Question

To test the presence of starch in a leaf why should we pluck it only from a plant which has been exposed to sunlight for at least 3 to 4 hours?

Answer 1

Testing a leaf for starch is the simplest photosynthesis lab.  A positive test for starch in a leaf provides evidence that photosynthesis has occurred. The test for starch is a leaf is  an is an extension of the Iodine Test for Starch.

Glucose is the product of photosynthesis, and is rapidly converted to granules of starch  - a polymer of glucose  - for storage.  Starch granules have been visualized in the stroma of the chloroplast as  well as the cytoplasm.

The test for starch in a leaf is also a part of the other photosynthesis experiments. So, take time to understand  the test for starch in a leaf.

Answer 2

$\huge\mathfrak\red{Answer :}$


Take a potted plant and put in a dark room.

After sometime pluck a leave from the plant.

Then boil it in water for 5 min to soft it and after doing that place the leave in a test tube containing alcohol.

Place the test tube in a beaker containg water.

Then, genlty heat the beaker till the alcohol dissolves in the chrolophyll and the leaves loses its green colour.

Wash the leaf and Water.

After doing that place the leaf on a plate and add a few drops of iodine solution.

The parts that turn blue black show the presence of starch in a leaf.

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