Answer: The roles of two test groups in the investigating a phenomenon known as positive phototropism. This phenomenon occurs in the plants that responds to external stimuli (light). In this experiment we can see that the pothos plant is having a positive response in both the cases :
1. When the light source is on one side the stems and leaves are bending towards the light source only on one side
2. On the other hand when the pothos plant is given lights from all the directions the growth of the plant takes place in all the directions equally hence it proves that the plant is showing positive responses in the directions where light is present