Question

The steps necessary for setting up the experiment, ‘To demonstrate that light is necessary for photosynthesis’ are not given here in proper sequence :
I. Keep the potted plant in sunlight for 3 to 4 hours.
II. Keep the potted plant in darkness for about 48 hours.
III. Cover a leaf of the plant with a strip of black paper.
IV. Pluck the leaf and test it for starch.
The correct sequence of steps is :
(1) I, III, IV, II
(2) I, IV, III, II
(3) II, IV, III, I
(4) II, III, I, IV

Answer 1

The following sequence should be followed for setting up the experiment "To demonstrate that light is necessary for photosynthesis" -

II. Keep the potted plant in darkness for about 48 hours. - This is done to destarch the leafs so that no starch is present in the beginning of the expriment itself.
III. Cover a leaf of the plant with a strip of black paper. - This is done to prevent the synthesis of starch in that region.
I. Keep the potted plant in sunlight for 3 to 4 hours. - This is done so that photosynthesis can occur and synthesis of starch can take place.
IV. Pluck the leaf and test it for starch. - The leaf is tested for the presence of starch.

II, III, I, IV

Hence, the correct answer is option 4.