Observe the picture below. The variegated leaves are used to determine the role of chlorophyll in photosynthesis. After adding Iodine solution, only green part of leaf show positive result. The possible reason for this is:

Iodine cannot diffuse into non-green parts of leaf.

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Iodine has more affinity towards towards green patches.

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Starch production takes place in green parts only.

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Starch production takes place in non-green plants.

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Solution

Starch test:
Iodine solution is used to test the presence of starch in samples. In the presence of starch, iodine turns blue-black in colour.
Variegated leaves:
The variegated leaves have yellow patches on the leaves with some green parts. The green parts are the region containing the green pigment called chlorophyll while the other regions lack chlorophyll. This is why green parts will trap the sunlight to perform photosynthesis. Therefore, carbohydrate in the form of starch will be stored in this region. When iodine is added, it shows a positive result only in green parts as there is starch production in those areas of the leaf only.

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Similar questions

Observe the picture below. The variegated leaves are used to determine the role of chlorophyll in photosynthesis. After adding Iodine solution, only green part of leaf show positive result. The possible reason for this is:

Q. A variegated leaf with green and yellow paths in used for an experiment to prove that chlorophyll is required for photosynthesis. Before the experiment, the green portions

(A)

, and the pale yellow portions

(B)

, are observed. What will be the color of

^{'} A^{'}

just before and after the starch test? Also, write the equation of photosynthesis and mark well as validate from which molecule the by-product is obtained.

Q. In the experiment to show that sunlight is necessary for photosynthesis:
(a) What is done to destarch the green leaves of the potted plant initially?
(b) What is done to a part of destarched leaf so that photosynthesis may not take place in that part of the leaf (before keeping the potted plant in sunlight)?
(c) How is chlorophyll removed from the green leaf before further testing?
(d) Which reagent is used to test the presence/absence of starch in the parts of experimental leaf?

Q. A star-shaped figure was cut in the black paper strip used for covering a part of the leaf of a destarched plant used for demonstrating that light is necessary for photosynthesis. At the end of the experiment (after the removal of chlorophyll), the leaf was tested for starch with iodine solution.

(a) What colour, if any, will be produced on the part of leaf under the star-shaped figure?
(b) Give reason for your answer.

Chlorophyll is a green pigment. It is essential for photosynthesis.

Given this information, can you guess which area of the leaf shown below will photosynthesize?

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