9.3 Fermentation

Understand Key Concepts

23. Because fermentation takes place in the absence of oxygen, it is said to be

    1. aerobic.

    2. anaerobic.

    3. cyclic.

    4. oxygen-rich.

24. The process carried out by yeast that causes bread dough to rise is

    1. alcoholic fermentation.

    2. lactic acid fermentation.

    3. cellular respiration.

    4. yeast mitosis.

25. During heavy exercise, the buildup of lactic acid in muscle cells results in

    1. cellular respiration.

    2. oxygen debt.

    3. fermentation.

    4. the Krebs cycle.

26. How are fermentation and cellular respiration similar?

27. Write equations to show how lactic acid fermentation compares with alcoholic fermentation. Which reactant(s) do they have in common?

Think Critically

28. Infer Certain types of bacteria thrive in conditions that lack oxygen. What does that fact indicate about the way they obtain energy?

29. Infer To function properly, heart muscle cells require a steady supply of oxygen. After a heart attack, small amounts of lactic acid are present. What does this evidence suggest about the nature of a heart attack?

30. Predict In certain cases, regular exercise causes an increase in the number of mitochondria in muscle cells. How might that situation improve an individual's ability to perform energy-requiring activities?

31. Formulate Hypotheses Yeast cells can carry out both fermentation and cellular respiration, depending on whether oxygen is present. In which case would you expect yeast cells to grow more rapidly? Explain.

32. Apply Concepts Carbon monoxide (CO) molecules bring the electron transport chain in a mitochondrion to a stop by binding to an electron carrier. Use this information to explain why carbon monoxide gas kills organisms.

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