Unformatted text preview: concentration gradient - a change in concentration across distance (in biology, this refers to a change in concentration across the membrane)
membrane, where the
simple diffusion -molecules crossmovement of some type of molecule across a to this type of molecule.movement is powered by the presence of a concentration gradient, and the
simply because the membrane is permeable
facilitated diffusion -molecules crossmovement of some type aidmolecule across a membrane, where the movement is powered by the presence of a concentration gradience, and the
the membrane with the
of a channel protein or a permease.
where the movement
against a concentration gradient so the movement is powered by
active transport -somedirectional movement ofsuppliedtype themolecule across a membrane, the membrane with thegoes of a permease.
usable energy source
cell, and the molecules cross
- the diffusion of solvent molecules (water molecules) towards regions of higher osmotic concentration....
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