Question

In an experiment, a destarched, long and narrow green leaf (still attached to a potted plant) is introduced into a wide-mouthed glass bottle through an airtight cork. The glass bottle contains some potassium hydroxide solution in its lower part (but the leaf remains above this solution). The whole set-up is placed in sunlight for 2-3 days. The leaf is then taken out. After removing chlorophyll, the leaf is treated with iodine solution. No blue-black colour is produced in the leaf.
(a) Which substance could not be synthesised in the green leaf?
(b) What is the function of potassium hydroxide solution inside the glass bottle?
(c) Which condition necessary for photosynthesis is not fulfilled in this experiment?

Answer 1

(a) Starch could not be synthesized in the green leaf.
(b) Potassium hydroxide absorbs the CO₂ of the air present in the glass bottle.
(c) CO₂ is required for the synthesis of starch and photosynthesis to occur. In the absence of carbon dioxide, photosynthesis will not occur as a result of which no starch will be synthesized.