During the transport of water, the value of which of the following is always negative ?

Options

A. water potential
B. Solute potential
C. Pressure potential
D. Both (B) and (C)

Answer

To solve the question "During the transport of water, the value of which of the following is always negative?", we will analyze the options provided and determine which one consistently has a negative value.

### Step-by-Step Solution:

1. **Understanding Water Potential**:
- Water potential (Ψ) is the measure of the potential energy of water in a system. It influences the movement of water between different areas. Water potential can be positive or negative depending on the solute concentration and pressure.
- **Conclusion**: Water potential is not always negative.

2. **Understanding Solute Potential**:
- Solute potential (Ψs) is the component of water potential that is due to the presence of solutes in the water. It is defined as the pressure required to prevent the inward flow of water across a semipermeable membrane.
- Solute potential is always negative because adding solutes to water decreases its free energy, which results in a negative value.
- **Conclusion**: Solute potential is always negative.

3. **Understanding Pressure Potential**:
- Pressure potential (Ψp) is the physical pressure exerted on the water in a plant cell. It can be positive when water enters the cell and creates turgor pressure against the cell wall.
- **Conclusion**: Pressure potential is always positive.

4. **Final Evaluation**:
- After analyzing the three components:
- Water potential: Not always negative.
- Solute potential: Always negative.
- Pressure potential: Always positive.
- The only option that is always negative is solute potential.

### Answer:
The value that is always negative during the transport of water is **solute potential**.

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