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Photosynthesis

Arun carried ...

Question

Arun carried out the following experiment with a croton (variegated) leaf. He drew the leaf in his notebook marking the green and the non-green area. He put the leaf in hot alcohol till all the green colour came out and the leaf turned white. He then washed the leaf in water and covered the leaf in iodine solution.
(a) Why did he draw the leaf and mark the green and non-green areas?
(b) What was the colour change in iodine solution?
(c) Which portions of the leaf show colour change?
(d) what can you conclude from this experiment?

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Solution

(a) Arun drew the leaf and marked the green and the non-green areas to identify the part of the leaf that can make food in the form of starch.
(b) The colour of the iodine solution turned blue-black from brown.
(c) The green portions of the leaf show the change in colour.
(d) We can conclude that the green portion of the leaf can make food, i.e. starch, in the presence of sunlight. This is because this portion has chlorophyll.

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Q. Question 1. What happens to the colour of the leaf? What is the colour of the solution?

Now dip the leaf in a dilute solution of iodine for a few minutes.
Take out the leaf and rinse off the iodine solution.
Observe the colour of the leaf and compare this with the tracing of the leaf done in the beginning.

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