Diffusion in cells refers to the movement of particles from regions of high concentration to regions of low concentration.

This process is fundamental to all living organisms and is classified as a type of passive transport, meaning it occurs without the expenditure of energy. Instead, diffusion relies on the inherent movement of particles, which naturally migrate from areas where they are densely packed to areas where they are less so. A common analogy is the way a drop of food coloring disperses in a glass of water, gradually spreading until it achieves an even distribution.

In cellular contexts, diffusion plays a critical role in the transport of various substances across the cell membrane, which acts as a semi-permeable barrier. This membrane permits certain substances to enter or exit the cell while restricting others. For instance, essential molecules such as oxygen and nutrients can diffuse into the cell from the surrounding environment, while waste products are expelled in a similar manner.

Several factors can affect the rate of diffusion. Key influences include the concentration gradient (the difference in concentration between two regions), temperature (as higher temperatures increase particle movement), and the size of the particles (with smaller particles generally diffusing at faster rates).

In summary, diffusion is an essential process that enables cells to acquire the necessary substances for survival and functionality. It is a passive mechanism driven by the natural tendency of particles to move from areas of high concentration to areas of low concentration.