Which of the following statements about plasmolysis is/ are ture I. Plasmolysis occurs when water moves into cell II. Cells shrink in hypotonic solution III. If the external solution balances the osmotic pressure of cytoplasm, it is said to be isotonic

Options

A. I only
B. II only
C. III only
D. I and II only

Answer

To determine which statements about plasmolysis are true, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement I: Plasmolysis occurs when water moves into the cell.**
- **Analysis**: This statement is incorrect. Plasmolysis is the process that occurs when a plant cell loses water and the cell membrane pulls away from the cell wall. This typically happens when the cell is placed in a hypertonic solution (where the concentration of solutes outside the cell is higher than inside), causing water to move out of the cell, not into it.
- **Conclusion**: **False**

2. **Statement II: Cells shrink in hypotonic solution.**
- **Analysis**: This statement is also incorrect. In a hypotonic solution, the concentration of solutes outside the cell is lower than inside the cell. As a result, water moves into the cell, causing it to swell and potentially burst, rather than shrink. Cells only shrink in hypertonic solutions.
- **Conclusion**: **False**

3. **Statement III: If the external solution balances the osmotic pressure of the cytoplasm, it is said to be isotonic.**
- **Analysis**: This statement is correct. An isotonic solution has the same osmotic pressure as the cytoplasm of the cell, meaning there is no net movement of water into or out of the cell. The cell remains in equilibrium with its surrounding environment.
- **Conclusion**: **True**

### Final Answer:
Only the third statement is true. Therefore, the correct answer is that **only Statement III is correct**.

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