Question

In the experiment to prove light is necessary for photosynthesis, why is the plant kept in dark for three to four days?

• A. To destroy the chlorophyll molecules.
• B. To soften the tissues of plants.
• C. To make the cell permeable to iodine.
• D. To use up the starch that was produced earlier.

Answer 1

The correct option is D To use up the starch that was produced earlier.

In the experiment to prove light is necessary for photosynthesis, the plant is kept in dark for three to four days in order to use up the starch that was produced earlier. It is done to avoid false positive results. Starch is produced only when photosynthesis takes place. So when the plant is again exposed to light, photosynthesis will begin and its end product i.e. starch can be tested using iodine test.