Question

A student performed starch test on the leaf. Identify the correct method to decolourise the leaf.
A. Put the leaf in boiling water
B. Put the leaf in iodine solution
C. Put the leaf in ethanol heated in a water bath
D. Put the leaf in water at room temperature

Answer 1

Answer:

put the leaf in water at room temperature

Answer 2

Answer:

C. Put the leaf in ethanol heated in a water bath.

Explanation:

The boiling ethanol dissolves the chlorophyll and removes the green colour from the leaf; turning it white. Ethanol is an organic solvent that causes the plant cells to become leaky. The chlorophyll inside the cells become available and dissolves in the ethanol. The purpose of boiling the leaf in the water is to break down the cell membrane, soften the cuticle layer and cells walls.