Diffusion is the random movement of molecules from an area of higher concentration of those molecules to an area of lower concentration. Diffusion also aids in the transport of nutrients and water in the xylem and phloem of plants. In those plants, it permits for the absorption of water into roots. An example of this process is the diffusion of a smell in a room. Eventually dynamic equilibrium will be reached. This means that the concentration of the molecules carrying the smell will be approximately equal through out the surrounding enclosed area and no net movement of the molecules will occur from one area to another.

Water potential is the measure of free energy of water in a solution. Water will always move from an area of higher water potential to an area of lower water potential. An important factor effecting of diffusion and osmosis is water potential. Water potential measures the tendency of water to leave one place in favor of another place. Water potential is affected by two physical factors. One factor is the addition of solute, which lowers the water potential. The other factor is pressure potential. An increase in pressure raised the waterpotential. The water potential of pure water at atmospheric pressure is defined as being zero. The Greek letter psi is used to represent water potential.

Osmosis and diffusion will continue until dynamic equilibrium is reached and net movement will no longer occur. Diffusion is effected by the solute size and concen-tration gradient across a selectively permeable membrane. Water potential greatly determines the results in sections of the experiment.

• potato corer (about 3 cm long)
• 250 ml beaker
• paper towels
• scale
  
• six cups
• knife
• paper
• pencil 
• 100 ml of distilled water
• 100 ml of 0.2 M glucose

• 100 ml of 0.4 M glucose

• 100 ml of 0.6 M glucose

• 100 ml of 0.8 glucose

• 100 ml of 1.0 M glucose.