Which of the following facillitates opening of stomatal aperture ?

Options

A. Contraction of outer wall of guard cells
B. Decrease in turgidity of tuard cells
C. Radial orientation of cellulose microfibrils in the cell wall of guard cells
D. Longitudinal orientation of cellulose microfibrils in the cell wall of guard cells

Answer

**Step-by-Step Text Solution:**

1. **Understanding Stomatal Aperture**: Stomatal apertures are small openings on the surfaces of leaves that allow for gas exchange. They are surrounded by specialized cells known as guard cells.

2. **Role of Guard Cells**: The guard cells regulate the opening and closing of the stomata. When the guard cells swell, they cause the stomatal aperture to open, allowing gases like carbon dioxide to enter and oxygen to exit.

3. **Options Analysis**: The question presents several options regarding what facilitates the opening of the stomatal aperture. We need to evaluate each option to determine which one is correct.

4. **Evaluating Each Option**:
- **Option 1: Contraction of the outer walls of guard cells**: This is incorrect. Contraction would lead to closing of the stomatal aperture, not opening.
- **Option 2: Decreased integrity of guard cells**: This is also incorrect. Decreased integrity would weaken the guard cells and likely cause them to malfunction, leading to closure rather than opening.
- **Option 3: Radial orientation of cellulose microfibrils in the cell wall of guard cells**: This is correct. The radial arrangement of cellulose microfibrils allows the guard cells to expand outward when they take up water, leading to the opening of the stomatal aperture.
- **Option 4: Longitudinal orientation of cellulose microfibrils**: This is incorrect. Longitudinal orientation would not facilitate the outward expansion necessary for opening the stomata.

5. **Conclusion**: The correct answer is the third option: "Radial orientation of cellulose microfibrils in the cell wall of guard cells" facilitates the opening of the stomatal aperture.

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