Question

The conversion of ammonia or ammonium ions to nitrite followed by its oxidation to nitrate is called as:

• A. Denitrification
• B. Nitrogen assimilation
• C. Nitrification
• D. Nitrogenation

Hint:

Nitrification = Ammonium $\rightarrow$ Nitrite $\rightarrow$ Nitrate. It is an Oxidation process (adding Oxygen).

Answer 1

The Correct Option is C

Concept: Nitrification is a critical aerobic process in the nitrogen cycle where reduced nitrogen compounds are oxidized into more mobile and accessible forms for plant uptake.

Step 1: The Two-Step Oxidation Process.
The process consists of two distinct biological stages:
• Stage 1: Ammonia/Ammonium ($NH_3/NH_4^+$) is oxidized to Nitrite ($NO_2^-$). This is typically performed by bacteria like Nitrosomonas.
• Stage 2: Nitrite ($NO_2^-$) is further oxidized to Nitrate ($NO_3^-$). This is typically performed by bacteria like Nitrobacter.

Step 2: Biological Significance.
This conversion is essential because, while plants can take up ammonium, they primarily prefer nitrate ($NO_3^-$) in many soil conditions. Additionally, this process prevents the accumulation of toxic levels of ammonia in the soil.

Step 3: Conclusion.
The overall biological transformation described—converting ammonium to nitrite and then to nitrate—is precisely defined as Nitrification.