Why is it necessary to place a plant in the dark before starting an experiment on photosynthesis? Explain.

A plant should be placed in the dark for about 24-48 hours before starting an experiment on photosynthesis to destarch the leaf. This is because starch is the evidence of photosynthesis. In the absence of starch, the experiments can be carried out more effectively.

Explanation: Starch being the evidence of photosynthesis, will affect the effectiveness of the experiment being carried out. During the incubation of few hours, the starch from the leaf cells will be removed and sent to the store organs in the leaf.