Nitrification in the Nitrogen Cycle

Steps:

• Recall the nitrogen cycle processes: fixation, ammonification, nitrification, denitrification.
• Identify the conversion: ammonia (NH3) to nitrites (NO2-) then nitrates (NO3-).
• Match to nitrification: bacteria like Nitrosomonas and Nitrobacter perform this oxidation.
• Eliminate unrelated processes: fixation makes ammonia, denitrification reverses to gases.

Why C is correct:

• Nitrification is the bacterial oxidation of ammonia to nitrates, essential for plant uptake in the nitrogen cycle.

Why the others are wrong:

• A. Denitrification converts nitrates back to nitrogen gas, reversing the process.
• B. Excretion releases nitrogenous wastes like ammonia but doesn't convert to nitrates.
• D. Nitrogen fixation converts atmospheric N2 to ammonia, not ammonia to nitrates.

Final answer: C