Red blood cells placed in a hypertonic solution shrink in size due to more flow of water out than into the cell –a process called crenation. Red blood cells placed in a hypotonic solution swell and burst due to more water flow into than out of the cells –a process called hemolysis.
In a hypotonic solution, water moves into plant cells, causing them to become turgid and maintain their rigidity, something that's absolutely essential for the health and growth of the plant.
The words hypotonic, hypertonic, and isotonic are most often used when comparing chemical solutions while discussing osmosis. A hypertonic solution has a higher concentration of solute than another solution, meaning water will flow into it.
A hypotonic solution has a lower solute concentration than the cell’s interior. Since the water outside is relatively “more dilute,” it flows into the cell to try to balance things out.
The term hypotonic has two parts: hypo means “less/under/beneath,” and tonic means “stretching or concentration of a solution.” A solution with a lower solute concentration or lower osmotic pressure across a semipermeable membrane is called a hypotonic solution.
If a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, and the cell will gain volume. If the solute concentration outside the cell is lower than inside the cell, and the solutes cannot cross the membrane, then that solution is hypotonic to the cell.
Hypotonicity refers to a state or condition characterized by having a lower degree of tone or tension. It is often used at the cellular level and at the tissue level. In particular, we say a solution surrounding a cell is hypotonic when it has a lower solute concentration.