AP BIOLOGY

Detailed explanation-1: -Since diffusion moves materials from an area of higher concentration to the lower, it is described as moving solutes “down the concentration gradient". The end result is an equal concentration, or equilibrium, of molecules on both sides of the membrane. At equilibrium, movement of molecules does not stop.

Detailed explanation-2: -Diffusion and osmosis are both passive transport processes that act to equalize the concentration of a solution. In diffusion, particles move from an area of higher concentration to one of lower concentration until equilibrium is reached.

Detailed explanation-3: -Answer and Explanation: The process by which particles or substances move from an area of low concentration to an area of high concentration is called active transport. This energy input is necessary in order to move these molecules against the concentration gradient.