Which one aids stomatal movement -

Options

A. Heterogenous nature of cell wall
B. Unique shape of guard cell
C. Radial orientation of cellulosic microfibrils in the guard cell
D. All

Answer

**Step-by-Step Solution:**

1. **Understanding Stomatal Movement:**
- Stomata are small openings on the surface of leaves that facilitate gas exchange (CO2 and O2) and transpiration (water vapor loss). The opening and closing of stomata are primarily controlled by guard cells.

2. **Role of Guard Cells:**
- Guard cells are specialized cells that surround each stoma. Their shape and structure allow them to change volume and thus control the size of the stomatal opening.

3. **Analyzing the Options:**
- **Option 1: Heterogeneous nature of cell wall**
- The guard cells have a heterogeneous cell wall, meaning the inner wall is thicker than the outer wall. This difference in thickness allows the guard cells to expand and contract effectively when water enters or leaves, aiding in stomatal movement.

- **Option 2: Unique shape of guard cell**
- The unique bean or kidney shape of guard cells allows them to open and close the stomata efficiently. When the guard cells take up water, they swell and curve, causing the stomata to open.

- **Option 3: Radial orientation of cell wall microfibers**
- The cellulose microfibers in the guard cell walls are oriented radially. This arrangement allows the guard cells to expand in a way that facilitates the opening of the stomata when water enters.

4. **Conclusion:**
- All three factors (heterogeneous cell wall, unique shape of guard cells, and radial orientation of microfibers) contribute to the movement of stomata. Therefore, the correct answer is **Option 4: All**.

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