What is the main global reservoir of nitrogen?

The direct product of nitrogen fixation is __________.

Which of the following is true of the nitrogen cycle?

The phosphorus cycle lacks a(n) __________ component.

Which of the following organisms is incorrectly paired with its trophic level?a. cyanobacterium—primary producerb. grasshopper—primary consumerc. zooplankton—primary producerd. fungus—detritivore

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 marshb. an open oceanc. a coral reefd. a tropical rain forest

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

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