Choose the option with correct expression.

Options

A. `psi_w=psi_s-psi_p`
B. `psi_s=psi_w+psi_p`
C. `psi_w=psi_s+psi_p`
D. `psi_w=psi_p-psi_s`

Answer

To solve the question regarding the correct expression for water potential, we need to understand the components that make up water potential in plants. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand Water Potential
Water potential (Ψ) is a measure of the potential energy of water in a system and is crucial for understanding how water moves in plants. It is influenced by solute concentration and pressure.

### Step 2: Identify Components of Water Potential
Water potential is composed of two main components:
- **Solute Potential (Ψs)**: This is the potential of water to move due to the presence of solutes. It is always negative or zero (pure water has a solute potential of zero).
- **Pressure Potential (Ψp)**: This refers to the physical pressure exerted on water in the plant cells. It can be positive, negative, or zero.

### Step 3: Formulate the Equation
The relationship between these components is expressed in the equation:
\[ Ψw = Ψs + Ψp \]
Where:
- Ψw = Water potential
- Ψs = Solute potential
- Ψp = Pressure potential

### Step 4: Choose the Correct Option
Given the options, we need to select the one that accurately represents the relationship between water potential, solute potential, and pressure potential. The correct expression is:
\[ Ψw = Ψs + Ψp \]
Thus, the answer is **Option C**.

### Final Answer
The correct expression for water potential is:
**Option C: Ψw = Ψs + Ψp**

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