Question

What is potometer?

Answer 1

1. A potometer is a piece of apparatus designed to measure water uptake in a leafy shoot.
2. There are 2 types of potometer – the bubble potometer and the weight potometer.

Bubble potometer

1. As water is transpired from the leaves, the shoot absorbs water from the photometer.
2. The distance the air bubble moves in a certain period of time can be used to calculate the rate of water uptake.
3. The apparatus is set up under water to prevent the entry of any unwanted air bubbles.
4. The junction between the shoot and potometer is sealed (usually with petroleum jelly) to prevent any air leaks.
5. The apparatus is reset using the reservoir or syringe so that water uptake in the same leafy shoot can be measured – making the investigation more reliable.

Weight potometer

1. The apparatus and plant is weighed and then left for a period of time.
2. When reweighed the amount of water lost by the plant can be calculated.
3. A top pan balance that measures to two decimal points provides great accuracy.