A destarched leaf and a potted plant is coated with Vaseline on both sides and placed in sunlight. After a few hours, it is tested for the presence of starch. Will the test be positive or negative?

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Solution

A destarched leaf is when coated with vaseline from both sides, then it closes the stomata of the leaves. This stops transpiration, respiration and photosynthesis. Starch is a type of carbohydrate. If photosynthesis will not occur, then starch will not be formed. So, the test for starch will be negative as there will be the absence of starch in the leaf.

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