`Psi_(w)` is maximum during/in

Options

A. Completely plasmolysed cell
B. Completely deplasmolysed cell
C. Fully turgid cell
D. 2 and 3

Answer

To determine when the water potential (Ψw) is maximum, we need to understand the concept of water potential and how it relates to the state of plant cells. Here’s a step-by-step solution:

### Step 1: Understand Water Potential (Ψw)
Water potential (Ψw) is a measure of the potential energy of water in a system and is influenced by the concentration of solutes and the pressure exerted on the water. It is defined as the tendency of water to move from one area to another.

**Hint:** Water potential is affected by both solute concentration and pressure.

### Step 2: Analyze the States of Plant Cells
1. **Completely Plasmolyzed Cells:** In this state, the cell has lost a significant amount of water, causing the cell membrane to pull away from the cell wall. This results in a low water potential because there is less water present.

**Hint:** Plasmolysis indicates a loss of water, leading to lower water potential.

2. **Completely De-Plasmolyzed Cells:** This state occurs when water enters a plasmolyzed cell, causing it to regain its turgidity. While the water potential increases as water enters, it does not reach the maximum level since the cell is still in transition.

**Hint:** De-plasmolyzed cells have increased water potential but are not at maximum.

3. **Fully Turgid Cells:** In a fully turgid cell, the cell is filled with water to the point where the cell membrane presses against the cell wall. This state represents maximum water potential because the concentration of water is at its highest.

**Hint:** Turgidity indicates maximum water content and thus maximum water potential.

### Step 3: Conclusion
Based on the analysis of the three states of plant cells, the water potential (Ψw) is maximum in fully turgid cells.

**Final Answer:** Ψw is maximum in fully turgid cells.