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?

Options

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 of atmospheric `N_(2)` to `NH_(3)`
D. Nitrogenase is insensitive to oxygen

Answer

**Step-by-Step Solution:**

1. **Understanding Symbiotic Nitrogen Fixation**: Leguminous plants form a symbiotic relationship with nitrogen-fixing bacteria, primarily Rhizobium. These bacteria reside in root nodules of the plants and are responsible for converting atmospheric nitrogen (N₂) into ammonia (NH₃), which plants can use.

2. **Analyzing the Statements**:
- **Statement 1**: "Leghemoglobin is given just oxygen and it is pinkish in color."
- Leghemoglobin is indeed pinkish in color and it helps in transporting oxygen within the root nodules. This statement is correct.

- **Statement 2**: "Nodule acts as a site for nitrogen fixation."
- The root nodules are indeed the sites where nitrogen fixation occurs due to the presence of Rhizobium bacteria. This statement is correct.

- **Statement 3**: "The enzyme nitrogenase catalyzes the conversion of atmospheric nitrogen to ammonia and for this nitrogen is insensitive to oxygen."
- Nitrogenase is the enzyme that catalyzes the conversion of atmospheric nitrogen to ammonia. However, this enzyme is sensitive to oxygen, meaning it cannot function in the presence of oxygen. Therefore, this statement is incorrect.

- **Statement 4**: "Nitrogen is insensitive to oxygen."
- This statement is incorrect because nitrogenase is indeed sensitive to oxygen, which means it requires an anaerobic environment to function effectively.

3. **Conclusion**: The statement that is not correct during the process of nitrogen fixation is the third one, which states that nitrogen is insensitive to oxygen.

**Final Answer**: The statement that is not correct is: "The enzyme nitrogenase catalyzes the conversion of atmospheric nitrogen to ammonia and for this nitrogen is insensitive to oxygen."

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