What is diffusion?

Diffusion is a natural process, definied as the net movement of particles from an area of high concentration to an area of low concentration.

But what does this mean?

Imagine you're going to see a big concert. You've arrived at the venue and you have your tickets. The doors haven't opened yet so you and thousands of people are tightly packed together into a small area outside. Then, all of a sudden, the doors open. Everyone floods into the arena, moving in random directions to fill this massive empty space. There is the same number of people inside the arena as there was waiting outside, but you are now all further apart. You have moved from an area of high concentration of people, to an area of low concentration of people - this is similar to the process of diffusion.

Try it at home...

You can carry out your own experiments at home to demonstrate diffusion. Pour a glass of water and add a tablespoon of squash (such as Robinsons or Mi Wadi). Initially the juice will stay in one area with a strong colour. Over the next couple of seconds the juice particles will start moving a random direction, from this area of high concentration to areas of low juice concentration throughout the rest of the glass. Eventually the juice will spread throughout the whole glass and its colour will appear a lot paler.

Why is diffusion important?

Many of the processes your body needs to stay alive are based on the principle of diffusion. One of the most important of which is breathing. Whenever you breath in, your body needs the oxygen that is in the air. Diffusion allows the oxygen to move from an area of high concentration (the air) to an area of low concentration (your body) - supplying your body's cells with the oxygen they need to function properly.

Name 3 organelles found in animal cells.

Related Biology GCSE answers

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What is meant by diffusion?