Question

Why does the uncovered part of leaf turn to blue black after putting the iodine?

Answer 1

hey there !!
here is your answer

The uncovered part of the leaf turn blue-black because it starts doing photosynthesis in presence of sunlight and starts producing starch. Starch on reacting with the iodine solution turns blue-black.

hope it helps : )

Answer 2

because it contain starch which results in the transforming of colour from grenn to blue when iodine is added