52. Ecosystems

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

Explain why decomposition rates in a field in Nebraska would differ from the decomposition rates in a field in the Amazon. How do decomposers regulate nutrient availability in ecosystems?

The Hubbard Brook watershed deforestation experiment yielded all of the following results except which of the following?

a. Most minerals were recycled within a forest ecosystem.

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

c. Deforestation increased water runoff.

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

The web of life refers to the

a. Evolutionary relationships among living organisms

b. Connections between species in an ecosystem

c. Complicated nature of genetic variability

d. Flow of information from parent to child

e. Predatory effect of humans on the rest of the natural world

Which of the following would be considered an example of bioremediation?

a. Adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability

b. Using a bulldozer to regrade a strip mine

c. Reconfiguring the channel of a river

d. Adding seeds of a chromium-accumulating plant to soil contaminated by chromium

Why are the open oceans nutrient poor? Why are coastal areas and intertidal habitats relatively nutrient rich?