What is true for cyanobacteria?

Options

A. Oxygenic with nitrogenase
B. Oxygenic without nitrogenase
C. Non oxygenic with nitrogenase
D. Non oxygenic without nitrogenase

Answer

**Step-by-Step Solution:**

1. **Understanding Cyanobacteria**:
- Cyanobacteria, commonly known as blue-green algae, are photosynthetic prokaryotes. This means they can perform photosynthesis and do not have membrane-bound organelles.

2. **Photosynthesis Type**:
- Cyanobacteria are classified as oxygenic phototrophic bacteria. This means they produce oxygen during the process of photosynthesis, using water as an electron donor.

3. **Nitrogen Fixation**:
- Many cyanobacteria have the ability to fix atmospheric nitrogen. This process is facilitated by an enzyme called nitrogenase, which allows them to convert nitrogen gas from the atmosphere into ammonia, a form that can be utilized by plants.

4. **Symbiotic Relationships**:
- Cyanobacteria often form symbiotic relationships with fungi and green plants. This means they can live in close association with these organisms, benefiting from each other.

5. **Ecological Importance**:
- They serve as a food source for various aquatic animals and are also cultivated for their nutritional value, such as spirulina, which is rich in protein and used in animal feeds.

6. **Conclusion**:
- Based on the information, the correct statement about cyanobacteria is that they are "oxygenic with nitrogenase."

**Final Answer**: The true statement for cyanobacteria is that they are "oxygenic with nitrogenase."

---