Which of the following does not happen during the stomatal opening ?

Options

A. Turgor pressure of guard cell increases
B. `K^+` concentration in guard cell increases .
C. Thin outer walls bulge outwards .
D. Guard cell loose turgor due to water loss.

Answer

To solve the question "Which of the following does not happen during the stomatal opening?", we need to understand the process of stomatal opening and the role of guard cells.

### Step-by-Step Solution:

1. **Understanding Guard Cells**:
- Stomata are small openings on the surface of leaves, and they are surrounded by guard cells.
- These guard cells control the opening and closing of the stomatal pore.

2. **Role of Turgor Pressure**:
- For stomata to open, guard cells must increase their turgor pressure.
- Turgor pressure is the pressure of the cell contents against the cell wall, which is crucial for the opening of stomata.

3. **Water Absorption**:
- The process begins with the guard cells absorbing water.
- As water enters the guard cells, it increases their turgor pressure.

4. **Microfibril Arrangement**:
- The guard cells have microfibrils arranged radially, which allows them to expand outward when turgor pressure increases.

5. **Potassium Ion Concentration**:
- The concentration of potassium ions (K+) in the guard cells also increases during stomatal opening, which aids in water absorption.

6. **Identifying Incorrect Statement**:
- The options provided include:
1. Turgor pressure of the guard cell increases.
2. K+ concentration in the guard cell increases.
3. The thin outer walls bulge outwards.
4. The guard cells lose turgor due to water loss.
- The fourth option states that "the guard cells lose turgor due to water loss." This is incorrect during stomatal opening, as losing turgor pressure is associated with stomatal closing.

### Conclusion:
The correct answer to the question is option 4: "The guard cells lose turgor due to water loss," as this does not happen during stomatal opening.