The figure given below represents an experimental set-up 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.
What is the purpose of keeping the test tube
B in the experimental set-up?
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1701164/original_54_1.png)