GCSE B2 Chapter 4

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  • Created by: emma998
  • Created on: 19-03-14 17:18

Aerobic respiration

  • Aerobic respiration takes place continually in plants and animals
  • Chemical reactions for respiration take place in mitochondria of cells and are controlled by enzymes
  • Glucose + oxygen = carbon dioxide + water [+energy]
  • The energy released from aerobic respiration can be ued to:
    • Build larger molecules from smaller ones
    • Maintain a constant body temperature in mammals and birds
    • Build sugars, nitrates and other nutrients into amino acids and then proteins in plants
    • Enable muscle contraction in animals
  • Investigations in aerobic respiration:
    • Temperature increase - Live peas in a thermos flask with thermometer and as control dead peas in thermos flask with thermometer. The live soaked peas will cause an increase in temperature
    • Carbon dioxide production - Attach limewater in a test tube to plant in test tube using a bung. Limewater turns cloudy in presence of CO2
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The effect of exercise on the body

  • When exercising the body needs more energy so that muscles can contract
  • Body needs increased oxygen and glucose
  • Body needs to get rid of CO2 quicker
  • Breathing rate and depth of breath increase - to increase oxygen uptake and increase removal of CO2
  • Heart rate increases and blood vessels dilate - to allow more blood containing oxygen and glucose to reach the muscles quicker
  • Muscles store glucose as glycogen
  • During exercise the glycogen can be converted back into glucose
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Anaerobic respiration

  • If, during exercise, the muscles cannot get enough oxygen to continue respiring aerobically they can respire anaerobically (without oxygen)
  • Glucose = lactic acid
  • It is not as efficient:
    • Glucose not completely broken down so not as much energy released
    • Lactic acid produced which causes muscle fatigue
    • Causes oxygen debt
  • After anaerobic respiration the lactic acid produced must be broken down which requires extra oxygen
  • The extra oxygen needed to break down the lactic acid is called oxygen debt
  • Blood flowing through muscles removes lactic acid
  • Eventually the lactic acid is oxidised to produce carbon dioxide and water
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