Can someone please answer this biology question please?

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A small piece of black paper was folded in half and used to cover part of the top and bottom portions of a leaf on a living geranium plant. After the plant was kept in sunlight for several days, the paper was removed. The leaf was then boiled in alcohol to remove the chlorophyll and placed in Lugol's iodine solution, which turns blue-black in the presence of starch. Only the part of the leaf that had not been covered turned blue-black. This investigation was most likely testing the hypotheses that

1. light is necessary for photosynthesis to occur
2. alcohol plus chlorophyll forms Lugol's iodine solution
3. green plants use carbon dioxide in photosynthesis
4. plants use alcohol in the production of chlorophyll
 
1. light is necessary for photosynthesis to occur

Photosynthesis produces glucose sugar. Starch is a polysaccharides made up of glucose monosaccharide units.

The side of the leaf that was not covered had starch present. This means photosynthesis occurred.

The side of the leaf that was covered has no starch present. This means photosynthesis did not occur because no glucose was made.

This means that if there is light, photosynthesis will occur. If there is not light, photosynthesis will not occur. So light is necessary for photosynthesis to occur.
 
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