Question

Sara placed a healthy potted plant in a dark room for 48 hours to perform an experiment on photosynthesis. She plucked one of the leaves and tested it for starch. The leaf did not turn blue-black on adding Iodine solution. (a) Name the structure.
(b) Label Gray matter and White matter.

Hint:

Boiling the leaf in alcohol removes pigments and helps in staining the starch with iodine. Without light, the plant cannot produce starch during the experiment.

Answer 1

(a) Why was the plant placed in the dark for 48 hours?
The plant was placed in the dark for 48 hours to deprive it of light. This is done to stop photosynthesis, as light is necessary for the plant to produce glucose. In the absence of light, the plant does not carry out photosynthesis and thus cannot produce starch. (b) What is the significance of boiling the leaf in alcohol during the starch test?
Boiling the leaf in alcohol helps to remove the chlorophyll from the leaf and makes it easier to detect the presence of starch. The alcohol also softens the leaf, making it more receptive to the iodine solution, which stains the starch blue-black if present.