Question

Why do we boil the leaf in alcohol when we are testing it for starch?

Answer 1

We boil the leaf in alcohol to remove the chlorophyll and decolourize it, so that the colour change from brownish-orange to blue-black is clearly visible when iodine is added. Additionally, the alcohol dissolves the waxy cuticle, allowing the iodine to penetrate the cells and reach any stored starch.