We can show that the chlorophyll is necessary for Photosynthesis by a test. In this test take a plant which has partly green and partly non-green leaves. Put the plant in sunlight for a few hours. Pluck a leaf from the plant and draw a outline on it to indicate the green and non-green portion.
Put this leaf in a test tube which containing alcohol. Place this test tube in a beaker containing water and heat the water. As the alcohol begins to boil, the chlorophyll from green part dissolves in it and after some time the leaf becomes pale. You have to remove the leaf from alcohol and wash it in warm water. Lay the leaf in a dish and put a few drops of iodine on it. The color of the leaf changes into blue-black. This color shows the presence of starch in the leaf. The Presence of starch on the green part of the leaf proves that the Chlorophyll is necessary for photosynthesis.