Final answer:
Osmosis is the movement of water across membranes from an area of high concentration to an area of low concentration. The tendency of solute solutions to reach equilibrium powers the movement of molecules across membranes.
Step-by-step explanation:
Osmosis, a special case of diffusion, is the movement of water across membranes from an area of high concentration to an area of low concentration. The tendency of solute solutions to reach equilibrium powers the movement of molecules across membranes because the molecules move from an area of high concentration to an area of lower concentration until an equilibrium is met. This movement of molecules continues at equal rates in both directions, resulting in a dynamic equilibrium.