Oxygen debt and the liver – Higher only

• What is the primary purpose of respiration in organisms?

  To release energy to fuel their living processes
• What are the two types of respiration mentioned?

  Aerobic and anaerobic respiration
• What does aerobic respiration use to produce energy?

  Glucose and oxygen
• What does anaerobic respiration use to produce energy?

  Only glucose
• What happens to lactic acid after exercise?

  • Lactic acid is taken to the liver by the blood
  • It can be oxidised to carbon dioxide and water
  • It can be converted to glucose, then glycogen
  • Glycogen levels in the liver and muscles can be restored
• Why is oxygen required after exercise?

  To remove lactic acid and replace the body's reserves of oxygen
• What is the term for the amount of oxygen required to remove lactic acid after exercise?

  Oxygen debt
• How long can it take to pay back an oxygen debt after normal exercise?

  A few hours
• How long can it take to pay back an oxygen debt after a marathon?

  Several days
• What are the processes involved in the removal of lactic acid from the body?

  1. Lactic acid is transported to the liver
  2. It is either oxidised to carbon dioxide and water
  3. Or converted to glucose, then glycogen
  4. Glycogen levels are restored in the liver and muscles