Osmosis

Osmosis is the diffusion of water across the cell's membrane. Molecules of water move from an area of higher concentration to an area of lower concentration of water.

There are three types of osmotic solutions: hypertonic, isotonic and hypotonic.

A hypertonic solution has more solute than a cell, therefore there is more water inside the cell. Since there is more water inside the cell, water exits or leaves the cell and then the cell shrivels or shrinks.

In an isotonic solution the same concentration of solutes is in both the solution and the cell, therefore the solution and the cell have equal amounts of water and the cell size remains constant or stays the same.

A hypotonic solution has less solute than a cell therefore there is more water in the solution than there is in the cell. This causes the water to move into the cell and the cell expands or swells and could possible burst.