What would be `Psi_p` of a fully flaccid cell?

Options

A. `+3`
B. `+2`
C. `-3`
D. 0

Answer

To determine the pressure potential (`Psi_p`) of a fully flaccid cell, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of a Flaccid Cell**:
- A flaccid cell is one that has lost turgor pressure, which occurs when it is placed in an isotonic solution. In this state, the cell is not under any pressure from the surrounding environment.

2. **Identify the Conditions of a Flaccid Cell**:
- In an isotonic solution, the concentration of solutes inside the cell is equal to that outside the cell. This means that there is no net movement of water into or out of the cell, leading to a state of equilibrium.

3. **Use the Water Potential Equation**:
- The water potential (`Psi_w`) of a cell can be expressed using the formula:
\[ \Psi_w = \Psi_s + \Psi_p \]
- Where:
- `Psi_w` = Water potential
- `Psi_s` = Solute potential
- `Psi_p` = Pressure potential

4. **Analyze the Pressure Potential in a Flaccid Cell**:
- In a fully flaccid cell, there is no turgor pressure exerted by the cell wall against the cell membrane. Therefore, the pressure potential (`Psi_p`) is zero.

5. **Conclusion**:
- Thus, for a fully flaccid cell, the value of `Psi_p` is:
\[ \Psi_p = 0 \]

### Final Answer:
The `Psi_p` of a fully flaccid cell is **0**.

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