what will happen if a leaf of a plant is covered ith red paper instead of black paper for verifying sunlight is essential for photosynthesis

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Solution

Black colour absorbs maximum amount of light that are focused on it and looks black in colour. When a leaf is covered by a black paper and is placed in sunlight the black paper will absorb all the light blocking the entry of sunlight inside the leaf. The leaf will fail to perform photosynthesis without sunlight. Same will happen in case of red paper. If the leaf is covered with red paper, when light is focused all colours except red will get absorbed. The red colour reflects back. So here also no light can able to pass through the paper to the leaf. As no light source is reaching the leaf, photosynthesis will not take place as happened in the case of black paper.

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Similar questions

Q. To determine that light is essential for photosynthesis, following are the steps, but not in
sequence :
(i) Pluck the leaf and do the starch test.
(ii) Keep the selected plant in sunlight.
(iii) Destarch the plant for 48 - 72 hours.
(iv) Cover the leaf with black paper strip.
The correct sequence is

(i) Pluck the leaf to be experimented

(ii) Cover a portion of leaf on both sides by using strips of black paper

(iii) Keep the plant in dark place for three days to destarch its leaves.

(iv) Test the experimental leaf the the presence of starch

(v) Expose the plant to sunlight for four hours

(vi) Remove the black paper strip from the leaf

Given in the box are steps written randomly for the experiment to show that light is essential for photosynthesis. Which of the following sequences of steps is to be followed by the successful run of the experiment?

Q. Sunlight is essential for photosynthesis by green plants.

Q. A portion of destarched leaf of a potted plant was covered with a black strip of paper. The plant was exposed to sunlight for six hours and then tested for starch. It was observed that :

A candidate studied the importance of certain factors in photosynthesis. He took a potted plant and kept it in the dark for over 24 hours. In the early hours of the next morning, he covered one of the leaves with dark paper in the centre only. Then he placed the plant in sunlight for a few hours and tested the leaf which was covered with black paper for starch.

(a) What aspect of photosynthesis was being investigated ?

(b) Is there any control in this experiment ? If so, state it.

(d) Describe step by step, how the candidate proceeded to test leaf for the presence of starch.

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