Concepts of Biology, 2013

116 Chapter 4 | How Cells Obtain Energy
a. lactic acid fermentation
b. alcohol fermentation
c. mixed acid fermentation
d. propionic fermentation
12. The cholesterol synthesized by cells uses which
component of the glycolytic pathway as a starting point?
a. glucose
b. acetyl CoA
c. pyruvate
d. carbon dioxide
13. Beta oxidation is ________.
a. the breakdown of sugars
b. the assembly of sugars
c. the breakdown of fatty acids
d. the removal of amino groups from amino acids
CRITICAL THINKING QUESTIONS
14. Does physical exercise to increase muscle mass
involve anabolic and/or catabolic processes? Give
evidence for your answer.
15. Explain in your own terms the difference between a
spontaneous reaction and one that occurs instantaneously,
and what causes this difference.
16. With regard to enzymes, why are vitamins and
minerals necessary for good health? Give examples.
17. Both prokaryotic and eukaryotic organisms carry out
some form of glycolysis. How does that fact support or not
support the assertion that glycolysis is one of the oldest
metabolic pathways?
18. We inhale oxygen when we breathe and exhale carbon
dioxide. What is the oxygen used for and where does the
carbon dioxide come from?
19. When muscle cells run out of oxygen, what happens to
the potential for energy extraction from sugars and what
pathways do the cell use?
20. Would you describe metabolic pathways as inherently
wasteful or inherently economical, and why?
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