Question

Potometers are made on the principle that

• A. The amount of water transpired is approximately equal to amount of water absorbed.
• B. The amount of water transpired is more than the amount of water absorbed.
• C. The amount of water transpired is less than the amount of water absorbed.
• D. Humidity causes reduction in transpiration.

Answer 1

The correct option is A The amount of water transpired is approximately equal to amount of water absorbed.

A potometer is a device used for measuring the rate of water loss from a plant (transpiration).

The rate of transpiration can be estimated in two ways:

1. By measuring the distance the water level drops in the graduated tube over a measured length of time. It is assumed that this is due to the cutting taking in water which in turn is necessary to replace an equal volume of water lost by transpiration.

2. By measuring the reduction in mass of the potometer over a period of time. Here it is assumed that any loss in mass is due to transpiration.

Thus, the correct answer is option A.