Question

Potometer is used to measure:
(a) Transpiration
(b) Photosynthesis
(c) Root pressure
(d) Ascent of sap

Answer 1

Hint: Potometer is used for measuring the rate of a phenomenon that is responsible for maximum water absorption by the roots. The Potometer was invented by Ganong. The phenomenon which is measured using a potometer was first observed by scientist Stephen Hales who was an English botanist.

Complete answer:
Potometer is a device also known as transpirometer is used for measuring transpiration by measuring the rate of water absorption by plants.

Additional Information:
- Transpiration is the process of loss of water in the form of water vapor from the leaf through stomatal openings and other aerial parts of the plant.
- Transpiration is mainly of three different types:
Cuticular transpiration: Transpiration occurs through the cuticle. It contributes 3-10% to the total transpiration is trees, but in herbs and ferns, cuticular transpiration accounts for almost 50% of the total transpiration.
Stomatal transpiration: Stomatal transpiration is how maximum water loss takes place. It accounts for 50-97% of total transpiration. It occurs only through leaves.
Lenticular Transpiration: Lenticels present on the woody stems may also take part in transpiration. They contribute a very small percentage to transpiration which is around 0.1 to 1%
- Transpiration helps in the cooling of plants when temperatures are too high.
- The rate of transpiration is dependent on several factors like humidity, wind speed, temperature, etc.
- Transpiration is absent in plants surviving under xerophytic conditions. Leaves of these plants are converted into spines to prevent water loss by transpiration.

So, the correct answer is, “Potometer is used to measure transpiration.”

Note: Potometer is a device that is used to measure the rate of transpiration indirectly. The basic working principle is that the amount of water absorbed by the plants equals the amount of transpired water vapor. This is because the absorption of water is dependent on the transpirational pull.