Which one of the following statements is TRUE regarding the nitrogen cycle?
A) Nitrogen fixation results in the production of nitrogen from carbon.
B) Atmospheric nitrogen cannot be used by living organisms because two nitrogen atoms are held tightly together by a triple covalent bond.
C) Plants rely on animals for their source of usable nitrogen.
D) Once nitrogen is "fixed," it must then be converted to nitrogen gas before it can be used by living organisms.
E) In a balanced ecosystem, denitrification occurs more often than nitrogen fixation.

Question

Quizplus · Accepted Answer

Atmospheric nitrogen cannot be used by living organisms because the nitrogen atoms are held tightly together by a triple covalent bond. Nitrogen fixation is the process by which nitrogen gas is converted into a form that can be used by living organisms, such as ammonia or nitrate. Plants can absorb these forms of nitrogen, either directly from the soil or via symbiotic relationships with nitrogen-fixing bacteria. Denitrification is the process by which nitrate is converted into nitrogen gas, which returns it to the atmosphere, completing the nitrogen cycle.

Which One of the Following Statements Is TRUE Regarding the Nitrogen