In the experiment to prove chlorophyll is necessary for photosynthesis- Q1 Why is a variegated leaf used? Q2 Why is the variegated leaves kept in a dark room for 3 day and then kept in sunlight for 6 hours?
In the experiment to prove chlorophyll is necessary for photosynthesis- Q1 Why is a variegated leaf used? Q2 Why is the variegated leaves kept in a dark room for 3 day and then kept in sunlight for 6 hours?
A variegated leaf is used in this experiment because it contains some part which is green and some part which is non-green. The green part of the leaf is green in color to the presence of chlorophyll and can perform photosynthesis, non-green part does not have chlorophyll and hence is non photosynthetic.
Then variegated plant is kept in a dark room for 2-3 days in order to prevent the photosynthesis process and there is no further food formation. So, during 2-3 days, all the stored food has been utilized by the plant.
Then the plant is placed in sunlight for six hours to allow photosynthesis to take place. Carbohydrate formation occurs as a result of photosynthesis only in the green parts of the leaf.
After that, variegated leaf is decolourised with alcohol and then dip it in a solution of iodine for a few minutes to detect the presence of starch. The leaf is treated with alcohol so that it loses its green colour (chlorophyll pigment) and blue-black colour obtained after treatment with iodine which confirms the presence of starch in the green portion of the leaf. The green parts of a variegated leaf contain chlorophyll. Therefore, only these parts could photosynthesize and manufacture food. Thus, the change in colour was observed only in these parts.
A variegated leaf is used in this experiment because it contains some part which is green and some part which is non-green. The green part of the leaf is green in color to the presence of chlorophyll and can perform photosynthesis, non-green part does not have chlorophyll and hence is non photosynthetic.
Then variegated plant is kept in a dark room for 2-3 days in order to prevent the photosynthesis process and there is no further food formation. So, during 2-3 days, all the stored food has been utilized by the plant.
Then the plant is placed in sunlight for six hours to allow photosynthesis to take place. Carbohydrate formation occurs as a result of photosynthesis only in the green parts of the leaf.
After that, variegated leaf is decolourised with alcohol and then dip it in a solution of iodine for a few minutes to detect the presence of starch. The leaf is treated with alcohol so that it loses its green colour (chlorophyll pigment) and blue-black colour obtained after treatment with iodine which confirms the presence of starch in the green portion of the leaf. The green parts of a variegated leaf contain chlorophyll. Therefore, only these parts could photosynthesize and manufacture food. Thus, the change in colour was observed only in these parts.
