What happens when concentration of solutes decreases in guard cells

Options

A. Water potential decreases
B. Water potential increases
C. Osmotic pressure increases
D. None of the above

Answer

### Step-by-Step Solution:

1. **Understanding Guard Cells**:
- Guard cells are specialized cells that surround the stomata (pores) in plant leaves. They regulate the opening and closing of these stomata, which is crucial for gas exchange and transpiration.

2. **Concept of Solute Concentration**:
- Solute concentration refers to the amount of solute present in a solution. In guard cells, solutes can include ions and other molecules that affect the osmotic balance.

3. **Effect of Decreasing Solute Concentration**:
- When the concentration of solutes in guard cells decreases, it leads to a decrease in solute potential. Solute potential is a measure of the potential energy of water in a solution due to the presence of solutes.

4. **Water Potential Equation**:
- Water potential (Ψ) is defined by the equation:
\[ Ψ = Ψ_p + Ψ_s \]
where Ψ_p is the pressure potential and Ψ_s is the solute potential.

5. **Impact on Water Potential**:
- A decrease in solute concentration results in a decrease in solute potential (Ψ_s). Since water potential is the sum of pressure potential and solute potential, a decrease in solute potential will lead to an increase in overall water potential (Ψ).

6. **Conclusion**:
- Therefore, when the concentration of solutes decreases in guard cells, the water potential increases.

### Final Answer:
- The correct answer is: **Water potential increases**.