Besides providing pink colour to the root nodules, leghaemoglobin performs the function of

Options

A. protecting enzyme nitrogenase from free oxygen
B. transporting nitrogen to host cells
C. protecting bacteroids from the enzymes of host cell
D. protecting leakage of fixed nitrogen to the soil atmosphere

Answer

### Step-by-Step Solution:

1. **Understanding Leghemoglobin**:
- Leghemoglobin is a pigment found in the root nodules of leguminous plants. It is responsible for the pink color of these nodules.

2. **Role of Leguminous Plants**:
- Leguminous plants have a symbiotic relationship with nitrogen-fixing bacteria (like Rhizobium) that reside in their root nodules. These bacteria convert atmospheric nitrogen (N₂) into forms that plants can utilize, such as nitrites and nitrates.

3. **Importance of Nitrogenase**:
- The enzyme responsible for nitrogen fixation is called nitrogenase. This enzyme is crucial for the conversion of atmospheric nitrogen into usable forms for plants.

4. **Anaerobic Conditions**:
- Nitrogenase requires anaerobic conditions (absence of oxygen) to function effectively. Oxygen can inhibit the activity of nitrogenase, making it inactive.

5. **Function of Leghemoglobin**:
- Leghemoglobin acts as an oxygen scavenger. It binds to free oxygen in the root nodules, thereby creating an anaerobic environment that is conducive for nitrogenase to function.

6. **Conclusion**:
- Besides providing the pink color to the root nodules, leghemoglobin protects the enzyme nitrogenase from free oxygen, allowing nitrogen fixation to occur efficiently.

### Final Answer:
Leghemoglobin performs the function of protecting the enzyme nitrogenase from free oxygen.

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