Problems
Chapters 13 and 14
1) A chemical reaction that has a negative ΔG0
a) is an endergonic reaction.
b) will require an input of energy.
c) is not a spontaneous reaction.
d) is an energy yielding reaction.
e) will absorb energy.
4) Which of these is the most widely used form of energy in cell processes?
a) glucose
b) NADH
c) pyruvate
d) ATP
e) citrate
5) The biochemical reaction, PEP + ADP → Pyruvate + ATP, is an example of which of these?
a) An oxidation/reduction reaction.
b) Oxidative phosphorylation.
c) Substrate-level phosphorylation.
d) An aldolase catalyzed reaction.
e) An electron transport reaction.
7) Oxidative phosphorylation uses ALL of the following for energy production EXCEPT:
a) electrons from NADH.
b) membrane-associated electron transport chain.
c) an ATP synthase.
d) phosphoenolpyruvate.
e) a proton motive force.
8) When oxygen reacts with hydrogen gas, water is produced as the product in this oxidationreduction reaction. Hydrogen donates electrons to oxygen in the reaction. Which statement
below is true about this reaction?
a) Oxygen is oxidized to water.
b) Oxygen is being reduced in the reaction.
c) Hydrogen is being reduced in the reaction.
d) The electron donor in this reaction is reduced.
e) The electron acceptor in this reaction is oxidized.
9) The standard reduction potential (E0’) for ferredoxin (Fdox/Fdred) is (-0.43 V). Based on this,
which of these would you expect to be true?
a) Oxidized ferredoxin to be a good electron donor.
b) Oxidized ferredoxin to be a good electron acceptor.
c) Reduced ferredoxin to be a good electron donor.
d) Reduced ferredoxin to be a good electron acceptor.
e) Cannot be determined without knowledge of the other reactant.
14) How many NET molecules of ATP are produced during the Embden-Meyerhof pathway of
glycolysis for every molecule of glucose that is converted into two molecules of pyruvate?
a) one
b) two
c) four
d) six
e) ten
15) What are the NET products of the Embden-Meyerhof pathway, when operating in the
catabolic direction?
a) Two pyruvate, two ATP, and two NADH.
b) Two pyruvate, four ATP, and four NADH.
c) Two CO2, four pyruvate, two ATP, and four NADH.
d) Two CO2, two pyruvate, four ATP, and four NADH.
e) Two CO2, two pyruvate, two ATP, and two NADH.
16) Which of these are important products of the pentose phosphate pathway that are used in
biosynthesis?
a) pyruvate, ribose-5-phosphate, and NADPH
b) NADPH, ribose-5-phosphate, and erythrose-4-phosphate
c) pyruvate, citrate, and erythrose-4-phosphate
d) pyruvate, erythrose-4-phosphate, and ribose-5-phosphate
e) citrate, NADPH, and ribose-5-phosphate
17) Microorganisms that rely solely on fermentation reactions for energy production make ATP
primarily by this method.
a) oxidative phosphorylation
b) electron transport phosphorylation
c) membrane bound ATPase
d) substrate-level phosphorylation
e) the oxidation of NADH
8) Fermentation can most accurately be described by which of these?
a) The reoxidation of NADH by an electron transport chain.
b) A process that occurs in the absence of oxygen.
c) An energy producing process found in all anaerobes.
d) The direct reoxidation of NADH by an internal organic molecule.
e) The use of a terminal electron acceptor other than oxygen.
19) Lactic acid is a common fermentation product. It is produced when ___________ is reduced
by electrons received from NADH.
a) ethanol
b) glucose
c) pyruvate
d) acetyl-CoA
e) 3-phosphoglyceraldehyde
23) Which of these sets are products of the TCA (Krebs) Cycle?
a) NADH, ATP, CO2, and oxaloacetate
b) NADH, FADH2, and ATP
c) NADH, FADH2, and oxaloacetate
d) NADH, FADH2, CO2, and ATP
e) NADH, FADH2, CO2, and oxaloacetate
24) Which of these is NOT an electron carrier used in the electron transport system?
a) flavoproteins
b) iron-sulfur proteins
c) ATPase
d) quinones
e) cytochromes
26) Which of these occurs in anaerobic respiration, but not in aerobic respiration?
a) A fermentation product is produced.
b) The terminal cytochrome oxidase is replaced by a cytochrome reductase.
c) Glucose is only partially oxidized to CO2.
d) NADH dehydrogenase is replaced by NADH oxidase.
28) What can the proton motive force generated by the electron transport system be used for?
a) NADH oxidation, ATP synthesis, and flagella rotation
b) NADH oxidation, ATP synthesis, and nutrient transport
c) ATP synthesis, flagella rotation, and nutrient transport
d) NADH oxidation, flagella rotation, and nutrient transport
e) oxygen reduction and ATP synthesis
6) Why is carbon dioxide considered a greenhouse gas?
a) It is fixed by plants during photosynthesis.
b) It is produced during the oxidation of organic compounds.
c) It is found in high concentrations in greenhouses.
d) It absorbs heat attempting to escape the atmosphere.
e) It is utilized by suspended microbes in the atmosphere.
) Which carbon reservoir is most actively cycled?
a) the atmosphere
b) ocean waters
c) underground limestone
d) forest mulch
e) ocean sediments
The main primary producers in aquatic environments are _______, while in terrestrial
environments the main primary producers are __________.
a) plants, plants
b) microbes, microbes
c) plants, microbes
d) microbes, plants
e) microbes and plants contribute equally in both environments
23) Which is the major nitrogen reservoir on Earth?
a) plants
b) microbes
c) the atmosphere
d) ocean biomass
e) organic matter in soil
24) Which of these summarizes the overall process of nitrogen fixation?
a) ammonia →→→ N2
b) N2 →→→ ammonia → biomass
c) NO3- →→→ ammonia → biomass
d) NO3- →→→N2
e) ammonia →→→ NO325) Which of these summarizes the overall reaction for nitrification?
a) NO3- → NO2b) biomass → ammonia
c) NO3- →→→ ammonia → biomass
d) NO3- →→→N2
e) ammonia →→→ NO326) Which of these summarizes the overall process of denitrification?
a) N2 → NH3
b) biomass → ammonia
c) NO3- →→→ ammonia → biomass
d) NO3- →→→N2
e) ammonia →→→ NO328) Why is the process of denitrification detrimental to the soil?
a) It leads to acidification of the soil.
b) It leads to loss of utilizable nitrogen from the soil.
c) It leads to loss of oxygen in the soil.
d) It leads to loss of organic matter from the soil.
e) It leads to the production of toxic nitrogen intermediates.
29) Which industrial process is used for the production of ammonia for land application?
a) Mattox
b) Havel – Brill
c) Dalgarno
d) Haber-Bosch
e) Anderson-Plamann
30) How can denitrification of soil be reduced?
a) By adding lime to the soil.
b) By adding ammonia to the soil.
c) By keeping the soil well aerated.
d) By adding potash to the soil.
e) By flooding the soil with water.
1. Electrons needed to reduce an oxidized electron acceptor are provided by
A) externally provided compounds such as H2, lactate or formate.
B) an intermediate electron carrier such as NADH.
C) O2.
D) Both a and b
E) All of the above
8. Which of the following is not used as an electron donor?
A) Ethanol
B) H2S
C) Formate
D) Glycerol
E) O2
12. The process by which ammonia is oxidized to nitrate by chemoautotrophs is
called
A) denitrification.
B) ammonification.
C) nitrification.
D) nitrogen fixation.
E) All of the above
15. How do hydrogen bacteria obtain their energy?
16. A nitrifier is an organism that oxidizes
A) nitrate to nitrite.
B) ammonia to nitrite.
C) nitrite to ammonia.
D) nitrite to nitrate.
E) nitrate to nitrogen gas.
17.
A)
B)
C)
D)
E)
23.
Iron-oxidizing chemoautotrophs
obtain energy by the oxidation of ferric iron.
must grow in environments of low pH or very low oxygen concentration.
use fermentation as a means to obtain energy.
must grow in environments of high pH.
None of the above
Thiobacillus ferrooxidans use iron as an energy source where the external
pH is 2. This condition allows the bacterium to
A) take advantage of the abundance of protons surrounding the outer membrane.
B)
C)
D)
E)
24.
A)
B)
C)
D)
E)
27.
A)
B)
C)
D)
E)
remove an electron from Fe2+ and produce insoluble Fe3+.
oxidize iron to harvest energy.
use an abbreviated electron transport chain.
All of the above
It has been calculated that the efficiency of oxidative phosphorylation is
about _______ percent of the energy conserved by the process as ATP.
4
10
40
50
100
The usual sequence of redox reactions in aerobic respiration is
cytochromes - nonheme iron protein - flavoprotein - CoQ - NADH.
NADH - flavoprotein - nonheme iron protein - CoQ - cytochromes.
flavoprotein - nonheme iron protein - CoQ - NADH - cytochromes.
NADH - nonheme iron protein - flavoprotein - CoQ - cytochromes.
NADH - CoQ - nonheme iron protein - flavoprotein - cytochromes.
28. As electrons are transported down the electron transport chain, the energy
released is used to
A) generate ATP by substrate-level phosphorylation.
B) hydrolyze ATP.
C) translocate protons to the exterior of the cytoplasmic membrane.
D) translocate protons to the interior of the cytoplasmic membrane.
E) reverse the electrochemical gradient.
29. Which of the following is essential to the formation of a proton motive
force?
A) An open membrane compartment to allow protons to drive ATP synthase
B) A closed membrane compartment that is impermeable to protons
C) A proton pump
D) A Q-loop
E) A terminal electron acceptor
31.
A)
B)
C)
D)
E)
The process involving NO3 -> NO2 -> NO -> N2O -> N is termed
nitrogen fixation.
nitrogen reduction.
denitrification.
ammonification.
nitrogen assimilation.
38.
A)
B)
C)
D)
E)
NAD+ is generally involved in _______ reactions.
biosynthesis.
anabolism.
energy-utilizing.
energy-generating.
None of the above
40.
A)
B)
C)
D)
A reaction that yields energy has a
positive DGo'.
negative DGo'.
positive DEo'.
negative DEo'.
E) negative DHo'.
41. Which of the following is the best definition of fermentation?
A) The reduction of glucose to pyruvic acid
B) The complete catabolism of glucose to CO2 and H2O
C) The oxidation of a carbohydrate with organic molecules serving as electron
donors and acceptors
D) The production of ATP from glucose
E) The production of ethanol from glucose
42. Oxidation and reduction reactions are always coupled because
A) electrons generally accompany protons.
B) protons generally accompany protons.
C) electrons cannot exist free in solution.
D) Both a and b
E) All of the above
43. How are aerobic respiration and anaerobic respiration similar?
A) Both use oxygen as a terminal electron carrier.
B) These are other names for glycolysis.
C) Both utilize inorganic molecules as terminal electron acceptors.
D) Neither receives electrons from glycolysis.
E) Anaerobic respiration does not exist in microbes.
44. Which of the following is the best definition of respiration?
A) The oxidation of glucose to ethanol
B) The complete oxidation of glucose to CO2 and H2O
C) The oxidation of a carbohydrate; organic molecules serve as the final
electron acceptors
D) The oxidation of a carbohydrate; inorganic molecules serve as the final
electron acceptors
E) The oxidation of a carbohydrate; oxygen (O2) serves as the final electron
acceptor
47. Look at the table of reduction potentials at the end of the problem set.
How much free energy is released under standard conditions when electrons
are passed from succinate to ubiquinone?
A) About 0.069 kcal/mol
B) About 6 kcal/mol
C) About 3.2 kcal/mol
D) About 1.6 kcal/mol
E) None of the above, energy is required for electrons to flow from succinate
to ubiquinone
48. For the reaction A + B Æ 2C, the equilibrium constant (Keq) is defined as
A) [C]/[A][B]
B) [A][B]/[C]
C) [C]2/[A][B]
D) 2[C]/[A][B]
50. Consider the reaction ATP ‡ AMP + 2 Pi. Calculate Keq if you made a 0.1M
A)
B)
C)
D)
E)
solution of ATP and later measured the following concentrations of
reactants and product at equilibrium. [ATP]=.00001 M, [AMP] = .1M, [Pi] =
.2M
5 x 10-4
.00001
.025
400
2000
Note: The Faraday constant F = 23.1 kcal/(mole x volt)
ATP formation from ADP and Pi has a _Go’ of 7.3 kcal/mol