The student likely saw small droplets of water inside the plastic bag around the plant's leaves because of transpiration. Transpiration is the process where plants release water vapor through tiny pores in their leaves called stomata. This continuous loss of water vapor from the leaves creates a pull, known as transpiration pull, that causes water to move up from the roots through the xylem vessels to replace the water lost.
This movement of water through the plant is made possible by cohesion, which is the attraction between water molecules. Cohesion allows water molecules to stick together, forming a column of water that can flow upwards through the xylem vessels like a straw. This process helps transport water and nutrients from the roots to the leaves and other parts of the plant.
In summary, the small droplets of water seen inside the plastic bag around the plant's leaves are likely a result of transpiration, where water is being lost from the leaves due to the process of photosynthesis and the subsequent movement of water up through the plant's vascular system, aided by cohesion.
