Question

Leguminous plants are able to fix atmospheric nitrogen through the process of symbiotic nitrogen fixation. Which one of the following statements is not correct during this process of nitrogen fixation?

• A. leghaemoglobin scavenges oxygen and is pinkish in colour
• B. nodules act as sites for nitrogen fixation
• C. the enzyme nitrogenase catalyses the conversion of atmospheric $N_2$ to $NH_3$
• D. nitrogenase is insensitive to oxygen

Answer 1

Answer: (D)

nitrogenase is insensitive to oxygen

Answer 2

1. The enzyme nitrogenase is sensitive to molecular oxygen. The enzyme requires anaerobic condition during nitrogen fixation, but live as aerobes under free-living conditions.
2. Leg-haemoglobin provides anaerobic condition to the enzyme nitrogenase. It protects the enzyme from oxygen. It scavenges oxygen and is pinkish in colour.
3. As nodules contain necessary biochemical components so that helps in fixing atmospheric nitrogen to ammonia. They act like sites of nitrogen fixation.
4. The enzyme nitrogenase catalyses the conversion of atmospheric nitrogen to ammonia. It requires 8 ATP. The energy obtained from the respiration of the host plant.