Quizlet Movement of substance

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  1. active transport: movement of solutes against a gradient and requires expenditure of energy (ATP usually); transport proteins in plasma membrane transfer solutes such as small ions, amino acids, and monosaccharides across membranes
  2. bulk flow: collective movement of substances in the same direction in response to a force or pressure. blood moving through a blood vessel is this
  3. countercurrent exchange: diffusion of substances b/w two regions in which substances are moving by bulk flow in opposite directions; water flow through fish gills/diffusion of oxygen from water to blood
  4. dialysis: diffusion of solutes across a selectively permeable membrane
  5. endocytosis: capture of a substance outside cell when plasma membrane merges to engulf it; substance enters cytoplasm enclosed in vesicle
  6. exocytosis: process of vesicles fusing with plasma membrane/ releasing contenets to outside of cell
  7. facilitated diffusion: diffusion of water/solutes through channel proteins in plasma membrane.
  8. hypertonic: solute with higher concentration of solutes
  9. hypotonic: solute with lower concentration of solutes
  10. isotonic: solute with equal concentration of solutes
  11. ligands: specific molecules in the fluid surrounding the cell
  12. osmosis: diffusion of water molecules across a selectively permeable membrane. when water moves into body by this process, hydrostatic pressure (osmotic) may build up inside body
  13. passive transport: describes movement of substances from regions of higher to lower concentrations/don't require expenditure of energy
  14. phagocytosis: occurs when undissolved material enters cell. plasma membrane wraps around solid material and engulfs it, forming phagocytic vesicle
  15. Pinocytosis: occurs when dissolved substances enter cells; plasma membrane folds inward to form channel allowing liquid to enter. plasma membrane closes off channel, encircling liquid inside vesicle
  16. plasmolysis: movement of water out of a cell that results in collapse of cell
  17. receptor mediated endocytosis: form of pinocytosis that occurs when specific molecules in fluid surrounding cell bind to receptors that concentrate in coated pits in plasma membrane; the pits, receptors, and molecules (ligands) fold inward and formation of vesicle follows
  18. selectively permeable membrane: such as plasma membrane; allows only specific substances to pass
  19. simple diffusion (diffusion): net movement of substances from area of high concentration to one of lower; occurs as result of random/constant motion characteristics of all molecules, motion that is independent from the motion of all molecules; state of equilibrium is reached where molecules are uniformly distributed but continue to move randomly
  20. vesicular transport: uses vesicles/other bodies in cytoplasm to move macromolecules/large particles across membrane