Diffusion
Particles - A collection of two or more atoms held together by chemical bonds. and Electrically charged particle, formed when an atom or molecule gains or loses electrons. - in a liquid and a gas move continuously. Because of this movement, particles will spread themselves evenly throughout a liquid or a gas.
If there is a situation where particles of a substance are in a higher concentration, they will therefore move from this region to where they are in a lower concentration. This is called The movement of molecules from an area of higher concentration to an area of lower concentration..
It is important to remember that the particles:
- will move in both directions, but there will be a The overall effect of something when all additions and deductions are calculated. movement from high to low concentration
- will end up evenly spread throughout the liquid or gas, but will continue to move
Importance to life
Diffusion is crucial in both single-celled and multi-celled organisms. In both single-celled organisms like prokaryotic bacteria and eukaryotic algae, oxygen and carbon dioxide molecules move by diffusion through cell membranes. Larger multi-cellular organisms such as vertebrates have specially adapted exchange surfaces, like lungs or gills. In these organisms, diffusion is still vital because it is this process that allows carbon dioxide and oxygen to move between the exchange surfaces.
Examples of diffusion in biological systems
Some substances move into and out of living cells by diffusion.
