Does diffusion require energy input?

Diffusion does not require energy input because it is a passive transport process. In diffusion, molecules move from an area of higher concentration to an area of lower concentration, seeking to achieve equilibrium. This movement occurs naturally due to the random motion of molecules and utilizes the inherent kinetic energy they possess.

Since diffusion is driven by concentration gradients rather than energy expenditure from the cell, it functions without the need for ATP or other energy sources. In contrast, processes that involve moving substances against their concentration gradient, such as active transport, do require energy. This distinction emphasizes the fundamental nature of diffusion as a thermodynamically favorable process that relies on the natural tendency of particles to spread out in space rather than any directed energy input.