Osmosis is a process by which by which solvent move from a region of lower solute concentration to region of higher solute concentration through a semi-permeable membrane. Cells utilize the process osmosis and osmotic pressure to transport substance in and out of the cell cytoplasm. Solution is made up of solute and solvent - concentration of a solution is the measure of the amount of solute that has been dissolved in a given quantity of solvent or solution. Spectrophotometer can be used to measure the optical density of the solution which relates to the change in concentration of the solution. As the concentration in any biological system will change the cells shape, size and number will change in that micro-environment.