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PASSIVE TRANSPORT. Movement of molecules across a membrane that requires no energy and always occurs down a concentration gradient Types of passive transport include: Diffusion Osmosis Facilitated diffusion. DIFFUSION.
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PASSIVE TRANSPORT • Movement of molecules across a membrane that requires no energy and always occurs down a concentration gradient • Types of passive transport include: • Diffusion • Osmosis • Facilitated diffusion
DIFFUSION • The movement of molecules from an area where they are in high concentration to an area where the molecules are in low concentration.
Rate of diffusion depends on: • Temperature • The higher the temperature the faster the diffusion will take place. • Size of the molecules • The smaller the molecules diffusing, the faster the molecules will diffuse
Concentration Gradient • The difference between the concentration of a particular molecule in one area and the concentration in an adjacent area. • Molecules move with or down the concentration gradient when moving from high to low concentration.
OSMOSIS • Diffusion of WATERacross a selectively permeable membrane, water moves down the concentration gradient. • Selectively permeable (semi-permeable)-some substances can move through the membrane and some cannot. • Solute-the dissolved substance in a solution (example: salt in water, the salt would be the solute) • Solvent-the dissolving substance in a solution (ex. salt water, the water would be the solvent)
Hypertonic solution • Solution with a higher concentration of solutes in comparison to the cell
Hypotonic solution • solution with a lower concentration of solutes in comparison to the cell
Isotonic solution • A solution with the same concentration of solutes the cell. • The concentration of solutes outside the cell is equal to the concentration of solutes inside the cell. • Water still moves into and out of the cell but at equal rates.