Question

Here is the diagram of an experimental set-up to demonstrate a certain phenomenon in plants.
What is the purpose of the spring balance in the set-up?

Answer 1

The purpose of the spring balance in the set-up is to measure the change in weight of the set-up. A small lightweight potted plant can be weighed before and after the end of a certain period of time. The soil surface and the pot should be fully covered to prevent evaporation from the surfaces other than the plant. The loss in weight by the plant during that time is due to loss of water by transpiration.