Biology - B2.4 - Energy From Respiration

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B2.4.1 - Aerobic Respiration

  • Aerobic respiration - takes places continually in plants and animals - process uses glucose and oxygen to release energy - CO2 and H2O are waste products - most aerobic respiration chemical reactions happen in mitochondria and are controlled by enzymes
  • Glucose + Oxygen -> Carbon Dioxide + Water (+ Energy)
  • Energy released may be used to:
    • build larger molecules from smaller ones
    • enable muscle contraction
    • maintain constant body temperatures
    • build sugars, nitrates and other nutrients to amino acids then proteins
  • Aerobic respiration experiments usually measure CO2 produced - limewater - faster turns cloudy = more CO2 - temperature rises when respiration happend
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B2.4.2 - The Effect of Exercise on the Body

  • Muscles need more energy to contract when exercising - need to increase rate oxygen and glucose reach muscle cells to respire and remove extra waste CO2 produced faster
  • Heart rate increases and blood vessels supplying muscles dilate - allows more blood containing oxygen and glucose to reach muscles
  • Breathing rate and breath depth increase - greater uptake of oxygen and release of CO2 at the lungs
  • Muscles stored glucose as glycogen - can be converted back to glucose when exercising
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B2.4.3 - Anaerobic Respiration

  • Use muscles for a long time - fatigued - won't contract efficiently
  • Can't get enough oxygen for aerobic respiration - respire anaerobically
  • Anaerobic respiration - glucose isn't broken down completely - lactic acid, less energy released, build up of lactic acid = muscle fatigue, blood flowing through muscles removes lactic acid
  • Anaerobic respiration - inefficient - incomplete breakdown of glucose - instead of CO2 and H2O, lactic acid is a waste product
  • Lactic acid = muscle fatigue, after exercise lactic acid must be broken down - need oxygen for this - extra oxygen called oxygen debt - oxidises lactic acid to CO2 and H2O
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