Which of the following hypostomatous leaves would dry up last

Options

A. Both surfaces greased
B. Both surfaces ungrased
C. Lower surfaces greased
D. Upper surfaces greased

Answer

To determine which hypostomatous leaf would dry up last, we need to understand the characteristics of hypostomatous leaves and the factors affecting transpiration.

### Step-by-Step Solution:

1. **Understanding Hypostomatous Leaves**:
- Hypostomatous leaves have a higher number of stomata on the lower surface compared to the upper surface. This is typical in dicotyledonous plants. The stomata are small openings that allow for gas exchange and transpiration.

**Hint**: Remember that stomata are crucial for gas exchange and water loss in plants.

2. **Transpiration Process**:
- Transpiration is the process through which water vapor is lost from the plant leaves to the atmosphere. The rate of transpiration is influenced by the number of stomata, humidity, temperature, and surface area of the leaf.

**Hint**: Consider how stomata density affects water loss.

3. **Effect of Greasing the Leaf**:
- If a leaf is greased on both surfaces, the stomata are effectively closed off. This prevents water loss through transpiration. Therefore, a greased leaf will retain moisture and not dry up quickly.

**Hint**: Think about how blocking stomata impacts transpiration rates.

4. **Comparison of Leaves**:
- When comparing different hypostomatous leaves, the one that has been greased on both surfaces will dry up last because it minimizes water loss. In contrast, leaves that are not treated will lose water more rapidly through their stomata.

**Hint**: Identify which leaf has been treated to reduce transpiration.

5. **Conclusion**:
- Based on the information provided, the hypostomatous leaf that has been greased on both surfaces will dry up last compared to other untreated leaves.

**Hint**: Look for the leaf that has been modified to reduce transpiration.

### Final Answer:
The hypostomatous leaf that has been greased on both surfaces will dry up last.