What happens when iodine solution is added to a leaf boiled in alcohol?

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Iodine tests are commonly used to test for the presence of starch in leaves. 

Plants containing chlorophyll pigment carry out the process of photosynthesis, in which they convert the light energy of the sun to the chemical energy of glucose molecules. These glucose molecules are then converted to starch in...

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Iodine tests are commonly used to test for the presence of starch in leaves. 

Plants containing chlorophyll pigment carry out the process of photosynthesis, in which they convert the light energy of the sun to the chemical energy of glucose molecules. These glucose molecules are then converted to starch in the plant. Iodine reacts with the starch. A color change is an indicator of the presence of starch and, by extension, photosynthesis. 

In this experiment, we boil the leaf in water to kill it and remove the waxy cuticles. Then it is boiled in alcohol to remove all the plant pigments. When we add iodine to this leaf, it reacts with the starch present in the leaf (if any) and turns blue-black.

The presence of this color is an indicator of the photosynthetic ability of the plant and the presence of starch in it. 

Hope this helps. 

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