BY 123 Mock Exam #2
Answer Key
Chapters 8,9,10,12,13
1) Catabolic and anabolic pathways are often coupled in a cell because:
a. The intermediates of a catabolic pathway are used in the anabolic pathway
b. Both pathways use the same enzymes
c. The free energy released from one pathway is used to drive the other pathway
d. The activation energy of the catabolic pathway can be used in the anabolic pathway
e. Their enzymes are controlled by the same activators and inhibitors
2) When a cell breaks down glucose, only about 34% of the energy is captured in ATP molecules.
The remaining 66% of the energy is:
a. Used to increase the order necessary for life to exist
b. Lost as heat, in accordance with the second law of thermodynamics
c. Used to increase the entropy of the system by converting kinetic energy into potential
energy
d. Stored in starch of glycogen for later use by the cell
e. Released when the ATP molecules are hydrolyzed
3) Coenzymes are _______________ like _______. Cofactors are usually _________ like
________.
a. Proteins, NADH, organic molecules, Mg2+.
b. Non-protein organic molecules, NAD+, metal ions, Mg2+
c. Metal ions, Mg2+, non-protein organic molecules, NAD+
d. Non-protein organic molecules, Mg2+, metal ions, NAD+
4) One way in which a cell maintains metabolic dis-equilibrium is to:
a. Siphon products of a reaction off to the next step in a metabolic pathway
b. Provide a constant supply of enzymes for critical reactions
c. Use feedback inhibition to turn off pathways
d. Use allosteric enzymes that can bind to activators or inhibitors
e. Use the energy from anabolic pathways to drive catabolic pathways
5) An endergonic reaction could be described as one that:
a. Proceeds spontaneously with the addition of activation energy
b. Produces products with more free energy that the reactants
c. Is not able to be catalyzed by enzymes
d. Releases energy
e. Produces ATP for energy coupling
6) In an experiment, changing the pH from 7 to 6 resulted in an increase in product formation.
From this we could conclude that:
a. The enzyme became saturated at pH 6
b. The enzyme’s optimal pH is 7
c. This enzyme works best at a neutral pH
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d. The temperature must have increased when the pH was changed to 6
e. The enzyme was in a more active shape at 6.
When substance A was added to an enzyme reaction, product formation decreased. The
addition of more substrate did not increase product formation. From this we conclude that
substance A could be :
a. Product molecules
b. A cofactor
c. An allosteric enzyme
d. A competitive inhibitor
e. A noncompetitive inhibitor
An enzyme raises which of the following parameters?
a. ΔG
b. ΔH
c. The free energy of activation
d. The speed of a reaction
e. The equilibrium of a reaction
In cooperativity,
a. A cellular organelle contains all the enzymes needed for a metabolic pathway
b. A product of a pathway serves as a competitive inhibitor of an enzyme early in the pathway
c. A molecule bound to the active site of one subunit of an enzyme affects the active site of
other subunits
d. The allosteric site is filled with an activator molecule
e. The product of one reaction serves as the substrate for the next reaction in intricately
ordered metabolic pathways.
Which is NOT a way to regulate enzyme activity:
a. Storing it as an inactive form ready for use when needed
b. Competitive inhibition
c. Allosteric enzymes
d. Dehydrogenase enzymes
e. Feedback inhibition
In the reaction C6H12O6 + 6O2  6CO2 + 6H2O
a. Glucose becomes reduced
b. Oxygen becomes reduces
c. Oxygen becomes oxidized
d. Water is a reducing agent
e. Oxygen is a reducing agent
Some prokaryotes use anaerobic respiration, a process that:
a. Does not involve an electron transport chain
b. Produces ATP solely by substrate-level phosphorylation
c. Uses a substance other than oxygen as the final electron acceptor
d. Does not rely on chemiosmosis for the production of ATP
e. Both A and B are correct
13) When pyruvate is converted to acetyl CoA,
a. CO2 and ATP are released
b. A multienzyme complex removes a carboxyl group, transfers electrons to NAD+, and
attached a coenzyme
c. One turn of the citric acid cycle is completed
d. NAD+ is regenerated so that glycolysis can continue to produce ATP by substrate-level
phosphorylation
e. Phosphofructosekinase is activated and glycolysis continues
14) How many molecules of CO2 are generated for each molecule of acetyl CoA introduced into the
citric acid cycle?
a. 1
b. 2
c. 3
d. 4
e. 6
15) Which of the following statements correctly describes the role of oxygen in cellular respiration?
a. It is reduced in glycolysis as glucose is oxidized
b. It combines with H+ diffusing through ATP sythase to produce H2O
c. It provides the activation energy needed for oxidation to occur
d. It is the final electron acceptor for the electron transport chain
e. IT combines with the carbon removed during the citric acid cycle to form CO2
16) In the chemiosmotic mechanism,
a. ATP production is linked to the proton gradient established by the electron transport chain
b. The difference in pH between the intermembrane space and the cytosol drives the
formation of ATP
c. The flow of H+ through ATP synthases rotates a rotor and rod, driving the hydrolysis of ADP.
d. The energy released by the reduction and subsequent oxidation of electron carriers
transfers a phosphate to ADP
e. The production of water in the mitochondrial matrix by the reduction of oxygen leads to a
net flow of water out of a mitochondrion
17) Which of the following statements is INCORRECT concerning oxidative phosphorylation?
a. It produces about 3 ATP for every NADH that is oxidized
b. It involves the reox reactions of the electron transport chain
c. It involves an ATP synthase located in the inner mitochondrial membrane
d. It uses oxygen as the final electron donor
e. It is an example of chemiosmosis
18) Which of the following statements correctly describes a metabolic effect of cyanide, a poison
that blocks the passage of electrons along the electron transport chain?
a. The pH of the intermembrane space becomes much lower than normal
b. Electrons are passed directly to oxygen, causing cells to explode.
c. Alcohol would build up in the muscles
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d. NADH supplies would be exhausted, and ATP synthesis would cease
e. No proton gradient would be produced, and ATP synthesis would cease.
Substrate-level phosphorylation:
a. Involves the shifting of a phosphate group from ATP to a substrate
b. Can use NADH or FADH2
c. Takes place only in the cytosol
d. Accounts for 10% of the ATP formed by fermentation
e. Is the energy source for facultative anaerobes under anaerobic conditions
Fermentation produces less ATP than cellular respiration because:
a. NAD+ is regenerated by alcohol or lactate production, without the electrons of NADH
passing through the electron transport chain
b. Pyruvate still contains most of the “hilltop” electrons that were present in glucose
c. Its starting reactant is pyruvate and not glucose
d. A and b are correct
e. A, b, and c are correct
Glycolysis is considered one of the first metabolic pathways to have evolved because:
a. It relies on fermentation, which is characteristic of archea and bacteria
b. It is found only in prokaryotes, whereas eukaryotes use mitochondria to produce ATP
c. It produces much less ATP than does the electron transport chain and chemiosmosis
d. It produces ATP only by substrate phosphorylation and does not involve redox reactions
e. It is nearly universal, is located in the cytosol, and does not involve O2
Which of the following statements is FALSE concerning the enzyme phosphofructokinase?
a. It is an allosteric enzyme
b. It is inhibited by citrate
c. It is the pacemaker of glycolysis and respiration
d. It is inhibited by Amp
e. It is an early enzyme in the glycolytic pathway.
Which of the following statements describes a possible function of brown fat, which has
uncoupler proteins that, when activated, make the inner mitochondrial membrane leaky to H+?
a. IT produces more ATP than does regular fat and is found in the flight muscles of ducks and
geese, providing more energy for long-distance migrations
b. IT lowers the pH of the intermembrane space, which results in the production of more ATP
per gram than is produced by the oxidation of glucose or regular fat tissue
c. Because it dissipates the proton gradient, it generates heat through cellular respiration
without producing ATP, thereby raising the body temperature of hibernating animals or
newborn infants
d. Its main function is insulation in the endothermic animals in which it is common
e. Both a and b are correct
During non-cyclic photophosphorylation, electrons in PS I are replaced:
a. Directly by the splitting of water
b. Indirectly by the splitting of water
c. Directly by electrons from PS II
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d. Indirectly by electrons form PS II
e. By light electrons
Given six amino acids, calculate the amount of ATP that would be produced from the complete
oxidation of all six molecules if they entered the process as a Pyruvate molecule.
a. 44
b. 90
c. 10
d. 18
e. 22
Given a 12 Carbon fatty acid, how many ATP will be produced after substrate-level
phosphoylation?
a. 12
b. 24
c. 6
d. 90
e. 18
Given a triglyceride with 4 Carbons on each chain, how many ATP will be produced only from
oxidative phosphorylation?
a. 66
b. 82
c. 12
d. 6
e. 90
When glucose and O2 are converted to CO2 and H2O, changes in total energy, entropy, and free
energy are correctly represented as:
a. –ΔH, -ΔS, -ΔG
b. –ΔH, +ΔS, -ΔG
c. –ΔH, +ΔS, +ΔG
d. +ΔH, +ΔS, +ΔG
e. +ΔH, -ΔS, +ΔG
When amino acids join to form a protein, which of the following energy and entropy changes
apply?
a. –ΔH, +ΔS, +ΔG
b. –ΔH, -ΔS, -ΔG
c. +ΔH, +ΔS, +ΔG
d. +ΔH, -ΔS, +ΔG
e. +ΔH, +ΔS, -ΔG
Which of the following processes or structures is mismatched with its location?
a. Light reactions—grana
b. Electron transport chain—thylakoid membrane
c. Calvin Cycle—stroma
d. ATP synthase—double membrane surrounding chloroplast
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e. Splitting of water—thylakoid space
Linear electron flow along with chemiosmosis in the chloroplast results in the formation of:
a. ATP only
b. ATP and NADPH
c. ATP and G3P
d. ATP and O2
e. ATP, NADPH, and O2
The chlorophyll known as P680+ has its electron “holes” filled by electrons from:
a. Photosystem I
b. Photosystem II
c. Water
d. NADPH
e. Accessory pigments
Which of the following substances is/are the final electron acceptors for the electron transport
chains in the light reactions of photosynthesis AND in cellular respiration?
a. O2 in both
b. CO2 in both
c. H2O in the light reactions, and O2 in respiration
d. P700 and NAD+ in the light reactions and NAD+ or FAD in respiration
e. NADP+ in the light reactions, and O2 in respiration
Which of the following parts of an illuminated plant cell would you expect to have the lowest
pH?
a. Nucleus
b. Cytosol
c. Chloroplast
d. Stroma of chloroplast
e. Thylakoid space
A difference between electron transport in photosynthesis and respiration is that in
photosynthesis:
a. NADPH rather than NADH passes electrons to the electron transport chain
b. ATP synthase releases ATP into the stroma rather than into the cytosol (not cytosol, matrix)
c. Light provides the energy to push electrons to the top of the electron chain, rather than
energy from the oxidation of food molecules
d. An H+ concentration gradient rather than a proton-motive force drives the phosphorylation
of ATP
e. Both a and c are correct
How does cyclic electron flow differ from linear electron flow?
a. No NADPH is produced in cyclic electron flow
b. No O2 is produced by cyclic electron flow
c. The cytochrome complex in the electron transport chain is not involved in cyclic electron
flow
d. Both a and b are correct
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e. A, b, and c are correct
Six molecules of G3P formed from the fixation of 3CO2 in the Calvin Cycle are used to produce:
a. Three molecules of glucose
b. Three molecules of RuBP and one G3P
c. One molecule of glucose and four molecules of 3-phosphoglycerate
d. One G3P and three four-carbon intermediates
e. None of the above, because three molecules of G3P result from three turns of the Calvin
Cycle
CAM plants avoid photorespiration by:
a. Keeping their stomata closed during the day
b. Performing the Calvin Cycle at night
c. Fixing CO2 into four-carbon compounds in the mesophyll, which then release CO2 in the
bundle sheath cells
d. Storing water in their stems and leaves
e. Fixing CO2 into organic acids during the night, which then provide CO2 during the day
A plant cell has 12 chromosomes at the end of mitosis. How many chromosomes would it have
in the G2 phase of its next cell cycle?
a. 6
b. 9
c. 12
d. 24
e. 48
In animal cells, cytokinesis involves :
a. The separation of sister chromatids
b. The contraction of a ring of actin microfilaments
c. Depolymerization of kinetochore microtubules
d. A protein kinase that phosphorylates other enzymes
e. Sliding of nonkinetechore microtubules past each other
Humans have 46 chromosomes. That number of chromosomes will be found:
a. In cells in anaphase
b. In egg and sperm cells
c. In somatic cells
d. In all the cells of the body
e. Only in cells in G1 of interphase
A cell in which of the following phases has the least amount of DNA?
a. G0
b. G2
c. Prophase
d. Metaphase
e. Anaphase
43) Which of the following is NOT an accurate statement?
a. Gametes transmit genes from two parents to offspring
b. You have 46 chromosomes in your somatic cells and 23 chromosomes in your gametes
c. Offspring differ from their parents because mutations occur during sexual reproduction
d. Each gene has a specific locus on a chromosome
e. A clone of genetically identical offspring is produced in asexual reproduction
44) What is a karyotype?
a. A genotype of an individual
b. A pictorial display of an individual’s chromosomes
c. A blood type determination of an individual
d. A unique combination of chromosomes found in a gamete
e. A species-specific diploid number of chromosomes
45) The DNA content of a diploid cell is measured in the G1 phase. After meiosis I, the DNA content
of the two cells produced is:
a. Equal to that of the G1 cell
b. Twice that of the G1 cell
c. One-half that of the G1 cell
d. One-fourth that of the G1 cell
e. Impossible to estimate due to independent assortment of homologous chromosomes
46) During meiosis I:
a. Homologous chromosomes separate
b. The chromosome number is reduced in half
c. Crossing over between nonsister chromatids occurs
d. Paternal and maternal chromosomes assort randomly
e. All of the above occur
47) Meiosis II is similar to mitosis because
a. Sister chromatids separate
b. Homologous chromosomes separate
c. DNA replication precedes the division
d. They both take the same amount of time
e. Haploid cells are almost always produced