What is the movement of a substance from an area of high concentration to an area of low concentration called?

The movement of a substance from an area of high concentration to an area of low concentration is called diffusion. This process occurs naturally as molecules move randomly and spread out to equalize their concentration across a space. Diffusion is a fundamental concept in various biological and physical systems, where it plays a crucial role in processes such as gas exchange in the lungs, nutrient absorption in cells, and the movement of molecules across cell membranes.

Osmosis specifically refers to the diffusion of water across a selectively permeable membrane, which is a more specialized form of diffusion. Active transport, on the other hand, involves the movement of substances against their concentration gradient, requiring energy input, typically in the form of ATP. Facilitated diffusion is a type of passive transport that also occurs down a concentration gradient but relies on specific transport proteins to facilitate the movement of larger or polar molecules. In contrast, basic diffusion does not depend on such proteins and applies to a wider range of substances.