Which of the following equations is wrong ?

Options

A. `Psi _w =Psi_s+Psi_p=0`
B. `DPD =OP +TP`
C. `Psi _w =Psi_s+Psi_p`
D. `DPD = (OP_1 -OP_2)-TP`

Answer

To solve the question "Which of the following equations is wrong?", we will analyze each of the provided equations step by step.

### Step 1: Analyze the first equation
**Equation:** \( \Psi_w = \Psi_s + \Psi_p = 0 \)

- **Explanation:** This equation represents the water potential (\( \Psi_w \)) of pure water at standard temperature and pressure. In pure water, the solute potential (\( \Psi_s \)) is 0, and the pressure potential (\( \Psi_p \)) is also 0. Therefore, the equation is correct as it reflects that the water potential of pure water is indeed 0.

### Step 2: Analyze the second equation
**Equation:** \( DPD = OP + dP \)

- **Explanation:** The Diffusion Pressure Deficit (DPD) is calculated using the formula \( DPD = OP - TP \) (where OP is Osmotic Pressure and TP is Turgor Pressure). The equation given here is incorrect because it states that DPD equals the sum of OP and dP, which does not align with the correct formula for DPD.

### Step 3: Analyze the third equation
**Equation:** \( DPD = OP_1 - OP_2 - TP \)

- **Explanation:** This equation also attempts to express DPD. However, the correct formula for DPD is \( DPD = OP - TP \). The equation presented here is incorrect as it introduces two osmotic pressures (OP1 and OP2) without a clear context or correct formulation.

### Step 4: Analyze the fourth equation
**Equation:** \( DPD = OP - TP \)

- **Explanation:** This is the correct formula for calculating the Diffusion Pressure Deficit. It states that DPD is equal to the difference between Osmotic Pressure and Turgor Pressure, which is accurate.

### Conclusion:
From the analysis, the second equation \( DPD = OP + dP \) is wrong, as well as the third equation \( DPD = OP_1 - OP_2 - TP \). However, since the question asks for which equation is wrong, the most straightforward incorrect equation is the second one.

### Final Answer:
The wrong equation is \( DPD = OP + dP \).

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