What characterizes the process of diffusion?

Diffusion is characterized by the movement of molecules from an area of higher concentration to an area of lower concentration. This process occurs as molecules tend to spread out evenly in a space, and it continues until equilibrium is reached, meaning the concentration is uniform throughout. This net movement is driven by the concentration gradient—molecules naturally move to areas where they are less concentrated, resulting in an overall decrease in concentration difference.

In biological systems, diffusion is a passive process, which means that it does not require an input of energy. It is essential for various cellular processes, such as the exchange of gases in the lungs or the uptake of nutrients by cells. Instead of moving against a gradient (which would require energy), the natural tendency of molecules to move from an area of high concentration to low concentration allows for essential exchanges that sustain life.

The concept is fundamental in understanding how substances like oxygen and carbon dioxide are exchanged in living organisms, contributing to essential metabolic functions.