For nitrogen fixation, the pigment useful is

Options

A. Nitrogenase
B. Hemoglobin
C. Myoglobin
D. Leghemoglobin

Answer

**Step-by-Step Solution:**

1. **Understanding Nitrogen Fixation**: Nitrogen fixation is the process by which molecular nitrogen (N₂) from the atmosphere is converted into ammonia (NH₃) or related nitrogenous compounds that can be utilized by plants and other organisms.

2. **Identifying the Role of Enzymes**: The conversion of nitrogen to ammonia is facilitated by specific enzymes known as nitrogenases. These enzymes are produced by certain bacteria, including cyanobacteria (blue-green algae).

3. **Analyzing the Options**: The question provides three options: nitrogenous hemoglobin, myoglobin, and leg hemoglobin.
- **Hemoglobin**: A protein found in red blood cells that helps in oxygen transport.
- **Myoglobin**: An iron and oxygen-binding protein found in muscle tissue.
- **Leg Hemoglobin**: A type of hemoglobin found in the root nodules of leguminous plants that helps in oxygen transport for nitrogen-fixing bacteria.

4. **Identifying the Correct Pigment**: Among the options, leg hemoglobin is specifically associated with nitrogen-fixing root nodules in legumes. It serves to transport oxygen to the nitrogen-fixing bacteria, allowing them to function effectively in converting nitrogen to ammonia.

5. **Conclusion**: Therefore, the pigment useful for nitrogen fixation is **leg hemoglobin**.

**Final Answer**: Leg hemoglobin.

---