When the cell is turgid

Options

A. (a) `Psi_(P) gt Psi_(S)`
B. (b) `Psi_(P) lt Psi_(S)`
C. (c) `Psi_(P) = Psi_(S)`
D. (d) `Psi_(P) ne Psi_(S)`

Answer

**Step-by-Step Solution:**

1. **Understanding Turgidity**: Turgidity in plant cells refers to the state when a cell is filled with water, causing it to swell and press against the cell wall. This is crucial for maintaining the structure and rigidity of the plant.

2. **Identifying Key Terms**:
- **Psi P (Pressure Potential)**: This is the pressure exerted by the fluid (in this case, the vacuole) against the cell wall. It is also known as turgor pressure.
- **Psi S (Solute Potential)**: This refers to the potential of water to move into the cell due to the concentration of solutes. It is also known as osmotic pressure.

3. **Conditions of Osmosis**:
- **Hypotonic Solution**: Water moves into the cell, causing it to become turgid.
- **Isotonic Solution**: The concentration of solutes is equal inside and outside the cell, leading to no net movement of water.
- **Hypertonic Solution**: Water moves out of the cell, leading to plasmolysis (the cell shrinks).

4. **Turgid Condition**: In a turgid cell, the pressure potential (Psi P) is equal to the solute potential (Psi S). This means that the pressure exerted by the vacuole against the cell wall balances the osmotic pressure due to solute concentration.

5. **Analyzing the Options**:
- If Psi P = Psi S, the cell is turgid.
- If Psi P > Psi S, it does not represent a turgid condition.
- If Psi S > Psi P, the cell is plasmolyzed.
- If Psi P is not equivalent to Psi S, it indicates either a plasmolyzed or flaccid state.

6. **Conclusion**: Therefore, when the cell is turgid, the correct relationship is Psi P = Psi S.

**Final Answer**: When the cell is turgid, Psi P is equal to Psi S.

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