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Osmosis is defined as the diffusion of water across a selectively permeable membrane depending on the concentration of solutes on the different sides of the membrane. If the water potential is high, then the solute concentration is low. If the water potential is low, then the solute concentration is high. In a hypotonic solution, there is more water than solute therefore it swells. In a hypertonic solution, there is more solutes than water so the cell shrinks. In an isotonic solution, the amount of solutes and water is even.
Diffusion is defined as the random movement of particles from an area of high concentration to an area of low concentration, resulting in an even distribution. There are three main types- facilitated, passive, and active.
1. Facilitated diffusion or transport is the transport of particles across a biological membrane through integral proteins embedded in the plasma membrane.
2. Passive diffusion or transport is defined as the movement of molecules across a plasma membrane without the use of energy (ATP).
3. Active diffusion of transport is defined as the movement of molecules across a plasma membrane with the use of energy (ATP).
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