Respiration – aerobic respiration, Krebs cycle & ETC

  • explain the relative energy values of carbohydrate, lipid and protein as respiratory substrates and explain why lipids are particularly energy-rich
  • explain that ATP is synthesised in substrate-linked reactions in glycolysis and in the Krebs cycle
  • explain that, when oxygen is available, pyruvate is converted into acetyl (2C) coenzyme A in the link reaction
  • outline the Krebs cycle, explaining that oxaloacetate (a 4C compound) acts as an acceptor of the 2C fragment from acetyl coenzyme A to form citrate (a 6C compound), which is reconverted to oxaloacetate in a series of small steps
  • explain that reactions in the Krebs cycle involve decarboxylation and dehydrogenation and the reduction of NAD and FAD
  • outline the process of oxidative phosphorylation including the role of oxygen as the final electron acceptor (no details of the carriers are required)
  • explain that during oxidative phosphorylation:
    • energetic electrons release energy as they pass through the electron transport system
    • the released energy is used to transfer protons across the inner mitochondrial membrane
    • protons return to the mitochondrial matrix by facilitated diffusion through ATP synthase providing energy for ATP synthesis (details of ATP synthase are not required)
  • outline the roles of the coenzymes NAD, FAD and coenzyme A in respiration
  • explain that the synthesis of ATP is associated with the electron transport chain on the membranes of mitochondria and chloroplasts
  • define the term respiratory quotient (RQ) and determine RQs from equations for respiration
  • describe investigations, using simple respirometers, to determine the RQ of germinating seeds or small invertebrates (e.g. blowfly larvae)
  • describe investigations which could be performed, using simple respirometers, to
  • describe the relationship between structure and function of the mitochondrion using diagrams and electron micrographs