Quiz 1.2 - Ch 3 -  Practice Quiz



Complete each statement.


           1.           Autotrophs capture energy from sunlight or ____________________ to produce food.


           2.           Organisms that break down organic matter and return it to the environment are called ____________________.




Figure 3-1


           3.           Of the organisms represented in Figure 3-1, the organisms in the oceans with the smallest total biomass are most likely the ____________________.


           4.           Water can enter the atmosphere through the processes of evaporation and ____________________.


           5.           Living organisms require nitrogen to make ____________________, which are used to build proteins.


Short Answer


           6.           Describe the role of algae in ocean food chains.


           7.           Describe the flow of energy among the following members of an ecosystem: decomposers, autotrophs, heterotrophs, and the sun.




Figure 3–2


           8.           Describe the flow of energy to the owl in Figure 3-2 if the tree provides 1500 calories of energy to the insects.


           9.           What is the most likely explanation for why Figure 3-2 shows only one organism at its base? In what way would an energy diagram be different?





Figure 3–3


           10.         Explain how seepage and transpiration in Figure 3-3 are related.




           11.         Describe the two sources of energy that fuel life on Earth.


           12.         How does a food web differ from a food chain?


           13.         Describe the three types of ecological pyramids.


           14.         Describe the roles of bacteria in the nitrogen cycle.


           15.         How might a large input of phosphorus affect a freshwater lake over time?










Figure 3–4


           16.         Predicting How might a large omnivore change the flow of energy in Figure 3-4, diagram II?


           17.         Inferring If a limiting nutrient is supplied to the producers in Figure 3-4, diagram II, what effect could it have on the birds?


           18.         Interpreting Graphics How many kilocalories (kcal) can the top carnivore in Figure 3-4, diagram I, store? Explain.


           19.         Applying Concepts What three scientific approaches do ecologists use to explain complex relationships, such as in the energy pyramid in Figure 3-4?


           20.         Applying Concepts Describe how chemosynthesis could contribute to the energy represented by Figure 3-4, diagram I.

Quiz 1.2 - Ch 3 -  Practice Quiz

Answer Section




           1.                    ANS:  chemicals


PTS:   1                     REF:   p. 67


           2.                    ANS: 




PTS:   1                     REF:   p. 69


           3.                    ANS:  sharks


PTS:   1                     REF:   p. 72


           4.                    ANS:  transpiration


PTS:   1                     REF:   p. 75


           5.                    ANS:  amino acids


PTS:   1                     REF:   p. 78




           6.                    ANS: 

The algae are autotrophs, the producers at the base of the food chain.


PTS:   1                     REF:   p. 67


           7.                    ANS: 

Energy flows from the sun to the autotrophs, and from the autotrophs to the heterotrophs. Energy also flows from the autotrophs and the heterotrophs to the decomposers.


PTS:   1                     REF:   p. 67 | p. 68 | p. 69    


           8.                    ANS: 

The insects would provide 10 percent (one tenth) of 1500 calories, or 150 calories, of energy to the shrews. The shrews would provide one tenth of 150 calories, or 15 calories to the owl.


PTS:   1                     REF:   p. 72


           9.                    ANS: 

The tree at the base has much more available energy than all the insects that live in it. An energy diagram would be broad at the base like a typical pyramid.


PTS:   1                     REF:   p. 72


           10.                  ANS: 

Water seeps through soil and into the ground water. Roots of trees and plants take the water up through their roots. Plants release the water through the process of transpiration. Both seepage and transpiration are parts of the water cycle.


PTS:   1                     REF:   p. 75




           11.                  ANS: 

Sunlight is the main energy source for life on Earth. Less than 3 percent of all the sun’s energy that reaches Earth is used by living things. Inorganic chemical compounds also provide energy for life on Earth. Plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food.


PTS:   1                     REF:   p. 67


           12.                  ANS: 

A food chain is a series of steps in which organisms transfer energy by eating and being eaten. A food web is a feeding relationship among the various organisms in an ecosystem that forms a network of complex interactions. A food web links together all the food chains in an ecosystem.


PTS:   1                     REF:   p. 69 | p. 70


           13.                  ANS: 

An energy pyramid is a diagram that shows the relative amounts of energy contained within each trophic level in a food chain or web. A biomass pyramid represents the amount of living tissue within each trophic level. A pyramid of numbers shows the relative number of organisms at each trophic level.


PTS:   1                     REF:   p. 72 | p. 73


           14.                  ANS: 

Certain types of bacteria are able to use nitrogen gas directly. These bacteria, which live in the soil and on the roots of legumes, convert nitrogen gas to ammonia during the process of nitrogen fixation. Other bacteria in the soil convert ammonia into nitrates and nitrites, which are also taken up directly by producers. Still other soil bacteria convert nitrates into nitrogen gas during the process of denitrification, returning the nitrogen to the atmosphere.


PTS:   1                     REF:   p. 78


           15.                  ANS: 

The growth of producers in a water environment like a lake is slowed by lack of a limiting nutrient. Phosphorus is a limiting nutrient in most freshwater environments. If phosphorus is added in large amounts, such as from runoff from heavily fertilized fields, an immediate rise in the amount of algae and other producers can occur. This result is called an algal bloom. If an algal bloom in a lake gets too extensive, it may cover the surface of the water.


PTS:   1                     REF:   p. 80




           16.                  ANS: 

Possible answer: A large omnivore would consume energy at every trophic level, reducing the amount of energy available to each level above the producers.


PTS:   1                     REF:   p. 72


           17.                  ANS: 

The producers are the bluegrass. Adding a limiting nutrient to the grass would increase the amount of primary productivity. The result would be an increased amount of biomass at the producer level, and increasing biomass and available energy at each successive level. The number of birds could increase, because there would be more for them to eat.


PTS:   1                     REF:   p. 80


           18.                  ANS: 

The bass is the top carnivore. It has 100 kcal available to it from the trophic level below it. The bass will use part of that energy for its life processes, lose some as heat, and be able to store only about 10 percent, or 10 kcal.


PTS:   1                     REF:   p. 72


           19.                  ANS: 

observing, experimenting, and modeling


PTS:   1                     REF:   p. 65


           20.                  ANS: 

Certain bacteria are chemosynthetic autotrophs and live in tidal marshes along the coast. They are producers that use inorganic molecules to produce food. The energy they produce would add to the total amount produced by plants to supply energy to the ecosystem.


PTS:   1                     REF:   p. 68