Here we learn how to prove that the leaves of plants contain starch, which is created as a result of photosynthesis? Remove a plant leaf and heat it in an alcohol bath as shown in the video. The alcohol removes the chlorophyll that makes the leaves green and the heat softens the leaf’s cell walls making chemical reactions easier to do . Dip this leaf into a dilute solution of iodine and watch the leaf turn dark green as a result of starch and iodine combining to form a violet coloured complex. Thus, we see that leaves contain starch.