The main difference in DPD and `Psi_(W)` is

Options

A. DPD has negative and `Psi_(W)` has positive value.
B. DPD depends on concentration of solvent wheras `Psi_(W)` on concentration of solute.
C. The direction of movement is from low DPD to high DPD but in `Psi_(W)` it is from high `Psi_(W)` to low `Psi_(W)` .
D. All of the above .

Answer

To address the question regarding the main differences between Diffusion Pressure Deficit (DPD) and Water Potential (Ψw), we can break down the explanation into several key points:

### Step-by-Step Solution:

1. **Definition of Terms**:
- **Diffusion Pressure Deficit (DPD)**: DPD is defined as the deficiency of water in a solution compared to pure water. It is essentially a measure of the difference in diffusion pressure between a solution and pure water. DPD is always a positive value.
- **Water Potential (Ψw)**: Water potential is defined as the potential energy of water in a system compared to pure water. It can be influenced by solute concentration and pressure. Water potential is typically expressed as a negative value.

2. **Value Characteristics**:
- DPD is always positive because it represents a deficit of water.
- Water potential (Ψw) is usually negative because it reflects the potential energy of water in a solution, which is lower than that of pure water.

3. **Dependence on Solute Concentration**:
- DPD depends on the concentration of solutes in the solution. As solute concentration increases, DPD increases because the water potential decreases.
- Water potential (Ψw) also depends on solute concentration, but it is expressed in terms of the potential energy of water.

4. **Direction of Water Movement**:
- Water moves from areas of low DPD to high DPD. This means that water will flow from regions where there is less deficiency of water to regions where there is more deficiency.
- Conversely, water moves from areas of high water potential (less negative) to low water potential (more negative). This indicates that water flows from regions with higher potential energy to regions with lower potential energy.

5. **Conclusion**:
- The main differences can be summarized as follows:
- DPD is always positive, while Ψw is typically negative.
- Both DPD and Ψw depend on solute concentration.
- The direction of water movement is from low DPD to high DPD, while it is from high Ψw to low Ψw.

### Final Answer:
The main difference in DPD and Ψw is that DPD is a positive value indicating water deficiency, while Ψw is a negative value indicating potential energy of water. Both depend on solute concentration, but the direction of water movement differs: from low DPD to high DPD and from high Ψw to low Ψw.