Physioex 9.0 Exercise 1

Diffusion is the movement of molecules from an area of greater concentration to an area of lesser concentration. e.g. Exchange of gases in the lungs or body tissues.

Osmosis is the diffusion of water through a semi-permeable membrane from an area of low solute to an area of high solute concentration.

Faciliated diffusion is the passive transport of molecules down a concentration gradient. It is simply diffusion that involves a protein to make diffusion happen more easily across a cell membrane.

Active transport is the moving of substances across the cell membrane using the cell's energy. Molecules are moved against a concentration gradient, i.e they move from an area of lesser concentration to an area of greater concentration. Tlhis is done by a carrier molecules which gets its energy from ATP.