Question

The diagram alongside is set up to demonstrate an experiment. Pondweed was placed in five water-filled tubes. The experiment was set up as shown in the diagram. The tubes were then left for 24 hours. Write the correct answer out of the five available choices:
Figure

(i) In which tube would you expect to find the plant with the least amount of starch?
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5

(ii) The tube in which most oxygen would be found is
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5

(iii) The tube in which least carbon dioxide would be found is
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5

(iv) The tube in which the plant would survive for the shortest length of time is
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5

Answer 1

(i) (e) 5
Plant in tube 5 is kept in dark; hence, no photosynthesis can take place in this plant. Therefore, it will show least amount of starch.

(ii) (a) 1
Plant in tube 1 is kept in light; hence, it will perform photosynthesis and produce oxygen. No snail is present there to consume oxygen in this tube along with the plant. Thus, maximum oxygen will be present in it.

(iii) (a) 1
No snail is present in tube 1 to respire and give out carbon dioxide. Also, plant is in light; therefore, it will perform photosynthesis and utilise the available carbon dioxide. Hence, tube 1 will have least carbon dioxide.

(iv) (e) 5
Plant kept in tube 5 is in dark; so, no photosynthesis can take place. Thus, no food will be made and plant will die soon.