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Skills Worksheet

Ch. 18 Interaction of Living Things -Chapter Review

Using key terms

1.Use each of the following terms in a separate sentence: symbiosis, mutualism, commensalism, and parasitism.

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Complete each of the following sentences by choosing the correct term from the word bank.

bioticabioticecosystemcommunity

2.The environment includes ______factors including water, rocks, and light.

3.The environment also includes ______, or living, factors.

4.A community of organisms and their environment is called a(n)______

For each pair of terms, explain how the meanings of the terms differ.

5.community and population

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6.ecosystem and biosphere

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Chapter Review continued

7.producers and consumers

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Understanding key IDEAS

Multiple Choice

_____8.A tick sucks blood from a dog. In this relationship, the tick is the ______and the dog is the ______.

a.parasite, prey c. parasite, host

b.predator, host d. host, parasite

_____9.Resources such as water, food, or sunlight are likely to be limiting factors

a.when population size is decreasing.

b.when predators eat their prey.

c.when the population is small.

d.when a population is approaching the carrying capacity.

_____ 10. Nature’s recyclers are

a.predators. c. producers.

b.decomposers. d. omnivores.

_____ 11. A beneficial association between coral and algae is an example of

a.commensalism. c. mutualism.

b.parasitism. d. predation.

_____ 12. The process by which energy moves through an ecosystem can be represented by

a.food chains.

b.energy pyramids.

c.food webs.

d.All of the above

_____ 13. Which organisms does the base of an energy pyramid represent?

a.producers c. herbivores

b.carnivores d. scavengers

_____ 14. Which of the following is the correct order in a food chain?

a.sunproducersherbivoresscavengerscarnivores

b.sunconsumerspredatorsparasiteshosts

c.sunproducersdecomposersconsumersomnivores

d.sunproducersherbivorescarnivoresscavengers

Chapter Review continued

_____ 15. Remoras and sharks have a relationship that is best described as

a.mutualism.

b.commensalism.

c.predator and prey.

d.parasitism.

Short Answer

16.Describe how energy flows through a food web.

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17.Explain how the food web changed when the gray wolf disappeared from Yellowstone National Park.

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18.How are the competition between two trees of the same species and the competition between two different species of trees similar?

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19.How do limiting factors affect the carrying capacity of an environment?

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20.What is coevolution?

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Chapter Review continued

critical thinking

21.Concept Mapping Use the following terms to create a concept map: herbivores, organisms, producers, populations, ecosystems, consumers, communities, carnivores, and biosphere.

22.Identifying Relationships Could a balanced ecosystem contain producers and consumers but not decomposers? Why or why not?

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23 Predicting Consequences Some biologists think that certain species, such as alligators and wolves, help maintain biological diversity in their ecosystems. Predict what might happen to other organisms, such as gar fish or herons, if alligators were to become extinct in the Florida Everglades.

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24.Expressing Opinions Do you think there is a carrying capacity for humans? Why or why not?

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Chapter Review continued

interpreting graphics

Use the energy pyramid below to answer the questions that follow.

25.According to the energy pyramid, are there more prairie dogs or plants?

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26.What level has the most energy?

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27.Would an energy pyramid such as this one exist in nature?

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28.How could you change this pyramid to look like one representing a real ecosystem?

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Answer Key

1.In symbiosis, two organisms have a close relationship with each other. In mutualism, two organisms that are interacting both benefit from the relationship. In commensalism, one organism is helped and the other is not affected. In parasitism, one organism is helped and the other is harmed by the relationship.

2.abiotic

3.biotic

4.ecosystem

5.Sample answer: A community is made up of populations.

6.Sample answer: All ecosystems are a part of the biosphere.

7.Sample answer: Producers make their own food while consumers must eat other organisms to get energy.

8.C

9.D

10.B

11.C

12.D

13.A

14.D

15.B

16.Sample answer: Energy flows from the sun to plants, or other producers. The energy stored in the cells of producers flows to consumers when the plants are eaten. In this way, energy flows from consumer to consumer and then finally to decomposers.

17.Sample answer: When the gray wolf disappeared, populations of its prey increased. This change caused overgrazing, which affected many of the populations in the park.

18.Sample answer: All trees might compete for sunlight, water, or space.

19.Sample answer: Limiting factors generally define an environment’s carrying capacity. Populations cannot grow without limits because all environments contain a limited amount of food, water, living space, and other needed resources.

20.Coevolution is a long-term change that takes place in two species that have a close relationship with each other.

21.An answer to this exercise can be found at the end of the Teacher Edition.

22.Sample answer: An ecosystem with no decomposers could not exist very long because the ecosystem would soon become buried in dead organisms. Decomposers are needed to return raw materials to the environment.

23.Sample answer: Species such as gar fish and herons would not be as healthy without alligators to eat sick or old individuals. Herons might experience a population increase, which would lead to fewer gar. Eventually, the herons may die off if the gar population becomes too small.

24.Answers may vary.

25.prairie dogs

26.the top level

27.No, an energy pyramid like this could not exist in nature.

28.Sample answer: The pyramid should be widened at the bottom and narrowed at the top.

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Holt Science and Technology1Interactions of Living Things