Question

The function of leghaemoglobin in the root nodules of legumes is

• A. inhibition of nitrogenase activity
• B. oxygen removal
• C. nodule differentiation
• D. expression of nif gene

Answer 1

The Correct Option is B

The function of leghaemoglobin in the root nodules of legumes is crucial for maintaining an optimal environment for the nitrogen-fixing bacteria present within these nodules. Let's examine the options to determine the correct answer:

1. Inhibition of nitrogenase activity: This option is incorrect. Leghaemoglobin does not inhibit nitrogenase activity; rather, it facilitates the environment necessary for its function.
2. Oxygen removal: This is the correct option. Leghaemoglobin helps in the removal of oxygen from the root nodules. It acts similarly to the haemoglobin in blood by binding to oxygen molecules, thereby reducing the free oxygen concentration, which is crucial for the optimal functioning of nitrogenase. Nitrogenase, the enzyme complex responsible for fixing nitrogen, is highly sensitive to oxygen and requires a low-oxygen environment to operate efficiently.
3. Nodule differentiation: This option is incorrect. Leghaemoglobin is not directly involved in the differentiation of nodules; rather, its primary role is related to oxygen regulation.
4. Expression of nif gene: This option is incorrect. The expression of nif genes, which are responsible for the synthesis of nitrogenase, does not directly depend on leghaemoglobin. Instead, leghaemoglobin provides the appropriate environment for the enzyme's activity post-expression.

In conclusion, the primary function of leghaemoglobin in the root nodules of legumes is oxygen removal. It ensures that the nitrogenase enzyme can function effectively in a low-oxygen environment, which is essential for the biological nitrogen fixation process.