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GCSE Biology Booster Video -Diffusion

A quick, visual, look at the process of diffusion.

· GCSE Science Notes


CELLS are the building blocks of life. They are little factories performing all the vital chemical reactions and processes that your body needs to maintain life. Many substances have to enter and leave cells for all these processes to take place. There are a few ways they can do this. Some substances enter and leave cells by a process called DIFFUSION.

The video shows a visual explanation of 

diffusion. Diffusion  is the movement of particles from an area of high concentration to an area of low concentration so that they evenly spread out.


Red blood cells carry oxygen around the body. They pick the oxygen up from the alveoli (air sacs) of the lungs. 

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Because you have just breathed in (inhaled) the concentration of the oxygen in the alveoli is high. The red blood cells have just returned from the body having released all their oxygen to the body’s cells, so they have a low oxygen concentration. The oxygen diffuses from the alveoli into the red blood cells. Now saturated with oxygen the red blood cells commence their oxygen distribution journey around the body.


Different factors can affect the rate of diffusion. These are:

  • The difference in concentrations (concentration gradient)
  • The temperature 
  • The surface area of the membrane


Amazing Factoid:

Human lungs contain almost 1500 miles of airways and over 300 million alveoli.

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