. Phyto- means plant. Plankton means drifting. So, phytoplankton are drifting plants, able to move from place to place. Phytoplankton State of New South Wales, Department of Education and Training, 2004 However, you can say that most plants are not able to move from place to place. 14 Living things

17 Plants are green but animals are not Plants are green. Well, what about wheat in the summertime, fruit trees in the autumn? Most plants are green but some are not. What makes plants green? There is colouring matter called chlorophyll present in plants. Chloro- means green in Greek and -phyll means leaf. Therefore, chlorophyll means green leaf. Chlorophyll is present in any parts of plants that are green, such as leaves and stems and flowers. Are there animals that are green? You may have thought of animals like tree frogs, caterpillars, grasshoppers, tree snakes, praying mantis, sea horse or grass parrots. mantis frog Green animals State of New South Wales, Department of Education and Training, 2004 sea horse There are quite a number of green animals, but most animals are not green. Animals do not generally contain chlorophyll even the green ones do not contain chlorophyll. Chlorophyll is generally only present in plants. Some marine animals such as giant clams and corals do contain some cells with chlorophyll in their bodies. But this is a special case and its more like these animals have plants living within their bodies. By now you probably have realised that identifying the differences between plants and animals is not as easy as you might have thought. In fact, the scientific community has used many different methods of sorting, or classifying, living things over the years. For example, writings from ancient China suggest that this culture used movement and growth to classify plants and animals. Part 2 What are plants and animals? 15

18 The classification system that is used by biologists today has developed from the ideas of other cultures. Additionally, the modern classification system has been greatly influenced by two technological developments. These are: the development of the printing press in 1440, because this enabled descriptions of living things to be communicated more easily between scientists the development of the microscope, because this enabled biologists to study living things more closely. So now, look at how modern biologists decide if a living thing is a plant or an animal. How do biologists classify plants and animals? Can you remember the name of the green chemicals in plants? This simple question leads into a way of classifying living things as plants or animals. Activity: Plants, animals and food Plants are green because they contain. The missing word is chlorophyll. Chlorophyll is an amazing substance. It can trap energy from sunlight. Plants take in carbon dioxide and water. These are the raw materials plants need to make their own food. Energy trapped by chlorophyll drives this process. The process is called photosynthesis. The word photosynthesis also comes from the Greek language. Can you deduce (work out) what it means? Remember photo- means light. Synthesis means to make or to put together. 16 Living things

19 What is photosynthesis? Photosynthesis means to make using light. This is how biologists group plants and animals. Plants make their own food using sunlight. On the other hand, animals cannot make their own food. Is this the only way that plants and animals could be classified? No. But this is the way scientists have decided to group plants and animals. Over the next few lessons, you'll learn more about what it means to call a plant a plant, and an animal an animal. Now that you have a list of the characteristics of living things you can further investigate the work of biologists. Are you making good progress? Try completing this summary in the exercise to find out. Go to the exercises section and complete Exercise 2.1 Classifying living things. What did you achieve? Tick what you can do. list some benefits of classifying classify living things as either plants or animals list some differences between plants and animals Part 2 What are plants and animals? 17

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21 Lesson 7 Photosynthesis In this lesson, you will be investigating how plants produce their own food. This process, called photosynthesis, is very important since animals rely on plants for food. Therefore, the study of plants (botany) is a very important one for the survival of all living things. As well as investigating the process of photosynthesis, you'll be learning how to change the presentation of information from words into drawings. It is sometimes faster to get information from a picture than by having to read a lot of words, so this is a good thing to be able to do. What is photosynthesis? In the last lesson, you discovered that one of the main differences between plants and animals is that plants can make their own food and animals cannot. What is the name of the process whereby plants make their own food? The process is called photosynthesis. Photosynthesis is probably the most important process that occurs on Earth. All life depends on it. Our present knowledge of photosynthesis is the outcome of many experiments and theories, built up over at least 300 years. Scientists are curious people, who like to investigate the world around them and suggest explanations for why things occur. The following Part 2 What are plants and animals? 19

22 investigations demonstrate this curiosity and the way that the scientific community has gone about answering questions about plants. van Helmont s experiment Johann Baptist van Helmont lived in Belgium and his findings were reported in At that time, most people thought that plants grew because they took materials out of the soil. Dr van Helmont devised a plan to test this idea. Dr van Helmont was investigating plant growth. He placed 90.9 kg of dry soil in a pot. In this he planted a 2.3 kg willow shoot. He watered the plant. After five years he weighed the plant (now a tree). It weighed 77.0 kg. He also weighed the dry soil. It weighed 90.8 kg. Let s examine what this experiment shows. Activity: van Helmont s experiment Analyse the experiment of van Helmont s experiment by answering the following questions. 1 How much weight had the plant gained? 2 How much weight had the soil lost? 3 How long did the experiment go on for? 4 What did van Helmont do to the plant during the experiment? The plant gained 74.7 kg in five years. ( = 74.7 kg). The soil lost 0.1 kg in five years. ( = 0.1 kg). The experiment went on for five years and only water was added during the experiment. 20 Living things

23 The drawing below was done by a Year 7 student, Daniel. This is one way to show how van Helmont carried out his experiment and the results he got. willow willow dry soil 5 years dry soil 2.3 kg 90.9 kg water only 90.8 kg 77 kg van Helmont s experiment State of New South Wales, Department of Education and Training, 2004 What can be learned from the experiment? Now you can see clearly how van Helmont did his experiment and the results that he obtained. You need to look at what he learned from his experiment. Why do you think that the willow tree increased in weight over five years? Van Helmont thought that the increase in weight was due to water alone. He did not consider the possibility that gases from the air might also be involved. Did you? What kinds of skills do you think a scientist should have? Did you say that a scientist should be able to make careful observations, measure accurately and make inferences? Did you also think that a scientist needs to be curious and not just accept what other people think? Maybe you even said that a scientist should be creative because van Helmont had to think up an experiment by himself. Part 2 What are plants and animals? 21

24 What do we know about plants so far? Plants grow without eating food. Plants need water Joseph Priestley s experiments The next evidence for photosynthesis is from the experiments of Joseph Priestley. Priestley was an Englishman who had been investigating gases, particularly oxygen. Gases, or vapours as they were called by most people of the time, were little understood. Vapours were thought to cause diseases. People closed their windows and covered their faces to try to protect themselves from vapours. Priestley, and other scientists of the 1700s, wanted to logically investigate what gases were and what they did. Priestley s first experiment Joseph Priestley had observed that a candle burning in a sealed jar soon went out. If a mouse was then put into the jar it soon suffocated. This was because burning uses up oxygen in the air. Animals need to breathe in oxygen. What are the important points in the passage above? Underline them. Did you choose these points? Burning uses oxygen. The mouse suffocates without oxygen in the air. The experiment took place in a sealed jar. Think about this experiment and then try the following activity. 22 Living things

25 Activity: Joseph Priestley s experiment 1 Draw a diagram that shows you how Priestley set up his first experiment. Priestley s first experiment Compare your answer with the one in the answer pages. Remember that there is no right or wrong drawing as long as all the information is presented in a way that most people can understand. Priestley s second experiment In another experiment, Priestley burned a candle in a sealed jar. He then placed a plant in the jar which contained air with no oxygen. The plant survived. Then Priestley placed a mouse in the jar that had the plant in it. The mouse did not suffocate. 2 What are the important points from the passage above? Part 2 What are plants and animals? 23

26 3 In the box following, draw a diagram to show the information in the passage called Experiment 2. Priestley s second experiment Compare your drawing with the one in the answer pages. Does your drawing show all the information clearly? Comparing Priestley's experiments How were Priestley's experiments similar? How were they different? Complete the following table to compare them. 4 For each experiment, put a tick beside each statement that is true and a cross beside each statement that is not true. Experiment 1 Experiment 2 a b c d A candle was burned in a sealed jar. A mouse was put into the sealed jar. A plant was put into the sealed jar. The mouse died. Check your response by going to the suggested answers section. 24 Living things

27 A, B and C are all things that Priestley did in his experiments. They are steps in his method. D is what happened. It is part of his results. To learn something new from Experiment 2, you need to compare it with Experiment 1. There is only one thing that Priestley did differently in his two experiments. This is called a fair test, or a controlled experiment. It means that you can see the effect on the results of changing, or varying, one thing. Controlled experiments are very important in science. Priestley's experiments The results could depend on a change made by the candle so he burned the candle in both experiments. The results could depend on putting the mouse into the jar so he did this in both experiments. Making these variables the same in both experiment is called controlling them, or making them constant. The only variable that was different was using the plant. It is the only thing that changed that could have altered the results. The results did change. The plant made the difference between the mouse living and dying. Now answer these questions about Priestley s experiments. 5 Together, do Experiment 1 and Experiment 2 make a controlled experiment? Why or why not? 6 What variable is Priestley testing in his experiments? 7 Can you think of a variable in Priestley's experiments that does not need to be controlled because it would not alter his results? What is it? Check your response by going to the suggested answers section. Part 2 What are plants and animals? 25

28 What can be learned from Priestley s experiments? Other scientists performed experiments that showed that the gas in Priestley's experiments was oxygen. From Priestley's results we can say that burning uses oxygen, animals need oxygen and plants give out oxygen. What do we know about photosynthesis so far? Plants grow without eating. Plants need water. Plants give out oxygen. Animals need the oxygen that plants produce. Jan Ingen-Housz s experiment In the late 1700s, the Dutchman, Jan Ingen-Housz, discovered that plants only gave out oxygen when they were in light. He also showed that only the green parts of plants give out oxygen. Do you remember what the green-coloured matter in plants is called? Well done if you remembered that it is called chlorophyll. Jean Senebier s experiment At the end of the eighteenth century, a Swiss minister named Jean Senebier worked out that another gas, carbon dioxide, is involved in photosynthesis. He also reasoned that the larger the plant the more carbon there was present. Carbon can be seen when plants are burnt. The bigger the tree, the more charcoal (carbon) Senebier produced. Senebier showed that the carbon came from the intake of carbon dioxide. Carry out the activity to summarise what these experiments tell us about plants. 26 Living things

29 Activity: Summary Complete this summary using these words: controlled oxygen sunlight carbon dioxide food variables make/produce water tests Summary Plants make their own. Plants need. Plants give out. Animals need the oxygen that plants. Photosynthesis occurs when plants are in. Plants take in _ during photosynthesis. are things that can be changed in an experiment. An experiment should be planned so that it one variable only. In a experiment, only one variable is changed; the other variables are kept the same. Check your response by going to the suggested answers section. Part 2 What are plants and animals? 27

30 Now use the information you have summarised to complete the exercises. Preparing for Exercise 2.2 In Exercise 2.2, you'll test your understanding of controlled experiments and variables, and your skill at presenting information as drawings. Go to the exercises section and complete Exercises 2.2 Discovering photosynthesis. What did you achieve? Tick what you can do. list the things needed by plants for photosynthesis complete a summary about photosynthesis and its importance identify variables in an experiment present information as drawings. 28 Living things

31 Lesson 8 What do animals eat? You have learned about how plants make their own food. The process is called photosynthesis. Plants are called producers because they make, or produce, their own food. Animals rely on plants since animals cannot make food. In this lesson, you will be investigating how animals obtain their food. Consumers Animals can be classified according what they eat their diet. This is one way of grouping animals. It is a useful way of studying feeding relationships in environments. Because animals cannot produce their own food, they are called consumers. You can group animals (consumers) on the basis of their diet, or what they eat. The gibbon is a consumer. State of New South Wales, Department of Education and Training, 2004 Part 2 What are plants and animals? 29

32 Omnivores Most humans are considered to be omnivores. Activity: Omnivores Look at the restaurant menu below. State of New South Wales, Department of Education and Training, List the foods from the menu which come from plants. Herbs, apricots, chocolate, fruit and coffee all come from plants. 30 Living things

33 2 List the foods which come from animals. Salmon, chicken, pork, cream, cheese and milk (in the coffee and hot chocolate) all come from animals. 3 What sort of diet does an omnivore have? Omnivores have a mixed diet. They eat both plants and animals. So, now you can write a definition for omnivores. 4 What is your definition of the term omnivore? Omnivores are animals that eat plants and meat or products from other animals magpie cockroach human pig Omnivores State of New South Wales, Department of Education and Training, 2004 Omnivore comes from Latin. Omni- means all and -voros means to eat. Therefore omnivore means to eat all things. This is not exactly the definition a biologist would use. A biologist would call an animal whose diet included both plants and animals, an omnivore. Part 2 What are plants and animals? 31

34 Carnivores The picture below shows a crocodile floating in a river. Crocodiles are often difficult to find. Even if you do come across one, you ll wish you hadn t! Crocodiles waiting for their prey. Source: Jane West This crocodile is lurking in the river, watching, waiting. Sooner or later an unsuspecting animal maybe a sheep or a dingo will be down at the river s edge having a quiet drink. Faster than you thought possible, the crocodile can get out of the water and wrap its great big jaws around the animal. Then it will pull the terrified animal back into the water to drown it. Later, the dead animal will be dragged from the bottom of the river to be eaten. 32 Living things

35 Think about this report. Is this report written scientifically? No. It is a story. It refers to feelings and emotions and does not use technical terms. The diagram below shows some carnivores. goanna shark blue-ringed octopus kingfisher dog dolphin tiger cat State of New South Wales, Department of Education and Training, 2004 Carnivores Other examples of carnivores include bream, killer whales, bluebottles and pelicans. Think about what all these animals eat. Activity: Carnivores Now write a definition for carnivore. Check your response by going to the suggested answers section. Part 2 What are plants and animals? 33

36 Carnivore comes from Latin. Carnis means flesh, or meat. Not all animals contain meat, but scientists say that any animal that eats other animals is called a carnivore. Herbivores Elephant eating bamboo Source: Julie Haeulser. Monkey eating silverbeet Source: Julie Haeulser. Silver beet and bamboo are both types of plants. The elephant and the monkey in the photographs are both herbivores. Other examples of herbivores include sheep, cows, rabbits, goats and horses. Activity: Herbivore Answer the following questions. 1 What sort of a diet does a herbivore have? 34 Living things

37 2 Write a definition for the term herbivore. Check your response by going to the suggested answers section. Herbivore comes from Latin. Herba means grass. So a herbivore eats grass or plants. Another word for herbivore is vegetarian. Omnivore, carnivore or herbivore? In this lesson, you have classified plants as producers and animals as consumers. Then you have classified the consumers (animals) according to what they eat, or what their diet is. In this way, animals can be classified as omnivores, carnivores or herbivores. Preparing for Exercise 2.3 In this exercise you will complete a summary about producers and consumers. Go to the exercises section and complete Exercises 2.3 What do animals eat? Part 2 What are plants and animals? 35

38 What did you achieve? Tick what you can do. distinguish between producers and consumers classify consumers using their diet define omnivore, herbivore, and carnivore identify omnivores, herbivores and carnivores 36 Living things

39 Lesson 9 Feeding relationships Plants make their own food. Therefore, plants are called producers. You know that animals depend on plants or on other animals for their food. Therefore, animals are called consumers. You already know quite a bit about how living things obtain their food. In this lesson, you will be investigating feeding relationships in an environment; you are going to be looking at what eats what. Food chains When you investigate the feeding relationships of living things in an environment, you need to be able to write it down clearly. This way, everyone can easily understand what each living thing in that environment eats. A study of feeding relationships, or food chains, helps us to better understand our environment. And if you study the feeding relationships in an environment, you are better able to predict what will happen if the plants and animals are threatened in any way. For example, you can predict that removing gum trees could endanger the lives of koalas if you know that koalas only eat certain gum leaves. You can see that a study of the environment and the living things in it is very important. This part of biology is called ecology. Let s start our look at ecology by trying to deduce what eats what in the scary situation described in the passage below. Part 2 What are plants and animals? 37

40 Danger lurks The natural environment is not a place for the faint-hearted. Lurking around every corner is a creature looking for something to eat. Imagine you are in the jungle. It s hot, humid and getting dark. You are lost! A distant growl sends shivers up your spine. You stumble on, hoping to get out of this one alive. Suddenly, without warning, a black and gold beast flashes by! A tiger. You can hear crashing and thrashing not far away. Then, you catch a glimpse and a scene unfolds. A hungry tiger, on the lookout for a meal, has caught a pig that has wandered away from the local village. Poor pig. It was caught unawares, feeding on new grass and roots in the forest. As the tiger is busy dismembering and devouring the pig, you take the chance to escape. You run blindly through the forest and eventually find your way back to the village you left hours ago. A casual stroll turned into a real adventure. Now answer the following questions. Activity: Food chains What ate what in the story called Danger lurks? The tiger ate the pig. The pig was eating grass and roots. It takes a long time to find the feeding relationships in the story because you have to read through the passage carefully. What is another way you can present this information so that it is easy to understand and doesn t take long to read? What about diagrams? 38 Living things

41 Writing food chains Here is a diagram of the feeding relationship in the story. Feeding relationship in the jungle State of New South Wales, Department of Education and Training, 2004 This diagram isn't complete because it does not clearly show what eats what. Its usual to add arrows to show food moving through the food chain. That is, means is eaten by. This is one way of drawing a food chain, but it isn t an easy way! When biologists want to draw a food chain, they normally just write the name of each living thing involved instead of drawing a picture. This makes it much simpler. For example, a biologist would record the food chain above as grass pig tiger. This food chain tells the reader that grass is eaten by a pig and a pig is eaten by a tiger. Preparing for Exercise 2.4 In Exercise 2.4, there are five, nearly complete food chains. Each food chain has one living thing missing. Think about the environment that each feeding relationship is from and fill in the name of a living thing that would fit in. Part 2 What are plants and animals? 39

42 Go to the exercises section and complete Exercises 2.4 Feeding relationships. Comparing food chains You are now going to compare the food chains you have just completed in Exercise 2.4. By looking at the common elements in all of the food chains, you may be able to write a list that will help you to write food chains in the future. Look again at the five food chains. What do they all have in common? That is, what are the similarities? Here are some questions that will help you to answer. Activity: Comparing food chains Using the information from the food chains above to answer the following questions. 1 What kind of living thing is at the start of each food chain? 2 What is the next link in the food chain? That is, what kind of living thing is second in a food chain? All food chains begin with a plant or a producer. The next organism (living thing) in the food chain is a consumer. This consumer is also a herbivore. 40 Living things

43 By comparing the food chains, you can see that all food chains begin with a plant. This shows us again that all animals depend on plants for food. Plants can make their own food but animals cannot. Summary Feeding relationships can be shown in a food chain. An arrow in a food chain means is eaten by. Food chains begin with a plant or producer. All other organisms in a food chain are animals or consumers. What did you achieve? Tick what you can do. complete food chains to show how producers and consumers are related compare food chains to find their similarities state that all food chains begin with a plant Part 2 What are plants and animals? 41

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45 Lesson 10 The mangroves Now you are going to investigate an environment that you may have experienced the mangrove swamp. You will use this environment to practise writing food chains. To do this, you are going on an excursion to a mangrove swamp. As you go on the excursion, you will be observing, comparing, contrasting and classifying the organisms that live in the swamp. The mangrove environment The mangrove swamp is a special type of environment that has a range of conditions. Mangroves occur where a river meets the sea. They are found in the tropical and sub-tropical regions of the world. The excursion This excursion is to a mangrove swamp. To go on this excursion, you will need the following things: some photographs and drawings of the mangrove organisms the audifile called Living things: The Swamp audio. You will go on the excursion by listening to the audio. Here are some of the photographs that were taken on the excursion. There are lines beside each picture which you may use to take personal notes while you are on the excursion. Part 2 What are plants and animals? 43

46 Photographs of a mangrove ecosystem Pneumatophores at low tide State of New South Wales, Department of Education and Training, 2004 Pneumatophores at mid tide State of New South Wales, Department of Education and Training, 2004 Mangroves at mid tide State of New South Wales, Department of Education and Training, Living things

47 Heron on a sand bank Source Jane West Flock of ibises digging for food State of New South Wales, Department of Education and Training, 2004 Seagrass, algae and small fish State of New South Wales, Department of Education and Training, 2004 Part 2 What are plants and animals? 45

48 Salt crystals on a mangrove leaf Source Jane West Nipper burrows and oysters State of New South Wales, Department of Education and Training, 2004 Ibises State of New South Wales, Department of Education and Training, Living things

49 Soldier crabs State of New South Wales, Department of Education and Training, 2004 Spider close up State of New South Wales, Department of Education and Training, 2004 Burrowing in the mud State of New South Wales, Department of Education and Training, 2004 Organisms seen on the mangrove excursion. Part 2 What are plants and animals? 47

50 Excursion sheet for mangrove excursion Small fish Mussel Pelican Blue swimmer crab Mangrove Seagrass Phytoplankton Prawn State of New South Wales, Department of Education and Training, Living things

51 Ibis Shark Whiting Soldier crab Leatherjacket Dragonfly Sea horse Spider State of New South Wales, Department of Education and Training, 2004 Now you are ready to more closely study the feeding relationships between these organisms. In this exercise you will be reporting on your virtual excursion to a mangrove. Go to the exercises section and complete Exercise 2.5 The mangroves: excursion notes. Part 2 What are plants and animals? 49

52 What did you achieve? Tick what you can do. describe the mangrove environment list some of the plants and animals that live in the mangroves write food chains for the mangrove environment state reasons why the mangrove environment is important. 50 Living things

53 Suggested answers Part 2 Check your responses against these suggested answers. Are there any other reasons to classify? Three benefits of classifying objects are that: it makes objects easier to find it is easier (and quicker) to communicate it is easier to identify or name unfamiliar objects. Classifying plants and animals Plants wheat dandelion grass pine gum tree Animals caribou butterfly bee cockroach sea urchin Joseph Priestley s experiments 1 The drawing below is one way that the information about Priestley s experiment on oxygen could be presented. State of New South Wales, Department of Education and Training, 2004 Part 2 What are plants and animals? 51

54 2 Here are some points that are important in the description of Priestley s second experiment. Your points may not be exactly the same. As long as what you have written means the same then you are doing well. The plant survived in air without oxygen. The plant replaced the oxygen in the air. The mouse did not suffocate because the plant replaced the oxygen at least until the mouse used up all the oxygen. 3 The drawing below is one way of presenting the information about Priestley s second experiment with oxygen. State of New South Wales, Department of Education and Training, 2004 Your diagram may not be exactly the same but this only means that you have chosen a different way to show all the important points. As long as the important points are shown and it is clear for the reader then you are doing well. 4 Experiment 1 Experiment 2 a b c d A candle was burned in a sealed jar. A mouse was put into the sealed jar. A plant was put into the sealed jar. The mouse died. 5 Experiment 1 and Experiment 2 make a controlled experiment because only one thing changes from Experiment 1 to Experiment 2. Experiment 2 uses a plant but Experiment 1 doesn't. 6 The variable that is being tested is the one thing that Priestley chose to change whether or not there was a plant in the test. (The variable that Priestley observes tells him whether the plant affects the results he observes whether the mouse lives or dies.) 7 Some variables that would not affect the results are: the kind of jar that was used (although the size of the jar might not be); the clothes Priestley was wearing; the weather; the colour of the mice. (All these things are still variables because they can be changed. It is just that changing them does not affect the experiment.) 52 Living things

55 Summary Plants grow without food. Plants need water. Plants give out oxygen. Animals need the oxygen that plants make or produce. Photosynthesis occurs when plants are in sunlight. Plants take in carbon dioxide during photosynthesis. Variables are things that can be changed in an experiment. An experiment should be planned so that it tests one variable only. In a controlled experiment, only one variable is changed. Carnivores A carnivore is an animal that eats other animals. Herbivores 1 Herbivores eat grass, roots, plants, vegetables, leaves, flowers, bark and seeds. In other words, herbivores eat plants. 2 A herbivore is an animal that eats plants only. (Herbivores may eat whole plants or parts of plants.) Part 2 What are plants and animals? 53

56 54 Living things

57 Exercises Part 2 Exercises 2.1 to 2.5 Name Teacher Exercise 2.1 Classifying living things Fill in the blanks on this summary using the following words: food living things animals plants can be classified as plants or animals. Most _ can move from place to place. Most are green. Plants make their but animals cannot. Part 2 What are plants and animals? 55

58 Exercise 2.2 Discovering photosynthesis 1 Complete this summary of photosynthesis using the words below. that is in to the and for their from as Plants and animals are living things. They are similar many ways. Both plants and animals grow, reproduce, respond stimuli and exchange materials with the environment. Plants and animals obtain their food in different ways. Green plants can make their own food, whereas animals rely on plants or other animals their food. Animals cannot make their own food. The process by which plants make own food is called photosynthesis. For photosynthesis to occur, plants need energy raw materials. Plants take in carbon dioxide through their leaves the air. Water is absorbed from the soil through the roots. These are the raw materials _ plants need to make food. Energy is needed so that plants can make their own food. The source of this energy sunlight. Green plants contain chlorophyll. Chlorophyll is the green pigment that can trap energy from sunlight. Photosynthesis produces oxygen and water as well food in plants. Oxygen and water are given out by plants through the leaves during day, since photosynthesis only occurs when there is light. Animals rely on plants for their food and their oxygen. 56 Living things

59 Exercise 2.3 What do animals eat? Complete the following summary using the words below. plants plants carnivores food omnivores animals producers consumers Plants are because they carry out photosynthesis. Living things that need to eat are called. Consumers can be classified by their. Humans usually eat both meat and plants, so we are in the group of animals called. Omnivores eat and. eat other animals or meat. Herbivores only eat. Part 2 What are plants and animals? 57

60 Exercise 2.4: Feeding relationships Fill in the blanks below 1 seaweed shark 2 kangaroo dingo 3 clover cow 4 caterpillar kookaburra 5 cabbage cabbage moth 58 Living things

61 Exercise 2.5 The mangroves Excursion notes Mangrove trees are often found around the shores where rivers meet the sea. They usually form extensive forests because so many of them group together. Sadly, mangrove areas have been used as rubbish dumps and for disposing of factory wastes. Mangroves have also been cut down to be replaced by tourist resorts. First impressions Describe the mangrove environment. List the animals that you have observed on your walk through the mangroves. Mangrove feeding relationships The diagram following shows a food web in a mangrove ecosystem. It is an unusual food web because many of the food chains start from a material called detritus. This material consists of the broken down leaves of mangrove trees as well as any other organic material. It forms a rich oozy material that is found on the floor of mangrove areas. These pieces of mangrove leaves become food for molluscs, worms, young fish, crabs and prawns. These animals are then eaten by larger fish, crabs and birds. Part 2 What are plants and animals? 59

62 Circle the producer(s) in the diagram below. The producers are eaten by herbivores. Write down two organisms that are herbivores. The herbivores are eaten by carnivores. Write down two organisms that are carnivores. pelican cormorant mangrove detritus small fish oysters bream prawns oystercatcher seagrass algae Mangrove food web Write three food chains to represent the feeding relationships in the mangrove environment. 60 Living things

63 Do you think that mangrove environments should be protected? Explain your answer. Part 2 What are plants and animals? 61