The fluid surrounding the paramecium is hypotonic. This is because a hypotonic solution has a lower concentration of solutes compared to the inside of the cell. In this case, as water moves osmotically into the paramecium, it indicates that the concentration of solutes inside the paramecium is higher than that in the surrounding water.
Paramecium, being a single-celled organism, lives in freshwater environments, which are typically hypotonic compared to the cytoplasm of the paramecium. As the water continues to flow into the cell, the contractile vacuole works to expel the excess fluid to prevent the cell from bursting. This mechanism is essential for maintaining the cell’s homeostasis in a hypotonic environment.