When a plasmolysed cell is placed in water or hypotonic solution, what happens?

Options

A. T.P. of cell decreases
B. T.P. of cell becomes zero
C. T.P. increases
D. Water potential of cell decreases

Answer

**Step-by-Step Solution:**

1. **Understanding Plasmolysis**: A plasmolyzed cell is one that has lost water and has undergone plasmolysis, where the cell membrane pulls away from the cell wall due to the loss of turgor pressure.

2. **Placing the Cell in Water or Hypotonic Solution**: When a plasmolyzed cell is placed in water or a hypotonic solution, the surrounding solution has a higher water potential compared to the inside of the cell.

3. **Water Movement into the Cell**: Due to osmosis, water will move from the area of higher water potential (the hypotonic solution) into the area of lower water potential (the plasmolyzed cell). This process is known as endo osmosis.

4. **De-plasmolysis**: As water enters the cell, it causes the cell to swell and regain turgor pressure. This process is referred to as de-plasmolysis, which is the reversal of plasmolysis.

5. **Effect on Turgor Pressure (TP)**: As water enters the cell, the turgor pressure (TP) of the cell increases. Turgor pressure is the pressure exerted by the fluid inside the cell against the cell wall.

6. **Evaluating the Options**:
- **Option 1**: TP of cell decreases - This is incorrect because TP increases as water enters.
- **Option 2**: TP becomes zero - This is incorrect because TP cannot become zero; it actually increases.
- **Option 3**: TP increases - This is correct as water entering the cell increases the pressure against the cell wall.
- **Option 4**: Water potential of cell decreases - This is incorrect because as TP increases, the water potential of the cell also increases.

7. **Conclusion**: The correct answer is that the turgor pressure (TP) of the cell increases when a plasmolyzed cell is placed in water or a hypotonic solution.

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