In testing for starch in a leaf the function of alcohol is to

A. kill the cells of the leaf
B. soften the veins of the leaf
C. aid iodine to penetrate the cells
D. be a component of the heating bath
E. extract the chlorophyll from the leaf

Correct Answer: Option E

E. extract the chlorophyll from the leaf


The hot water kills the leaf and the alcohol breaks down the chlorophyll, taking the green color out of the leaf. When you put iodine on the leaves, one of them will turn blue-black and the other will be a reddish-brown. Iodine is an indicator that turns blue-black in the presence of starch. The leaf that was in the light turns blue-black, which demonstrates that the leaf has been performing photosynthesis and producing starch.