Transport is necessary for the movement of substances within, into and out of cells so as to enable vital life processes to occur. Transport can be carried out through diffusion, osmosis or mass flow. Diffusion is the movement of particles from a region of high concentration to a region of low concentration.
Transport of materials is necessary in living organisms as every cell needs a regular supply of nutrients and oxygen for releasing energy through respiration. The food that we eat is broken down into smaller components to be absorbed by the cells.

There are two ways through which substances can move across the membrane. 
Materials in living organisms move by diffusion, osmosis and mass flow.