Question

1. The diagram given alongside is an apparatus used to study a particular phenomenon in plants.
   1. Name the apparatus.
   2. What is it used for?
   3. What is the role played by the air bubble in this experiment?
   4. Of what use is the reservoir?
2. What happens to the movement of the air-bubble if the apparatus is kept
   1. in dark,
   2. in sunlight,
   3. in front of fan?

Give a reason in each case.

Answer 1

1. 1. Potometer
   2. A potometer is used to measure the rate of transpiration.
   3. The rate of movement of the air bubble will indicate the rate of transpiration.
   4. The reservoir is used to provide water to the potometer.
2. 1. Movement of the air bubble will decrease or slow down.
      Reason: During the dark, stomata remain closed, so the rate of transpiration decreases, decreasing the movement of the air bubble.
   2. Movement of the air bubble will be faster.
      Reason: In sunlight, stomata remain open, which increases the rate of transpiration and hence the movement of the air bubble.
   3. Movement of the air bubble will be faster.
      Reason: Moving air produces dry air, which increases the rate of transpiration, hence increasing the movement of the air bubble.