In which group of organisms the cell walls form two thin overlapping shells which fit together

Options

A. (a) Chrysophytes
B. (b) Euglenoids
C. (c) Dinoflagellates
D. (d) Slime moulds

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks about a group of organisms whose cell walls form two thin overlapping shells that fit together.

2. **Analyze the Options**: The options provided are all protists. We need to evaluate which of these groups is known for having overlapping shells.

3. **Recall Characteristics of Dinoflagellates**: Among the protists, dinoflagellates are known for their unique cell structure. They possess a complex covering known as amphiesma.

4. **Understand the Structure of Amphiesma**: The amphiesma consists of two cell wall plates called theca plates. These plates are arranged in such a way that they overlap and fit together, forming an inner and outer covering.

5. **Functions of the Overlapping Shells**: The overlapping shells serve two main purposes:
- They provide protection, acting like armor for the organism.
- They allow for flexibility, enabling the dinoflagellates to expand and contract.

6. **Conclusion**: Based on the characteristics and functions of the cell walls, the correct answer to the question is **C) Dinoflagellates**.

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