The characterisitic of blue green algea is
Or
Blue- green algae are called cynobacteria because
(a) DNA without histone
(b) Nucleus absent
(c) Nuclear membrane absent
(d) All of the above

Options

A. DNAwithouthistone
B. Nucleus absent
C. Nuclear membrane absent
D. Nuclear membrane absent

Answer

To answer the question regarding the characteristics of blue-green algae, also known as cyanobacteria, we need to analyze each option provided:

1. **Understanding Blue-Green Algae (Cyanobacteria)**:
- Blue-green algae are classified as cyanobacteria due to their prokaryotic nature. This means they lack a true nucleus and other membrane-bound organelles.

2. **Analyzing Each Option**:
- **Option (a): DNA without histone**:
- Cyanobacteria have DNA that is not associated with histone proteins, which is a characteristic feature of prokaryotic cells.

- **Option (b): Nucleus absent**:
- Cyanobacteria do not possess a nucleus. Instead, their genetic material is found in the cytoplasm.

- **Option (c): Nuclear membrane absent**:
- Since cyanobacteria do not have a nucleus, they also lack a nuclear membrane. Their DNA is freely present in the cytoplasm.

- **Option (d): All of the above**:
- Since options (a), (b), and (c) are all true, this option is also correct.

3. **Conclusion**:
- All the characteristics mentioned in options (a), (b), and (c) are true for blue-green algae (cyanobacteria). Therefore, the correct answer is **(d) All of the above**.

### Final Answer:
**(d) All of the above**