(a) Photosynthesis is the process by which plant cells prepare food (carbohydrates) from inorganic raw materials such as carbon dioxide and water in presence of sunlight and chlorophyll.
The factors other than sunlight affecting the rate of photosynthesis are:
(b) Experiment to demonstrate that light is necessary for photosynthesis:
It can be observed that the leaf taken from the plant kept in sunlight develops blue-black patches whereas the leaf taken from the plant kept in the dark room does not show any patches.
Reason for the observation:
Plants which receive sunlight prepare their own food through the process of photosynthesis. It is the presence of starch that turns the colour of iodine solution blue-black. Therefore, blue-black patches are observed on the leaf taken from the plant kept in sunlight. In contrast, the leaf of the plant kept in the dark room does not produce any starch. Therefore, no patches are observed on it.