Experiment: Light is essential for Photosynthesis - QS Study
QS Study

Requirements: A potted plant with green leaves, Black paper, Alcohol, Iodine solution, and clips, (the plant should keep in dark for a long time before experiment).

Procedure: Cover both side of a leaf with black paper and clip so that Sunlight cannot reach inside. Then let the pot with the plant be kept in Sunlight. After one hour tear the leaf and boil in alcohol so that the leaf becomes chlorophyll free. Now let the leaf be immersed in iodine solution.

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Observation: On taking out from the iodine solution it will be seen that all the area except the covered area became blue (deep violet or black).

Conclusion: Carbohydrate react with iodine solution turns to blue (deep violet or black). Sunlight did not reach the area covered with black paper photosynthesis did not occur there, that is carbohydrate did not produce. As carbohydrate did not produce there the area did not turn blue (deep violet or black). Thus it is proved that Sunlight is essential for photosynthesis so to say for manufacture of carbohydrate.