Topic 12: Respiration

• Define the term 'respiration'?

  the chemical reactions in cells that break down nutrient molecules and release energy for metabolism.
• Define aerobic respiration?

  a chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

  
  

  • releases relatively large amount of energy per glucose molecule
• Define anaerobic respiration?

  a chemical reaction in cells that breaks down nutrient molecules to release energy without using oxygen.

  
  

  • release relatively small amount of energy per glucose molecule.
• Why does anaerobic respiration release small amount of energy?

  Due to an incomplete breakdown and the absence of oxygen
• Differences of aerobic and anaerobic?

  Aerobic:

  • uses oxygen
  • no alcohol or lactic acid made
  • large amount of energy released
  • carbon dioxide as product

  Anaerobic:

  • no oxygen
  • alcohol in yeast and lactic acids in animal
  • less energy released
  • carbon as product for yeast and animal
• Anaerobic respiration in yeast : fermentation

  • Flour contains starch and protein called gluten which is then mixed with water and yeast to make dough.
  • Amylase enzymes break down some of the starch to make maltose and glucose which the yeast can use for anaerobic respiration
  • This produces bubbles of carbon dioxide
  • Gluten is stretchy making bubbles of carbon dioxide to cause the dough to rise.
  • Limited supply of oxygen-->anaerobic respiration happens, releases ethanol and carbon dioxide.
• Is it only amylase present in yeast?

  No, not only amylase, maltase also present in yeast to breakdown maltose.
• Oxygen debt removal

  1. Lactic acids produced

  2. Muscles carry out anaerobic respiration

  3. Brain detects increasing levels of lactic acids

  4. Signal is sent to lungs and intercostal muscles to increase rate and depth of breathing

  5. Breathing rate and volume of air increases

  6. More gaseous exchange takes place

  7. More oxygen taken in to pay off debt

  8. Brain sends impulse to the heart muscles to contract faster

  9. Lactic acids in the blood can be transported faster into liver

  10. Lactic acids taken to liver through bloodstream via diffusion process

  11. More oxygen supplied to the body is used to break down the lactic acids into carbon dioxide and water
• What is oxygen debt?

  the lactic acid that is built up during anaerobic respiration needs to be broken down in the liver.

  • blood carries the lactic acid in the liver
  • oxygen is needed to breakdown lactic acids
• What happens when lactic acid is taken to the blood or liver?

  Lactic acid is oxidised to carbon dioxide and water or converted to glucose then glycogen -glycogen levels in the liver and muscles can be restored.
• Heavy breathing after exercise, during recovery- provides extra oxygen to breakdown the lactic acid and paying off the oxygen debt
• glucose-> lactic acid + energy
• lactic acid + oxygen -> carbon dioxide + water