Question

Keep a potter plant inside a dark room for a few hour water it regularly after a day keep the potter plant in sunlight place one of the leaves a glass jar containing potassium hydroxide observe the changes what would happen when starch test is done with the leaf kept in jar

Answer 1

Iodine test is used to test for the presence of starch.

When a plant is kept in the dark for 72 hours it is denied light which is a condition necessary for photosynthesis.

Photosynthesis leas to formation of starch.

When an iodine test is carried out for the leaf of the plant kept in the dark, the columns of iodine remain unchanged.

This is because of the absence of starch.

However when an Udine test is performed on the leaf of the plant kept in the light, the colour of the I done solution turns blue black indicating the presence of starch in the leaf.