BIOCHEMISTRY, CELL AND MOLECULAR BIOLOGY TEST
Time—170 minutes
181 Questions
Directions: Each of the questions or incomplete statements below is followed by five suggested answers or
completions. Select the one that is best in each case and then completely fill in the corresponding space on the
answer sheet.
1.
DNA contains all the following molecules
EXCEPT:
a. Uracil
b. Guanine
c. Adenine
d. Deoxyribose
e. Phosphate
2.
In aerobic respiration, the final electron
acceptor in the electron transport chain is
a. NAD+
b. O2
c. H2O
d. NADP+
e. H2
3.
All of the following statements are correct
6.
7.
8.
5.
Which of the following are characteristics of
both bacteria and fungi?
a. cell wall, unicellularity, and mitochondria
b. cell wall, DNA, and plasma membrane
c. nucleus, organelles, and unicellularity
d. plasma membrane, multicellularity, and
Golgi apparatus
e. nucleus, RNA, and cell wall
regarding alleles EXCEPT:
a. A gene can have more than one allele.
b. Two identical alleles are said to be
heterozygous with respect to that gene.
c. Alleles are found on corresponding loci of
homologous chromosomes.
d. Alleles are alternative forms of the same
gene.
e. One allele can be dominant and the other
can be recessive.
4.
A feature of amino acids not found in
carbohydrates is the presence of:
a. Phosphorous
b. Nitrogen
c. Hydrogen
d. Oxygen
e. Carbon
Crossing over occurs during which of the
following phases in sexual reproduction?
a. Metaphase I
b. Metaphase II
c. Prophase I
d. Prophase II
e. Anaphase I
9.
The Krebs cycle in humans occurs in the
a. intermembrane phase
b. inner mitochondrial membrane
c. outer mitochondrial membrane
d. cytoplasm
e. mitochondrial matrix
A macromolecule which consists of a polymer
of amino acids.
a. Glycogen
b. Cellulose
c. Protein
d. Triglyceride
e. Nucleic Acid
10. Vitamins are essential to the human diet
because they act as
a. Neurotransmitters
b. Enzymes
c. Cofactors
d. Hormones
e. Coenzymes
A researcher performs a cross between 2 mice,
both having black fur. Black fur is dominant
over white fur. 75% of the offspring have black
coats and 25% have white coats. The
researcher can assume that the parents
genotypes were most likely:
a. BB x BB
b. BB x Bb
c. BB x bb
d. Bb x Bb
e. bb x bb
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11. Here is a picture of a chromosome. The box
labeled "A" outlines a structure called
a(n)___1___; the structure labeled "B" is
a(n)__2____. (blanks 1 and 2 should be filled
respectively with:
16. C 14 spontaneously turns into N at a constant
rate, with a half-life of 5,600 years. After
11,200 years, what proportion of the original C
14 will be left?
a. 1.0
b. 0.5
c. 0.25
d. 0.1
e. 0
17. Consider the two molecules below. Which
label describes them accurately?
a.
b.
c.
d.
e.
1- aster, 2-chromatid
1- chromatid, 2- centromere
1- kinetochore, 2- chromatid
1- telomere, 2- centromere
1- nucleolus, 2- kinetochore
a. Two isotopes
b. Two structural isomers
c. Two geometric isomers
d. Two stereoisomers
e. Two enantiomers
18. Which best describes the alpha helix structure
of proteins? It results from:
a. covalent bonds between C and C
b. ionic bonds between N and H
c. covalent bonds between N and O
d. hydrogen bonds between H and O
e. hydrogen bonds between N and O
12. Free energy is defined as:
a. heat.
b. entropy.
c. kinetic energy of molecules.
d. energy which does not cost anything.
e. energy which is available to do work.
13. When diffusion occurs, so that molecules are
arranged more randomly in a solution, which
of the following would increase?
a. Heat
b. Gravity
c. Entropy
d. magnetism
e. potential energy
19. Homeostasis refers to a constancy which is the
result of:
a. no input or output.
b. imbalance of input and output.
c. controlled balance of input and output.
d. a dynamic equilibrium.
e. c and d.
14. The heat necessary to raise the temperatureof
a kilogram of water by 1 degree Celcius is
called a:
a. kilocalorie.
b. mole.
c. kilometer.
d. kilomole.
e. Kilojoule
20. If the pH of a solution goes from 8 to 7, this
means that the hydrogen ion concentration
has:
a. decreased by 1 mole/liter.
b. increased by 1 mole/liter.
c. decreased 10 fold.
d. increased 10 fold.
e. both a and c.
15. Which of the following is an important
functional group in fatty acids?
a. Hydroxyl
b. Phosphate
c. Carboxyl
d. sulphide
e. carbonyl
21. A molecule which releases hydrogen ion when
added to a solution (thus raising the hydrogen
ion concentration of the solution and lowering
the pH) is called:
a. a base
b. an acid
c. an antacid
d. a pH
e. a buffer
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22. Which functional group is found in both
aldehydes and ketones?
a. hydroxyl
b. carbonyl
c. carboxyl
d. amino
e. phosphate
27. Which of the following statements regarding
catabolic and anabolic processes is true?
a. Anabolic processes create ATP
b. Muscle contraction and ion transport are
types of anabolic processes
c. Carbohydrates and proteins are broken
down in anabolic processes
d. Catabolism is considered the utilization
phase of the energy cycle
e. Absorption, breakdown, and oxidation are
the three phases of anabolic processes
23. Mendel’s Law of Independent Assortment
applies to which of the following?
a. The inheritance pattern of two genes that
lie at opposite ends of a chromosome.
b. The inheritance pattern of two alleles of
the same gene.
c. The inheritance pattern of two genes that
reside on different autosomal
chromosomes.
d. The inheritance pattern of genes that lie
on the X and Y chromosomes.
e. The inheritance pattern of two genes that
lie close together on a single
chromosome.
28. All of the following statements about allosteric
enzymes are true except:
a. allosteric enzymes usually contain more
than one subunit
b. allosteric enzymes display MichaelisMenten kinetics
c. allosteric enzymes are often subject to
feedback inhibition
d. allosteric enzymes are often regulated by
ligands binding to sites different than the
active sites
e. allosteric effectors can act to either
increase or decrease affinity for substrate
at the active sites
24. What would be the result if meiosis 2 were
eliminated?
a. The process of recombination or crossingover will be eliminated
b. The progeny will be haploid (1N)
c. The progeny will be tetraploid or 4N
d. There will be no change to the genetic
make-up of the progeny (2N)
e. cells will re enter meiosis 1.
29. The differences between hemoglobin and
myoglobin include
a. hemoglobin is a tetramer whereas
myoglobin is a monomer.
b. hemoglobin exhibits a sigmoidal O2
saturation curve while myoglobin exhibits
a hyperbolic curve.
c. hemoglobin exhibits O2 binding
cooperativity while myoglobin does not.
d. hemoglobin exhibits a lower degree of O2
saturation at all physiologically relevant
partial pressures of O2 than does
myoglobin.
e. all of the above
25. What is the effect on the overall rate of
transcription within a cell if the level of
Histone Acetyl Transferase (HAT) proteins is
reduced by mutations?
a. Increase
b. Decrease
c. No change in transcription will be
observed
d. There will be localized increases at some
genes and localized decreases at other
genes.
e. an increase in cell HDAC (Histone
DeAcetylase) Production.
26. What is the ∆G0’ of the reaction:
ATP  Pi + ADP
If the equilibrium concentrations are [ATP] = 10 M,
o’
[Pi] = 0.1 M, [ADP] = 10
+ 1.4log[products]/[reactants]
a.
b.
c.
d.
e.
-1.4 kcal/mol
-2.8 kcal/mol
+2.8 kcal/mol
-0.14 kcal/mol
+1.4 kcal/mol
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30. Which of the following statements about
protein structure is correct?
a. The α-helix is stabilized primarily by ionic
interactions between the side chains of
amino acids.
b. The formation of the disulfide bond in a
protein requires that the two participating
cystein residues be adjacent to each other
in the primary sequence of the protein.
c. The stability of quaternary structure in
proteins is mainly due to covalent bonds
among the subunits.
d. The denaturation of proteins always leads
to irreversible loss of secondary and
tertiary structure.
e. The information for the correct folding of
a protein is contained in the specific
sequence of amino acids along the
polypeptide chain.
33. On the basis of the graphs shown above,
which of the following statements correctly
describes the nature of the
inhibitor/inhibition?
a. The inhibitor is competitive.
b. The inhibitor is non-competitive.
c. The inhibitor acts as a positive effector.
d. The inhibitor is likely to bind to a site
distinct from the active site of the
enzyme.
e. The inhibitor is likely to act as an allosteric
effector.
34. Which of the following best illustrates
hydrophobic forces that stabilize the
conformation of some proteins?
a. clustering of nonpolar amino acid side
chains in the interior of globular proteins.
b. heat denaturation of globular proteins.
c. the unfolding of proteins at low pH.
d. the formation of α-helices.
e. the formation of β-pleated sheets
In the figure below, the solid line shows the
dependence of the rate of an enzyme catalyzed
reaction v (μmol/min) as a function of the substrate
concentration [S] (mM). Also shown (dotted line) is
the dependence of the rate on substrate
concentration in the presence of an inhibitor (at a
concentration of 2 mM). Questions 31-33 refer to
this figure.
35. As shown above, phosphoric acid has three
ionizable protons, with the pKa values
indicated. The buffering capacity of
phosphoric acid is LEAST at pH:
a. 2.1
b. 4.6
c. 6.8
d. 7.4
e. 12.3
O
31. Regarding the activity of the enzyme in the
absence of the inhibitor (solid line), which of
the following conclusions is correct?
a. The Vmax of the enzyme is 0.5 μmol/min.
b. The Km of the enzyme is 2 mM.
c. When [S] = 2 mM, v = 2 μmol/min.
d. Vmax/Km = 0.5 μmol/min (mM)-1
e. When [S] = 1 mM, v = 1 μmol/min.
O
-
C O
C O-
H C OH
C O
CH3
CH3
1
2
36. In the reaction drawn above, what has
happened to molecule 1 to convert it to
molecule 2?
a. Phosphorylation
b. Oxidation
c. Isomerization
d. Dehydration
e. Reduction
32. In the presence of the inhibitor (dotted line),
the Km' (apparent Km) of the enzyme, in units
of mM, is:
a. 0.25
b. 0.5
c. 1.0
d. 2.0
e. 4.0
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37. For the reaction drawn above, what type of
enzyme would carry out this reaction?
a. Epimerase
b. Isomerase
c. Hydrolase
d. Kinase
e. Dehydrogenase
41. Consider the following reactions:
CH2OH
C
OH
C
CH2OH
O
H
OH
H
C
C
H
OH
H
OH
C
C
OH
H
1
C
O
H
OH
H
C
C
H
OH
CH2OH O
OH
OH
H
H
CH2OH
OH
3
2
43. Which of the cell junctions listed below
involves adhesion to laminin?
a. tight junction
b. zonula adherens
c. hemi-desmosome
d. desmosome
e. gap junction F. focal adhesion
CH2OH
HO CH2
H
O
H
OH
H
OH
H
OH
4
OH
C
H
C
O
H
OH
H
C
C
H
OH
∆Go’ = -0.8 kcal/mol
42. Treatment of quiescent cells in G0 with a drug
that blocks phosphorylation of lamins, and
hence keeps them in a dephosphorylated
state, would:
a. have no effect on the structure of the
nucleus.
b. would prevent reformation of the nucleus.
c. would prevent nuclear pores from
associating with the nuclear membrane.
d. would disrupt nucleolar structure.
e. prevent translocation of proteins into the
nucleus.
OH
H
CD
change (∆G’) of the reaction: A + C  B + D
be if [A] = 1.0 M, [B] = 0.1 M, [C] = 10 M and
[D] = 0.1 M ∆G’ = ∆Go’
+1.4log[products]/[reactants]
a. +0.3 kcal/mol
b. -1.7 kcal/mol
c. +1.7 kcal/mol
d. +8.7 kcal/mol
e. +1.1 kcal/mol
H
C
∆Go’ = +5.3 kcal/mol
If a single enzyme is capable of coupling the
two reactions what would the free energy
38. A substrate S can be degraded by two different
isozymes (#1 and #2), both obeying MichaelisMenten kinetics. The Km for isozyme #1 is 0.1
mM and the corresponding value for isozyme
#2 is 10 mM. Both isozymes have the same
Vmax. If [S] = 5 mM, which of the following
statements is correct?
a. Isozyme #1 will degrade S faster than
isozyme #2.
b. sozyme #2 will degrade S faster than
isozyme #1.
c. Isozyme #1 will degrade S at a rate equal
to half of its maximal velocity.
d. Isozyme #2 will degrade S at a rate equal
to half of its maximal velocity.
e. Isozyme #2 will degrade S at its maximal
velocity.
H
AB
OH
C
H
5
39. Which of the above molecules are anomers?
a. molecules 1 and 2
b. molecules 2 and 5
c. molecules 1 and 5
d. molecules 3 and 4
e. molecules 1 and 4
44. Which of the following pairs is INCORRECT?
a. cristae - inner mitochondrial membrane
b. nucleotide triphosphates - intermembrane
space
c. porin - inner mitochondrial membrane
d. ATP synthetase - inner mitochondrial
membrane
e. citric acid cycle – matrix
40. Which of the above molecules is a component
of ribonucleotides?
a. molecule 1
b. molecule 2
c. molecule 3
d. molecule 4
e. molecule 5
45. Which of the following refers to a change in
the structure of a protein that results in the
loss of the biological
a. activity of the protein?
b. cooperativity
c. renaturation
d. denaturation
e. specific activity
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46. For a prokaryotic chromosome, which of the
following is true?
a. RNAs can be transcribed off either DNA
strand, depending on the gene, but are
always made 5´ > 3´.
b. RNAs can be transcribed off either DNA
strand, depending on the gene, but are
always made 3´ > 5´
c. RNAs from all genes are synthesized 5´ >
3´ off the same DNA strand.
d. RNAs from all genes are synthesized
3´ > 5´ off the same DNA strand.
e. Different genes can be transcribed off
either strand, some in the 5´ > 3´
direction and some in the 3´ > 5´
direction.
50. What is the correct enzyme name for the
CO2
ATP
ADP + Pi
O
O
-
CH3C SCoA
O C CH2
O
C SCoA
reaction drawn below?
a.
b.
c.
d.
e.
malonyl-CoA synthase
acetyl CoA kinase
fatty acyl CoA synthetase
acetyl CoA carboxylase
acetyl CoA synthetase
51. For the study of a protein in detail, an effort is
usually made to first:
a. conjugate the protein to a known
molecule.
b. determine its amino acid composition.
c. determine its molecular weight.
d. determine its amino acid sequence.
e. purify the protein.
47. Which of the following refers to a technique
for determining the sequence of amino acids
in a peptide?
a. Edman’s degradation
b. Sanger’s reagent
c. hydrolysis
d. Merrifield Solid-Phase method
e. specific cleavage
52. Which of the following events is responsible
for setting the frame of translation?
a. Attachment of the large ribosomal subunit
to the small subunit
b. mRNA alignment with the small ribosomal
subunit
c. mRNA alignment with the initial Met-tRNA
d. Ribosome “hopping” down the mRNA
three bases at a time
e. RNA-RNA base pairing between the
ribosome and the Shine-Delgarno
sequence in the transcript
48. Which of the following features is NOT true of
nucleosomes?
a. They contain five different kinds of
histone proteins.
b. New histones are made while the DNA is
replicated and assembled immediately
into new nucleosomes.
c. They form a “spool”, which the DNA
wraps around about 30 times.
d. They are the only proteins that are part of
the chromatin.
e. They are characteristic of eukaryotic
chromosomes, but not of viral or bacterial
chromosomes.
53. Viral infections are frequently detected using
tests that assess the presence or absence of
patient antibodies against viral proteins. If
antibodies against the viral proteins are
present, then this is taken as evidence that the
patient is infected with the virus. However, a
flaw in this method of detection is the
existence of a "latent period", i.e., a time
period after infection with the virus has
occurred, but before the patient's body begins
to make antibodies. It is frequently possible to
detect viral nucleic acids in blood during the
latent period using which of the following
techniques?
a. enzyme-linked immunosorbent assay
(ELISA)
b. western blot (immunoblot analysis) C.
SDS-PAGE
c. polymerase chain reaction (PCR)
d. transmission electron microscopy (TEM)
e. scanning electron microscopy (SEM)
49. If DNA polymerases could add nucleotides in
the 3' to 5' direction during replication, there
would be no need for
a. DNA ligase
b. RNA primers
c. Okazaki fragments
d. gyrase
e. helicase
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54. When the pH is 2 units below the pKa of a
specific group, the ratio of protonated to
unprotonated species in the solution is
a. 10:1 in favor of the protonated form.
b. 100:1 in favor of the unprotonated form.
c. 1000:1 in favor of the unprotonated form.
d. 100:1 in favor of the protonated form.
e. Equal amount of the protonated and
unprotonated forms.
59. Mitochondria:
a. obtain most of their phospholipids from
phospholipid exchange proteins that
transport the lipids from the endoplasmic
reticulum.
b. reproduce by fusing with bacteria that
have been taken up by phagocytosis.
c. are the primary site of ATP degradation to
ADP.
d. contain elementary particles which
synthesize all of the components of the
electron transport chain.
e. form peroxisomes by fission followed by
import of newly synthesized peroxisomal
proteins
55. The Golgi apparatus performs which of the
following functions?
a. synthesis of the unglycosylated mannose6-phosphate receptor protein
b. addition of a high mannose
oligosaccharide precursor to serine or
threonine residues
c. cleavage of the signal peptide
d. removal and addition of sugars to the high
mannose oligosaccharide precursor
e. degradation of heat shock proteins
complexed with improperly folded
nascent proteins
60. Inhibitory neurotransmitters such as GABA and
glycine mediate which of the following?
a. open K+ channels on the postsynaptic
membrane
b. open Cl- channels on the postsynaptic
membrane
c. close Cl- channels on the postsynaptic
membrane
d. open Na+ channels on the postsynaptic
membrane
e. close Na+ channels on the postsynaptic
membrane
56. Which of the following would DECREASE the
propagation velocity of an action potential
down an axon?
a. increase in distance between the axon
hillock and axon terminal
b. increase in diameter of axon
c. increased myelination of internodes
d. decreased myelination of internodes
e. decrease in internal resistance of axonal
cytosol to current flow
61. Which of the following is NOT a mechanism for
sex determination in at least one species?
a. the presence of a Y-chromosome
b. the ratio of X-chromosomes to autosomes
c. the lack of any X-chromosome
d. the total number of chromosomes
(haploid versus diploid)
e. all of the above ARE real mechanisms
57. Amino acids are referred to as being
amphoteric because
a. they are positively charged at neutral
pH’s.
b. they can act as both acids and bases.
c. they can exist in either the D or L
configuration.
d. they are never found in a protein.
e. all optically active.
62. If an organism has a diploid number of 8, how
many CHROMATIDS are present during
prophase (beginning) of MITOSIS?
a. 3
b. 4
c. 6
d. 8
e. 16
58. Colchicine treatment of cells is used for
karyotype analyses. Its mechanism of action is
to depolymerize spindle microtubules and
thus:
a. arrest mitosis during the relatively long
period of prophase.
b. prevent inactivation of MPF, and hence
block mitosis in metaphase.
c. arrest mitosis during cytokinesis.
d. activate MPF, and hence allow all the cells
to leave interphase and enter mitosis.
e. prevent inactivation of MPF, and hence
block mitosis at telophase.
63. A pool of mammalian cells with defective
glucagon receptors has been isolated.
Sequencing of the receptor gene revealed that
the G protein binding domain has been
mutated and rendered nonfunctional. What
could be the most direct consequence of this
mutation?
a. Inability to bind glucagons
b. Inability to activate adenyl cyclase
c. Inability to bind cholera toxin
d. Inability to induce receptor dimerization
e. Inability to phosphorylate the target
protein
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64. Which of the following is not normally found in
proteins?
a. 4-hydroxyproline
b. ornithine
c. -carboxyglutamic acid.
d. histidine
e. glutamine
The next two questions refer to the graph
A
B
[ OXYGEN ]
C
65. A clinical investigator has hypothesized that a
bacteria, helicobacter pylori, may cause ulcers.
As part of a clinical research study, a 34-yearold man with a history of stomach ulcers has
an endoscopic examination in which a small
biopsy of the stomach lining is removed. The
biopsy is processed by fixation, followed by
coating with a heavy metal., In order to check
for the presence of spiral bacteria,
helicobacter pylori, lying on the surface of the
stomach epithelium, the investigator would
use which of the following type of
microscope?
a. transmission electron microscope
b. scanning electron microscope
c. phase contrast microscope
d. dark field microscope
e. fluorescence microscope
E
D
O2= 0
TIME
67. The respiratory control ratio (RCR) can be used
to assess “coupled” mitochondria. Given the
representative RCR oxygen consumption graph
and assuming all required substrates are
added at time = 0, which position on the graph
(labeled A – E) represents the point at which
ADP = 0?
a. A
b. B
c. C
d. D
e. E
66. In the isoelectric form of a tetrapeptide:
a. the amino and carboxyl termini are not
charged.
b. two internal amino acids of the
tetrapeptide cannot have ionizable R
groups.
c. the total net charge is zero.
d. there are four ionic charges.
e. only the amino and carboxyl termini
contribute charge.
68. On the RCR oxygen consumption graph, if the
positions labeled “D” and “E” represent the
points at which mitochondrial poisons are
added, which of the following best describes
which ones they would be? (2,4-DNP = 2,4dinitrophenol)
“D”
“E”
a. 2,4-DNP
oligomycin
b. antimycin
2,4-DNP
c. oligomycin
2,4-DNP
d. 2,4-DNP
Cyanide
e. Azide
2,4 DNP
69. Eukaryotic chromosomal replication
a. is unidirectional.
b. occurs from a single, unique origin, called
oriC.
c. depends on specific termination
sequences.
d. involves a q -shaped conformation.
e. has many replication forks.
70. A sample of normal double-stranded frog DNA
was found to have a guanine content of 18%.
What is the expected proportion of adenine?
a. 9%
b. 32%
c. 36%
d. 68%
e. 82%
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71. Which of the following statements about the
glycosylation of a protein is TRUE?
a. equires the presence of mannose-6phosphate
b. occurs in the condensing vesicles of the
late endosome
c. occurs on tyrosine residues
d. begins in the rough endoplasmic
reticulum
e. occurs on an amino acid present in the
signal peptide
76. The side chains of basic amino acids are best
categorized:
a. as ring structures.
b. as containing groups with a positive
charge at neutral pH’s.
c. as containing groups with a negative
charge at neutral pH’s.
d. as neutral hydrocarbon structures.
e. by the presence of a hydroxyl, carboxyl, or
sulfur-containing group.
77. Which of the following statements concerning
the lipid composition of the plasma membrane
is FALSE?
a. Membrane phospholipids are amphipathic
and contain two hydrophobic fatty acyl
chains, each typically containing an even
number of carbon atoms.
b. Glycolipids represent the most abundant
class of membrane lipids.
c. Cholesterol intercalates between
phospholipids and slows their lateral
movement within the plasma membrane.
d. The hydrophobic effect drives the
formation of the phospholipid bilayer.
e. non of the above
72. In a highly acidic solution, pH = 1.3, the
dominant form of glycine is:
a. NH2-CH2-COOH.
b. NH3+-CH2-COOH.
c. NH2-CH2-CO–.
d. NH3+-CH2-COO–.
e. NH2-CH3+-COO–.
73. At which points during the cell cycle is the
nuclear envelope broken down and then
reassembled?
a. broken down during prophase,
reassembled in telophase
b. broken down during prometaphase,
reassembled in anaphase
c. broken down during G2, reassembled in
G1
d. broken down during prophase,
reassembled in metaphase
e. broken down during interphase,
reassembled in mitosis
78. Which of the following compounds CANNOT
exhibit intermolecular hydrogen bonding?
a. CH3–CH2–OH
b. CH3–O–CH3
c. H–F
d. NH3
e. t-butyl alcohol
74. Which of the following cleaves a polypeptide
chain at the carboxyl side of aromatic amino
acids like
a. phenylalanine?
b. chymotrypsin
c. carboxypeptidase
d. trypsin
e. pepsin
f. cyanogens bromide
79. Which of the following statements concerning
the voltage-gated K+ channel is FALSE?
a. This selective channel is composed of four
separate subunits, each containing six
transmembrane a helices.
b. The S4 helix of each subunit of this
channel senses depolarization and causes
a conformational change to open the
channel pore.
c. The nonhelical sequence of this channel
between S5 and S6 dips into and lines the
channel pore with hydrophilic amino acid
residues.
d. The extracellular domain of this channel
functions as a "ball and chain" and is thus
responsible for inactivation (closing) of
the channel.
e. None of the above statements are false
75. In the purple penguin, a series of alleles occurs
at the P locus on an autosome. All alleles
affect the color of feathers: P1= dark-purple,
P2= medium-purple, P3 = light-purple, and P4
= very pale purple (almost white). The order of
dominance is P1>P2>P3>P4. If a heterozygous
light-purple female is crossed to a dark-purple
male who is heterozygous for medium-purple,
the ratio of phenotypes expected among the
baby penguins would be
a. 2 dark:1 medium:1 light
b. 2 dark:1 light:1 very pale
c. 1 dark:1 medium:1 light:1 very pale
d. 1 dark:1 medium
e. 1 medium:1 light
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80. Bence-Jones protein is a protein of a
characteristic molecular weight (~150 kDa)
found in very high amounts in the urine of
patients with multiple myeloma. Multiple
myeloma is a disease in which certain
lymphocytes multiply and destroy bone
marrow and bone. The affected lymphocytes
produce the Bence-Jones protein. The disease
can be diagnosed by using which of the
following techniques to identify the BenceJones protein in urine?
a. SDS-PAGE
b. fluorescence microscopy
c. PCR
d. electron microscopy
e. FACS
82. Which of the following statements concerning
microtubule assembly/disassembly is FALSE?
a. During assembly, GTP binds to tubulin B
subunits and is subsequently hydrolyzed
to GDP.
b. GDP-capped microtubules are unstable
and loose tubulin subunits from the plus
end of the microtubule.
c. Assembly/disassembly are blocked by the
centrosome complex at the minus end of
the microtubule.
d. Microtubule stability reflects the fact that
assembly always occurs at a faster rate
than disassembly.
e. Microtubule assembly is blocked by low
concentrations of colchicine.
81. Which of the following situations would result
in an increase in ketone body synthesis?
a. High insulin/glucagon ratio
b. High citrate levels in the cytosol
c. High levels of fructose 2,6-bisphosphate
d. Low oxaloacetate levels in the
mitochondria
e. Low acetyl CoA levels in the mitochondria
83. Which of the following forces would be the
most important in the intermolecular
interactions of water molecules?
a. London Forces
b. van der Waal’s Forces
c. Dipole-dipole interactions
d. Hydrogen Bonding
e. Ion-ion attraction
84. One enzyme of the glycolytic pathway is regulated by feed forward activation. Which of the following pairs
listed below gives the correct enzyme and the regulatory intermediate?
Enzyme
a.
b.
c.
d.
e.
Intermediate
phosphofructokinase
hexokinase
pyruvate kinase
phosphoglycerate kinase
glyceraldehyde 3-phosphate dehydrogenase
glucose 6-phosphate
2-phosphoglycerate
fructose 1,6-bisphosphate
fructose 2,6-bisphosphate
fructose 6-phosphate
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O
CH3
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
C SCoA
molecule A
[G]
Reaction 1
[H]
H O
CH3
[CH2]10
CH2
C C C SCoA
H
molecule B
[I]
Reaction 2
CH3
[CH2]10
CH2
OH
O
C CH2
C SCoA
H
molecule C
[J]
Reaction 3
[K]
O
CH3
O
[CH2]10 CH2 C CH2
molecule D
C SCoA
[L]
Reaction 4
O
O
CH3
[CH2]10
CH2
molecule E
C SCoA
+
CH3
C SCoA
molecule F
The following two questions refer to the pathway drawn above.
85. Which of the following statements describing the above pathway is correct?
a. Acetyl CoA carboxylase attaches CoA to the free fatty acid to make molecule A.
b. The enzymes that catalyze reactions 1 and 3 require FAD and NAD+, respectively.
c. Glucagon inhibits this pathway.
d. The 4 reactions, respectively, are dehydrogenation, dehydration, dehydrogenation, and cleavage.
e. Steps 1 through 4 require high concentrations of ATP.
86. Repeating reactions 1 through 4 will ultimately yield:
a. 7 acetyl CoA, 6 FADH2, 6 NADH + H+
b. 1 propionyl CoA, 5 acetyl CoA, 5 FADH2, 5 NADH + H+
c. 1 propionyl CoA, 6 acetyl CoA, 6 FADH2, 6 NADH + H+
d. 8 acetyl CoA, 7 FADH2, 7 NADH + H+
e. Palmitate
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87. What is the correct order in which G protein
coupled receptor systems are activated?
a. Hormone – Receptor – Protein kinase A –
Adenyl cyclase – G protein – Cellular
response
b. Hormone – Receptor – G protein – Adenyl
cyclase – Protein kinase A – Cellular
response
c. Hormone – Receptor – G protein – Protein
kinase A – Adenyl cyclase – Cellular
response
d. Hormone – Receptor – Adenyl cyclase – G
protein – Protein kinase A – Cellular
response
e. Hormone – Receptor – Adenyl cyclase –
Protein kinase A – G protein – Cellular
response
91. Consider the following statements about the
cell cycle. Which is FALSE?
a. G0 is a special type of G1 for senescent
cells.
b. The cell spends the most time in G2
phase.
c. G1 is the most variable time of the cell
cycle.
d. G1 is the time when the cell increases in
size.
e. Mature neurons are in G0 phase
92. Ketone bodies
a. are the main fuel source for the brain.
b. are hydrophobic and require a carrier for
transport in the blood.
c. include acetoacetate, which can
spontaneously decarboxylate.
d. include acetone, which is a fuel source for
many tissues.
e. are formed from three molecules of
malonyl CoA.
88. A recently discovered membrane-associated
protein exhibits the following properties:
molecular weight = 130,000; three separate
stretches of nonpolar amino acids that form a
helices; long hydrophilic extracellular domain
that contains sugar residues; and a short
hydrophilic intracellular domain. This protein
would be most ACCURATELY described by
which of the following?
a. tripartite, single-pass integral membrane
glycoprotein
b. multipass integral membrane glycoprotein
with one extracellular loop
c. multipass integral membrane glycoprotein
with two intracellular loops
d. large transmembrane protein with an
extracellular ligand-binding domain large
integral membrane protein with two
extracellular loops
e. non of the above
93. Which of the following statements concerning
delayed voltage-gated K+ channels is FALSE?
a. Opening of these channels does not occur
until the action potential is near its peak.
b. Opening of these channels reduces the
length of the refractory period.
c. These channels are closed when the
membrane potential returns to a value
close to the K+ equilibrium potential.
d. Without the opening of these channels,
membrane repolarization would occur
more slowly.
e. These channels become fully activated
when the membrane potential has shifted
to -50mV
89. Which of the following statements is correct?
a. Lipid soluble vitamins are readily excreted
from the body.
b. All of the carbons in cholesterol synthesis
come from molecules of acetyl CoA.
c. Sphingosine is derived from palmitoyl CoA
and glycerol phosphate.
d. CTP (cytidine triphosphate) is used to
activate ceramide in glycolipid synthesis.
e. Bile salts are derived from vitamin D.
94. The primary structure a protein determines
the _______ level of structure mostly due to
its ________.
a. quaternary; ion-binding capacity
b. secondary; hydrophobicity
c. tertiary; lack of charge
d. secondary; sulfur atoms
e. tertiary; side-chain chemistry
95. Some parrots have a sex-linked disease,
caused by a recessive allele, that makes their
legs crooked. These bow-legged parrots are
a. likely to be color blind also.
b. more likely to be male than female.
c. more likely to be female than male.
d. equally likely to be male or female.
e. likely to die as nestlings.
90. In the tripeptide asp-his-arg, which of the
following groups is not free to ionize?
a. the -carboxyl of aspartic acid
b. the -carboxyl of arginine
c. the -carboxyl of histidine
d. the -amino of aspartic acid
e. the guanido group of arginine
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96. A biologist interested in cell motility has
noticed that when he treats cultured
fibroblasts with phalloidin, all movement
stops. The most appropriate conclusion that
should be drawn from this observation alone is
that:
a. Depolymerization of actin filaments blocks
cell protrusion and attachment.
b. Polymerization of actin filaments is
required for cell retraction.
c. Actin filament polymerization as well as
depolymerization are required for proper
functioning of lamellipodia.
d. Disassembly of actin filaments is required
for cell motility.
e. None of the above.
101. All of the following statements about meiosis
are true, EXCEPT which one?
a. Meiosis only occurs in eukaryotes.
b. At the end of meiosis, each daughter cell
is haploid.
c. Meiosis II is essentially a mitotic division.
d. The chromosomal material replicates
twice during meiosis.
e. The daughter cells produced during
meiosis are not necessarily gametes.
102. Which of the following does NOT influence the
specificity of a cation channel?
a. extent of channel phosphorylation
b. pore size
c. differences in hydration of specific cations
in solution
d. ability of different cations to interact
electrostatically with polar residues lining
the channel
e. ability of different cations to undergo
instantaneous dehydration and pass
through sieve of channel
97. Which of the following is NOT a property of
intermediate filaments?
a. consists of non-polar, insoluble fibers
b. have a diameter of 24 nm and are
composed of globular protein subunits
c. contain fibrous proteins whose
polymerization does not require ATP
hydrolysis
d. composed of monomers that contain
variable NH2- and COOH-domains and a
conserved central a-helical region
e. interact with intermediate filament
associated proteins including skelemin
and ankyrin
103. Which of the following statements about
tRNAs is incorrect?
a. There are between one and four tRNAs for
each of the 20 amino acids.
b. tRNAs always adopt a clover-leaf
conformation.
c. During initiation, the tRNA anticodon
basepairs to a complementary sequence
of the ribosomal RNA.
d. tRNAs participate in both stable and
transient RNA:RNA base pairings.
e. All of the above statements are correct
98. The signal recognition partical (SRP)
a. binds to ribophorin I and II
b. directs lysosomal enzymes to endosomes
c. accelarates the translation of mRNA
d. binds to a receptor that is an integral
protein in the rough endoplasmic
reticulum.
e. directs nuclear proteins into the nucleus
104. Which of the following is NOT a function
performed by the Golgi apparatus?
a. cleavage of sugars from the N-linked
precursor oligosaccharide
b. addition of sugars to the N-linked
precursor oligosaccharide
c. addition of sialic acid to N-linked
oligosaccharides in the cis Golgi
d. addition of sugars to lipids
e. addition of sulfate and phosphate
modifications to proteins
99. Which of the following molecules binds in a
heterophilic manner?
a. cadherin
b. N-CAM
c. selectin
d. desmoglein
e. connexin
100. Which of the following statements about
anticodons is incorrect?
a. Each type of tRNAs has a unique
anticodon.
b. There are specific anticodons that bind to
start and stop codons.
c. Each anticodon consists of three bases.
d. Anticodons may include modified bases.
e. Anticodon “wobble” pairing results in
degeneracy of the genetic code.
105. For double stranded DNA, which is NOT true?
a. [A] / [T] = 1
b. [C] / [G] = 1
c. [A] + [G] = [T] + [C]
d. [A] + [T] = [G] + [C]
e. [A] + [C] = [T] + [G]
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106. What is the name given to a molecule that
does not contain amino acids that is attached
to a protein?
a. enzyme
b. terminus
c. ligand
d. monoclonal antibody
e. prosthetic group
111. You have discovered a new mutant lab mouse
that is tailless. You breed your mouse to a
normal, tailed mouse and half of the offspring
are tailless. You then breed together a brother
and sister from this litter, both of whom are
tailless, and get about one-third tailled
offspring and two thirds tailless offspring.
What kind of mutant allele best explains these
results?
a. incompletely dominant
b. codominant in embryos
c. dominantly lethal in older adults
d. recessively lethal in embryos
e. most recessive allele in a series
107. Specificity and versatility of G-protein-linked
receptors is (are) due to:
a. the receptor.
b. the G-protein composition, especially the
alpha (a) subunit.
c. the final effector system, e.g. adenylyl
cyclase, ion channel, phospholipase C.
d. none of the above are correct.
e. all of the above are correct.
112. Following a carbohydrate rich meal, which of
the following would correctly describe the
metabolic state of your cells?
a. The pyruvate dehydrogenase (PDH)
complex would be phosphorylated and
inactive
b. Glycogen phosphorylase would be
phosphorylated and inactive
c. Fructose 2,6-bisphosphate will be
increased and fructose 1,6bisphosphatase (FBP1) will be inactive
d. Pyruvate carboxylase will be active
e. The TCA (tricarboxylic acid cycle) enzyme
malate dehydrogenase will favor the
production of malate
108. Polyribosomes (polysomes) present in the
cytosol:
a. consist of ribosomes that are different
from those bound to the rough
endoplasmic reticulum.
b. can make plasma membrane integral
membrane proteins.
c. can synthesize Golgi apparatus integral
membrane proteins.
d. can synthesize proteins that are secreted
in a regulated manner.
e. can synthesize mitochondrial proteins.
113. Which of the following statements concerning
the intestinal glucose-Na+ symport system is
FALSE?
a. The symport protein itself is a large
integral membrane protein with distinct
extracellular binding sites for Na+ and
glucose.
b. This symport system is an example of
secondary active transport.
c. Binding of Na+ and glucose to the symport
protein induces a conformational change
and creates a channel through which they
can be transported into the cytosol.
d. This symport system facilitates the
diffusion of glucose down its
concentration gradient and across the
apical membrane of an intestinal cell.
e. Inhibition of the Na+/K+-ATPase activity
with ouabain would ultimately cause this
symport system to cease functioning.
109. Which of the following-proteins is NOT found
on shuttle vesicles that transport proteins
from the cis to the medial Golgi apparatus?
a. sv-SNARE
b. coatomer
c. ARF
d. clathrin
e. Rab
110. You are a brilliant medical student who
discovers a new genetic disease that is
characterized by the absence of a key enzyme
of the citric acid cycle in mitochondria. You
work hard in the laboratory and discover that
the missing protein is synthesized in the
cytoplasm but fails to be targeted to its proper
site in mitochondria. You suspect that there is
a mutation in what?
a. the contact site
b. ATP synthetase
c. BiP
d. the amino terminus of the protein
e. the transmembrane domain of the protein
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114. A red blood cell (RBC) requires a constant
supply of NADPH and energy from the glucose
entering the cell. Which of the following lists
three enzymes necessary to meet the RBC’s
needs?
a. Hexokinase, transketolase, fructose 1,6bisphosphatase
b. Glucose 6-phosphate dehydrogenase,
pyruvate carboxylase, phosphoglycerate
kinase
c. Phosphoglycerate mutase, transaldolase,
phosphoenolpyruvate carboxykinase
d. Phosphoglucomutase, glucose 6phosphate dehydrogenase,
glyceraldehyde 3-phosphate
dehydrogenase
e. Glucose 6-phosphate dehydrogenase, 6phosphogluconate dehydrogenase,
phosphoglycerate kinase
118. Which of the following is an INCORRECT
description of a property of water?
a. Water has a low dielectric constant.
b. For a small molecule, water has a
relatively high melting and boiling point.
c. Water has a high heat capacity.
d. Water is a polar molecule with a high
dipole moment.
e. Water readily dissolves many ionic
compounds.
119. The term substrate level phosphorylation
applies to which glycolytic reactions?
a. Enolase and pyruvate kinase
b. Glyceraldehyde 3-phosphate
dehydrogenase and phosphoglycerate
kinase
c. Phosphoglycerate kinase and
phosphoglycerate mutase
d. Glucokinase and phosphoglucose
isomerase
e. Triose phosphate isomerase and
glyceraldehyde 3-phosphate
dehydrogenase
115. The nuclear envelope is the primary
determinant of nuclear stability and shape.
a. The nuclear lamina binds heterochromatin
during telophase.
b. The nucleolus is composed of lysozome
precursors.
c. A constant number of nucleoli is
maintained during interphase.
d. Ribosomal proteins are assembled with
ribosomal RNAs on the outer membrane
of the nuclear envelope near the nuclear
pores.
e. Nuclear proteins are secreted via the
default pathway.
120. Edman’s Deagradation uses what reagent to
initially react with the terminal amino acid?
a. Carboxypeptidase
b. Cyanogen bromide
c. Fluorodinitrobenzene
d. Phenyl isothiocyanate
e. Dicyclohexylcarbodiimide
116. Transport of soluble proteins greater than ~9
nm diameter into the nucleoplasm occurs:
a. through a mechanism identical to the
insertion of large proteins into the lumen
of the rough endoplasmic reticulum.
b. while the nuclear membrane is
dissociated during mitosis.
c. following synthesis on nuclear-bound
ribosomes.
d. by conformational changes that reduce
the diameter of the protein to less than 9
nm.
e. via a diaphragm-like opening of a pore in
the nuclear membrane.
117. A new disease has been described in which an
enzyme, a proteinase with a neutral pH
optimum, is secreted in large amounts from
liver cells. Which of the following statements
about this disease is TRUE?
a. The proteinase contains a KDEL sequence.
b. The proteinase binds to SKL receptors.
c. The proteinase is synthesized in the
cytosol.
d. The proteinase is an integral membrane
protein.
e. The proteinase is synthesized on bound
polysomes.
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Directions: Each group of questions below consists of five lettered headings followed by a list of numbered
words, phrases, or sentences. For each numbered word, phrase or sentence, select the one heading that is most
closely related to it and fill in completely the corresponding space on the answer sheet. One heading may be
used once, more than once, or not at all in each group.
Questions 121-125 refer to the following terms:
a.
b.
c.
d.
e.
Questions 136-138 refer to the following terms:
heterogametic sex
pseudoautosomal
codominance
pleiotropy
nondisjunction
a.
b.
c.
d.
e.
121. associated with mixed or combination
phenotypes in heterozygotes
122. when several phenotypes are affected by one
gene
123. specialized region of a sex chromosome that is
vital for meiotic pairing
124. failure of chromosomes to separate during cell
division
125. the sex that has a pair of heteromorphic
chromosomes
136. This protein complex mediates the action of
endogenous double-stranded microRNAs in
either translational interference or mRNA
degradation.
137. This protein can bind both a carbohydrate and
a specific sequence of DNA.
138. This protein plays a key role in converting
heterochromatin to euchromatin.
Questions 139-143 refer to the following terms:
Questions 126-130 refer to the following terms:
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
Primordial germ cell in embryo
Oogonium
Primary oocyte
Secondary oocyte
Ovum
126. Direct result of lutenizing hormone surge
127. Ovary-specific stem cell
128. Arrested in meiosis I
129. Maturation triggered by entry of sperm
130. Undifferentiated cells
DNA polymerase I
DNA polymerase III
RNA polymerase
polyA polymerase
telomerase
139. Does not require a primer (i.e. free 3’-OH of a
nucleotide). - c
140. Does not require a template.- d
141. Removes primers during DNA replication in E.
coli. -a
142. Exhibits three enzymatic activities: (i) 5’--->3’
DNA polymerase; (ii) 5’ --->3’ exonuclease; and
(iii) 3’ ---> 5’ exonuclease. - a
143. Uses RNA template for DNA synthesis. – e
Questions 131-135 refer to the following
molecules with their biological roles:
a.
b.
c.
d.
e.
A. Telomerase
B. Estrogen responsive element (ERE)
C. Histone acetyl transferase (HAT)
D. lac repressor protein
E. RNA-induced silencing complex (RISC)
starch
chitin
cellulose
peptidoglycan
hyaluronate
131. extracellular matrix of animal tissues
132. exoskeleton of insects
133. structural component of bacterial cell wall
134. carbohydrate storage in plants
135. structural component of plant cell walls
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Directions: Each group of questions below concerns a laboratory or an experimental situation. In each case, first
study the description of the situation. Then choose the one best answer to each question and fill in completely
the corresponding space on the answer sheet.
Questions 144-146
A person is brought into the emergency room suffering from incoordination, impaired reflexes, respiratory
distress and central nervous system depression. You quickly conclude that the patient has been poisoned
Working with the local police you learn that the patient’s wife is a noted biochemist. You suspect that she used
her expertise to deduce she could get rid of her husband by drastically increasing his dose of Lipitor, a cholesterol
lowering drug. You realize that this would lead to an almost complete loss of CoQ (also known as CoQ10 and
ubiquinol) and ultimately lead to complete mitochondrial dysfunction.
144. Given what you know about the electron transport chain, the loss of CoQ would limit the ability of which
complex or complexes to donate their reducing equivalents to the electron transport chain?
a. Complex I
b. Complex II
c. Complex III
d. A and B
e. All of the above
145. If you were able to isolate the mitochondria of the poisoned patient and measure their oxygen
consumption rates before (compared to a healthy sample) and after the addition 2,4 dinitrophenol (2,4
DNP, compared to no 2,4 DNP) what would you observe?
a.
b.
c.
d.
e.
O2 consumption
without 2,4 DNP
Compared to healthy sample
Near normal
Near normal
Suppressed
Suppressed
Increased
O2 consumption
Presence of 2,4 DNP
compared to sample before 2,4 DNP addition
unchanged
increased
unchanged
increased
unchanged
146. Given the relationship between the function of the electron transport chain and the utilization of reducing
equivalents, what glycolytic enzyme would most directly be affected by mitochondrial dysfunction caused
by the loss of CoQ?
a.
b.
c.
d.
e.
Phosphofructokinase 1
Glyceraldehyde 3-phosphate dehydrogenase
Phosphoglycerate kinase
Glucokinase
Enolase
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Questions 147-149
In muscle cells, Ca2+ is actively transported into the sarcoplasmic reticulum. The membranes of the sarcoplasmic
reticulum can be isolated in the form of microsomes. Each microsome contains several hundred molecules of an
enzyme that uses ATP as an energy source to drive the inward transport of calcium ions that are added
externally. In one experiment, the results shown below were obtained.
Experimental conditions:
1.0 ml of 0.1 M KCl containing:
5 mM MgCl2
5 mM ATP
0.1 mM CaCl2
0.1 mg protein (ATPase)
147. What is the rate of ATP hydrolysis, expressed as
micromoles of ATP hydrolyzed per milligram of
protein per minute?
a. 2
b. 1
c. 0.5
d. 0.25
e. 0.1
148. What is the ratio of calcium pumped per ATP
hydrolyzed?
a. 1:4
b. 1:2
c. 1:1
d. 2:1
e. 4:1
149. The specific activity for the ATPase enzyme is
expressed in units of
a. mole ATPase_sec−1
b. mole ATP_sec−1_mg protein−1
c. mole ADP_sec−1
d. mole ADP_sec−1_mg protein−1
e. mole ADP_sec−1_mole ATPase−1
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Questions 150-152
The graph below contains data obtained in an experiment designed to elucidate the mechanism of sucrose
uptake by the marine bacterium Vibrio alginolyticus. Sucrose uptake was determined by incubating washed cells
in [14C]-sucrose for short periods of time, harvesting, rewashing the cells, and measuring the sucrose present.
Uptake was measured in the presence of Na+, Na+ plus CCCP (an inhibitor of proton gradient formation), K+, and
Li+.
150. Based on the data, which of the following
statements best describes the uptake of
sucrose by
these cells?
a. Sucrose crosses the membrane by simple
diffusion.
b. Sucrose is transported by a carriermediated system.
c. Sucrose transport is not dependent on
Na+.
d. Sucrose transport occurs by only one
mechanism.
e. Sucrose is not transported into the cell
under most conditions.
152. Which of the following is the best explanation
for the effects of Li+ and K+ on the uptake of
sucrose?
a. These ions bind to sucrose and block its
entry into the cell.
b. These ions decrease the net Na+ available
in the cells for cotransport.
c. These ions uncouple the respiratory
process that generates energy for the
uptake of sucrose.
d. These ions are not transported rapidly by
the Na+/sucrose cotransporter system.
e. These ions are allosteric effectors of the
sucrose transporter system.
151. The primary reason for testing the effects of
CCCP is to determine whether
a. the effect of Li+ is dependent on Na+
b. a proton gradient is required for sucrose
transport
c. Na+ transport occurs alone
d. nonsaturable transport occurs
e. K+ can substitute for Na+ in sucrose
transport
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Questions 153-156
In experiments to determine possible metabolic side effects of a new industrial by-product X941, the rate of
respiratory oxygen consumption by isolated mitochondria was assayed. The mitochondria were maintained in a
solution containing high concentrations of dissolved oxygen and inorganic phosphate.
Figure 1 shows the results of a control experiment. Pyruvic acid, the principal metabolic precursor for the citric
acid cycle, was added to isolated mitochondria, followed a short time later by the addition of ADP. Figure 2
illustrates the effect of adding X941 instead of ADP.
153. Which of the following best explains why O2
concentration does not decrease until after
the addition of ADP, as shown in Figure 1 ?
a. The proton gradient that drives electron
transport can be produced only by
phosphorylation of ADP.
b. A complete turn of the citric acid cycle
requires several ADP’s directly.
c. ADP is a substrate, along with pyruvate,
for pyruvate dehydrogenase.
d. ADP is an allosteric activator of
cytochrome oxidase, which is unable to
transfer electrons to O2 without ADP.
e. The proton gradient produced by pyruvate
metabolism quickly inhibits electron
transport; the inhibition is released by ATP
synthesis.
155. In Figure 2, the addition of X941 results in the
nearly complete depletion of the O2 in the
assay mixture. A further test showed that this
depletion occurred even when inorganic
phosphate was omitted from the assay. The
most likely explanation for the effect of X941
is that X941
a. allows O2 to leak out of the mitochondria
b. is a precursor to the synthesis of ADP
c. uncouples ADP phosphorylation from
electron transport
d. serves as an alternative electron acceptor
in the system
e. serves as an allosteric activator of
pyruvate dehydrogenase
156. If X941 is an ionophore, which of the following
best describes its mode of action?
a. It rearranges the mitochondrial
membrane, thus allowing O2 to pick up
electrons of higher energy.
b. It allows O2 to diffuse through the inner
mitochondrial membrane more quickly.
c. It sequesters ions that are known to
inhibit the transfer of electrons to O2.
d. It allows protons to diffuse through the
inner mitochondrial membrane, thus
dissipating the proton gradient.
e. It acts as an electron donor, thus
providing the electron transport system
with a large number of electrons to
reduce O2.
154. Which of the following is the most likely
reason that O2 consumption stops a short
time after the addition of ADP, as shown in
Figure 1 ?
a. The O2 concentration has fallen to zero.
b. Most of the ADP has been
phosphorylated.
c. The mitochondria have burst from excess
ATP.
d. The pyruvate dehydrogenase activity has
been destroyed.
e. The electron transport system has been
denatured.
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Questions 157-159
Lymphocytes extracted from the rat kangaroo, Potorous tridactylus, were grown in culture for karyotype analysis.
To obtain chromosome spreads, such as that illustrated below, lymphocytes were incubated in the antimitotic
drug colchicine for 30 minutes before fixation and staining. The chromosomes depicted below are representative
of the karyotype found in all of the cells of the culture.
157. Which of the following correctly describes the
chromosome number in this rat kangaroo cell?
a. The haploid chromosome number is 12.
b. The haploid chromosome number is 24.
c. The diploid chromosome number is 12.
d. The diploid chromosome number is 24.
e. The triploid chromosome number is 24.
159. During S phase, DNA synthesis originates at
specific sequences in the chromosomal DNA.
How many sites for initiation of DNA synthesis
would be expected among the chromosomes
within the rat kangaroo karyotype during S
phase?
a. Fewer than 12
b. 12
c. Between 12 and 24
d. 24
e. More than 24
158. During anaphase, how many kinetochores
would be expected in a normal rat kangaroo
lymphocyte?
a. 12
b. 18
c. 24
d. 36
e. 48
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Questions 160-164
The diagram below is a pedigree of three generations showing the occurrence of two genetically-transmitted
diseases. Phenotypes of affected individuals are shown. Circles represent females, and squares represent males.
Assume that the diseases are rare, unlinked, and that individuals not blood related to I-a sad I-b (“in-laws") do
not have either disease-producing allele.
160. Which one of the following is true concerning
Individual I-a?
a. He is homozygous for Disease 1. and the
allele for this disease is autosomal
recessive.
b. He is heterozygous for Disease 1. and the
allele for this disease is X-linked recessive.
c. He is heterozygous for Disease 1. and the
allele for this disease is dominant.
d. He is heterozygous for Disease 1. and the
allele for this disease is recessive.
e. Cannot be determined from the
information gives
164. 5. In a certain randomly-mating population,
the frequency of the allele causing Disease 1 is
0.l. What would be the frequency of affected
individuals in this population?
a. 0.01
b. 0.l
c. 0.19
d. 0.9
e. 0.09
161. 2. The genotype of Individual l-h for Disease 2
is:
a. homozygous recessive.
b. heterozygous.
c. homozygous dominant.
d. spontaneous mutant
e. Not enough information to determine
162. 3. lf Individual III - r marries a normal man with
a homozygous wild-type genotype. what is the
probability that their son would have Disease
2?
a. 0
b. 1/4
c. 1/2
d. 3/4
e. 7/8
163. 4. If Individual III-v marries a normal man,
what is the probability that their son would be
afflicted by both diseases?
a. 0
b. 1/16
c. 1/8
d. 1/4
e. 1/2
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Questions 165-168
Some individuals suffer from an autosomal recessive disorder known as "alpha |-antitrypsin deficiency.” The
recessive homozygote for this disorder lacks the enzyme that ordinarily degrades trypsin. The genotype of the
recessive disorder may be designated as aa. Normal individuals are either homozygous dominant (AA) or
heterozygous carriers (Aa).
Enzymatic tests and colorimetric analysis reveal that a given individual possesses one of three distinct levels of
alpha,-antitrypsin enzyme activity. The data below show the levels of trypsin inhibited per milliliter of serum
(which contains the antitrypsin enzyme) in three different groups.
Group l: The general population
Group II: Several families in which some members have alpha,-antitrypsin deficiency
Group III: Patients with alpha,-antitrypsin deficiency
165. When the serum of an adult woman was
tested colorimetrically, a level of 0.5 milligram
of trypsin inhibited per milliliter of serum was
found. This can be interpreted as indicating
which of the following?
a. She is homozygous dominant.
b. She is an asymptomatic heterozygous
carrier.
c. She will exhibit alpha,-antitrypsin
deficiency.
d. She will always transmit the abnormal
recessive gene to her offspring.
e. Her mother was most likely homozygous
dominant.
167. The possible genotypes of a person possessing
a 0.2-milligram level of trypsin inhibited per
milliliter of serum include
a. AA only
b. Aa only
c. aa only
d. AA and Aa
e. Aa and aa
168. The distribution of values in the general
population can be interpreted to indicate that
a. heterozygous individuals (Aa) fail to
reproduce
b. affected offspring (aa) are derived largely
from matings of two recessive parents (aa
x aa)
c. the recessive gene (a) is lethal at birth
d. the recessive gene (a) is harbored mostly
in heterozygous individuals
e. the mutation process from A to a will lead
to a decrease in the number of recessive
genes
166. lf an offspring displays alpha,-antitrypsin
deficiency, then it can be reasonably predicted
that the phenotypically normal father would
have a value for trypsin inhibition of
a. 0,24 mg mL̄ 1
b. 0.50 mg mL̄ 1
c. 1.20 mg mL̄ 1
d. 1.60 mg mL̄ 1
e. 2.00 mg mL̄ 1
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Questions 169-172
To determine the intracellular pathways of three proteins, X, Y, and Z, four identical cultures of cells were
labeled with 3 H-amino acids for 5 minutes. One culture was harvested at the end of the 5-minute labeling
period. The other three cultures were rinsed and then were put into media with twentyfold excess of unlabeled
amino acids for I0 minutes, 20 minutes, and 30 minutes, respectively, before harvesting. After harvesting, the
cells were put on ice and broken open, and the cellular fractions were obtained by differential centrifugation. The
cellular fractions harvested include: mitochondria, rough endoplasmic reticulum (rough ER), Golgi apparatus,
plasma membranes, free ribosomes, and soluble cellular supernatant (cytosol). In each of these fractions, the
amount of newly synthesized protein was determined. The data, expressed as the percentage of the total newly
synthesized protein of a particular type in each fraction, were recorded in the table below.
169. The association of proteins X and Z with free ribosomes at a harvest time of 5 minutes indicates which of the
following about the proteins?
a. They are ribosomal proteins. b. They are at the site of synthesis.
c. They are glycosylated proteins.
d. There is an artifact in the measurement.
e. They are identical.
170. The inferred steps in the pathway of protein Y are correctly designated by which of the following?
a. Endoplasmic reticulum
Golgi apparatus
plasma membrane
plasma membrane
b.
Endoplasmic reticulum
Golgi apparatus
c.
Plasma membrane
d.
Plasma membrane
Golgi apparatus
endoplasmic reticulum
endoplasmic reticulum
Golgi apparatus
e.
Golgi apparatus
endoplasmic reticulum
171. Protein Z would be considered a
a. ribosomal protein
b. cytosolic protein
c. mitochondrial protein
d. Golgi apparatus protein
172. At a harvest time of 10 minutes, which of the following statements is correct about protein X compared with
protein Z `?
a. Protein X is synthesized more rapidly than protein Z.
b. Protein X is degraded more slowly than protein Z.
c. Protein X is degraded more rapidly than protein Z.
d. Protein X is released from ribosomes more slowly than protein Z.
e. Protein X is released from ribosomes more rapidly than protein Z.
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Questions 173-176
Nuclei from both the liver and brain cells of a rat are isolated and incubated with highly radioactive RNA
precursors. The RNA transcripts synthesized in these nuclei become radioactively labeled. These radioactive RNA
molecules are incubated with a single-stranded DNA segment (cDNA) complementary to an mRNA molecule
found in liver-cell cytoplasm but not brain-cell cytoplasm. The RNA and DNA are allowed to form RN AIDNA
hybrid double helices with the specific cDNA probe. An RNA-digesting enzyme is added to destroy RNA that is not
in hybrid form. Radioactivity in the remaining hybrids is measured as counts per minute.
The results are presented in the table below.
Incubation Components
Liver cDNA probe plus
primary RNA transcripts
from liver-cell nuclei
Liver cDNA probe plus
primary RNA transcripts
from brain-cell nuclei
Counts per Minute
15,000
150
173. Which of the following statements concerning
the DNA sequence corresponding to this liver
specific mRNA molecule is best supported by
the data?
a. It is transcribed in brain-cell nuclei only.
b. It is transcribed in both brain- and livercell nuclei at approximately the same rate.
c. It is not transcribed in brain-cell nuclei but
is transcribed in liver-cell nuclei.
d. It is not transcribed in either liver- or
brain- cell nuclei.
e. It may be transcribed in both brain- and
liver- cell nuclei but cannot be -detected
by this experimental procedure.
176. The regulation of the expression of mRNA in
the isolated nuclei from the two cell types as
demonstrated in this experiment is an
example of
a. translational control
b. mRNA degradation control
c. transcriptional control
d. transport control
e. lack of control
174. To produce radiolabeled transcripts, the
isolated nuclei from both liver and brain must
have which of the following?
a. DNA polymerase
b. RNA polymerase
c. Reverse transcriptase
d. Ribosomes
e. Plasmid DNA
175. To make the single-stranded cDNA used in this
experiment, which of the following enzymes
was required?
a. DNA polymerase
b. Reverse transcriptase
c. DNase
d. Protease
e. Protein kinase
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Questions 177-180
Two types of preparations from leaves were used to determine whether photosynthesis can provide energy for
synthesis of a particular chloroplast protein (CP). Identical amounts of 14C amino acids were introduced into
preparations of whole-cell homogenates and of isolated chloroplasts, each containing equal quantities of
chlorophyll. As indicated in the table below, reactions were carried out in light or dark. After each reaction was
terminated, labeled CP was isolated and counted. Additives used in treatments 5, 6, and 7 were supplied before
the introduction of 14C amino acids.
SYNTHESIS OF CHLOROPLAST PROTEIN (CP)
Treatment
1
2
3
4
5
6
7
Preparation
Chloroplasts
Chloroplasts
Whole-cell homogenates
Whole-cell homogenates
Chloroplasts
Chloroplasts
Chloroplasts
Condition
Dark
Light
Dark
Light
Dark
Light
Light
177. Which of the following is the best conclusion
from the results of treatments l and 2?
a. The synthesis of CP by chloroplasts
requires light.
b. The synthesis of CP by chloroplasts
requires photosynthesis.
c. The synthesis of CP by chloroplasts
requires dark.
d. Chloroplasts photosynthesize in the light.
e. Chloroplasts respire in the dark.
Additives
------------ATP
ATP
DCMU
Amino Acid Incorporation
(counts per minute/mg
chlorophyll/hr)
56
525,315
25,650
150,418
446,519
525,313
41,740
180. If treatments 1 and 2 are used as controls,
which of the following is the best conclusion
from the results of treatments 5 and 6?
a. Exogenous ATP has no effect on the
synthesis of CP in the light or in the dark.
b. Exogenous ATP stimulates the synthesis of
CP in the light above control levels.
c. Exogenous ATP stimulates CP synthesis in
whole-cell homogenates.
d. ATP inhibits the synthesis of CP.
e. ATP added to dark-incubated preparations
178. Which of the following is the best conclusion
from the results of treatments 1, 2, 3, and 4?
a. Whole-cell homogenates contain no
chloroplasts.
b. Whole-cell homogenates contain nuclei
and mitochondria.
c. In the dark, whole-cell homogenates make
no CP.
d. In the dark, whole-cell homogenates are
less effective than chloroplasts are in
synthesizing CP.
e. In the dark, a component of the whole-cell
homogenate is required for the synthesis
of CP.
181. Stimulates CP synthesis to a level about 85% of
that in the light. Which of the following can be
best concluded about the added DCMU, a
known inhibitor of photosystem lI ?
a. It blocked all photosynthetic ATP
formation and, since some CP synthesis
remained, ATP is not required for the
process.
b. It blocked ATP formation associated with
noncyclic electron flow, but probably not
that associated with cyclic electron flow.
c. It is required for the synthesis of CP.
d. It would probably increase the synthesis
of CP in whole-cell homogenates.
e. It would probably increase the synthesis
of CP by chloroplasts in the dark.
179. Which of the following is the best conclusion
about whole-cell homogenates in the light?
a. They have mitochondria and nuclei that
code for the synthesis of CP.
b. They photosynthesize more than isolated
chloroplasts do.
c. They make some intermediate needed for
the synthesis of CP in smaller amounts
than are made in the dark.
d. They make some component needed for
the synthesis of CP in larger amounts than
are made in the dark.
e. They make none of the intermediates
needed for the synthesis of CP.
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Worksheet for the Biochemistry Test Only
Answer Key and Percentages* of Examinees Answering Each Question Correctly
Question
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
 181 B
Answer
A
B
B
E
D
B
C
B
C
E
B
E
C
A
D
C
C
D
E
D
B
B
C
C
B
E
B
B
E
E
E
D
A
A
B
B
E
A
B
D
A
A
C
C
D
A
A
D
C
D
E
C
C
D
D
A
B
B
A
B
Question
Number
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
Answer
C
E
B
B
B
C
D
C
E
B
D
B
A
B
D
B
B
B
D
A
D
D
D
D
B
C
B
B
B
C
B
C
E
E
C
D
B
D
C
B
D
A
C
C
D
E
E
E
D
D
D
C
D
E
A
E
E
A
B
D
Question
Number
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
Answer
C
D
B
E
A
E
B
C
D
D
E
B
D
A
C
E
D
C
C
D
A
A
E
D
C
B
C
D
D
B
B
D
E
B
C
D
C
C
E
C
B
C
C
C
B
B
C
D
B
A
C
D
C
B
B
C
A
E
D
E
Total correct: _________
Total Incorrect: ________
Score: ____________
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