| A | B |
|---|
| homeostasis | a stable level of internal conditions |
| carrier protein | a protein that transports specific substances across a cell membrane |
| concentration gradient | the difference in concentration of a substance across a space |
| contractile vacuole | an organelle in unicellular organism that pumps water out |
| cytolysis | the bursting of a cell |
| diffusion | the process by which molecules move from an area of greater concentration to an area of lower concentration |
| equilibrium | a state that exists when the concentration of a substance is the same throughout a space |
| facilitated diffusion | a process in which substnaces move down their concentration gradient across the cell membrane with the help of carrier proteins |
| hypertonic | describing a solution whose solute concentration is higher than the inside of a cell causing water to exit the cell |
| hypotonic | describing a solution whose solute concentration is lower than that inside a cell causing water to move into the cell |
| ion channel | a membrane protein that provides a passageway across the cell membrane through which an ion can diffuse |
| isotonic | describing a solution whose solute concentration equals that inside a cell |
| osmosis | the diffusion of water across a selectively permeable membrane |
| passive transport | the movement of substances across a cell membrane without the use of cell energy |
| plasmolysis | the shrinking or wilting of a cell in a hypertonic solution |
| turgor pressure | water pressure within a plant cell |
| active transport | the movement of a substance across a cell membrane against a concentration gradient; requires the cell to use energy |
| endocytosis | the process by which a cell surrounds and engulfs substances |
| exocytosis | a process in which a vesicle inside a cell fuses with the cell membrane and releases its contents to the external environment |
| phagocyte | a cell that engulfs and destroys whole cells |
| phagocytosis | a type of endocytosis in which a cell engulfs a whole cell or large food particles; "cell eating" |
| pinocytosis | a type of endocytosis in which a cell engulfs fluids; "cell drinking" |
| sodium-potassium pump | a carrier protein that actively transports potassium ions into and sodium ions out of the cell |
| vesicle | a membrane bound sac in a eukaryotic cell that contains materials involved in endocytosis, exocytosis or transport within the cell |
| cell membrane | selectively permeable barrier to the cell; made of a bilayer of phospholipids and proteins |
