Final answer:
Blood cells in a hypotonic solution will expand or swell due to water entering the cells through osmosis.
Step-by-step explanation:
When blood cells are submerged in a hypotonic solution, they will expand. This is because the external solution has a lower concentration of solutes than the fluid inside the blood cells. Due to osmosis, water moves into the cells to balance the solute concentrations, causing the cells to swell. If the solution is too hypotonic, the red blood cells can take in so much water that they may rupture, a process known as hemolysis.