Which of the following feature is correct for cyanobacteria ?

Options

A. Presence of flagellum throughout the life cycle
B. Presence of chlorophyll a
C. Asexual reproduction is absent
D. Cannot perform nitrogen fixation

Answer

To solve the question "Which of the following feature is correct for cyanobacteria?", we will analyze each option provided and determine which statement is accurate regarding cyanobacteria.

### Step-by-Step Solution:

1. **Understand Cyanobacteria**:
- Cyanobacteria are a group of photosynthetic bacteria also known as blue-green algae. They are known for their ability to perform photosynthesis and nitrogen fixation.

2. **Evaluate Each Option**:
- **Option 1: Presence of the flagellum throughout the life cycle**:
- This statement is incorrect. Cyanobacteria do not have flagella throughout their life cycle. They are generally non-motile or may move using gliding mechanisms, but they do not possess flagella.

- **Option 2: Presence of chlorophyll-A**:
- This statement is correct. Cyanobacteria contain chlorophyll-A, which is essential for photosynthesis. This pigment allows them to capture light energy and convert it into chemical energy.

- **Option 3: Asexual reproduction is absent**:
- This statement is incorrect. Cyanobacteria reproduce asexually through processes such as binary fission and multiple fission. Therefore, they do have asexual reproduction.

- **Option 4: Cannot perform nitrogen fixation**:
- This statement is also incorrect. Cyanobacteria are well-known for their ability to fix atmospheric nitrogen, which is crucial for soil fertility and ecosystem functioning.

3. **Conclusion**:
- After evaluating all the options, the only correct statement regarding cyanobacteria is **Option 2: Presence of chlorophyll-A**.

### Final Answer:
The correct feature for cyanobacteria is **Option 2: Presence of chlorophyll-A**.