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Definition
passive transport
the movement of substances across a cell membrane without the use of energy by the cell |
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Definition
diffusion
the movement of particles from regions of higher density to regions of lower density |
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Definition
concentration
the amount of a particular substance in a given quantity of a mixture, solution, or ore |
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Definition
equilibrium
in chemistry, the state in which a chemical process and the reverse chemical process occur at the same rate such that the concentrations of reactants and products do not change |
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Definition
osmosis
the diffusion of water or another solvent from a more dilute solution (of a solute) to a more concentrated solution (of the solute) through a membrane that is permeable to the solvent |
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hypotonic
describes a solution whose solute concentration is lower than the solute concentration inside a cell |
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Definition
| Describes a solution whose solute concentration is equal to the solute concentration inside a cell |
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Definition
contractile vacuole
in protozoans, an organelle that accumulates water and then releases it periodically to maintain osmotic pressure |
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Definition
turgor pressure
the pressure that is exerted on the inside of cell walls and that is caused by the movement of water into the cell |
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Definition
plasmolysis
the contraction or shrinking of the cell membrane of a plant cell in a hypertonic solution in response to the loss of water by osmosis |
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facilitated diffusion
the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins |
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Definition
| a protein that transports substances across a cell membrane |
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Definition
ion channel
a pore in a cell membrane through which ions can pass |
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Definition
active transport
the movement of chemical substances, usually across the cell membrane, against a concentration gradient; requires cells to use energy |
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Definition
sodium-potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell |
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Definition
endocytosis
the process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell |
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Definition
vesicle
a small cavity or sac that contains materials in a eukaryotic cell; forms when part of the cell membrane surrounds the materials to be taken into the cell or transported within the cell |
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Definition
pinocytosis
a method of active transport across the cell membrane in which the cell takes in extracellular fluids |
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Definition
phagocytosis
the process by which a cell engulfs large particles or whole cells, either as a defense mechanism or as a means to obtain food |
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Definition
phagocyte
a cell that ingests and destroys (digests) foreign matter or microorganisms |
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Definition
exocytosis
exocytosis
the process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out |
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