Question

During starch test, why is leaf boiled in alcohol for a short time

Answer 1

For starch test,we need to observe the brown to blue color change of iodine put on leaves. But the leaf is initially green in color which masks the observation and does not give the accurate inference of the test as color change is not viewed properly. So chlorophyll responsible for green color is to be removed first.

Methylated spirits contain alcohol methanol and ethanol.Chlorophyll dissolves in this organic solvents (alcohol). So when leaf is heated in alcohol,they decolorize as alcohol extracts the chlorophyll of the leaf and thus leaf becomes pale yellow.