Fill in the blanks in the table below summarizing terrestrial ­nutrient cycles.

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.