1. Cellular Respiration and Fermentation

2. Cellular respiration can best be described as
using energy released from breaking high-energy covalent bonds in organic molecules to force ATP formation from ADP and phosphate.
taking electrons from food and giving them to phosphate to make ATP.
taking electrons from food and giving them to oxygen to make water and using the energy released to drive ATP formation.
converting higher-energy organic molecules to lower-energy organic molecules and using the energy released to drive ATP formation.
Answer: C

3. Cellular respiration can best be described as
using energy released from breaking high-energy covalent bonds in organic molecules to force ATP formation from ADP and phosphate.
taking electrons from food and giving them to phosphate to make ATP.
taking electrons from food and giving them to oxygen to make water and using the energy released to drive ATP formation.
converting higher-energy organic molecules to lower-energy organic molecules and using the energy released to drive ATP formation.

4. Which of the following statements about glycolysis is true?
It splits water.
It produces FADH2.
It occurs in the cytoplasm.
It makes the most ATP compared to the two other steps.
It splits lipids.
Answer: C 4

5. Which of the following statements about glycolysis is true?
It splits water.
It produces FADH2.
It occurs in the cytoplasm.
It makes the most ATP compared to the two other steps.
It splits lipids. 5

6. Which of the following statements about the citric acid cycle is true?
It occurs during the movement from the cytosol through the mitochondrial membranes.
It makes ATP through substrate-level phosphorylation.
It makes the most ATP compared to the other steps.
It occurs in the eukaryotic cytoplasm.
It splits glucose.
Answer: B 6

7. Which of the following statements about the citric acid cycle is true?
It occurs during the movement from the cytosol through the mitochondrial membranes.
It makes ATP through substrate-level phosphorylation.
It makes the most ATP compared to the other steps.
It occurs in the eukaryotic cytoplasm.
It splits glucose. 7

8. What do cells require to sustain high rates of glycolysis under anaerobic conditions?
functioning mitochondria
oxygen
oxidative phosphorylation of ATP
NAD
All of the above are correct.
Answer: D 8

9. What do cells require to sustain high rates of glycolysis under anaerobic conditions?
functioning mitochondria
oxygen
oxidative phosphorylation of ATP
NAD
All of the above are correct. 9

10. Drugs known as uncouplers facilitate diffusion of protons across the membrane. Brown fat can generate heat without ATP by using uncouplers. With an uncoupler, what will happen to ATP synthesis and oxygen consumption if the rates of glycolysis and the citric acid cycle stay the same?
Both ATP synthesis and oxygen consumption will decrease.
ATP synthesis will decrease; oxygen consumption will greatly increase.
ATP synthesis will increase; oxygen consumption will decrease.
Both ATP synthesis and oxygen consumption will increase.
ATP synthesis will decrease; oxygen consumption will stay roughly the same.
Answer: E 10

11. Drugs known as uncouplers facilitate diffusion of protons across the membrane. Brown fat can generate heat without ATP by using uncouplers. With an uncoupler, what will happen to ATP synthesis and oxygen consumption if the rates of glycolysis and the citric acid cycle stay the same?
Both ATP synthesis and oxygen consumption will decrease.
ATP synthesis will decrease; oxygen consumption will greatly increase.
ATP synthesis will increase; oxygen consumption will decrease.
Both ATP synthesis and oxygen consumption will increase.
ATP synthesis will decrease; oxygen consumption will stay roughly the same. 11

12. The hydrogens taken from glucose or a breakdown product of glucose are added to oxygen, releasing energy to
actively transport H into the intermembrane space.
actively transport NAD into the intermembrane space.
actively transport Na into the matrix.
power facilitated diffusion of H into the matrix.
actively transport H into the matrix.
Answer: A
Respiration will occur only through alternative substrates such as FADH2 that are oxidized downstream of complex I. 12

13. The hydrogens taken from glucose or a breakdown product of glucose are added to oxygen, releasing energy to
actively transport H into the intermembrane space.
actively transport NAD into the intermembrane space.
actively transport Na into the matrix.
power facilitated diffusion of H into the matrix.
actively transport H into the matrix. 13

14. ATP synthase at the inner mitochondrial membrane makes ATP and water, from ADP and phosphate, by coupling this to which other process?
allowing H to move down its electrochemical gradient
allowing H to move against its electrochemical gradient
facilitated diffusion of H
active transport of H
active transport of Na
Answer: A
Respiration will occur only through alternative substrates such as FADH2 that are oxidized downstream of complex I. 14

15. ATP synthase at the inner mitochondrial membrane makes ATP and water, from ADP and phosphate, by coupling this to which other process?
allowing H to move down its electrochemical gradient
allowing H to move against its electrochemical gradient
facilitated diffusion of H
active transport of H
active transport of Na 15

16. Newborn mammals have a specialized organ called brown fat, where cells burn fat to CO2 without capturing the energy to reduce electron carriers or drive ATP formation. How can this energy be used instead?
to synthesize glucose from CO2
to directly power muscle contraction
to provide energy for endergonic biosynthetic reactions
to generate heat
Answer: D
This question could be used with the question on uncouplers: Thermogenin is a proton channel in the inner membrane that uncouples respiration from ATP synthesis to generate heat. Some bees and some philodendron flowers use similar mechanisms to generate heat. 16

17. Newborn mammals have a specialized organ called brown fat, where cells burn fat to CO2 without capturing the energy to reduce electron carriers or drive ATP formation. How can this energy be used instead?
to synthesize glucose from CO2
to directly power muscle contraction
to provide energy for endergonic biosynthetic reactions
to generate heat 17

18. What is the purpose of fermentation reactions?
to regenerate NAD so glycolysis can continue
to make alcohol or lactic acid that cells can metabolize for energy under anaerobic conditions
to make additional ATP when respiration can’t make ATP fast enough
to slow down cellular oxygen consumption when oxygen is scarce
to make organic molecules that cells can store until oxygen becomes available
Answer: A 18

19. What is the purpose of fermentation reactions?
to regenerate NAD so glycolysis can continue
to make alcohol or lactic acid that cells can metabolize for energy under anaerobic conditions
to make additional ATP when respiration can’t make ATP fast enough
to slow down cellular oxygen consumption when oxygen is scarce
to make organic molecules that cells can store until oxygen becomes available 19

20. During intense exercise, muscles lack sufficient oxygen, so which process will these muscles mainly use?
alcoholic fermentation
the citric acid cycle
only glycolysis, with NAD not utilized
lactic acid fermentation
chemiosmosis
Answer: D 20

21. During intense exercise, muscles lack sufficient oxygen, so which process will these muscles mainly use?
alcoholic fermentation
the citric acid cycle
only glycolysis, with NAD not utilized
lactic acid fermentation
chemiosmosis 21

22. Because of differences in their initial oxidation state, the full oxidation of a single carbon molecule can result in different free energy changes, even though each forms just one CO2 molecule. Which choice correctly matches the reactions shown with the proper relative energy change in attojoules (1 aJ  J)?
CH4  2 O2 → CO2  2 H2O
CH3OH  3/2 O2 → CO2  2 H2O
H2CO  O2 → CO2  H2O
HCOOH  1/2 O2 → CO2  H2O
1: 0.32 aJ; 2 0.57 aJ; 3 0.89 aJ; 4 1.14 aJ
1: 0.32 aJ; 2 1.14 aJ; 3 0.89 aJ; 4 0.57 aJ
1: 0.57 aJ; 2 0.32 aJ; 3 1.14 aJ; 4 0.89 aJ
1: 0.89 aJ; 2 0.32 aJ; 3 0.57 aJ; 4 1.14 aJ
1: 1.14 aJ; 2 0.89 aJ; 3 0.57 aJ; 4 0.32 aJ
Answer: E
Energy calculations based on: Cotterill R Biophysics. An Introduction. Pgs John Wiley & Sons. West Sussex,
England.

23. Because of differences in their initial oxidation state, the full oxidation of a single carbon molecule can result in different free energy changes, even though each forms just one CO2 molecule. Which choice correctly matches the reactions shown with the proper relative energy change in attojoules (1 aJ  J)?
CH4  2 O2 → CO2  2 H2O
CH3OH  3/2 O2 → CO2  2 H2O
H2CO  O2 → CO2  H2O
HCOOH  1/2 O2 → CO2  H2O
1: 0.32 aJ; 2 0.57 aJ; 3 0.89 aJ; 4 1.14 aJ
1: 0.32 aJ; 2 1.14 aJ; 3 0.89 aJ; 4 0.57 aJ
1: 0.57 aJ; 2 0.32 aJ; 3 1.14 aJ; 4 0.89 aJ
1: 0.89 aJ; 2 0.32 aJ; 3 0.57 aJ; 4 1.14 aJ
1: 1.14 aJ; 2 0.89 aJ; 3 0.57 aJ; 4 0.32 aJ

24. Which of the following statements comparing substrate-level phosphorylation and phosphorylation by chemiosmosis is INCORRECT?
Both involve accessing energy in the form of an electrochemical gradient across a membrane.
Both lead to the formation of ATP by coupling this reaction to some other exergonic change.
Both involve reactions that are catalyzed by specific enzymes whose activities can be controlled.
Both involve some energy being converted to heat during their operation.
Both are done by many prokaryotes and by many eukaryotes.
Answer: A

25. Which of the following statements comparing substrate-level phosphorylation and phosphorylation by chemiosmosis is INCORRECT?
Both involve accessing energy in the form of an electrochemical gradient across a membrane.
Both lead to the formation of ATP by coupling this reaction to some other exergonic change.
Both involve reactions that are catalyzed by specific enzymes whose activities can be controlled.
Both involve some energy being converted to heat during their operation.
Both are done by many prokaryotes and by many eukaryotes.

26. Compared to the carbons in glyceraldehyde 3-phosphate, the carbons in 1,3-bisphosphoglycerate have _______, so these carbons are more _____.
fewer bonds with oxygen and more bonds with hydrogen; oxidized
fewer bonds with hydrogen and more bonds with oxygen; oxidized
more bonds with oxygen and fewer bonds with other carbons; oxidized
more bonds with oxygen and fewer bonds with hydrogen; reduced
more bonds with hydrogen and fewer bonds with oxygen; reduced
Answer: B
(Molecular structures based on step 6 of fig. 9.9.)

27. Compared to the carbons in glyceraldehyde 3-phosphate, the carbons in 1,3-bisphosphoglycerate have _______, so these carbons are more _____.
fewer bonds with oxygen and more bonds with hydrogen; oxidized
fewer bonds with hydrogen and more bonds with oxygen; oxidized
more bonds with oxygen and fewer bonds with other carbons; oxidized
more bonds with oxygen and fewer bonds with hydrogen; reduced
more bonds with hydrogen and fewer bonds with oxygen; reduced

28. Which of the following processes is INCORRECTLY matched with its location in a eukaryotic cell?
the production of ethanol by fermentation—the cytosol of the cell
production of FADH2—the matrix of the mitochondria.
formation of ATP by substrate-level phosphorylation—via the F1F0-ATP synthase in the inner mitochondrial membrane
reduction of NAD+—in both the cytosol of the cell and the matrix of the mitochondria
reduction of oxygen gas to water—in the matrix of the mitochondria
Answer: C

29. Which of the following processes is INCORRECTLY matched with its location in a eukaryotic cell?
the production of ethanol by fermentation—the cytosol of the cell
production of FADH2—the matrix of the mitochondria
formation of ATP by substrate-level phosphorylation—via the F1F0-ATP synthase in the inner mitochondrial membrane
reduction of NAD+—in both the cytosol of the cell and the matrix of the mitochondria
reduction of oxygen gas to water—in the matrix of the mitochondria
Answer: C

30. Which choice correctly orders the following four reactions from that with the highest free energy change to that with the lowest free energy change?
NADH  H+ → NAD+  2 H
C6H12O6  6 O2 → 6 CO2  6 H2O
ATP  H2O → ADP  H3PO4
pyruvate  CoA → acetyl-CoA  CO2  2 H
3 > 1 > 4 > 2 d) 3 > 2 > 1 > 4
2 > 4 > 1 > 3 e) 2 > 1 > 4 > 3
1 > 3 > 4 > 2
Answer: B

31. Which choice correctly orders the following four reactions from that with the highest free energy change to that with the lowest free energy change?
NADH  H+ → NAD+  2 H
C6H12O6  6 O2 → 6 CO2  6 H2O
ATP  H2O → ADP  H3PO4
pyruvate  CoA → acetyl-CoA  CO2  2 H
3 > 1 > 4 > 2 d) 3 > 2 > 1 > 4
2 > 4 > 1 > 3 e) 2 > 1 > 4 > 3
1 > 3 > 4 > 2
Answer: B

32. Complex IV of the mitochondrial electron transport chain combines O2 with hydrogens (that is, electrons and protons) to form water. (See figure on next slide.) Which choice correctly describes the ultimate source of these hydrogens?
The electrons are taken directly from the carbons of glucose, but the protons (H+) are taken from bulk water.
These hydrogens are taken from carboxyl groups found on organic acids in the mitochondrial matrix.
These hydrogens are taken from highly oxidized carbon atoms during their reduction.
Enzymes strip these hydrogens from carbons of glucose during their oxidation and pass them to NAD+ and FAD to bring to the electron transport chain.
The hydrolysis of ATP, or of GTP, supplies these hydrogens to this complex.
Answer: D
(Image modified from fig )

34. Complex IV of the mitochondrial electron transport chain combines O2 with hydrogens (that is, electrons and protons) to form water. (See figure on next slide.) Which choice correctly describes the ultimate source of these hydrogens?
The electrons are taken directly from the carbons of glucose, but the protons (H+) are taken from bulk water.
These hydrogens are taken from carboxyl groups found on organic acids in the mitochondrial matrix.
These hydrogens are taken from highly oxidized carbon atoms during their reduction.
Enzymes strip these hydrogens from carbons of glucose during their oxidation and pass them to NAD+ and FAD to bring to the electron transport chain.
The hydrolysis of ATP, or of GTP, supplies these hydrogens to this complex.

35. Which of the following is NOT an immediate net product of the typical mitochondrial electron transport chain (see figure)?
ATP
water
NAD+
FAD
a proton electrochemical gradient
Answer: A
(Image, modified from fig. 9.15; note the lack of labels.)

36. Which of the following is NOT an immediate net product of the typical mitochondrial electron transport chain (see figure)?
ATP
water
NAD+
FAD
a proton electrochemical gradient

37. During lactic acid fermentation pyruvate is given two additional hydrogen atoms. The immediate source of these hydrogens is from ____, which earlier got those hydrogens directly from _____.
NADH; water
FADH2; ADP and Pi
NAD+; glucose
NADPH; phosphoenol-pyruvate
NADH; glyceraldehyde 3-phosphate
Answer: E
(Image modified from fig )

38. During lactic acid fermentation pyruvate is given two additional hydrogen atoms. The immediate source of these hydrogens is from ____, which earlier got those hydrogens directly from _____.
NADH; water
FADH2; ADP and Pi
NAD+; glucose
NADPH; phosphoenol-pyruvate
NADH; glyceraldehyde 3-phosphate
Answer: E
(Image modified from fig )

39. Humans make many of our own amino acids
Humans make many of our own amino acids. Which situation would best promote the production of a needed type of amino acid by a healthy liver cell?
high rates of ATP hydrolysis and a good supply of fats
high concentrations of glucose and ADP in the cytosol
excess amounts of other amino acids and a high ATP/AMP ratio in the cytosol
anaerobic conditions and a good supply of carbohydrates
inhibition of oxidative phosphorylation
Answer: C

40. Humans make many of our own amino acids
Humans make many of our own amino acids. Which situation would best promote the production of a needed type of amino acid by a healthy liver cell?
high rates of ATP hydrolysis and a good supply of fats
high concentrations of glucose and ADP in the cytosol
excess amounts of other amino acids, and a high ATP/AMP ratio in the cytosol
anaerobic conditions, and a good supply of carbohydrates
inhibition of oxidative phosphorylation

41. Through beta-oxidation, fats are converted to acetyl-CoAs
Through beta-oxidation, fats are converted to acetyl-CoAs. The further respiration of these acetyl-CoAs typically bypasses which parts of normal aerobic respiration?
the citric acid cycle and oxidative phosphorylation
glycolysis and chemiosmosis
the citric acid cycle and fermentation
pyruvate oxidation and the citric acid cycle
glycolysis and pyruvate oxidation
Answer: E

42. Through beta-oxidation, fats are converted to acetyl-CoAs
Through beta-oxidation, fats are converted to acetyl-CoAs. The further respiration of these acetyl-CoAs typically bypasses which parts of normal aerobic respiration?
the citric acid cycle and oxidative phosphorylation.
glycolysis and chemiosmosis.
the citric acid cycle and fermentation.
pyruvate oxidation and the citric acid cycle.
glycolysis and pyruvate oxidation.