If by radiation all nitrogenase enzyme are inactivated, then there will be no:-

Options

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

Answer

To solve the question, we need to understand the role of the nitrogenase enzyme in nitrogen fixation and analyze the options provided. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand Nitrogenase Enzyme
- The nitrogenase enzyme is crucial for the process of nitrogen fixation, which converts atmospheric nitrogen (N₂) into ammonia (NH₃). This process is essential for making nitrogen available to plants in a usable form.

**Hint:** Remember that nitrogenase is specifically involved in converting atmospheric nitrogen to ammonia.

### Step 2: Analyze the Options
- **Option A:** Fixation of atmospheric nitrogen
- This process requires nitrogenase to convert N₂ into NH₃. If nitrogenase is inactivated, this process cannot occur.

**Hint:** Think about the primary function of nitrogenase in nitrogen fixation.

- **Option B:** Conversion of nitrate to nitrite
- This process is known as nitrification and does not involve nitrogenase. It is carried out by different types of bacteria.

**Hint:** Consider whether this step is related to nitrogen fixation or not.

- **Option C:** Conversion from ammonia to nitrate
- This is also part of nitrification and does not require nitrogenase.

**Hint:** Again, this step is not directly related to nitrogen fixation.

- **Option D:** Fixation of nitrogen in legumes
- This refers to the biological nitrogen fixation that occurs in legumes through symbiotic bacteria (like Rhizobium) that possess nitrogenase. If nitrogenase is inactivated, this process will not occur.

**Hint:** Focus on the biological aspect of nitrogen fixation in legumes.

### Step 3: Conclusion
- Since the nitrogenase enzyme is essential for the fixation of atmospheric nitrogen into ammonia, if it is inactivated, the process of nitrogen fixation in legumes (Option D) will not occur. Therefore, the correct answer is:

**Answer:** D) Fixation of nitrogen in legumes.