Question

Why a leaf is boiled in alcohol before doing starch test ?

CBSE Class X Science SA 1 ( 2 marks)

Answer 1

Ans.

Before doing starch test with a leaf it becomes relevant to boil the leaf in alcohol, in order to remove the chlorophyll from the green leaf.

On doing this, the leaf becomes de colorized, and it is then when it is treated with iodine and blue black color so as to test the presence of starch in the leaf.

Answer 2

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