Anaerobic Respiration and Fermentation

Concept: Anaerobic Respiration


Concept: Fermentation


Concept: Metabolic Pathways


Anaerobic Respiration and Fermentation Additional Practice Problems

Yeast can grow both aerobically and anaerobically on glucose. Explain why the rate of glucose consumption decreases when yeast cells that have been maintained under anaerobic conditions are exposed to oxygen.

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Lactic acid can only be produced in the presence of O2.

A. True

B. False

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One function of both alcohol fermentation and lactic acid fermentation is to

A. reduce NAD+ to NADH

B. reduce FAD+ to FADH2

C. oxidize NADH to NAD+

D. reduce FADH2 to FAD+

E. do none of the above

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Fermentation of sugars by yeast results in the formation of which of the following molecule(s)?

A. Oxygen

B. Lactic Acid

C. Glucose


E. Acetyl CoA


G. Ethanol

H. Carbon dioxide

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Suppose you discovered a mutant yeast whose glycolytic pathway was shorter because of the presence of a new enzyme catalyzing the following reaction:

Glyceraldehyde 3-phosphate + H2O + NAD+ → NADH + H+ + 3-phosphoglycerate

Which of the following changes would you expect to find in the growth and metabolism of the mutant yeast?

A. The mutation will cause the yeast to grow faster under aerobic conditions.

B. The formation of pyruvate from glucose will be energetically more favorable.

C. The formation of pyruvate from glucose will be energetically less favorable.

D. The mutation will cause the yeast to grow faster under anaerobic conditions.

E. The mutant will not grow under anaerobic conditions.

F. The mutant will not grow under aerobic conditions.

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At first glance, fermentation of pyruvate to lactate might appear to be an optional add-on reaction to glycolysis. After all, couldn't cells growing in the absence of oxygen simply disregard pyruvate as a waste product? In the absence of fermentation, which products deried from glycolysis would accumulate in cells under anaerobic conditions? Could the metabolism of glucose via the glycolytic pathway continue in the absence of oxygen in cells that cannot carry out fermentation? Why or why not?

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Fermentation of a glucose molecule has the potential to produce a net number of _____ ATPs.

A. 0

B. 2

C. 4

D. 40

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NAD+ is the _____ form of NADH while NADH is the _____ form of NAD+.

A. product; substrate

B. oxidized; reduced

C. substrate; product

D. cation; anion

E. reduced; oxidized

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Give the function of each of the following: (a) coenzyme (b) allosteric site.

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What is the difference between the terms; anaerobic bs aerobic.

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Fermentation, an anaerobic respiration, is characterized by the following electron acceptor(s):

A. organic compounds

B. oxygen



E. More than one of the above are correct

F. None of the above are correct

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During what conditions do organisms switch from aerobic respiration to fermentation?

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Which of the products below are potential fermentation products?

A. Ethanol

B. Lactate or lactic acid

C. Hydrogen

D. A and B

E. A, B, and C

F. none of the above

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In fermentation of sugars by yeast, what are the reactants and what are the products?

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Which of the following statements is TRUE regarding fermentation?

A. It can be used as an alternative to photosynthesis.

B. It results in the partial oxidation of C6H12O6.

C. It can only be done by prokaryotes.

D. It requires oxygen.

E. It releases more energy from C6H12O6 than cellular respiration.

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Yeasts and many bacteria are facultative anaerobes that is, they make ATP by fermentation in the absence of oxygen, but if oxsygen is present, they can undergo aerobic respiration. Why would it be advantageous for them to be able to make ATP by aerobic respiration? Hint: Compare the amount of ATP produced in each process.

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the net products of anaerobic respiration are

A. 2 ATP, NAD+, either lactic acid or ethanol and CO2.

B. 2 ATP, NADH, either lactic acid or ethanol and CO2.

C. 2 ATP, NADH, ethanol and CO2.

D. 4 ATP, NAD+, either lactic acid or ethanol and CO2.

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What is the role of fermentation in yeast? Under what environmental conditions will fermentation occur? What product is produced and secreted by the yeast as a result?

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Describe the major differences between fermentation, aerobic respiration, anaerobic respiration? Which has the potential to yield the most energy?

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What do aerobic cellular respiration and fermentation have in common? 

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What purpose does calcium sulfate serve in the Winogradsky column?

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What is the key metabolic difference between anaerobic respiration and fermentation?

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What is the difference between a strict anacrobe and a facultative anaerobe?

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1. Where in the cell does each reaction take place?

Fermentation -

2. Name the Reactant and Products for each reaction

- Glycolysis



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Compare and contrast anaerobic respiration and fermentation. How are they similar and how do they differ?

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Fermentation can be described as a process

a. that takes place only in the absence of oxygen

b. in which water is not one of the by-products

c. in which the Krebs cycle and electron transfer through ETC do not occur

d. all of the above are true

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What cellular evolutionary event is most likely responsible for a switch from Fermentation to the Citric Acid Cycle and Oxidative Phosphorylation?

a. The evolution of the endoplasmic reticulum

b. The development of the nuclear envelope and a true membrane bound nucleus

c. The introduction of a mitochondrion into an animal cell

d. The development of a flagellum

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No O2 was necessary for the citric acid cycle.

During oxygen debt, why would muscle cells choose lactic acid fermentation (which produces no ATP) over sending the pyruvate molecules to the citric acid cycle (2 more ATP molecules)?

a. Muscle cells do not have mitochondria

b. The ATP produced in the citric acid cycle cannot be used for cellular work

c. The production of CO2 in the citric acid cycle is detrimental to the cell

d. The citric acid cycle does not provide a mechanism for oxidizing NADH back to NAD+

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Why do our muscle cells perform fermentation to produce lactic acid during strenuous exercise when more ATP can be generated by cellular respiration?

a. Fermentation is a quicker process

b. Muscle cells don’t need energy, they just want to get rid of excess glucose

c. Lactic acid has a positive effect on muscle cell function

d. There is not enough O2 in the cells to perform cellular respiration

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