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 diffusion | the movement of molecules from an area of higher concentration to an area of lower concentration |
| osmosis | diffusion of water across a membrane |
| active transport | the movement of materials through a cell membrane using energy |
| endocytosis | process by which a cell takes in a substance by surrounding it with the cell membrane |
| exocytosis | a process in which a vesicle inside a cell fuses with the cell membrane and releases its contents to the external environment |
| equilibrium | a state that exists when the concentration of a substance is the same throughout a space |
| heat energy | the reason molecules move |
| concentration | amount of substance in a particular area |