This page is brought to by:  "Principles of Diffusion and
Osmosis" is an .interactive tutorial written and designed by Ian
Emerson, Associate Professor, Department of Biology; graphics
and text programmed by Dean William Barnes   Diffusion and
osmosis are examples of passive transport whereby ions or
molecules driven by thermal motion move down concentration
gradients set up between solutions separated by biological
membranes in living systems.  Diffusion occurs in solutions
consisting of particles  Air and drinking water are both
examples of solutions consisting of mixtures of different types
of particles. In air these particles are mainly molecules of
nitrogen, oxygen, and carbon dioxide; whereas, drinking water
consists of molecules of water and some dissolved ions  Click on
Fish for an interactive question  Diffusion results from the
movement of particles in liquids and gases.  Regardless of their
type, particles in liquids and gases are in constant motion
driven by energy which they absorb from the heat