Isotonic means the concentration of the solute is the same as that of the cell. In these solutions no change occurs to the cell. The diagram below shows the effect of isotonic solutions on cells.
A Hypotonic solution is one in which the concentration of the solute in the solution is less than that of the cell. Examples of these include dilute sugar solutions or water. In these solutions the plant cell will absorb water by osmosis to become turgid (stiff), the cytoplasm and vacuole will also increase in volume and the cell wall will stretch. The diagram below shows a plant cell in a hypotonic solution.
A Hypertonic solution is one in which the concentration of the solute in solution is greater than the concentration in the cell. Here the cells have a higher water potential than the solute. The plant cell loses water by osmosis to become flaccid, its vacuole decreases in volume and the plasma membrane shrinks from the cell wall. The diagram below shows this effect:
To perform a lab/experiment involving plant cells immersed in different solutions click here