Given alongside is the diagram of an experimental set-up:

(a) What is objective of this experiment?

(b) Will it work satisfactorily? Give reason.

(c) What alteration(s) will you make in it for obtaining expected result?

(d) Would you take any step before starting the experiment? Describe this step and explain its necessity.

(a) The aim of this experiment is to show that carbon dioxide is important for photosynthesis.

(b) In the given figure, lime water is present in the flask. But lime water does not absorb the carbon dioxide formed, hence, the leaf will anyway show the presence of starch formed during photosynthesis. This deviates from our aim of proving the role of carbon dioxide during photosynthesis.

(c) To rectify the above, lime water should be replaced by pellets of potassium hydroxide as it absorbs carbon dioxide.

(d) Yes, the plant should be kept for 24-48 hours in the dark to destarch it.

i. The leaves are dipped in boiling water to kill the cells.

ii. Then, it is boiled in methylated spirit over a water bath to remove the chlorophyll.

iii. It is then placed in hot water to soften it.

iv. Iodine solution is poured and the presence of starch is confirmed in regions where the leaf turns bluish-black. A leaf without starch will show brown colouration.

Destarching will ensure that the starch formed after the experiment on carbon dioxide, is formed under experimental conditions only. This will be a much more effective way of experimenting with photosynthesis.