How can you prove that sunlight is essetial for photosynthesis?

Explanation

Material required for the experiment : Black paper , clips, potted plant, iodine, methylated spirit, petridish.
Procedure:
) Keep potted plant in dark for one week to remove starch. Take one black paper and cut it with your own design.
ii) Keep design paper properly on the both sides with the help of clips. Ensure that light does not penetrate through covered area with black paper.
iii) Keep the arranged apparatus at sunlight available area. After few hours detach the leaf.
iv) Boil the leaf in methylated spirit over water bath. It becomes pale white due to the removal of chlorophyll. Take the leaf from test tube and spread the leaf in a petri dish.
v) Add few drops of Iodine on leaf. The parts of the leaf, which could get light through the cut out design, turns blue-black colour. The parts of the leaf which could not get light a:re not turned into blue - black colour.
Observation : It will be observed that only the parts of the leaf, which could get sunlight through the cutout design, turns blue - black showing the presence of starch.
Result : This experiment proves that light is necessary for photosynthesis.