Which is correct about nitrogen fixation by legumes. They fix nitrogen through

Options

A. Specialised bacteria in their leaves
B. Specialised bacteria in their roots
C. Independent of bacteria that live in their roots
D. The statement is wrong.

Answer

To answer the question about how legumes fix nitrogen, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nitrogen Fixation**:
- Nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into a form that plants can use, such as ammonia (NH₃). This is crucial for plant growth as nitrogen is a key nutrient.

2. **Role of Microbes**:
- Certain microbes, particularly bacteria, are responsible for this process. In legumes, the primary nitrogen-fixing bacteria are from the genus **Rhizobium**.

3. **Location of Nitrogen Fixation**:
- In legumes, nitrogen fixation occurs in specialized structures called **root nodules**. These nodules are formed when Rhizobium bacteria infect the roots of the legume plants.

4. **Enzyme Involvement**:
- The enzyme **nitrogenase** is essential for the nitrogen fixation process. It catalyzes the conversion of nitrogen gas into ammonia. However, it is important to note that nitrogenase is sensitive to oxygen, which is why it is located in the anaerobic environment of the root nodules.

5. **Conclusion**:
- Therefore, the correct statement regarding nitrogen fixation by legumes is that they fix nitrogen through **specialized bacteria in their roots**. This corresponds to option B.

### Final Answer:
Legumes fix nitrogen through specialized bacteria in their roots.

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