Simple diffusion may occur through the lipid bilayer Simple diffusion may occur through aqueous channels formed within integral proteins.
Osmosis is the diffusion of water.
A solution with high solute concentration is hypertonic or hyperosmotic. A solution with lower solute concentration is hypotonic or hypoosmotic. Hypotonic solutions cause cells to swell, hypertonic solutions cause cells to shrink. When internal cellular solute concentration is equal to the external solute concentration, the internal and external fluids are isotonic or isosmotic. Plant cells are generally hypertonic compared to their fluid environment.