GCSE Biology Unit 3 : Micro-organisms

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  • Created by: ellie
  • Created on: 11-05-11 19:27


In industry

Making alcohol and bread:

  • A type of fungus called yeast is used, it is a single-celled organismyeast_cell.gif
  • When it respires anaerobically(without oxygen) it produces CO2 and ethanol
  • ie. Yeast + Glucose > Ethanol + CO2


In the production of beer:

  • Barley grains are soaked in water and kept warm(this is called malting)
  • Enzymes are used to break down the starch into a sugary solution
  • The solution is extracted and used as an energy source for the yeast
  • This is then fermented to produce ethanol
  • Hops are added for flavour

Making yoghurt:

  • A type of bacteria is used
  • When it respires anaerobically it produces lactic acid
  • ie. Bacteria + Glucose > Lactic acid


  • Skimmed milk is heated to 80 degrees for 15 seconds(this is called pasteurising) which destroys unwanted microbes in the milk
  • A starter of bacteria…


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