The inner wall of each guard cell, towards the pore or stomatal aperture, is

Options

A. thick and elastic
B. thick and inelastic
C. thin and elastic
D. thin and inelastic

Explanation

### Step-by-Step Solution:

1. **Understanding Guard Cells**:
- Guard cells are specialized cells that surround the stomatal pores on the surface of leaves. They regulate the opening and closing of these pores, which is crucial for gas exchange and transpiration.

2. **Identifying the Inner Wall**:
- The inner wall of each guard cell is the wall that faces the stomatal pore (stomatal aperture).

3. **Comparing Wall Thickness**:
- The inner wall of the guard cells is thicker than the outer wall. This differential thickness is important for the function of the guard cells.

4. **Elasticity of the Inner Wall**:
- The inner wall is not only thicker but also elastic. This elasticity allows the inner wall to respond to changes in turgor pressure within the guard cells.

5. **Role of Radial Cellulose Fibrils**:
- The inner wall has radial cellulose fibrils. These fibrils help in maintaining the structure of the guard cells and play a role in their movement.

6. **Function During Turgidity**:
- When the guard cells take up water and become turgid, the thin outer wall bulges outward. This outward bulging pulls on the thicker inner wall due to the radial cellulose fibrils.

7. **Resulting Action**:
- As the inner wall is pulled outward, it causes the stomatal pore to open. This mechanism is essential for allowing gas exchange (CO2 in, O2 out) and transpiration to occur.

8. **Conclusion**:
- Therefore, the inner wall of each guard cell towards the stomatal aperture is thick and elastic.

### Final Answer:
The inner wall of each guard cell towards the stomatal aperture is **thick and elastic**.

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