In a stomatal apparatus , cellulosic microfibril are oriented

Options

A. Longitudinally on subsidiary cells
B. Radially in the cell walls of guard cells
C. Radially and longitudinally in wall of guard cells
D. Longitudinally on both guard cells

Answer

### Step-by-Step Solution:

1. **Understanding Stomata**:
- Stomata are small openings found on the epidermis of leaves. They play a crucial role in gas exchange, allowing oxygen to enter and carbon dioxide to exit the plant. They also facilitate transpiration, which is the process of water vapor loss from the plant.

2. **Role of Guard Cells**:
- Each stoma is surrounded by a pair of specialized cells known as guard cells. These cells regulate the opening and closing of the stomata, thus controlling gas exchange and water loss.

3. **Cellulose Microfibrils**:
- The cell walls of guard cells are primarily composed of cellulose microfibrils. These microfibrils are formed from chains of beta-1,4-glucan, which bond together to create a strong structural framework.

4. **Orientation of Cellulosic Microfibrils**:
- In guard cells, the cellulose microfibrils are oriented radially. This radial arrangement allows the guard cells to expand and contract effectively, enabling the stomata to open and close. If the microfibrils were oriented longitudinally or sub-sidially, the guard cells would not be able to function properly, and the stomata would not open efficiently.

5. **Conclusion**:
- Thus, the orientation of cellulosic microfibrils in the stomatal apparatus is crucial for the proper functioning of stomata, allowing for effective gas exchange and transpiration in plants.