Aerobic & Anaerobic Respiration

• Aerobic respiration needs plenty of oxygen
• Aerobic respiration is respiration using oxygen. It's the most efficient way to transfer energy from glucose
• Aerobic respiration goes on all the time in plants and animals
• Most of the reactions in aerobic respiration happen inside mitochondria
• Aerobic respiration:

  Glucose + oxygen -> carbon dioxide + water

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• Anaerobic respiration is used if there's not enough oxygen
• When you do vigorous exercise and your body can't supply enough oxygen to your muscles, they start doing anaerobic respiration as well as aerobic respiration
• Anaerobic means without oxygen. It's the incomplete breakdown of glucose, making lactic acid
• Anaerobic respiration in muscle cells:

  Glucose -> lactic acid
• Anaerobic respiration does not transfer nearly as much energy as aerobic respiration. This is because glucose isn't fully oxidised (because it doesn't combine with oxygen)
• Anaerobic respiration is only useful in emergencies, e.g. during exercise when it allows you to keep on using your muscles for a while longer
• Anaerobic respiration in plants and yeast is slightly different
• Plants and yeast cells can respire without oxygen too, but they produce ethanol and carbon dioxide instead of lactic acid
• Anaerobic respiration in plants and yeast cells:

  Glucose -> ethanol + carbon dioxide
• Anaerobic respiration in yeast cells is called fermentation
• In the food and drinks industry, fermentation by yeast is of great value, because it's used to make bread and alcoholic drinks, e.g. beer and wine
• In bread-making, it's the carbon dioxide from fermentation that makes bread rise
• In beer and wine making, it's the fermentation process that produces alcohol
• Yeast are single-celled organisms