What term describes the net movement of molecules from a region of high concentration to one of low concentration?

The term that describes the net movement of molecules from a region of high concentration to one of low concentration is diffusion. This process occurs naturally as molecules move to establish a balance in concentration throughout a given space. In diffusion, molecules tend to spread out evenly in a medium, whether it be a gas, liquid, or solid, until they reach equilibrium where their concentration is uniform across the space.

Osmosis is a specific type of diffusion that involves the movement of water molecules through a selectively permeable membrane. Active transport involves the movement of molecules against their concentration gradient, which requires energy, unlike diffusion, which is a passive process. Equilibrium refers to the state where the concentrations of molecules are equal throughout a space, rather than the process of movement itself. Thus, diffusion fundamentally captures the essence of molecules moving down their concentration gradient.