`Psi_(w)=Psi_(s)` is not applied to

Options

A. Turgid cell
B. Normal cell
C. Plasmolysed cell
D. Flaccid cell

Answer

To solve the question "Psi_(w)=Psi_(s) is not applied to", we need to analyze the four options provided: target cell, normal cell, plasmolyzed cell, and flaccid cell.

### Step-by-Step Solution:

1. **Understanding Psi_(w) and Psi_(s)**:
- Psi_(w) refers to the water potential of a cell.
- Psi_(s) refers to the solute potential of a cell.
- The relationship is given by the formula: Psi_(w) = Psi_(s) + Psi_(p), where Psi_(p) is the pressure potential.

2. **Analyzing Each Cell Type**:
- **Turgid Cell**: A turgid cell is one that is fully filled with water. In this case, Psi_(w) is zero because the pressure potential (Psi_(p)) is equal to the solute potential (Psi_(s)) with opposite signs. Thus, Psi_(w) = Psi_(s) is not applicable here.

- **Normal Cell**: In a normal cell, the water potential (Psi_(w)) is influenced by both solute potential (Psi_(s)) and pressure potential (Psi_(p)). Since Psi_(p) exists, Psi_(w) cannot equal Psi_(s) because Psi_(p) contributes positively to Psi_(w). Therefore, Psi_(w) = Psi_(s) does not hold true for a normal cell.

- **Plasmolyzed Cell**: A plasmolyzed cell is one that has lost water due to being in a hypertonic solution. In this case, the pressure potential (Psi_(p)) becomes zero, leading to the condition where Psi_(w) equals Psi_(s). Thus, Psi_(w) = Psi_(s) is applicable here.

- **Flaccid Cell**: Similar to a plasmolyzed cell, a flaccid cell also has a pressure potential (Psi_(p)) that is zero due to water loss in a hypertonic solution. Therefore, Psi_(w) = Psi_(s) is applicable here as well.

3. **Conclusion**:
- The only cell type where Psi_(w) does not equal Psi_(s) is the **Normal Cell**. In a normal cell, the presence of pressure potential means that Psi_(w) is not equal to Psi_(s).

### Final Answer:
**Normal Cell (Option B)**