Question

The following are the steps followed to perfom the Iodine test for the detection of starch production in plants.
i) Iodine solution is added
ii) Leaf that was partly covered is boiled in alcohol
iii) Potted plant with a leaf partly covered with aluminium foil is exposed to sunlight
iv) the leaf is rinsed in water

The correct sequence of steps to perform the test is

• A. i, ii, iii & iv
• B. iii, ii, iv & i
• C. iv, iii, i & ii
• D. ii, i, iii & iv

Answer 1

The correct option is B iii, ii, iv & i

The Iodine Test for Starch is used to determine the presence of starch in biological materials.
The steps followed to test the presence of starch in leaves are:
Step 1: A potted plant with one leaf partly covered with aluminium foil is kept in the sun
Step 2: The leaf that was partly covered is plucked and bolied in alcohol. This soften the cells of the leaf and removes chlorophyll from it
Step 3: The leaf is rinsed in water to remove excess alcohol
Step 4: Iodine solution is added to this leaf. The parts of the leaf where blue-black colour appears when iodine solution is added, indicates the presence of starch.