52. Ecosystems

Which of the following organisms is incorrectly paired with its trophic level?

a. Cyanobacterium—primary producer

b. Grasshopper—primary consumer

c. Zooplankton—primary producer

d. Fungus—detritivore

What is the main global reservoir of nitrogen?

Add labels to the figure that follows, which illustrates the interacting factors in a declining population that contribute to the extinction vortex.

Which of these ecosystems has the lowest net primary production per square meter?

a. A salt marsh

b. An open ocean

c. A coral reef

d. A tropical rain forest

True or False: Most of the net primary productivity that is consumed is used for growth by primary consumers. Explain.

Which of the following is the longest-lived reservoir for carbon?

a. Atmospheric CO₂

b. Marine plankton (primary producers and consumers)

c. Fossil fuels

d. Wood

Nitrifying bacteria participate in the nitrogen cycle mainly by

a. Converting nitrogen gas to ammonia

b. Releasing ammonium from organic compounds, thus returning it to the soil

c. Converting ammonium to nitrate, which plants absorb

d. Incorporating nitrogen into amino acids and organic compounds

Which of these is a consequence of biological magnification?

a. Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.

b. Populations of top-level predators are generally smaller than populations of primary consumers.

c. The biomass of producers in an ecosystem is generally higher than the biomass of primary consumers.

d. Only a small portion of the energy captured by producers is transferred to consumers.

Devegetation has what effect on ecosystem dynamics?

a. It increases belowground biomass.

b. It increases nutrient export.

c. It increases NPP.

d. It increases soil organic matter.

Which of the following has the greatest effect on the rate of chemical cycling in an ecosystem?

a. The rate of decomposition in the ecosystem

b. The production efficiency of the ecosystem's consumers

c. The trophic efficiency of the ecosystem

d. The location of the nutrient reservoirs in the ecosystem

If the GPP of a grassland is 5000 kcal/m²/year and 55 percent is used up by cellular respiration, what is the NPP?

a. 2250 kcal/m²/year

b. 2750 kcal/m²/year

c. 5000 kcal/m²/year

d. Need more data

Which of the following was a result of the Hubbard Brook watershed deforestation experiment?

a. Most minerals were not recycled within the intact forest ecosystem

b. Calcium levels remained high in the soil of deforested areas

c. Deforestation decreased water runoff

d. The nitrate concentration in waters draining the deforested area became dangerously high