Question

What is a potometer?

Answer 1

Potometer is also known as a transpirometer or Ganong’s potometer. The potometer is made of a glass tube that is bent twice and consists of a large-mouthed glass cylinder, a horizontal glass rod with a capillary tube inserted within, and a reservoir connected to the horizontal rod. The potometer is of different types- Bubble potometer, Mass potometer, Darwin's photometer, and Ganong's potometer.

Complete explanation:
A potometer is an apparatus designed to measure the water uptake in a leafy shoot. The water uptake is almost equal to the water lost through transpiration and so the rate of transpiration can be estimated with the help of a potometer.
The two main types of potometer are bubble’s potometer and mass potometer. In a mass potometer, the plant along with its root is submerged in a beaker containing. The beaker is then placed on a digital scale and readings can be taken to determine the quantity of water lost by the plant.
In a bubble’s potometer, the distance moved by an air bubble in a certain period of time can be used to calculate the rate of water uptake. This apparatus is set up under water to prevent the entry of other unwanted air bubbles.

Note:
It is important to note that a potometer does not measure the loss of water during the transpiration but measures the water uptake by the cut shoot. It works on the principle that the amount of water absorbed by the plant will be equal to the amount of water lost during transpiration. It is also important for the potometer to have an air-tight seal in order to get an accurate reading to show how much water is lost through transcription.