Question

in an activity we destarch the plant then why we cover the leaf with a black paper

Answer 1

In the activity to test that light is necessary for photosynthesis, the leaf of the plant is covered with black paper so that the light could not reach that part of the leaf while it could reach the remaining part. This is done to test that sunlight is necessary for photosynthesis. After the experiment it was observed that starch was present on the remaining part of the leaf leaving the portion which was covered with the black strip.