Photosynthesis is a process performed mainly by autotrophs to prepare food with the help of CO2, water and minerals and sunlight in the presence of chlorophyll.
To show sunlight is essential for the process of photosynthesis, we can conduct an experiment following below steps :-
Take a potted plant and place it in a dark room for 2-3 days, so that the starch present in leaves gets used up.
Using paper clips, fix two strips of black on both sides of the leaf.
Now, put the potted plant in sunlight for 3-4 hours.
Pluck the leaf covered with black paper strips and remove these strips.
Boil the leaf in boiling water followed by boiling in alcohol.
Now, rinse the leaf with cold water.
Put iodine solution on the leaf to test the presence of starch.
Observation :-
The portion of leaf covered by black paper strips does not turn blue black after putting iodine solution but the uncovered parts turned blue black.
This shows that photosynthesis occurred only on the uncovered regions of the leaf.
Hence,sunlight is necessary for photosynthesis.
Final answer :-
Hence,this is the explanation that sunlight is essential for photosynthesis.