The figure given below represents an experimental setup with a weighing machine to demonstrate a particular process in plants. The experimental set -up was placed in bright sunlight. Study the diagram and answer the following questions :

When the weight of the test tube (A & B) is taken before and after the experiment, what is observed? Give reasons to justify your observation in A & B.

Explanation

Weight of test tube A will decrease after the experiment because water will be lost from it through the leaves by transpiration. Weight of test tube B will remain same after the experiment because water will not be lost by transpiration as there is no plant in it and nor by evaporation as oil is spread over it, which will not allow evaporation.