Question

Given below is the diagram of an apparatus used to study a particular phenomenon in plants :

(a) Name the apparatus.

(b) What is it used for ?

(c) What is the role played by the air-bubble in this experiment ?

(d) What is the use of the reservoir ?

(e) What happens to the movement of the air-bubble if the apparatus is kept :

(i) in the dark; (ii) in sunlight; (iii) in front of a fan ?

Give a reason in each case.

Answer 1

(a) Ganong’s Potometer.

(b) It is used to measure the rate of transpiration of a leafy shoot.

(c) The movement of air-bubble per minute gives the rate of transpiration.

(d) It is used to adjust the position of air-bubble in the capillary tube.

(e) (i) The air-bubble will move very slowly as stomata is closed.

(ii) The air-bubble will move faster as stomata are opened.

(iii) The air-bubble will move very faster as the transpiration increases with the velocity of the wind.