Question

A well watered healthy potted plant with variegated leaves was kept in darkness for about 24 hours. It was then set up as shown in the diagram and exposed to light for about 12 hours. At the end of this time, leaf x and y were tested for starch. Study the diagram and answer the questions that follow:
(i) Why was the plant initially kept in darkness for 24 hours?
(ii) What is the function of sodium hydroxide solution in the flask?
(iii) Select the correct leaf from the five available choices shown in the diagram as a, b, c, d and e. Rewrite the correct answer by filling in the appropriate letter for the questions that follow:
1. After the starch test, leaf x would look like ______.
2. After the starch test, leaf y would look like ______.
(iv) The experiment with leaf y shows that photosynthesis requires the presence of certain factors. Mention any one factor.

Answer 1

(i) The plant was kept in the dark to destarch the leaves.
(ii) Sodium hydroxide absorbs CO₂ thereby making the flask CO₂ free.
(iii) (1) C, (2) E
(iv) Sunlight