If by radiation all nitrogenase enzymes are inactivated, then there will be no

Options

A. (a) fixation of nitrogen in legumes
B. (b) conversion of nitrate into nitrogen
C. (c) conversion from nitrate to nitrite in legumes
D. (d) conversion from ammonium to nitrate in soil

Explanation

### Step-by-Step Solution:

1. **Understanding Nitrogenase**:
- Nitrogenase is an enzyme that plays a crucial role in the process of nitrogen fixation, which is the conversion of atmospheric nitrogen (N₂) into a form that plants can utilize, such as ammonia (NH₃).

2. **Impact of Radiation on Nitrogenase**:
- If radiation inactivates all nitrogenase enzymes, the ability of leguminous plants (such as peas, beans, and clover) to fix atmospheric nitrogen will be severely affected.

3. **Biological Nitrogen Fixation**:
- Biological nitrogen fixation is primarily carried out by certain bacteria that possess nitrogenase. These bacteria often form symbiotic relationships with leguminous plants, allowing them to convert atmospheric nitrogen into ammonia.

4. **Consequences of Inactivation**:
- With the inactivation of nitrogenase, the process of nitrogen fixation in leguminous plants will cease. This means that these plants will not be able to convert atmospheric nitrogen into a usable form, leading to a deficiency of nitrogen in the soil.

5. **Evaluating the Options**:
- Option A states that there will be no fixation of nitrogen in legumes, which is directly impacted by the inactivation of nitrogenase.
- Other options (conversion of nitrate into nitrogen, conversion from nitrate into nitrite, and conversion from ammonia to nitrate) are not primarily dependent on nitrogenase and will not be directly affected by its inactivation.

6. **Final Conclusion**:
- Since nitrogenase is essential for nitrogen fixation in legumes, if it is inactivated, the correct conclusion is that there will be no nitrogen fixation in leguminous plants.

### Final Answer:
- Hence, the correct answer is **Option A**: There will be no fixation of nitrogen in leguminous plants.

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