Of the following four dorsivantral leaves which will show the maximum loss of weight

Options

A. Smeared with vaseline on both surfaces
B. Smeared with vaseline on the upper surface
C. Smeared with vaseline on the lower surface
D. Unsmeared

Answer

To determine which of the four dorsiventral leaves will show the maximum loss of weight due to transpiration, we will analyze each option based on the effect of Vaseline on transpiration.

### Step-by-Step Solution:

1. **Understanding Transpiration**:
- Transpiration is the process by which water vapor is lost from the surface of leaves. This loss of water results in a decrease in the weight of the leaves.

2. **Analyzing Each Option**:
- **Option 1**: Leaf smeared with Vaseline on both surfaces.
- Since both surfaces are covered with Vaseline, transpiration will be completely inhibited. Therefore, there will be no loss of weight.

- **Option 2**: Leaf smeared with Vaseline on the upper surface.
- With Vaseline on the upper surface, transpiration will occur only from the lower surface. However, this will be less than a leaf that is completely unsmeared, resulting in some loss of weight but not maximum.

- **Option 3**: Leaf smeared with Vaseline on the lower surface.
- In this case, transpiration will occur primarily from the upper surface. Similar to Option 2, there will be some loss of weight, but it will not be the maximum possible.

- **Option 4**: Unsmeared leaf.
- An unsmeared leaf will have both surfaces available for transpiration. This will allow for maximum water loss in the form of vapor, leading to the greatest loss of weight.

3. **Conclusion**:
- Among all the options analyzed, the unsmeared leaf (Option 4) will show the maximum loss of weight due to the highest rate of transpiration.

### Final Answer:
The leaf that will show the maximum loss of weight is **Option 4: Unsmeared leaf**.

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