Osmosis Osmosis is the net movement of water molecules over a partially permeable membrane from an area of less osmotic potential to an area of more negative osmotic potential.

Water potential Water potential is a measure of water molecule potential for movement in a solution. Water always moves by osmosis from less negative to more negative water potential. The highest possible water potential is that of pure water which is 0, all other solutions have a negative water potential. Water potential is measured in Pa.

Hypertonic Solutions Hypertonic solutions contain a high concentration of solute relative to another solution for example the cells cytoplasm. Water diffuses out of a cell when it is placed in isotonic solution which causes the cell to shrivel.

Hypotonic Solutions Hypotonic Solutions have a high concentration of solute relative to a different solution i.e. the cells cytoplasm. Water diffuses into the cell when it is placed in a hypotonic solution, this means the cell swells and possibly explode.

Isotonic solutions Isotonic solution has the same concentration as another solution for example the cells cytoplasm. Water diffuses in and out of the cell at the same rate when placed in an isotonic solution. The fluid surrounding body cells is isotonic.