Question

Potometer works on the principle of
A) Amount of water absorbed equals the amount transpired.
B) Osmotic pressure
C) Root Pressure
D) Potential difference between the tip of the tube and that of the plant.

Answer 1

Hint: An apparatus which measures the rate at which a plant draws water.

Complete Answer:
A potometer, also referred to as a transpirometer, is a device used to measure a leafy shoot's water absorption rate that is approximately equal to the water lost by transpiration. Photosynthesis and transpiration are the sources of the water uptake.

The transpiration rate can be appraised in two ways:
1) Indirectly by calculating the distance the level of the water drops. In the graduated tube over a given period; this is due to water cutting, which is necessary in order to offset the equivalent amount of water lost by transpiration.
2)Calculating potometer mass reduction directly over a given period of time. Here it is assumed that every mass loss is due to transpiration.

There are two main types of potometers:
Bubble potometer and mass potometer.
The Weight Potometer is a plant Immersed in a beaker, with foundation. This beaker is then set to digital equilibrium; it can be calculated to determine the amount of water that the plant loses.
The Disadvantages of using the potometer: The addition of air bubbles is not very easy. The twig can not last for long. Any changes in external temperature can affect the location of the air bubble on the capillary tube. Potometer does not quantify the water lost during transpiration, but measures the water taken up by the cut shoot.

So the answer is option A.

Note: Transpiration is the removal of leaves and stems from water, and is an important process in green plants. The humidity and air temperature, the strength of light and wind are some factors that can influence the transpiration rate.