20. How many equivalents of ATP are produced from a mole of glucose in the entire respiratory process, from glycolysis through the reaction with 0₂?

21. What purpose does the respiratory chain play in energy extraction? Why is it called a "chain"? What are flavoproteins, quinones, and cytochromes, and what part do they play in the respiratory chain? Where, and how often, is ATP synthesized as electrons flow down the chain? Where do the electrons eventually go? What happens to the NAD⁺ and FAD that are produced by the chain?

22. Where are the enzymes of the citric acid cycle and the components of the respiratory chain located in a eucaryotic cell?

23. What is gluconeogenesis? How is it related to glycolysis? Why is it useful to have the biochemical capabilities conferred by gluconeogenesis? Why is it likely that gluconeogenesis and glycolysis are evolutionarily related?

24. What are the light and dark reactions of photosynthesis? In what sense is the "photo-" term inapplicable to the dark reactions, and ”-synthesis" inapplicable to the light reactions?

25. Which set of reactions, light or dark, is evolutionarily related to gluconeogenesis? Which is believed to be older?

26. How has the straight chain of successive reactions found in gluconeogenesis and glycolysis been turned into a cyclic process in the Calvin cycle? What does the Calvin cycle accomplish?

27. How do the chemosynthetic bacteria find ways of replacing the light reactions of photosynthesis?

28. What is meant by cyclic and noncyclic photophosphorylation? Which is more characteristic of purple sulfur bacteria? How do purple sulfur bacteria obtain NADH? How do they obtain ATP?

29. How do purple nonsulfur bacteria obtain ATP? Which kind of photophosphorylation do they use? How do they obtain NADH?