Question

the following diagram describes the nitrogen cycle. arrow iv shows nitrogen moving from the atmosphere to microorganisms in the soil and plant roots. which process is represented by arrow iv? choose 1 answer: a nitrification b denitrification c nitrogen fixation d ammonification

Explanation:

To determine the process of Arrow IV, we analyze each option:

• Nitrification: Converts ammonia to nitrates, not atmospheric \( \text{N}_2 \) to organisms. Eliminate A.
• Denitrification: Converts nitrates to atmospheric \( \text{N}_2 \), opposite direction. Eliminate B.
• Nitrogen fixation: Converts atmospheric \( \text{N}_2 \) into forms usable by organisms (e.g., by nitrogen - fixing microbes in soil/roots). Arrow IV shows \( \text{N}_2 \) to soil microbes/plant roots, matching this.
• Ammonification: Converts organic nitrogen to ammonia, no atmospheric \( \text{N}_2 \) involvement. Eliminate D.

Answer:

C. nitrogen fixation