Question

In biological nitrogen fixation conversion of dinitrogen molecule into ammonia is carried out by enzyme.

• A. Hydrogenase
• B. Dehydrogenase
• C. Nitrogenase
• D. Nitrate reductase

Hint:

Directly associate the process {Nitrogen fixation} with the enzyme {Nitrogenase}. The names are directly linked, making it an easy-to-remember pair.

Answer 1

The Correct Option is C

Step 1: Concept Overview:
Biological nitrogen fixation is the conversion of atmospheric nitrogen (\(N_2\)) into ammonia (\(NH_3\)), a usable form of nitrogen for plants. This process is performed by microorganisms. The question identifies the enzyme responsible for this conversion.
Step 2: Enzyme Analysis:
Hydrogenase: Catalyzes the oxidation of \(H_2\). While sometimes linked to nitrogen fixation by recycling \(H_2\) byproduct, it does not directly act on \(N_2\).
Dehydrogenase: Oxidizes substrates via hydride transfer to acceptors like NAD\(^+\)/NADP\(^+\). Involved in respiration, not nitrogen fixation.
Nitrogenase: The enzyme complex that performs biological nitrogen fixation. It reduces dinitrogen to ammonia. Exclusively found in prokaryotes.
Nitrate reductase: Catalyzes the reduction of \(NO_3^-\) to \(NO_2^-\), a step in nitrogen assimilation, not nitrogen fixation.
Step 3: Conclusion:
Nitrogenase is the enzyme that converts dinitrogen into ammonia.