Which one is a nitrogen fixer?

Options

A. Ulothrix
B. Anabaena
C. Ulva
D. Hydrodictyon

Answer

**Step-by-Step Text Solution:**

1. **Understanding Nitrogen Fixation**: Nitrogen fixation is the process by which certain microorganisms convert atmospheric nitrogen (N₂) into ammonia (NH₃), which can then be utilized by plants. This process is crucial for increasing soil fertility and enhancing crop yields.

2. **Identifying the Options**: The options given are:
- Trix
- Anabena
- Vulva
- Hydrodictyon

3. **Analyzing Each Option**:
- **Trix**: This option is not mentioned in the context of nitrogen fixation in the transcript.
- **Anabena**: This is a genus of cyanobacteria known for its ability to fix nitrogen. It often forms symbiotic relationships with aquatic plants like Azolla, enhancing nitrogen availability in the soil.
- **Vulva**: Also known as sea lotus, this is an edible green algae found in marine and brackish waters but does not fix nitrogen.
- **Hydrodictyon**: Known as water net, this is a freshwater green algae that does not have nitrogen-fixing capabilities.

4. **Conclusion**: Among the options provided, **Anabena** is identified as the nitrogen fixer due to its ability to convert atmospheric nitrogen into ammonia, thereby enriching the soil.

5. **Final Answer**: The nitrogen fixer among the given options is **Anabena**.

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