74 Critical Thinking Questions

15. Compare how you feel when you are in a crowded room with when you are on a walk in the woods. What might account for the differences? Relate the differences you identify to the process of cellular respiration.

16. Why is it beneficial for cells to use ATP rather than energy directly from the bonds of carbohydrates? What are the greatest drawbacks to harnessing energy directly from the bonds of several different compounds?

17. Nearly all organisms on Earth carry out some form of glycolysis. How does this fact support or not support the assertion that glycolysis is one of the oldest metabolic pathways?

18. Compare the numbers of ATP molecules produced per glucose molecule by glycolysis and by the mitochondria. Propose an explanation for how early eukaryotic cells benefitted from the acquisition of mitochondria through endosymbiosis.

19. Because they lose their mitochondria during development, red blood cells cannot perform aerobic respiration; however, they do perform glycolysis in the cytoplasm. Why do all cells need an energy source, and what would happen if glycolysis were blocked in a red blood cell?

20. What is the primary difference between a circular pathway and a linear pathway?

21. How do the roles of ubiquinone and cytochrome c differ from the roles of the other components of the electron transport chain?

22. What accounts for the different number of ATP molecules that are formed through cellular respiration?

23. What is the primary difference between fermentation and anaerobic respiration?

24. Would you describe metabolic pathways as inherently wasteful or inherently economical? Why?