Work Step by Step
A red blood cell in a hypotonic solution will take in water. This occurs because the fluid inside the red blood cell is hypertonic, meaning it contains more solutes than the solution outside of the cell. Semipermeable membranes allow water to pass freely from one side of the membrane to the other via osmosis. In order to make the concentration of solutes both inside and outside the cell equal to one another, causing the solutions to become isotonic, water will flow from the area with less solutes to the area with more solutes, that is, from the hypotonic solution outside the cell into the red blood cell.