Question

Nitrogenase enzyme involved in nitrogen fixation works best in:

• A. Aerobic conditions
• B. Anaerobic conditions
• C. Insensitive to oxygen
• D. Both aerobic and anaerobic conditions

Hint:

Nitrogen fixation is the chemical process in which the atmospheric nitrogen is converted into ammonia. Nitrogenase enzymes are extremely sensitive to oxygen, that is why it works in anaerobic conditions and bacteria such as Rhizobium have specialized structures called leghemoglobin which is used to remove oxygen from the environment.

Answer 1

The Correct Option is B

Nitrogenase is the enzyme responsible for biological nitrogen fixation, that is converting atmospheric nitrogen (N2) into ammonia (NH3). It is extremely sensitive to oxygen, meaning it is irreversibly inactivated by it. The nitrogenase requires anaerobic conditions to function effectively. Many nitrogen fixing organisms have special adaptations to create an environment of low oxygen partial pressure for the functioning of nitrogenase. For example, in legumes, leghemoglobin in the root nodules creates an oxygen-free environment. This is because oxygen is an oxidizing agent that interferes with the redox reactions of the nitrogenase enzyme. Therefore, nitrogen fixation is favored in oxygen free conditions.