Cyanobacteria do not possess following structure or character

Options

A. Atmospheric nitrogen fixing ability
B. Hormogonia
C. Trichomes
D. sexual reproduction

Answer

To solve the question regarding which structure or character cyanobacteria do not possess, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Cyanobacteria**: Recognize that cyanobacteria, also known as blue-green algae, are a group of photosynthetic bacteria that can fix atmospheric nitrogen.

2. **Analyze the Options**:
- **Atmospheric Nitrogen Fixing Ability**: Cyanobacteria have the ability to fix atmospheric nitrogen, which is a characteristic feature.
- **Harmogonia**: These are specialized filaments formed by cyanobacteria to establish symbiotic relationships, indicating that they do possess this structure.
- **Trichomes**: Cyanobacteria can form trichomes, which are long chains of cells, thus they possess this structure as well.
- **Sexual Reproduction**: Cyanobacteria reproduce asexually and do not have a sexual reproduction cycle.

3. **Determine the Correct Answer**: Since cyanobacteria do not engage in sexual reproduction, the correct answer to the question is **sexual reproduction**.

### Final Answer:
Cyanobacteria do not possess sexual reproduction.

---