Given alongside is a sketch of a leaf partially covered with black paper and which is to be used in the experiment to show that light is compulsory for the process of photosynthesis. At the end of the experiment, which one of the leaf parts labelled I, II and III will become blue black when dipped in iodine solution?

(1) I only
(2) II only
(3) I and III
(4) II and III

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Solution

According to the above sketch, parts I and III will become blue black when dipped in iodine. It is because the starch will be synthesized in parts I and III and whereas it will not be synthesized in part II.

Hence, the correct answer is option 3.

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Similar questions

Q. In the experiment to show that light is necessary for photosynthesis, some of the steps of the experiment deal with the following activities:
I. Starch reacts with iodine and gives blue-black colour
II. Chlorophyll is dissolved in ethanol
III. Hot water makes leaf tissue soft
The correct sequence of these steps is :
(1) I–II–III
(2) II–III–I
(3) III–II–I
(4) I–III–II

Q. The steps necessary for setting up the experiment, ‘To demonstrate that light is necessary for photosynthesis’ are not given here in proper sequence :
I. Keep the potted plant in sunlight for 3 to 4 hours.
II. Keep the potted plant in darkness for about 48 hours.
III. Cover a leaf of the plant with a strip of black paper.
IV. Pluck the leaf and test it for starch.
The correct sequence of steps is :
(1) I, III, IV, II
(2) I, IV, III, II
(3) II, IV, III, I
(4) II, III, I, IV

Q. A star-shaped figure was cut in the black paper strip used for covering the leaf of a destarched plant used for demonstrating that light is necessary for photosynthesis. At the end of the experiment when the leaf was tested for starch with iodine, the star-shaped figure on the leaf was found to be:

(1) colourless
(2) green in colour
(3) brown in colour
(4) blue-black in colour

Q. In the sketch of stomatal apparatus given alongside, the parts I, II, III and IV were labelled differently by four students. The correct labelling is shown in :

(1) (I) guard cells, (II) stoma, (III) starch granule, (IV) nucleus
(2) (I) cytoplasm, (II) nucleus, (III) stoma, (IV) chloroplast
(3) (I) guard cells, (II) starch, (III) nucleus, (IV) stoma
(4) (I) cytoplasm, (II) chloroplast, (III) stoma, (IV) nucleus

Q.
Following compounds are given

(i) CH₃ CH₂ OH (ii) CH₃ CO CH₃

_(iii)(iv) CH₃ OH

Which of the above compounds, on being warmed with iodine solution andNaOH , will give Iodo form?

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According to the above sketch, parts I and III will become blue black when dipped in iodine. It is because the starch will be synthesized in parts I and III and whereas it will not be synthesized in part II. Hence, the correct answer is option 3.

According to the above sketch, parts I and III will become blue black when dipped in iodine. It is because the starch will be synthesized in parts I and III and whereas it will not be synthesized in part II.

Hence, the correct answer is option 3.