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Diffusion/Osmosis Quiz Study Guide – Cells Unit
Terms to Know
 Cell membrane – controls what goes in and out of each cell; made up of phospholipid
and protein
o Permeable membrane – allows all substances to pass through
o Selectively permeable membrane – allows some substances to pass through
o Impermeable membrane – allows nothing to pass through
 Passive transport – the movement of a substance from high to low concentration
without energy
o Diffusion – the movement of particles from high to low concentration
o Osmosis – the diffusion of water
 Active transport – the movement of particles against the direction of diffusion; requires
energy
o Engulfing – cell membrane surrounds a particle, engulfs it, and a vacuole forms
o Transport protein – ‘picks up’ molecules from outside the cell
 Concentration – the amount of molecules in a specified area
 Concentration gradient – a difference in amount of molecules between two areas
 Equilibrium – concentration of two molecules that is evenly distributed
 Hypertonic – a cell in this type of solution will shrink and shrivel
 Hypotonic – a cell in this type of solution will swell, and possibly explode
 Isotonic – equal amounts of molecules within a solution or across a cell membrane
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Methods of passive transport – diffusion, osmosis
Methods of active transport – transport proteins, engulfing
Speed up diffusion by – heating the mixture, stirring the mixture
Factors that control substances entering/exiting a cell – size of particles, type of
membrane, concentration gradient
Examples of diffusion:
 The smell of cookies baking in your oven
 Food coloring dropped in a beaker of water
 Making a pitcher of lemonade
 Adding chemicals to a pool
 Making chocolate milk
 Aromatherapy (air freshener)