Which of the following statement is not correct about enzyme nitrogenase ?

Options

A. It is highly sensitive to molecular oxygen.
B. It has the ability to oxidise molecular nitrogen through-nitrogen fixation
C. It is an Fe-Mo-protein complex
D. Nitrogenase is not actve when Rhizobium is freely present in soil.

Answer

To solve the question regarding which statement is not correct about the enzyme nitrogenase, let's analyze each of the provided statements step by step.

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

### Step 2: Analyzing the Statements
1. **Statement 1:** "It is highly sensitive to molecular oxygen."
- This statement is **correct**. Nitrogenase is indeed highly sensitive to oxygen, which can inhibit its activity.

2. **Statement 2:** "It has the ability to oxidize molecular nitrogen through nitrogen fixation."
- This statement is **incorrect**. Nitrogenase does not oxidize nitrogen; instead, it reduces molecular nitrogen (N₂) to ammonia (NH₃) during the nitrogen fixation process.

3. **Statement 3:** "It is an iron molybdenum protein complex."
- This statement is **correct**. Nitrogenase is known to be an iron-molybdenum protein complex.

4. **Statement 4:** "Nitrogenase is not active when rhizobium is freely present in soil."
- This statement is **correct**. Nitrogenase is typically active in symbiotic relationships, such as in root nodules of legumes, where rhizobium bacteria are present. In free-living conditions, nitrogenase activity is reduced.

### Step 3: Conclusion
Based on the analysis, the statement that is **not correct** about nitrogenase is **Statement 2**: "It has the ability to oxidize molecular nitrogen through nitrogen fixation."

### Final Answer
The incorrect statement about the enzyme nitrogenase is: **"It has the ability to oxidize molecular nitrogen through nitrogen fixation."**

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