Centrioles and centrosomes occur in the cells of

Options

A. Green plants
B. Animals
C. Bacteria and Cyanobacteria
D. Both B and C

Answer

**Step-by-Step Solution:**

1. **Understanding Centrioles and Centrosomes**:
- Centrioles are cylindrical structures that are part of the centrosome, which serves as the main microtubule organizing center in cells.

2. **Identifying the Types of Cells**:
- Centrioles and centrosomes are primarily found in animal cells. They play a crucial role in cell division and the formation of the cytoskeleton.

3. **Analyzing the Options**:
- The question provides four options: green plants, animals, bacteria, and cyanobacteria, as well as the option of both B and C (bacteria and cyanobacteria).

4. **Evaluating Each Option**:
- **Green Plants**: Centrioles and centrosomes are not present in most plant cells. Instead, plant cells have other structures for organizing microtubules.
- **Animals**: Centrioles and centrosomes are present in animal cells, making this option correct.
- **Bacteria**: Bacteria are prokaryotic cells and do not have centrioles or centrosomes.
- **Cyanobacteria**: Similar to bacteria, cyanobacteria also lack these structures.

5. **Conclusion**:
- Based on the analysis, the correct answer is that centrioles and centrosomes occur in the cells of animals only. Therefore, the answer is "animals."

**Final Answer**: Centrioles and centrosomes occur in the cells of animals.

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