Question

A plant is kept in a dark room for about 24 hours before conducting any experiment on photosynthesis in order to _______.
a) remove chlorophyll from the leaf
b) remove starch from the leaves
c) ensure that photosynthesis occurred
d) to prove transpiration

Answer 1

Dear Student,

◆ Answer - (b)

A plant is kept in a dark room for about 24 hours before conducting any experiment on photosynthesis in order to remove starch from the leaves.

◆ Experiment to show sunlight is necessary for photosynthesis -

• For this experiment, plant is first kept for 24 hrs in the dark so that all starch gets used up.
• Now some part of leaf is covered with black paper and other is kept open to sunlight for few days.
• After few days, starch test is done on leaf to detect photosynthesis.
• Part of the leaf exposed to sunlight will synthesize starch and give postive starch test.
• Part of leaf covered by black paper will not synthesise starch and give negative starch test.

Thanks dear. Hope this helps you...

Answer 2

A ‘plant’ is kept in a dark room for about 24 hours before conducting any ‘experiment on photosynthesis’ in order to ‘remove starch from the leaves’.

Answer: Option (b)

Explanation:

‘Photosynthesis’ is the process of preparation of food by a green plant in the ‘presence of sunlight’, carbon dioxide, water, and chlorophyll. The food produced is stored as starch in the leaves. In order to conduct any experiment on photosynthesis it must be ensured that there should not be any starch present.  

This can only be done if the plant is kept in a ‘dark room’ for about twenty four hours. In darkness the plant does not receive sunlight and hence cannot manufacture starch. Thus the leaves get de-starched and are ready for experimentation.