Which is must for nitrogen fixation by symbiotic bacteria in root nodules?

Options

A. Phycocyanin
B. Carotenoids
C. Leghaemoglobin
D. Bacteria viridin

Answer

To solve the question, "Which is must for nitrogen fixation by symbiotic bacteria in root nodules?", we will analyze the options provided and determine which one is essential for the process of nitrogen fixation.

### Step-by-Step Solution:

1. **Understanding Nitrogen Fixation**: Nitrogen fixation is the process by which nitrogen in the atmosphere is converted into ammonia by certain bacteria. This process is crucial for plants as they cannot utilize atmospheric nitrogen directly.

2. **Identifying the Options**: The options given are:
- A) Phycocyanin
- B) Carotenoids
- C) Laghemoglobin
- D) Bacterioviridin

3. **Analyzing Phycocyanin**:
- Phycocyanin is a blue pigment found in cyanobacteria (blue-green algae). It is an accessory pigment that helps in light harvesting for photosynthesis but does not play a role in nitrogen fixation.
- **Conclusion**: Not essential for nitrogen fixation.

4. **Analyzing Carotenoids**:
- Carotenoids are pigments found in plants, algae, and photosynthetic bacteria. They are important for light absorption during photosynthesis and provide color to fruits and vegetables. However, they do not directly contribute to nitrogen fixation.
- **Conclusion**: Not essential for nitrogen fixation.

5. **Analyzing Laghemoglobin**:
- Laghemoglobin is an oxygen-carrying protein found in the root nodules of leguminous plants. It is produced in response to the colonization of roots by nitrogen-fixing bacteria (like Rhizobium). Laghemoglobin helps to maintain an anaerobic environment necessary for the activity of nitrogen-fixing bacteria.
- **Conclusion**: Essential for nitrogen fixation.

6. **Analyzing Bacterioviridin**:
- Bacterioviridin is a photosynthetic pigment found in certain bacteria, particularly phototropic bacteria. While it plays a role in photosynthesis, it is not involved in nitrogen fixation.
- **Conclusion**: Not essential for nitrogen fixation.

7. **Final Answer**: Based on the analysis, the correct answer is **C) Laghemoglobin**, as it is crucial for nitrogen fixation by symbiotic bacteria in root nodules.