Ask a Teacher

Search



what is diffusion

Diffusion is the tendency of molecules to spread into an available space. Without other outside forces at work, substances will diffuse from a more concentrated environment to a less concentrated environment.

Passive transport is the diffusion of substances across a membrane. This is a spontaneous process and cellular energy is not expended. Molecules will move from where the substance is more concentrated to where it is less concentrated. The rate of diffusion for different substances is affected by membrane permeability. For instance, water diffuses freely across the cell membrane but other molecules cannot. They must be helped across the cell membrane through a process called facilitated diffusion


comments powered by Disqus