Name____________________________ Class ________________ Date ____________

Chapter 3

Section 3–1 What Is Ecology? (pages 64–68)

Studying Our Living Planet

  1. 1. What is ecology? It



2.      What does the biosphere contain?



3.      Label each level organization on the diagram below.





















Biotic and Abiotic Factors

  1. 4. Use the terms in the box to fill in the Venn diagram. List parts of the environment that consist of biotic factors, abiotic factors, and some components that are a mixture of both.

Text Box: air                                           heat                                  precipitation
animals                                 mushrooms                                    soil
bacteria                                      plants                                   sunlight
Text Box: Abiotic Factors
Text Box: Both
Text Box: Biotic Factors






























Ecological Methods

  1. 5. Why are many ecological phenomena difficult to study? T



6.      Why do ecologists make models?





Section 3–2 Energy, Producers, and Consumers (pages 69–72) At Primary Producers organisms rely on the energy stored in inorganic chemical compounds.

  1. 7. What do autotrophs do during photosynthesis?



  1. 8. Can some organisms survive without energy from the sun? Explain your answer.




  1. 9. Can organisms create their own energy? Explain your answer.They live in remote places, such as





  1. Complete the table about types of heterotrophs.

Types of Heterotrophs






Cows, rabbits



Heterotroph that eats animals




Humans, bears, pigs











Heterotroph that consumes the carcasses of dead animals but does not typically kill them itself



  1.  What is a consumer?




Section 3–3 Energy Flow in Ecosystems (pages 73–78)

Food Chains and Food Webs


  1. 12. What is a food chain?



  1. 13. What does a food web link together?




14.  Draw arrows between the organisms to show how energy moves through this food chain. Write producer, herbivore, or carnivore under each organism.




  1. 15. What would happen to this food chain if a disturbance caused a serious decline in the shark population?




Trophic Levels and Ecological Pyramids

Write True or False on the line provided.

                    16.  Primary consumers always make up the first trophic level in a food web.

                    17.  Ecological pyramids show the relative amount of energy or matter contained within each trophic level in a given food web.

                    18.  On average, about 50 percent of the energy available within one trophic level is transferred to the next trophic level.

                    19.  The more levels that exist between a producer and a given consumer, the larger the percentage of the original energy from producers is available to that consumer.

tUse the diagram to answer Questions 20–27.

Match the organism with its trophic level. A trophic level may be used more than once.


Organism                                                                    Trophic Level

                20.  algae

                21.  grasshopper                                          A.  primary producer

                22.  marsh grass                                           B.  first-level consumer

                23.  marsh hawk                                          C.  second-level consumer

                24.  plankton-eating fish                              D.  third-level consumer

                25.  ribbed mussel

                26.  shrew

                27.  zooplankton



28.  A pyramid of _______________ illustrates the relative amount of living organic matter available at each trophic level in an ecosystem.

29.  A pyramid of _______________ shows the relative numbers of individual organisms at the trophic levels in an ecosystem.

30.  A pyramid of _______________ shows the relative amounts of energy available at the trophic levels of a food chain or food web.





Section 3–4 Cycles of Matter (pages 79–86)

Recycling in the Biosphere

. For Questions 31–33, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.

                                31.  The four elements that make up over 95 percent of the body in most organisms are oxygen, sulfur, nitrogen, and hydrogen.

                                32.  Matter moves through an ecosystem in cycles.

                                33.  Chemical and physical processes include the formation of clouds and precipitation, “burning” food, and the flow of running water.


  1. Explain why Earth is considered a closed system.



The Water Cycle

  1. What role do plants play in the water cycle?



Nutrient Cycles

                36.   The carbon in coal, oil, and natural gas came from

A. the combustion of fossil fuels.

B. the remains of dead organisms.

C. carbon-fixing bacteria in swamp soil.

D. carbon dioxide dissolved in ocean water.

                37.   How does most of the carbon in an organism’s body return to the environment after the organism dies?

A. Decomposers break the body down into simpler compounds.

B. Heat from the sun causes the carbon in the body to evaporate.

C. Geological processes cause the body to turn into a fossil fuel.

D. Rainwater dissolves the carbon in the body and carries it to the ocean.

                38.   Human processes mainly contribute to the

A. release of carbon dioxide into the atmosphere.

B. decrease of the total amount of carbon found on Earth.

C. depletion of carbon dioxide reserves in the atmosphere.

D. increase in the amount of carbon contained in rock materials.


Write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.

                             39.  Nitrogen, in the form of ammonia, nitrate, and nitrite, is found in the                         soil.

                             40.  Nitrogen fixation is the process in which certain bacteria convert nitrogen gas into nitrates.

                             41.  Denitrification is the process by which some soil bacteria convert nitrates into nitrogen gas.

                             42.  All organisms require nitrogen to make amino acids, which in turn are           used to build carbohydrates.

                             43.  Phosphate is released as rocks and sediments wear down.

                             44.  Plants absorb phosphate from the soil or from water.

                             45.  Phosphorus is the most abundant gas in the atmosphere.

                             46.  Organic phosphate is taken up by producers during photosynthesis                            and released by cellular respiration.

                             47.  Phosphorus forms part of the important life-sustaining molecules such                      as DNA and RNA.

                             48.  Plants absorb phosphorus from the atmosphere or water.


It forms part of important life

  1. What is atmospheric nitrogen fixation, and how does it affect organisms?



  1. How do humans add nitrogen to the biosphere?




  1. Which parts of the phosphorus cycle are geological processes?



Nutrient Limitation

  1. If a nutrient were in short supply in an ecosystem, how might it affect an organism?




  1. When is a substance a limiting nutrient?