Entry of water into a cell causes swelling of protoplast due to
(a) DPD
(b) Osmotic pressure
(c) Imbibition
(d) Turgor pressure

Options

A. DPD
B. Osmotic pressure
C. Imbibition
D. Turgor pressure .

Answer

To solve the question regarding the entry of water into a cell and its effect on the protoplast, we will analyze each option provided:

1. **Understanding the Question**: The question asks what causes the swelling of the protoplast when water enters a cell. The protoplast is the living part of the cell, including the cytoplasm and the cell membrane.

2. **Analyzing the Options**:
- **(a) DPD (Diffusion Pressure Deficit)**: This term refers to the difference in diffusion pressure between pure water and a solution. It is not directly responsible for the entry of water or the swelling of the protoplast. Therefore, this option is incorrect.

- **(b) Osmotic Pressure**: Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane due to osmosis. While it is related to the movement of water, it does not directly cause swelling; rather, it prevents water from entering. Thus, this option is also incorrect.

- **(c) Imbibition**: Imbibition is the process of absorption of water by solids, especially colloids. It describes how materials absorb water but does not specifically account for the swelling of protoplasts in cells. Hence, this option is incorrect.

- **(d) Turgor Pressure**: Turgor pressure is the pressure exerted by the fluid (water) inside the cell against the cell wall. When water enters the cell, it fills the vacuole and exerts pressure against the cell wall, causing the protoplast to swell. This pressure is crucial for maintaining cell structure and rigidity. Therefore, this option is correct.

3. **Conclusion**: The correct answer is **(d) Turgor pressure**, as it is the pressure that causes the swelling of the protoplast when water enters the cell.