Question

multiple choice 1 point
nitrogen cycle (diagram showing processes: lightning, nitrogen fixation, denitrification, nitrogen fixing bacteria, nh₄, no₂, nitrification, nh₃, nitrifying bacteria, no₃, assimilation, denitrification bacteria; cows, tree, soil, atmosphere)
identify the process that breaks down fixed nitrogen and returns unfixed nitrogen to the atmosphere.
options: leaching, nitrogen fixation, denitrification, assimilation

Explanation:

To solve this, we analyze each option:

• Leaching: Involves nutrient movement in water, not nitrogen return to atmosphere.
• Nitrogen fixation: Converts atmospheric \(N_2\) to fixed forms, opposite of returning to atmosphere.
• Denitrification: Denitrifying bacteria break down fixed nitrogen (like \(NO_3^-\)) and release \(N_2\) back to the atmosphere, matching the description.
• Assimilation: Organisms take in nitrogen for growth, not releasing to atmosphere.

Answer:

C. Denitrification