In a dicot pot herb, vaseline/vegetable oil was applied on the upper surface of one leaf (Experimental leaf 1) and on the lower surface of another leaf (Experimental leaf 2). Vaseline/Vegetable oil was not applied to the control leaf. The plant was deliberately not watered for several days. Which leaf will dry up last?

In a dicot pot herb, vaseline/vegetable oil was applied on the upper surface of one leaf (Experimental leaf 1) and on the lower surface of another leaf (Experimental leaf 2). Vaseline/Vegetable oil was not applied to the control leaf. The plant was deliberately not watered for several days. Which leaf will dry up last? Correct Answer Experimental leaf 2

The correct answer is Experimental leaf 2.

Key Points

• Loss of water to the air through evaporation from the leaves is called transpiration.
• Leaves have numerous pores known as stomata on the bottom of their surface.
• Stomata help the plants to take up carbon dioxide, which they use in photosynthesis or the process of food-making.
• Plants need stomata to release the oxygen formed during photosynthesis too.
• Hence, if the stomata are blocked, transpiration would not occur, and the leaves will remain fresh for a longer period.
• On Experimental leaf 2, Vaseline was applied underneath the leaf, thus stomata get completely blocked thereby preventing transpiration. Hence it'll dry up last.

Additional Information

• On Experimental leaf 1, the vaseline was applied on the upper surface, so the stomata would not be affected much and transpire a little slower than usual. Hence it'll dry up a little slower.
• Control leaf had no vaseline, so it'll function as usual in transpiration with water content already available. Hence it'll dry up first.