movement of substances

• what is diffusion: the net movement of particles from a region of higher concentration to a region of lower concentration
• what is osmosis: net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane
• what is active transport: process in which energy is used to move the particles of a substance across a membrane, against a concentration gradient, from a region of lower concentration. only occurs in living cells for respiration