Food Webs Classwork
5 th Grade PSI
Name: _______________________________
1) Why is a food web useful? What does it show?
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2) If animals cannot make their own food or create their own energy, where does their energy come from?
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3) Look at the food web in the slides: What do you hypothesize would happen if the
Sun was to stop shining in this area? What impact would it have on a food web?
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4) Describe the difference between a primary consumer and a secondary consumer.
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5) Correctly set up the following food web: a. Bears are secondary consumers of rabbits, deer and foxes b. Deer eat berries and leaves c. Rabbits eat berries and leaves d. Foxes eat rabbits www.njctl.org 5 th Grade PSI Ecosystem Dynamics

Food Webs Homework
5 th Grade PSI
Name: _______________________________
6) What kind of food would an herbivore eat? Give an example.
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7) What kind of food would a carnivore eat? Give an example.
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8) What kind of food would an omnivore eat? Give an example.
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9) What level of consumers are humans?
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10) Create a food web of your local area. Include at least 2 producers, 2 primary consumers and 2 secondary consumers. www.njctl.org 5 th Grade PSI Ecosystem Dynamics

Decomposers Classwork
5 th Grade PSI
Name: _______________________________
11) Define decomposition.
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12) What are two organisms that help with decomposition?
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13) What effect does the growth of mushrooms have on the surrounding environment?
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14) Why is composting a positive thing to do in your garden?
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15) List three factors that impact the rate of decomposition.
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Decomposers Homework
5 th Grade PSI
Name: _______________________________
16) What types of organisms are examples of fungi?
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17) Why is decomposition important for an ecosystem?
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18) How can you speed up the process of decomposition?
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19) Bill is testing the effects of decomposition on two identical pieces of bread. One piece of bread is placed in an empty plastic bag. One is placed in a bag with water. One is placed in a bag with water and placed under a heat lamp. Which do you expect to rot the most? Why?
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________________________________________________________________ www.njctl.org 5 th Grade PSI Ecosystem Dynamics

Cycles of Matter Classwork
5 th Grade PSI
Name: _______________________________
20) How do we define matter? Give two examples.
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21) What are all living things primarily made up of?
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22) How does the matter that makes up plants make its way to a secondary consumer?
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23) What is responsible for recycling dead matter?
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24) What role does the environment play in the cycle of matter? Give two examples.
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Cycles of Matter Homework
5 th Grade PSI
Name: _______________________________
25) What is soil composed of?
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26) How does the Law of the Conservation of Mass apply to a food web?
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27) What are the three main elements that make up the human body? Which substance makes up between 60%-75% of the human body?
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28) What would happen if matter was not returned to the soil?
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29) Create a model that displays the movement of matter between plants, animals, decomposers and the environment. www.njctl.org 5 th Grade PSI Ecosystem Dynamics

Maintaining an Ecosystem Classwork Name: _______________________________
5 th Grade PSI
30) What are the four basic needs of organisms?
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31) Why are plants so important to an ecosystem?
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32) What negative effects does overpopulation have on an ecosystem?
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33) Why is the introduction of the cane toad in Australia having negative effects on the ecosystem? What efforts are being made to stop their spread?
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Maintaining an Ecosystem Homework Name: _______________________________
5 th Grade PSI
34) Why are ecosystems considered fragile?
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35) How do organisms make sure that they maintain a proper population balance?
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36) What negative effects does over-hunting have on an ecosystem?
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37) What is the difference between a native species and an alien species?
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Ecosystem Dynamics Answer Key
1) A food web is a visual of what eats what in a given ecosystem. It shows the relationship between all living things in an ecosystem.
2) Since animals cannot make their own food, they get energy from eating other living organisms. The organisms at the bottom of a food chain are plants that produce their energy through photosynthesis
3) If the Sun were to stop shining, this would stop the process of photosynthesis. If this happened, there would be no producers and the food chain would not begin.
Without the sun shining plants would not be able to create food which other organisms depend upon and thus the entire food web would collapse.
4) Primary consumers only eat plants and are the first level of consumers in a food web. While secondary consumers only eat other animals and are the second level of consumers in a food web.
5)
6) Answers will vary, but they should be plants, fruits and vegetables.
7) Answers will vary, but it must be some kind of animal product.
8) Answers will vary, but students must say that these organisms eat both plants and animals.
9) Humans are both it just depends what they are eating. When eating plants, humans play the role of primary consumer and when eating other animals, humans are secondary consumers.
10) Food webs can vary but must include 2 producers, 2 primary consumers and 2 secondary consumers.
11) Decomposition (which is sometimes called "rotting") is the process of breaking down a once-living object into small pieces that are usable once again.
12) Bacteria, fungi, worms, mold, yeast.
13) As mushrooms grow, they release carbon dioxide into the air and break the dead organism into nutrients that go back into the soil.
14) Composting provides your plants with a natural fertilizer and also allows you to recycle old waste such as food scraps.
15) Temperature, Oxygen, Water, Size, location and preservatives.
16) Molds, yeasts and mushrooms are examples of fungi.
17) Decomposition helps recycle the matter from on organism into others. Without decomposition all of the elements and minerals that made up the object would become trapped and unusable again. www.njctl.org 5 th Grade PSI Ecosystem Dynamics

18) Decomposition is sped up by increasing the temperature, increasing the amount of oxygen or adding water. Breaking the object down into a smaller size to increase decomposition and move the object onto the soil.
19) The bread that is in water and under a heat lamp will rot the most because it has two factors that contribute to the creation of more bacteria.
20) Matter is anyth ing that has mass, or weight, and takes up space. It is the “stuff” that makes up everything in the universe.
21) All living things are made up primarily of carbon and water.
22) The stuff that makes up plants becomes the stuff that makes up Primary Consumers when the plant is eaten. When the Primary Consumer (herbivore) is eaten by a
Secondary Consumer (carnivore), its mass is passed on to the next animal.
23) Decomposers
24) Matter is cycled to and from the environment constantly. Examples might include; plants absorbing CO2, water and nutrients from the soil, plants creating oxygen that is used by other organisms, organisms releasing CO2 that is used by plants, the decomposition of living things returns nutrients to the soil or other relevant examples.
25) Soil is composed of air, water, minerals and organic matter.
26) The Law of the Conservation of Mass states that matter can neither be created nor destroyed, but can be transformed. When looking at a food web, matter is being transformed as it moved upwards.
27) The human body is made up primarily of Oxygen, Carbon and Hydrogen. 60%-75% of the human body is made up of Water.
28) If matter was not returned to the soil it would be less fertile. Plants rely upon nutrients and minerals that come from decomposed organic material.
29) Models should correctly display the movement of matter between plants, animals, decomposers and the environment.
30) Food, water, air and shelter.
31) Plants are important in an ecosystem because they convert poisonous carbon dioxide into oxygen for us to breather and they are a food source for us and other animals.
32) Overpopulation puts a strain on the resources that are necessary for survival, such as food and water.
33) Since cane toads are an alien species to Australia, the native animals do not have necessary defens e systems to protect themselves against the cane toad’s poison.
This is causing many animals, especially snakes, to die very quickly. Cane toads are also spreading at an alarming rate because they have no natural predators in
Australia and they reproduce at an incredible rate. Australian groups are trying to stop the cane toads from spreading by trying to kill off the toads and coming up with ways to protect against the poison.
34) Ecosystems are fragile because they require the balance of all living things. If one aspect of an ecosystem is out of alignment it can damage or destroy the whole system.
35) Organisms make sure they maintain a proper population balance by creating enough offspring to survive whatever natural hazards there may be. Organisms typically www.njctl.org 5 th Grade PSI Ecosystem Dynamics

have far more children than will survive to account for the ones that will end up dying before reaching adulthood.
36) Overhunting can cause an organism’s population to decline at an exceptionally quick rate. This can lead to extinction if an organism cannot produce enough offspring.
37) An organism is considered a native species if it can be found naturally in a particular ecosystem or area. An alien species is a species that is introduced by unnatural causes, such as if a human was to take a plant or animal from America to Africa. www.njctl.org 5 th Grade PSI Ecosystem Dynamics