Question

Given below are the steps to be followed for performing ‘starch test’ on a green leaf.
(A) Boil the leaf in alcohol
(B) Boil the leaf in water
(C) Dip the leaf in iodine solution
(D) Wash the leaf in water
Which one of the following sequences should the students follow to get the correct result?
(1) (A), (D), (B), (C)
(2) (D), (A), (B), (C)
(3) (B), (D), (A), (C)
(4) (B), (A), (D), (C)

Answer 1

The following sequence should be followed by students to obtain the correct result in starch experiment -

(B) Boil the leaf in water - to break down the cell membrane of leaf cells and making them more permeable to iodine solution.
(A) Boil the leaf in alcohol - to remove the cholorphyll which interferes in test for starch
(D) Wash the leaf in water - to soften it and remove any chlorophyll molecules attacahed to it
(C) Dip the leaf in iodine solution - to check the presence of starch

(B), (A), (D), (C)

Hence, the correct answer is option 4.