Name: 
 

ap unit5 molecularbio study guide250


Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. This is because
a.
proteins have a greater variety of three-dimensional forms than does DNA.
b.
proteins have two different levels of structural organization; DNA has four.
c.
proteins are made of 20 amino acids and DNA is made of four nucleotides.
d.
Only A and C are correct.
e.
A, B, and C are correct.
 

 2. 
In his transformation experiments, Griffith observed that
a.
mutant mice were resistant to bacterial infections.
b.
mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
c.
mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic.
d.
infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains.
e.
mice infected with a pathogenic strain of bacteria can spread the infection to other mice.
 

 3. 
What does transformation involve in bacteria?
a.
the creation of a strand of DNA from an RNA molecule
b.
the creation of a strand of RNA from a DNA molecule
c.
the infection of cells by a phage DNA molecule
d.
the type of semiconservative replication shown by DNA
e.
assimilation of external DNA into a cell
 

 4. 
Avery and his colleagues purified various chemicals from pathogenic bacteria and showed that ____ was (were) the transforming agent.
a.
DNA
b.
protein
c.
lipids
d.
carbohydrates
e.
phage
 

 5. 
The following scientists made significant contributions to our understanding of the structure and function of DNA. Place the scientists' names in the correct chronological order, starting with the first scientist(s) to make a contribution.

I.Avery, McCarty, and MacLeod
II.Griffith
III.Hershey and Chase
IV.Meselson and Stahl
V.Watson and Crick

a.
V, IV, II, I, III
b.
II, I, III, V, IV
c.
I, II, III, V, IV
d.
I, II, V, IV, III
e.
II, III, IV, V, I
 

 6. 
After mixing a heat-killed, phosphorescent strain of bacteria with a living non-phosphorescent strain, you discover that some of the living cells are now phosphorescent. The best evidence that the ability to fluoresce is a heritable trait would be an observation that
a.
DNA passed from the heat-killed strain to the living strain.
b.
protein passed from the heat-killed strain to the living strain.
c.
the phosphorescence in the living strain is especially bright.
d.
descendants of the living cells are also phosphorescent.
e.
both DNA and protein passed from the heat-killed strain to the living strain.
 

 7. 
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?
a.
There is no radioactive isotope of nitrogen.
b.
Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long.
c.
Meselson and Stahl already did this experiment.
d.
Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive.
e.
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
 
 
Match the investigator(s) to the appropriate discovery of about the nature of genes.

A. Frederick Griffith
B. Alfred Hershey and Martha Chase
C. Oswald Avery, Maclyn McCarty, and Colin MacLeod
D. Erwin Chargaff
E. Matthew Meselson and Franklin Stahl
 

 8. 
Chemicals from heat-killed S cells were purified. The chemicals were tested for the ability to transform live R cells. The transforming agent was found to be DNA.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 9. 
Phage with labeled proteins or DNA was allowed to infect bacteria. It was shown that the DNA, but not the protein, entered the bacterial cells, and was therefore the genetic material.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 10. 
When T2 phages infect bacteria and make more viruses in the presence of radioactive sulfur, what is the result?
a.
The viral DNA will be radioactive.
b.
The viral proteins will be radioactive.
c.
The bacterial DNA will be radioactive.
d.
both A and B
e.
both A and C
 

 11. 
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately, what percentage of the nucleotides in this sample will be thymine?
a.
12
b.
24
c.
31
d.
38
e.
It cannot be determined from the information provided.
 

 12. 
Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that
a.
the relative proportion of each of the four bases differs from species to species.
b.
the human genome is more complex than that of other species.
c.
the amount of A is always equivalent to T, and C to G.
d.
both A and C
e.
both B and C
 

 13. 
All of the following can be determined directly from X-ray diffraction photographs of crystallized DNA except the
a.
diameter of the helix.
b.
helical shape of DNA.
c.
sequence of nucleotides.
d.
spacing of the nitrogenous bases along the helix.
e.
number of strands in a helix.
 

 14. 
The DNA double helix has a uniform diameter because ____, which have two rings, always pair with ____, which have one ring.
a.
purines; pyrimidines
b.
pyrimidines; purines
c.
deoxyribose sugars; ribose sugars
d.
ribose sugars; deoxyribose sugars
e.
nucleotides; nucleoside triphosphates
 

 15. 
What kind of chemical bond is found between paired bases of the DNA double helix?
a.
hydrogen
b.
ionic
c.
covalent
d.
sulfhydryl
e.
phosphate
 

 16. 
It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in its
a.
sequence of bases.
b.
phosphate-sugar backbones.
c.
complementary pairing of bases.
d.
side groups of nitrogenous bases.
e.
different five-carbon sugars.
 

 17. 
In an analysis of the nucleotide composition of DNA, which of the following is true?
a.
A = C
b.
A = G and C = T
c.
A + C = G + T
d.
G + A = T + C
e.
both C and D
 

 18. 
Which of the following statements is false when comparing prokaryotes with eukaryotes?
a.
The prokaryotic chromosome is circular, whereas eukaryotic chromosomes are linear.
b.
Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.
c.
The rate of elongation during DNA replication is higher in prokaryotes than in eukaryotes.
d.
Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.
e.
Eukaryotes have telomeres, and prokaryotes do not.
 

 19. 
The strands that make up DNA are antiparallel. This means that
a.
the twisting nature of DNA creates nonparallel strands.
b.
the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
c.
base pairings create unequal spacing between the two DNA strands.
d.
one strand is positively charged and the other is negatively charged.
e.
one strand contains only purines and the other contains only pyrimidines.
 
 
Use the figure below to answer the following questions.

nar002-1.jpg
 

 20. 
In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure above would be expected after one DNA replication in the presence of 14N?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 21. 
A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium. Which pattern in the figure above would you expect if the DNA was replicated in a conservative manner?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 22. 
Which of the following is least related to the others on the list?
a.
Okazaki fragments
b.
replication fork
c.
telomerase
d.
DNA polymerase
e.
semiconservative model
 

 23. 
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
a.
leading strands and Okazaki fragments.
b.
lagging strands and Okazaki fragments.
c.
Okazaki fragments and RNA primers.
d.
leading strands and RNA primers.
e.
RNA primers and mitochondrial DNA.
 
 
Refer to the list of enzymes below to answer the following questions. The answers may be used once, more than once, or not at all.

A. helicase
B. nuclease
C. ligase
D. DNA polymerase I
E. primase
 

 24. 
removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments
a.
A
b.
B
c.
C
d.
D
e.
E
 

 25. 
covalently connects segments of DNA
a.
A
b.
B
c.
C
d.
D
e.
E
 

 26. 
synthesizes short segments of RNA
a.
A
b.
B
c.
C
d.
D
e.
E
 

 27. 
DNA-cutting enzymes used in the repair of DNA damage
a.
A
b.
B
c.
C
d.
D
e.
E
 

 28. 
The Y-shaped structure where the DNA double helix is actively unwound during DNA replication is called the
a.
replication fork.
b.
replication Y.
c.
elongation junction.
d.
unwinding point.
e.
Y junction.
 

 29. 
The leading and the lagging strands differ in that
a.
the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
b.
the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.
c.
the leading strand is synthesized continuously, whereas the lagging strand is synthesized in short fragments that are ultimately stitched together.
d.
both A and B
e.
both A and C
 

 30. 
Which of the following best describes the addition of nucleotides to a growing DNA chain?
a.
A nucleoside triphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate.
b.
A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate.
c.
A nucleoside diphosphate is added to the 5' end of the DNA, releasing a molecule of phosphate.
d.
A nucleoside diphosphate is added to the 3' end of the DNA, releasing a molecule of phosphate.
e.
A nucleoside monophosphate is added to the 3' end of the DNA.
 

 31. 
A new DNA strand elongates only in the 5' to 3' direction because
a.
DNA polymerase begins adding nucleotides at the 5' end of the template.
b.
Okazaki fragments prevent elongation in the 3' to 5' direction.
c.
the polarity of the DNA molecule prevents addition of nucleotides at the 3' end.
d.
replication must progress toward the replication fork.
e.
DNA polymerase can only add nucleotides to the free 3' end.
 

 32. 
Replicating the lagging strand of DNA-that is, adding bases in the 3' mc032-1.jpg 5' direction-utilizes which of the following?
a.
DNA ligase
b.
RNA primers
c.
Okazaki fragments
d.
A and B only
e.
A, B, and C
 

 33. 
What kind of molecule or substance is the primer that is used to initiate the synthesis of a new DNA strand?
a.
RNA
b.
DNA
c.
protein
d.
phosphate
e.
sulfur
 

 34. 
What is the function of topoisomerase?
a.
relieving strain in the DNA ahead of the replication fork
b.
elongation of new DNA at a replication fork by addition of nucleotides to the existing chain
c.
the addition of methyl groups to bases of DNA
d.
unwinding of the double helix
e.
stabilizing single-stranded DNA at the replication fork
 

 35. 
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
a.
synthesize RNA nucleotides to make a primer
b.
catalyze the lengthening of telomeres
c.
join Okazaki fragments together
d.
unwind the parental double helix
e.
stabilize the unwound parental DNA
 

 36. 
All of the following are functions of DNA polymerase in DNA replication except
a.
covalently adding nucleotides to the new strands.
b.
proofreading each added nucleotide for correct base pairing.
c.
replacing RNA primers with DNA.
d.
initiating a polynucleotide strand.
e.
none of the above
 

 37. 
Which of the following help to hold the DNA strands apart while they are being replicated?
a.
primase
b.
ligase
c.
DNA polymerase
d.
single-strand binding proteins
e.
exonuclease
 

 38. 
Which of these mechanisms ensures that the DNA sequence in the genome remains accurate?
a.
proofreading during DNA replication
b.
mismatch repair
c.
excision repair
d.
complementary base pairing during DNA replication
e.
all of the above
 

 39. 
Which of the following is analogous to telomeres?
a.
the pull tab on a soft drink can
b.
the two ends of a shoelace
c.
the central spindle that a CD fits around while in the case
d.
the mechanism of a zipper that allows the separated parts to be joined
e.
the correct letters used to replace errors in a document after they have been deleted in a word processor
 

 40. 
Which of the following statements about telomeres is correct?
a.
They contain multiple copies of a short RNA sequence.
b.
They are present at the ends of eukaryotic chromosomes.
c.
They can be extended by an enzyme called telomerase.
d.
both A and B
e.
both B and C
 

 41. 
Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because
a.
genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.
b.
enzymes are made of DNA, and affected individuals lack DNA polymerase.
c.
many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA.
d.
certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors.
e.
metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.
 
 
The following questions refer to the following simple metabolic pathway:

enzyme A
enzyme B
nar004-1.jpg
nar004-2.jpg
 

 42. 
According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?
a.
0
b.
1
c.
2
d.
3
e.
It cannot be determined from the pathway.
 

 43. 
A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?
a.
an accumulation of A and no production of B and C
b.
an accumulation of A and B and no production of C
c.
an accumulation of B and no production of A and C
d.
an accumulation of B and C and no production of A
e.
an accumulation of C and no production of A and B
 

 44. 
If A, B, and C are all required for growth, a strain mutant for the gene encoding enzyme B would be capable of growing on which of the following media?
a.
minimal medium
b.
minimal medium supplemented with "A"
c.
minimal medium supplemented with "B"
d.
minimal medium supplemented with "C"
e.
answers B and C
 

 45. 
Which of the following represents a similarity between RNA and DNA?
a.
Both are double-stranded.
b.
the presence of uracil
c.
the presence of an OH group on the 2' carbon of the sugar
d.
nucleotides consisting of a phosphate, sugar, and nitrogenous base
e.
Both are found exclusively in the nucleus.
 

 46. 
The nitrogenous base adenine is found in all members of which group?
a.
proteins, triglycerides, and testosterone
b.
proteins, ATP, and DNA
c.
ATP, RNA, and DNA
d.
alpha glucose, ATP, and DNA
e.
proteins, carbohydrates, and ATP
 

 47. 
A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is
a.
AGT.
b.
UGA.
c.
TCA.
d.
ACU.
e.
either UCA or TCA, depending on wobble in the first base
 
 
Use the table of condons below to answer the following questions.

nar005-1.jpg
 

 48. 
What amino acid sequence will be generated, based on the following mRNA codon sequence?
5'AUG-UCU-UCG-UUA-UCC-UUG
a.
met-arg-glu-arg-glu-arg
b.
met-glu-arg-arg-gln-leu
c.
met-ser-leu-ser-leu-ser
d.
met-ser-ser-leu-ser-leu
e.
met-leu-phe-arg-glu-glu
 

 49. 
A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA codes for this peptide?
a.
3' UUU-CCC-AAA-GGG-UUU-CCC
b.
3' AUG-AAA-GGG-TTT-CCC-AAA-GGG
c.
5' TTT-CCC-AAA-GGG-TTT-CCC
d.
5' GGG-AAA-TTT-AAA-CCC-ACT-GGG
e.
5' ACT-TAC-CAT-AAA-CAT-TAC-UGA
 

 50. 
A codon
a.
consists of two nucleotides.
b.
may code for the same amino acid as another codon.
c.
consists of discrete amino acid regions.
d.
catalyzes RNA synthesis.
e.
is found in all eukaryotes, but not in prokaryotes.
 

 51. 
If the triplet CCC codes for the amino acid proline in bacteria, then in plants CCC should code for
a.
leucine.
b.
valine.
c.
cystine.
d.
phenylalanine.
e.
proline.
 

 52. 
Which of the following are transcribed from DNA?
a.
protein
b.
exons
c.
rRNA
d.
B and C only
e.
A, B, and C
 

 53. 
RNA polymerase and DNA polymerase differ in that
a.
RNA polymerase uses RNA as a template, and DNA polymerase uses a DNA template.
b.
RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to double-stranded DNA.
c.
RNA polymerase is much more accurate than DNA polymerase.
d.
RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.
e.
RNA polymerase does not need to separate the two strands of DNA in order to synthesize an RNA copy, whereas DNA polymerase must unwind the double helix before it can replicate the DNA.
 

 54. 
Which of the following is not a part of the eukaryotic transcription initiation complex?
a.
promoter
b.
RNA polymerase
c.
transcription factors
d.
snRNP
e.
TATA box
 

 55. 
Which of the following is least related to the other items?
a.
translation
b.
TATA box
c.
transcription
d.
template strand
e.
RNA polymerase II
 

 56. 
Which of the following statements best describes the termination of transcription in prokaryotes?
a.
RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase.
b.
RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript.
c.
RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript.
d.
Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome.
e.
RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.
 

 57. 
RNA polymerase moves along the template strand of DNA in the ____ direction, and adds nucleotides to the ____ end of the growing transcript.
a.
3' to 5'; 5'
b.
3' to 5'; 3'
c.
5' to 3'; 5'
d.
5' to 3'; 3'
 

 58. 
All of the following are found in prokaryotic mRNA except
a.
the AUG codon.
b.
the UGA codon.
c.
introns.
d.
uracil.
e.
cytosine.
 

 59. 
Which of the following helps to stabilize mRNA by inhibiting its degradation?
a.
TATA box
b.
spliceosomes
c.
5' cap
d.
poly-A tail
e.
both C and D
 

 60. 
Introns are significant to biological evolution because
a.
their presence allows exons to be moved around more easily, creating proteins with new combinations of functional domains.
b.
they protect the mRNA from degeneration.
c.
they are translated into essential amino acids.
d.
they maintain the genetic code by preventing incorrect DNA base pairings.
e.
they correct enzymatic alterations of DNA bases.
 

 61. 
A mutation in which of the following parts of a gene is likely to be most damaging to a cell?
a.
intron
b.
exon
c.
5' UTR
d.
3' UTR
e.
All would be equally damaging.
 

 62. 
Which of the following is (are) true of snRNPs?
a.
They are made up of both protein and RNA.
b.
They bind to splice sites at each end of the intron.
c.
They join together to form a large structure called the spliceosome.
d.
Only A and C are true.
e.
A, B, and C are true
 

 63. 
All of the following are directly involved in translation except
a.
mRNA.
b.
tRNA.
c.
ribosomes.
d.
DNA.
e.
aminoacyl-tRNA synthetase enzymes.
 

 64. 
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
a.
TTT.
b.
UUA.
c.
UUU.
d.
AAA.
e.
either UAA or TAA, depending on first base wobble.
 

 65. 
What is an anticodon part of?
a.
DNA
b.
tRNA
c.
mRNA
d.
a ribosome
e.
an activating enzyme
 

 66. 
A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form.

tRNA Anticodon
Amino Acid
GGC
Proline
CGU
Alanine
UGC
Threonine
CCG
Glycine
ACG
Cysteine
CGG
Alanine

The dipeptide that will form will be
a.
cysteine-alanine.
b.
proline-threonine.
c.
glycine-cysteine.
d.
alanine-alanine.
e.
threonine-glycine.
 

 67. 
The figure below represents tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid?

mc067-1.jpg

a.
UGG
b.
GUG
c.
GUA
d.
UUC
e.
CAU
 

 68. 
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
a.
some tRNAs have anticodons that recognize two or more different codons.
b.
the rules for base pairing between the third base of a codon and tRNA are flexible.
c.
many codons are never used, so the tRNAs that recognize them are dispensable.
d.
A and B only
e.
A, B, and C
 

 69. 
What are ribosomes composed of?
a.
rRNA only
b.
proteins only
c.
both rRNA and protein
d.
mRNA, rRNA, and protein
e.
mRNA, tRNA, rRNA, and protein
 

 70. 
Where is eukaryotic ribosomal RNA transcribed?
a.
the Golgi apparatus
b.
ribosomes
c.
the nucleolus
d.
X chromosomes
e.
prokaryotic cells only
 

 71. 
What is the most abundant type of RNA?
a.
mRNA
b.
tRNA
c.
rRNA
d.
pre-mRNA
e.
hnRNA
 

 72. 
From the following list, which is the first event in translation in eukaryotes?
a.
elongation of the polypeptide
b.
base pairing of activated methionine-tRNA to AUG of the messenger RNA
c.
binding of the larger ribosomal subunit to smaller ribosomal subunits
d.
covalent bonding between the first two amino acids
e.
Both B and D occur simultaneously.
 

 73. 
Choose the answer that has these events of protein synthesis in the proper sequence.
1. An aminoacyl-tRNA binds to the A site.
2. A peptide bond forms between the new amino acid and a polypeptide chain.
3. tRNA leaves the P site, and the P site remains vacant.
4. A small ribosomal subunit binds with mRNA.
5. tRNA translocates to the P site.
a.
1, 3, 2, 4, 5
b.
4, 1, 2, 5, 3
c.
5, 4, 3, 2, 1
d.
4, 1, 3, 2, 5
e.
2, 4, 5, 1, 3
 

 74. 
Which of the following is not directly involved in the process of translation?
a.
ligase
b.
tRNA
c.
rRNA
d.
mRNA
e.
aminoacyl-tRNA synthetase
 

 75. 
Which of the following components are present upon the completion of translation initiation?
a.
small ribosomal subunit
b.
large ribosomal subunit
c.
initiator tRNA
d.
A and C only
e.
A, B, and C
 

 76. 
During translation, chain elongation continues until what happens?
a.
No further amino acids are needed by the cell.
b.
All tRNAs are empty.
c.
The polypeptide is long enough.
d.
A stop codon is encountered.
e.
The ribosomes run off the end of mRNA.
 

 77. 
As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?
a.
The tRNA that was in the A site moves into the P site.
b.
The tRNA that was in the P site moves into the A site.
c.
The tRNA that was in the P site moves to the E site and is released.
d.
The tRNA that was in the A site departs from the ribosome.
e.
Both A and C are correct.
 

 78. 
What are polyribosomes?
a.
groups of ribosomes reading a single mRNA simultaneously
b.
ribosomes containing more than two subunits
c.
multiple copies of ribosomes associated with giant chromosomes
d.
aggregations of vesicles containing ribosomal RNA
e.
ribosomes associated with more than one tRNA
 

 79. 
What is one function of a signal peptide?
a.
to direct an mRNA molecule into the cisternal space of the ER
b.
to bind RNA polymerase to DNA and initiate transcription
c.
to terminate translation of the messenger RNA
d.
to translocate polypeptides across the ER membrane
e.
to signal the initiation of transcription
 

 80. 
Which of the following is least related to the other items?
a.
exons
b.
introns
c.
RNA splicing
d.
signal-recognition particles (SRPs)
e.
mRNA
 

 81. 
Which of the following is not related to ribosomal activity?
a.
A site
b.
spliceosome
c.
codon recognition
d.
peptide bond formation
e.
P site
 

 82. 
When does translation begin in prokaryotic cells?
a.
after a transcription initiation complex has been formed
b.
during transcription
c.
after the 5' caps are converted to mRNA
d.
once the pre-mRNA has been converted to mRNA
e.
as soon as the DNA introns are removed from the template
 

 83. 
Which of the following statements are true about protein synthesis in prokaryotes?
a.
Translation can begin while transcription is still in progress.
b.
Extensive RNA processing is required before prokaryotic transcripts can be translated.
c.
Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles.
d.
Only A and B are true.
e.
A, B, and C are true.
 

 84. 
Of the following types of mutations, which one is likely to be the most common?
a.
point mutation
b.
missense mutation
c.
base-pair substitution
d.
nonsense mutation
e.
frameshift mutation
 
 
Each of the following is a modification of the sentence THECATATETHERAT.

A.THERATATETHECAT
B. THETACATETHERAT
C. THECATARETHERAT
D. THECATATTHERAT
E. CATATETHERAT
 

 85. 
Which of the above is analogous to a frameshift mutation?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 86. 
Which of the above is analogous to a single substitution mutation?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 87. 
Sickle-cell disease is probably the result of which kind of mutation?
a.
point
b.
frameshift
c.
nonsense
d.
nondisjunction
e.
both B and D
 

 88. 
A frameshift mutation could result from
a.
a base insertion only.
b.
a base deletion only.
c.
a base substitution only.
d.
deletion of three consecutive bases.
e.
either an insertion or a deletion of a base.
 

 89. 
Which of the following DNA mutations is the most likely to be damaging to the protein it specifies?
a.
a base-pair deletion
b.
a codon substitution
c.
a substitution in the last base of a codon
d.
a codon deletion
e.
a point mutation
 

 90. 
Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?
a.
a base substitution
b.
a base deletion near the start of a gene
c.
a base deletion near the end of the coding sequence, but not in the terminator codon
d.
deletion of three bases near the start of the coding sequence, but not in the initiator codon
e.
a base insertion near the end of the coding sequence, but not in the terminator codon
 

 91. 
Which of the following is (are) true about viruses?
a.
Viruses are classified below the cellular level of biological organization.
b.
A single virus particle contains both DNA and RNA.
c.
Even small virus particles are visible with light microscopes.
d.
Only A and B are true.
e.
A, B, and C are true.
 

 92. 
Which of the following is not a reason scientists suspected that something other than bacteria was the cause of tobacco mosaic disease?
a.
Passing infectious sap through a fine filter failed to remove the infectious agent.
b.
Treating infectious sap with alcohol failed to remove the infectious agent.
c.
No cells could be seen in the infectious sap using a light microscope.
d.
The infectious agent in the sap could reproduce, as its ability to cause disease was undiluted even after many transfers from plant to plant.
e.
The infectious agent could not be cultivated on nutrient media in petri dishes or in test tubes.
 

 93. 
Which of the following is a characteristic of all viruses?
a.
a nucleic acid genome
b.
a protein capsid
c.
a viral envelope
d.
A and B only
e.
A, B, and C
 

 94. 
Viral genomes can consist of any of the following except
a.
double-stranded DNA.
b.
double-stranded RNA.
c.
single-stranded DNA.
d.
single-stranded RNA.
e.
helical capsomeres.
 

 95. 
The host range of a virus is determined by
a.
the proteins on its surface.
b.
whether its nucleic acid is DNA or RNA.
c.
the proteins on the surface of the host cell.
d.
the enzymes produced by the virus before it infects the cell.
e.
both A and C
 

 96. 
Viruses are referred to as obligate parasites because
a.
they cannot reproduce outside of a host cell.
b.
viral DNA always inserts itself into host DNA.
c.
they invariably kill any cell they infect.
d.
they can incorporate nucleic acids from other viruses.
e.
they must use enzymes encoded by the virus itself.
 

 97. 
Which of the following is characteristic of the lytic cycle?
a.
Many bacterial cells containing viral DNA are produced.
b.
Viral DNA is incorporated into the host genome.
c.
The viral genome replicates without destroying the host.
d.
A large number of phages are released at a time.
e.
The virus-host relationship usually lasts for generations.
 

 98. 
Bacteriophage DNA that have become integrated into the host cell chromosome are called
a.
intemperate bacteriophages.
b.
transposons.
c.
prophages.
d.
T-even phages.
e.
plasmids.
 

 99. 
Which of the following statements about the lysogenic cycle of lambda (mc099-1.jpg. phage is incorrect?
a.
After infection the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses.
b.
Most of the prophage genes are silenced by the product of a particular prophage gene.
c.
The phage genome replicates along with the host genome.
d.
Certain environmental triggers can cause the phage to exit the host genome, switching from the lysogenic to the lytic cycle.
e.
The phage DNA is incorporated by genetic recombination (crossing over. into a specific site on the host cell's DNA.
 

 100. 
What is the function of the single-stranded RNA in certain animal viruses?
a.
It can serve directly as mRNA.
b.
It can serve as a template for mRNA synthesis.
c.
It can serve as a template for DNA synthesis.
d.
Only A and C are correct.
e.
A, B, and C are correct.
 

 101. 
Viruses with single-stranded RNA that acts as a template for DNA synthesis are known as
a.
retroviruses.
b.
proviruses.
c.
viroids.
d.
bacteriophages.
e.
lytic phages.
 

 102. 
What is the function of reverse transcriptase in retroviruses?
a.
It hydrolyzes the host cell's DNA.
b.
It uses viral RNA as a template for DNA synthesis.
c.
It converts host cell RNA into viral DNA.
d.
It translates viral RNA into proteins.
e.
It uses viral RNA as a template for making complementary RNA strands.
 

 103. 
The membrane making up the viral envelope can come from
a.
the virus itself, using enzymes encoded by the virus.
b.
the nuclear membrane of an infected cell.
c.
the plasma membrane of an infected cell.
d.
both A and B
e.
both B and C
 

 104. 
Viral envelopes contain proteins with covalently attached carbohydrate groups called
a.
glycoproteins.
b.
proteosugars.
c.
carbopeptides.
d.
peptidocarbs.
e.
carboproteins.
 

 105. 
The simplest infectious biological systems are
a.
bacteria.
b.
viruses.
c.
viroids.
d.
both A and B
e.
both B and C
 

 106. 
Which of the following is a true statement?
a.
Viruses are uncommon.
b.
Viruses can cause diarrhea, colds, and measles.
c.
All viruses have a similar capsid and membranous envelope.
d.
All viruses contain the nucleic acid RNA.
e.
Viruses only invade animal cells.
 

 107. 
Which of the following can be effective against viral diseases?
a.
vaccination
b.
nucleoside analogs that inhibit DNA synthesis
c.
antibiotics
d.
A and B only
e.
A, B, and C
 

 108. 
RNA viruses appear to have higher rates of mutation because
a.
RNA nucleotides are more unstable than DNA nucleotides.
b.
replication of their genomes does not involve the proofreading steps of DNA replication.
c.
RNA viruses replicate faster.
d.
RNA viruses can incorporate a variety of nonstandard bases.
e.
RNA viruses are more sensitive to mutagens.
 
 
Refer to the treatments listed below to answer the following questions.

You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.

I.treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious
II.filtering the substance to remove all elements smaller than what can be easily seen under a light microscope
III.culturing the substance by itself on nutritive medium, away from any plant cells
IV.treating the sample with proteases that digest all proteins and then determining whether it is still infectious
 

 109. 
If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?
a.
I
b.
II
c.
III
d.
IV
e.
either II or IV
 

 110. 
Which treatment would you use to determine if the agent is a prion?
a.
I only
b.
II only
c.
III only
d.
IV only
e.
either I or IV
 

 111. 
Which of the following contributes to the emergence of viral disease?
a.
production of new virus strains through mutation
b.
spread of existing virus from one host species to another
c.
transformation from lytic to lysogenic activity
d.
A and B only
e.
A, B, and C
 

 112. 
Which of the following is true of plant virus infections?
a.
They can be controlled by the use of antibiotics.
b.
They are spread throughout a plant by passing through the plasmodesmata.
c.
They have little effect on plant growth.
d.
Only A and B are correct.
e.
A, B, and C are correct.
 

 113. 
Which of the following represents a difference between viruses and viroids?
a.
Viruses infect many types of cells, whereas viroids infect only prokaryotic cells.
b.
Viruses have capsids composed of protein, whereas viroids have no capsids.
c.
Viruses contain introns; viroids have only exons.
d.
Viruses always have genomes composed of DNA, whereas viroids always have genomes composed of RNA.
e.
Viruses cannot pass through plasmodesmata; viroids can.
 

 114. 
The difference between vertical and horizontal transmission of plant viruses is that
a.
vertical transmission refers to the transmission of a virus from a parent plant to its progeny, and horizontal transmission refers to one plant spreading the virus to another plant.
b.
vertical transmission refers to the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission refers to the spread of a virus among leaves at the same general level.
c.
vertical transmission refers to the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission refers to the spread of viruses among plants of similar size.
d.
vertical transmission refers to the transfer of DNA from one type of plant virus to another, and horizontal transmission refers to the exchange of DNA between two plant viruses of the same type.
e.
vertical transmission refers to the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission refers to the spread of viruses among plants of the same species.
 

 115. 
What are prions?
a.
misfolded versions of normal brain protein
b.
tiny molecules of RNA that infect plants
c.
viral DNA that has had to attach itself to the host genome
d.
viruses that invade bacteria
e.
a mobile segment of DNA
 

 116. 
Reproduction in bacteria requires
a.
the production of a mitotic spindle.
b.
a plasmid.
c.
cyclic AMP.
d.
replication of DNA.
e.
both B and D
 

 117. 
What is the most common source of genetic diversity in a bacterial colony?
a.
transposons
b.
plasmids
c.
meiotic recombination
d.
crossing over
e.
mutation
 
 
Use the following answers for the following questions. The answers may be used once, more than once, or not at all.

A. transduction
B. transposition
C. translation
D. transformation
E. conjugation
 

 118. 
External DNA is assimilated by a cell.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 119. 
DNA is transferred from one bacterium to another by a virus.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 120. 
In biotechnology, genes are commonly introduced into bacterial cells by incubating the cells together with DNA and high concentrations of calcium ions. This is an example of
a.
transformation.
b.
translocation.
c.
transduction.
d.
conjugation.
e.
transposition.
 

 121. 
An Hfr bacterium is one that has
a.
at least one plasmid present in the cytosol.
b.
a special recognition site that will take up closely related DNA from its environment.
c.
several insertion sequences scattered throughout its chromosome.
d.
several copies of a single transposon repeated randomly throughout its chromosome.
e.
a plasmid that has become integrated into its chromosome.
 

 122. 
Which of the following statements regarding transposons is not true?
a.
Transposons are genes that encode sex pili and enable plasmid transfers between bacteria.
b.
Transposons are found in both prokaryotes and eukaryotes.
c.
Transposons can move from a plasmid to the bacterial circular chromosome.
d.
Transposons may replicate at an original site and insert a copy at another site.
e.
Transposons may carry only the genes necessary for insertion.
 

 123. 
An R plasmid can
a.
facilitate bacterial resistance to antibiotics.
b.
adjust the rates of metabolic pathways.
c.
repress gene expression.
d.
convert an F+ to an F– bacterium.
e.
reverse the direction of transcription.
 

 124. 
What does the operon model attempt to explain?
a.
the coordinated control of gene expression in bacteria
b.
bacterial resistance to antibiotics
c.
how genes move between homologous regions of DNA
d.
the mechanism of viral attachment to a host cell
e.
horizontal transmission of plant viruses
 

 125. 
All of the following are made up of nucleic acid except a
a.
repressor.
b.
structural gene.
c.
promoter.
d.
regulatory gene.
e.
operator.
 

 126. 
The role of a metabolite that controls a repressible operon is to
a.
bind to the promoter region and decrease the affinity of RNA polymerase for the promoter.
b.
bind to the operator region and block the attachment of RNA polymerase to the promoter.
c.
increase the production of inactive repressor proteins.
d.
bind to the repressor protein and inactivate it.
e.
bind to the repressor protein and activate it.
 

 127. 
The tryptophan operon is a repressible operon that is
a.
permanently turned on.
b.
turned on only when tryptophan is present in the growth medium.
c.
turned off only when glucose is present in the growth medium.
d.
turned on only when glucose is present in the growth medium.
e.
turned off whenever tryptophan is added to the growth medium.
 
 
For the following questions, match the terms below with the appropriate phrase or description below. Each term can be used once, more than once, or not at all.

A. operon
B. inducer
C. promoter
D. repressor
E. corepressor
 

 128. 
A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 129. 
A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
a.
continuous transcription of the structural gene controlled by that regulator.
b.
complete inhibition of transcription of the structural gene controlled by that regulator.
c.
irreversible binding of the repressor to the operator.
d.
inactivation of RNA polymerase.
e.
both B and C
 

 130. 
Transcription of the structural genes in an inducible operon
a.
occurs all the time.
b.
starts when the pathway's substrate is present.
c.
starts when the pathway's product is present.
d.
stops when the pathway's product is present.
e.
does not produce enzymes.
 

 131. 
How does active CAP induce expression of the genes of the lactose operon?
a.
It terminates production of repressor molecules.
b.
It degrades the substrate allolactose.
c.
It stimulates splicing of the encoded genes.
d.
It stimulates the binding of RNA polymerase to the promoter.
e.
It binds steroid hormones and controls translation.
 

 132. 
For a repressible operon to be transcribed, which of the following must be true?
a.
A corepressor must be present.
b.
RNA polymerase and the active repressor must be present.
c.
RNA polymerase must bind to the promoter, and the repressor must be inactive.
d.
RNA polymerase cannot be present, and the repressor must be inactive.
e.
RNA polymerase must not occupy the promoter, and the repressor must be inactive.
 

 133. 
Of the following, which is least related to the others?
a.
corepressor
b.
repressor
c.
inducer
d.
transposon
e.
cAMP receptor protein
 

 134. 
The condensed chromosomes observed in mitosis include all of the following structures except
a.
nucleosomes.
b.
30-nm fibers.
c.
300-nm fibers.
d.
looped domain.
e.
ribosomes.
 

 135. 
Under the electron microscope, unfolded chromatin resembles "beads on a string." What do the "beads" represent?
a.
nucleosomes
b.
ribosomes
c.
beadosomes
d.
molecules of DNA polymerase
e.
molecules of RNA polymerase
 

 136. 
If a cell were unable to produce histone proteins, which of the following would be expected to occur?
a.
There would be an increase in the amount of "satellite" DNA produced during centrifugation.
b.
The cell's DNA couldn't be packed into its nucleus.
c.
Spindle fibers would not form during prophase.
d.
Amplification of other genes would compensate for the lack of histones.
e.
Pseudogenes would be transcribed to compensate for the decreased protein in the cell.
 

 137. 
Which of the following statements about histones is incorrect?
a.
Each nucleosome consists of two molecules, each of four types of histone.
b.
Histone H1 is not present in the nucleosome bead; instead it is involved in the formation of higher-level chromatin structures.
c.
The amino end of each histone extends outward from the nucleosome and is called a "histone tail."
d.
Histones are found in mammals, but not in other animals or in plants.
e.
The mass of histone in chromatin is approximately equal to the mass of DNA.
 

 138. 
Why do histones bind tightly to DNA?
a.
Histones are positively charged, and DNA is negatively charged.
b.
Histones are negatively charged, and DNA is positively charged.
c.
Both histones and DNA are strongly hydrophobic.
d.
Histones are covalently linked to the DNA.
e.
Histones are highly hydrophobic, and DNA is hydrophilic.
 

 139. 
Which of the following statements is true?
a.
Heterochromatin is composed of DNA, whereas euchromatin is made of DNA and RNA.
b.
Both heterochromatin and euchromatin are found in the cytoplasm.
c.
Heterochromatin is highly condensed, whereas euchromatin is less compact.
d.
Euchromatin is not transcribed, whereas heterochromatin is transcribed.
e.
Only euchromatin is visible under the light microscope.
 

 140. 
In a nucleosome, the DNA is wrapped around
a.
polymerase molecules.
b.
ribosomes.
c.
histones.
d.
the nucleolus.
e.
satellite DNA.
 

 141. 
Muscle cells and nerve cells in one species of animal owe their differences in structure to
a.
having different genes.
b.
having different chromosomes.
c.
using different genetic codes.
d.
differential gene expression.
e.
having unique ribosomes.
 

 142. 
Which of the following mechanisms is (are) used to coordinately control the expression of multiple, related genes in eukaryotic cells?
a.
organization of the genes into clusters, with local chromatin structures influencing the expression of all the genes at once
b.
each of the genes sharing a common control element, allowing a single activator to turn on their transcription at once, regardless of their location in the genome
c.
organizing the genes into large operons, allowing them to be transcribed as a single unit
d.
A and B only
e.
A, B, and C
 

 143. 
In which of the following would you expect to find the most methylation of DNA?
a.
tandem arrays for ribosomal genes
b.
pseudogenes
c.
inactivated mammalian X chromosomes
d.
globin genes
e.
transposons
 

 144. 
A eukaryotic gene typically has all of the following features except
a.
introns.
b.
a promoter.
c.
an operator.
d.
control elements.
e.
a terminator.
 

 145. 
Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA?
a.
83%
b.
46%
c.
32%
d.
13%
e.
2%
 

 146. 
Two potential devices that eukaryotic cells use to regulate transcription are DNA ____ and histone ____.
a.
methylation; amplification
b.
amplification; methylation
c.
acetylation; methylation
d.
methylation; acetylation
e.
amplification; acetylation
 

 147. 
In both eukaryotes and prokaryotes, gene expression is primarily regulated at the level of
a.
transcription.
b.
translation.
c.
mRNA stability.
d.
mRNA splicing.
e.
protein stability.
 

 148. 
In eukaryotes, transcription is generally associated with
a.
euchromatin only.
b.
heterochromatin only.
c.
very tightly packed DNA only.
d.
highly methylated DNA only.
e.
both euchromatin and histone acetylation.
 

 149. 
A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. A likely explanation for the lack of transgene expression in the fifth cell line is that the
a.
transgene integrated into a heterochromatic region of the genome.
b.
transgene integrated into a euchromatic region of the genome.
c.
transgene was mutated during the process of integration into the host cell genome.
d.
host cell lacks the enzymes necessary to express the transgene.
e.
transgene integrated into a region of the genome characterized by high histone acetylation.
 

 150. 
A significant difference between eukaryotes and prokaryotes is that
a.
DNA is wound around proteins to form chromatin in eukaryotes, but in prokaryotes the DNA is not associated with proteins.
b.
gene expression is largely regulated by transcription in prokaryotes, but not in eukaryotes.
c.
prokaryotic genes do not contain introns.
d.
noncoding DNA sequences are found in prokaryotes, but not in eukaryotes.
e.
prokaryotes have less DNA but more noncoding segments than eukaryotes.
 

 151. 
Eukaryotic cells control gene expression by which of the following mechanisms?
a.
histone acetylation of nucleosomes
b.
DNA methylation
c.
enzyme modification of chromatin structure
d.
A and B only
e.
A, B, and C
 

 152. 
General transcription factors
a.
are required for the expression of all protein-encoding genes.
b.
bind to other proteins or to a sequence element within the promoter called the TATA box.
c.
help RNA polymerase bind to the promoter and begin transcribing.
d.
usually only lead to a low level of transcription in the absence of additional proteins called specific transcription factors.
e.
all of the above
 
 
Use the terms below to answer the following questions. Each term may be used once, more than once, or not at all.

A. enhancer
B. promoter
C. activator
D. repressor
E. terminator
 

 153. 
binds to a site in the DNA far from the promoter to stimulate transcription
a.
A
b.
B
c.
C
d.
D
e.
E
 

 154. 
site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3' end of the transcript
a.
A
b.
B
c.
C
d.
D
e.
E
 

 155. 
Steroid hormones produce their effects in cells by
a.
activating key enzymes in metabolic pathways.
b.
activating translation of certain mRNAs.
c.
promoting the degradation of specific mRNAs.
d.
binding to intracellular receptors and promoting transcription of specific genes.
e.
promoting the formation of looped domains in certain regions of DNA.
 

 156. 
The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called
a.
RNA interference.
b.
RNA obstruction.
c.
RNA blocking.
d.
RNA targeting.
e.
RNA disposal.
 

 157. 
Which of the following is not a mechanism whereby a proto-oncogene is converted to an oncogene?
a.
methylation of bases
b.
point mutation
c.
gene transposition
d.
gene amplification
e.
chromosome translocation
 

 158. 
Which of the following statements concerning proto-oncogenes is false?
a.
They can code for proteins associated with cell growth.
b.
They are similar to oncogenes found in retroviruses.
c.
They are produced by somatic mutations induced by carcinogenic substances.
d.
They can be involved in producing proteins for cell adhesion.
e.
They can code for proteins involved in cell division.
 

 159. 
Which of the following is not a characteristic of the product of the p53 gene? It
a.
is an activator for other genes.
b.
slows down the cell cycle.
c.
causes cell death.
d.
prevents cells from passing on mutations due to DNA damage.
e.
slows down the rate of DNA replication by interfering with the binding of DNA polymerase.
 

 160. 
The Ras protein is involved in ____, and cancer-causing forms of the protein are usually ____.
a.
relaying a signal from a growth factor receptor; hyperactive
b.
DNA replication; nonfunctional
c.
DNA repair; hyperactive
d.
cell-cell adhesion; nonfunctional
e.
cell division; nonfunctional
 

 161. 
A genetic test to detect predisposition to cancer would likely examine the APC gene for ____ cancer and the BRCA1 and BRCA2 genes for ____ cancer.
a.
colorectal; breast
b.
lung; breast
c.
breast; lung
d.
colorectal; lung
e.
lung; prostate
 

 162. 
Which of the following can contribute to the development of cancer?
a.
random spontaneous mutations
b.
mutations caused by X-rays
c.
transposition
d.
A and B only
e.
A, B, and C
 

 163. 
The most prominent component of the DNA in eukaryotic genomes is
a.
operons.
b.
tandemly repeating DNA.
c.
gene regulatory sequences.
d.
transposable elements and related sequences.
e.
Alu elements.
 

 164. 
Reverse transcriptase may be present in cells that have not been infected by a retrovirus because of the presence of
a.
immunoglobulins.
b.
retrotransposons.
c.
genomic imprinting.
d.
proteasomes.
e.
oncogenes.
 
 
Use the terms below to answer the following questions. Each term may be used once, more than once, or not at all.

A. transposons
B. simple sequence DNA
C. multigene family
D. methylated DNA
E. pseudogenes
 

 165. 
This is most commonly found in inactivated DNA regions.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 166. 
When pieces of DNA are centrifuged, a "satellite" band develops that is separate from the rest of the DNA. This layer is composed of ____.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 167. 
mc167-1.jpg-globins and mc167-2.jpg-globins are classic examples of which type of DNA?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 168. 
This class of DNA codes for the three largest ribosomal RNA molecules.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 169. 
In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to
a.
nonidentical genes that produce different versions of globins during development.
b.
identical genes that generate many copies of the ribosomes needed for fetal globin production.
c.
pseudogenes, which interfere with gene expression in adults.
d.
the attachment of methyl groups to cytosine following birth, which changes the type of hemoglobin produced.
e.
histone proteins changing shape during embryonic development.
 

 170. 
What do pseudogenes and introns have in common?
a.
They code for RNA end products, rather than proteins.
b.
They both contain uracil.
c.
They have multiple promoter sites.
d.
They both code for histones.
e.
They are not expressed, nor do they code for functional proteins.
 

 171. 
One of the best pieces of evidence for the process of gene duplication and mutation is the occurrence of
a.
pseudogenes.
b.
introns.
c.
transposons.
d.
oncogenes.
e.
heterochromatin.
 

 172. 
If a pseudogene were transposed between a functioning gene and its "upstream" regulatory components, which of the following would most likely occur?
a.
The functioning gene would not be transcribed.
b.
The pseudogene would not be transcribed.
c.
The pseudogene would be transcribed.
d.
Both genes would be transcribed.
e.
Both A and C would probably occur.
 

 173. 
Two genes that are evolutionarily related by gene duplication are likely to have which of the following properties?
a.
They will often have related functions.
b.
Their sequences will be similar or identical.
c.
They will often be located near each other in the genome.
d.
Only A and B are correct.
e.
A, B, and C are correct.
 

 174. 
Scientists often deduce the evolutionary history of the different members of a gene family by
a.
comparing the sequences of the genes.
b.
determining which of the genes are mutated in human diseases.
c.
comparing the relative enzymatic activities of the proteins encoded by the genes.
d.
overexpressing each of the genes in a cell and determining which has the most destructive effect.
e.
examining the relative stability of the mRNAs produced from the genes.
 

 175. 
The number of repeated units of simple sequence repeat DNA can vary between homologous chromosomes or between individuals. Such variation could be caused by
a.
slippage of DNA polymerase during replication.
b.
unequal crossing over events.
c.
meiotic errors that result in polyploidy.
d.
A and B only
e.
A, B, and C
 
 
The table below indicates the exons present in six different genes. Gene 1, for example, contains exons A, B, C, and D, in this order, and gene 2 has a similar structure, although exons A and B have been replaced by related but distinct versions called A' and B'.

GeneExons
1A-B-C-D
2A'-B'-C-D
3A-B'-C-D
4A-A-B-C-D
5A-B-C-D'
6E-F-B-G
 

 176. 
The structural similarity seen in genes 1 through 5 suggests that they were most likely produced by
a.
gene duplication.
b.
exon shuffling.
c.
exon duplication.
d.
translocation.
e.
polyploidy.
 

 177. 
Gene 6 is mostly unrelated to the other genes, except for the presence of exon B. This is most likely a product of
a.
exon shuffling.
b.
exon duplication.
c.
gene duplication.
d.
polyploidy.
e.
translocation.
 

 178. 
Plasmids are important in biotechnology because they are
a.
a vehicle for the insertion of foreign genes into bacteria.
b.
recognition sites on recombinant DNA strands.
c.
surfaces for protein synthesis in eukaryotic recombinants.
d.
surfaces for respiratory processes in bacteria.
e.
proviruses incorporated into the host DNA.
 

 179. 
If you discovered a bacterial cell that contained no restriction enzymes, which of the following would you expect to happen?
a.
The cell would be unable to replicate its DNA.
b.
The cell would create incomplete plasmids.
c.
The cell would be easily infected and lysed by bacteriophages.
d.
The cell would become an obligate parasite.
e.
Both A and D would occur.
 

 180. 
Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to
a.
insert the fragments cut with X directly into the plasmid without cutting the plasmid.
b.
cut the plasmid with restriction enzyme X and insert the fragments cut with Y into the plasmid.
c.
cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.
d.
cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X.
e.
cut the plasmid with enzyme X and then insert the gene into the plasmid.
 

 181. 
What is the enzymatic function of restriction enzymes?
a.
to add new nucleotides to the growing strand of DNA
b.
to join nucleotides during replication
c.
to join nucleotides during transcription
d.
to cleave nucleic acids at specific sites
e.
to repair breaks in sugar-phosphate backbones
 

 182. 
What are the typical characteristics of a cloning vector?
a.
Bacterial cells cannot survive without it when grown under certain conditions.
b.
It contains restriction sites that allow the insertion of foreign DNA segments.
c.
It can replicate in bacterial cells.
d.
Only B and C are correct.
e.
A, B, and C are correct.
 

 183. 
Bacteria containing recombinant plasmids are often identified by which process?
a.
examining the cells with an electron microscope
b.
using radioactive tracers to locate the plasmids
c.
exposing the bacteria to an antibiotic that kills cells lacking the plasmid
d.
removing the DNA of all cells in a culture to see which cells have plasmids
e.
producing antibodies specific for each bacterium containing a recombinant plasmid
 
 
Use the following information to answer the questions below.

A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics.
 

 184. 
Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in
a.
the nutrient broth only.
b.
the nutrient broth and the tetracycline broth only.
c.
the nutrient broth, the ampicillin broth, and the tetracycline broth.
d.
all four types of broth.
e.
the ampicillin broth and the nutrient broth.
 

 185. 
Bacteria that do not take up any plasmids would grow on which media?
a.
the nutrient broth
b.
the nutrient broth and the tetracycline broth
c.
the nutrient broth and the ampicillin broth
d.
the tetracycline and ampicillin broth
e.
all four broths
 

 186. 
The principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that
a.
prokaryotes use a different genetic code from that of eukaryotes.
b.
bacteria translate polycistronic messages only.
c.
bacteria cannot remove eukaryotic introns.
d.
bacterial RNA polymerase cannot make RNA complementary to mammalian DNA.
e.
bacterial DNA is not found in a membrane-bounded nucleus and is therefore incompatible with mammalian DNA.
 

 187. 
Mutations in these genes lead to transformations in the identity of entire body parts.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 188. 
These genes are expressed by the mother, and their products are deposited into the developing egg.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 189. 
These genes form gradients and help establish the axes and other features of an embryo.
a.
A
b.
B
c.
C
d.
D
e.
E
 

 190. 
The DNA fragments making up a genomic library are generally contained in
a.
recombinant plasmids of bacteria.
b.
recombinant viral DNA.
c.
eukaryotic chromosomes.
d.
both A and B
e.
A, B, and C
 

 191. 
A eukaryotic protein can be made in bacteria by inserting the gene encoding the protein into a(n)
a.
protein plasmid.
b.
expression vector.
c.
yeast artificial chromosome (YAC).
d.
PCR vector.
e.
restriction plasmid.
 

 192. 
How does a genomic library differ from a cDNA library?
a.
A genomic library contains both noncoding sequences and coding sequences, whereas a cDNA library contains only coding sequences.
b.
A genomic library is identical regardless of the cell type used to make it, whereas the content of a cDNA library depends on the cell type used in its construction.
c.
A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase.
d.
Only B and C are correct.
e.
A, B and C are correct.
 

 193. 
The polymerase chain reaction is important because it allows us to
a.
insert eukaryotic genes into prokaryotic plasmids.
b.
incorporate genes into viruses.
c.
make DNA from RNA transcripts.
d.
make many copies of a targeted segment of DNA.
e.
insert regulatory sequences into eukaryotic genes.
 

 194. 
Yeast artificial chromosomes contain which of the following elements?
a.
centromere
b.
telomeres
c.
origin of replication
d.
both A and B
e.
A, B, and C
 

 195. 
The polymerase chain reaction (PCR) has been used to amplify DNA from which of the following?
a.
fossils
b.
fetal cells
c.
viruses
d.
bacteria
e.
all of the above
 

 196. 
Which of the following best describes the complete sequence of steps occurring during every cycle of PCR?
1. The primers hybridize to the target DNA.
2. The mixture is heated to a high temperature to denature the double stranded target DNA.
3. Fresh DNA polymerase is added.
4. DNA polymerase extends the primers to make a copy of the target DNA.
a.
2, 1, 4
b.
1, 3, 2, 4
c.
3, 4, 1, 2
d.
3, 4, 2
e.
2, 3, 4
 
 
The following questions refer to the techniques, tools, or substances listed below. Answers may be used once, more than once, or not at all.

A. restriction enzymes
B. gene cloning
C. DNA ligase
D. gel electrophoresis
E. reverse transcriptase
 

 197. 
____ produces multiple identical copies of a gene for basic research or for large-scale production of a gene product
a.
A
b.
B
c.
C
d.
D
e.
E
 

 198. 
____ seals the sticky ends of restriction fragments to make recombinant DNA
a.
A
b.
B
c.
C
d.
D
e.
E
 

 199. 
____ is used to make complementary DNA (cDNA) from RNA
a.
A
b.
B
c.
C
d.
D
e.
E
 

 200. 
____ cuts DNA molecules at specific locations
a.
A
b.
B
c.
C
d.
D
e.
E
 

 201. 
Restriction fragments of DNA are typically separated from one another by which process?
a.
filtering
b.
centrifugation
c.
gel electrophoresis
d.
PCR
e.
electron microscopy
 

 202. 
Which of the following is least related to the others?
a.
denaturation
b.
DNA ligase
c.
sticky ends
d.
restriction enzymes
e.
cloning vector
 

 203. 
Probes are short, single-stranded DNA or RNA segments that are used to identify DNA fragments with a particular sequence. In order to identify a specific restriction fragment using a probe, what must be done?
a.
The fragments must be separated by electrophoresis.
b.
The fragments must be treated with heat or chemicals to separate the strands of the double helix.
c.
The probe must be hybridized with the fragment.
d.
Only A and B are correct.
e.
A, B, and C are correct.
 

 204. 
DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. The purpose of transferring the DNA from a gel to a nitrocellulose paper is to
a.
permanently attach the DNA fragments to a substrate.
b.
separate the two complementary DNA strands.
c.
transfer only the DNA that is of interest.
d.
prepare the DNA for digestion with restriction enzymes.
e.
separate out the PCRs.
 

 205. 
RFLP analysis can be used to distinguish between alleles based on differences in
a.
restriction enzyme recognition sites between the alleles.
b.
the amount of DNA amplified from the alleles during PCR.
c.
the ability of the alleles to be replicated in bacterial cells.
d.
the proteins expressed from the alleles.
e.
the ability of nucleic acid probes to hybridize to the alleles.
 

 206. 
After being digested with a restriction enzyme, genomic DNA fragments are separated by gel electrophoresis. Specific fragments can then be identified through the use of a
a.
plasmid.
b.
restriction enzyme.
c.
sticky end.
d.
nucleic acid probe.
e.
RFLP.
 

 207. 
The segment of DNA shown in the figure below has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments?

mc207-1.jpg

a.
mc207-2.jpg
b.
mc207-3.jpg
c.
mc207-4.jpg
d.
mc207-5.jpg
e.
mc207-6.jpg
 

 208. 
The major advantage of using artificial chromosomes such as YACs and BACs instead of plasmids for cloning genes is that
a.
plasmids are unable to replicate in cells.
b.
only one copy of a plasmid can be present in any given cell, whereas many copies of a YAC or BAC can coexist in a single cell.
c.
YACs and BACs can carry much larger DNA fragments than plasmids can.
d.
YACs and BACs can be used to express proteins encoded by inserted genes, but plasmids cannot.
e.
all of the above
 

 209. 
The "shotgun" approach used by Craig Venter to sequence the human genome skipped which of the following steps that were used by the Human Genome Project?
a.
genetic mapping
b.
physical mapping
c.
DNA sequencing
d.
A and B only
e.
A, B, and C
 

 210. 
The completion of the Human Genome Project revealed that the human genome contains fewer genes than expected, not so many more than simpler organisms. How can this be reconciled with the greater complexity of humans relative to many other organisms?
a.
RNA transcripts of human genes are more likely to undergo alternative splicing.
b.
Post-translational processing adds diversity to the resulting polypeptides.
c.
Polypeptide domains are combined in a variety of ways.
d.
Gene expression patterns in humans are often more complex than those in other organisms.
e.
All of the above are correct.
 

 211. 
Genomics includes the study of all of the following except
a.
identifying the location of all of the genes present in the genome.
b.
comparing genomes between different organisms.
c.
studying the coordinated expression of groups of genes under various conditions or in different cell types.
d.
studying how the genome is duplicated and segregated within the cell cycle.
e.
identifying the functions of all of the genes in the genome.
 

 212. 
Upon the completion of genome sequencing projects, how do scientists generally go about asking how many genes there are in the genome and where they are located?
a.
mutating nucleotides throughout the genome and looking for phenotypes
b.
using software to scan the genome sequence for gene-related sequence elements such as promoters and transcription start and stop sites
c.
using RNA interference to pinpoint gene regulatory elements such as enhancers
d.
examining the expression of all potential genes using DNA microchips
e.
using PCR to amplify sequences throughout the genome and looking for gene-like amplification patterns
 

 213. 
The function of a gene can be determined by
a.
comparing its sequence to genes of known function from other organisms.
b.
eliminating the function of the gene by in vitro mutagenesis and examining the consequences.
c.
eliminating the expression of the gene using RNA interference and examining the consequences.
d.
A and B only
e.
A, B, and C
 

 214. 
DNA microarrays have made a huge impact on genomic studies because they
a.
can be used to eliminate the function of any gene in the genome.
b.
can be used to introduce entire genomes into bacterial cells.
c.
allow the expression of many or even all of the genes in the genome to be compared at once.
d.
allow physical maps of the genome to be assembled in a very short time.
e.
dramatically enhance the efficiency of restriction enzymes.
 
 
Use the figure below to answer the following questions. The DNA profiles below represent four different individuals.

nar015-1.jpg
 

 215. 
Which of the following statements is consistent with the results?
a.
B is the child of A and C.
b.
C is the child of A and B.
c.
D is the child of B and C.
d.
A is the child of B and C.
e.
A is the child of C and D.
 

 216. 
Which of the following are probably siblings?
a.
A and B
b.
A and C
c.
A and D
d.
C and D
e.
B and D
 

 217. 
Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses?
a.
production of human insulin
b.
production of human growth hormone
c.
production of tissue plasminogen activator
d.
genetic modification of plants to produce vaccines
e.
creation of products that will remove poisons from the human body
 

 218. 
The most powerful way of increasing the specificity of a DNA profile analysis is to
a.
select markers present on the sex chromosomes rather than on the autosomes.
b.
analyze each marker by PCR rather than RFLP analysis.
c.
increase the number of markers used.
d.
repeat the analysis multiple times.
e.
analyze DNA obtained from skin cells rather than blood cells.
 

 219. 
A DNA profile is produced by
a.
treating selected segments of DNA with restriction enzymes.
b.
electrophoresis of restriction fragments.
c.
using a probe to locate specific nucleotide sequences.
d.
A and B only
e.
A, B, and C
 

 220. 
Genetically engineered plants
a.
are more difficult to engineer than animals.
b.
include a transgenic rice plant that could help prevent vitamin A deficiency.
c.
are being rapidly developed, but traditional plant breeding programs are still the only method used to develop new plants.
d.
are able to fix nitrogen themselves.
e.
are banned throughout the world.
 

 221. 
Current applications of biotechnology include
a.
cleaning up toxic waste.
b.
development of artificial photosynthetic machines.
c.
manufacturing human growth hormone.
d.
A and C only
e.
A, B, and C
 

 222. 
Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures?
a.
Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.
b.
Genetically modified organisms cannot be part of our food supply.
c.
Transgenic plants are engineered so that the plant genes cannot hybridize.
d.
Experiments involving HIV or other potentially dangerous viruses have been banned.
e.
Recombinant plasmids cannot be replicated.
 

 223. 
A model organism for genetic studies of development should ideally meet certain criteria. Which of these is not one of the criteria?
a.
readily observable embryos
b.
short generation times
c.
relatively small genomes
d.
the presence of unique features not observed in other organisms
e.
availability of detailed knowledge concerning the organism's genes
 

 224. 
Which of the following is (are) involved in embryonic development?
a.
cell division
b.
cell differentiation
c.
morphogenesis
d.
A and B only
e.
A, B, and C
 

 225. 
One striking difference between development in plants and development in animals is the importance of cell ____ in animal embryos.
a.
division
b.
differentiation
c.
growth
d.
movement
e.
death
 

 226. 
One striking difference between development in plants and development in animals is that in plant development
a.
growth and morphogenesis continue throughout the life of the plant.
b.
cell differentiation never stops.
c.
once a structure develops, it cannot reverse its path.
d.
cell differentiation is rarely permanent.
e.
chemical signals play a much greater role than in animal development.
 

 227. 
What is the term for the physical processes that give rise to the shape of an organism?
a.
morphogenesis
b.
differentiation
c.
totipotency
d.
pluripotency
e.
mitosis
 

 228. 
"Genomic equivalence" refers to the
a.
similarity in genomes among all individuals of the same species.
b.
similarity in genomes between males and females of the same species.
c.
fact that all the cells of an organism express the same genes, regardless of differences in their genomes.
d.
fact that all the somatic cells of an organism have identical genomes, regardless of their state of differentiation.
e.
organizational similarity of the genomes of all living organisms, reflecting their common ancestry.
 

 229. 
The fact that plants can be cloned from somatic cells demonstrates that
a.
differentiated cells retain all the genes of the zygote.
b.
genes are lost during differentiation.
c.
the differentiated state is normally very unstable.
d.
differentiated cells contain masked mRNA.
e.
differentiation does not occur in plants.
 

 230. 
"Nuclear transplantation" refers to a(n)
a.
cloning method involving the transfer of a nucleus from a differentiated cell into an enucleated egg cell or zygote.
b.
form of gene therapy involving the transfer of nuclei from a healthy individual to the cells of a patient with a genetic disorder.
c.
method of creating new species by injecting diploid nuclei into diploid zygotes in order to produce tetraploid embryos.
d.
method of gene therapy in which nuclei are isolated from cells of an individual with a genetic disorder, transfected with recombinant DNA, and reintroduced into the individual's cells.
e.
experimental method involving transferring nuclei from cells of an organism of one species into cells of an organism from another species, and examining the resulting phenotype.
 

 231. 
A cell that remains entirely flexible in its developmental possibilities is said to be
a.
differentiated.
b.
determined.
c.
totipotent.
d.
genomically equivalent.
e.
epigenetic.
 

 232. 
Why was the cloning of "Dolly" considered a major scientific breakthrough?
a.
It showed that differentiated adult cells of mammals can dedifferentiate.
b.
It showed that cells can be arrested in the cell cycle.
c.
It was the first time a surrogate mother was used successfully.
d.
It was evidence that DNA methylation regulates gene expression.
e.
It proved that the pattern of gene expression is controlled at transcription.
 

 233. 
Despite the extensive success that scientists have had in cloning animals, the process is still quite inefficient and cloned animals often show a variety of defects. This is likely because
a.
the epigenetic features of the chromatin in differentiated donor nuclei are not completely erased in the cloning process.
b.
cloned animals only have one parent, and therefore carry a high number of homozygous mutations in their genomes.
c.
cloned animals have fewer genes than other animals, and often lack proteins required for normal health.
d.
the surrogate mothers that give birth to cloned animals tend to neglect cloned animals in favor of their own biological offspring.
e.
scientists usually damage the donor cell nuclei in the process of transplantation.
 

 234. 
What is considered to be the first evidence of differentiation in the cells of an embryo?
a.
cell division
b.
the occurrence of mRNAs for the production of tissue-specific proteins
c.
determination
d.
changes in the size and shape of the cell
e.
changes resulting from induction
 

 235. 
In most cases, differentiation is controlled at the level of
a.
replication of the DNA.
b.
nucleosome formation.
c.
transcription.
d.
translation.
e.
post-translational activation of the proteins.
 

 236. 
Which of the following serve as sources of developmental information?
a.
cytoplasmic determinants such as mRNAs and proteins produced before fertilization
b.
signal molecules produced by neighboring cells
c.
ubiquitous enzymes such as DNA polymerase and DNA ligase
d.
A and B only
e.
A, B, and C
 

 237. 
The MyoD protein
a.
can promote muscle development in all cell types.
b.
is a transcription factor that binds to and activates the transcription of muscle-related genes.
c.
was used by researchers to convert differentiated liver cells into muscle cells.
d.
B and C only
e.
A, B and C
 

 238. 
Which of the following statements is false?
a.
Induction involves cells communicating with each other.
b.
Induction usually involves transcriptional regulation.
c.
Induction can play an essential role in the formation of complex organs.
d.
Induction may involve stimulating cells to die as well as to divide and grow.
e.
Induction signals are almost always small carbohydrates.
 

 239. 
Which of the following is least related to the others?
a.
cell division
b.
morphogenesis
c.
induction
d.
differentiation
e.
bacterial transformation
 

 240. 
Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development?
a.
morphogenesis
b.
determination
c.
induction
d.
differentiation
e.
pattern formation
 

 241. 
Of the approximately 13,700 genes in Drosophila, how many were found to be essential for embryonic development by Christiane Nüsslein-Volhard and Eric Wieschaus?
a.
about 120 genes
b.
about 240 genes
c.
about 1,200 genes
d.
about 6,000 genes
e.
about 9,000 genes
 

 242. 
The product of the bicoid gene in Drosophila provides essential information about
a.
the anterior-posterior axis.
b.
the dorsal-ventral axis.
c.
the left-right axis.
d.
segmentation.
e.
lethal genes.
 

 243. 
If a Drosophila female has a homozygous mutation for a maternal effect gene,
a.
she will not develop past the early embryonic stage.
b.
all of her offspring will show the mutant phenotype, regardless of their genotype.
c.
only her male offspring will show the mutant phenotype.
d.
her offspring will show the mutant phenotype only if they are also homozygous for the mutation.
e.
only her female offspring will show the mutant phenotype.
 

 244. 
The product of the bicoid gene in Drosophila could be considered a
a.
tissue-specific protein.
b.
cytoplasmic determinant.
c.
morphogen.
d.
B and C only
e.
A, B, and C
 

 245. 
What do gap genes, pair-rule genes, segment polarity genes, and homeotic genes all have in common?
a.
Their products act as transcription factors.
b.
They have no counterparts in animals other than Drosophila.
c.
Their products are all synthesized prior to fertilization.
d.
They act independently of other positional information.
e.
They apparently can be activated and inactivated at any time of the fly's life.
 

 246. 
Which of the following is least related to the others?
a.
gap genes
b.
cyclin genes
c.
pair-rule genes
d.
segment polarity genes
e.
segmentation genes
 

 247. 
The fasciated mutant in tomatoes
a.
affects the identity of the floral organs produced by the plant.
b.
affects the number of floral organs produced by the plant.
c.
affects the overall height of the plant.
d.
is an example of an "organ identity gene."
e.
both A and D
 

 248. 
Which of the following is not true concerning homeotic genes?
a.
They are found in all animals, but nothing like them exists in plants.
b.
A specific 180-nucleotide DNA sequence is common to all of the genes.
c.
They were first identified in Drosophila by Edward Lewis.
d.
The peptide gene product is a regulatory protein that controls transcription.
e.
A mutation may cause alterations in the identity of body segments.
 

 249. 
A small, impermeable membrane is placed between the anchor cell and the other vulva precursor cells in a larva of C. elegans. What would you expect the result to be?
a.
The vulva would continue to develop normally.
b.
The vulva would not develop at all.
c.
The outer part of the vulva would develop, but the inner part would not.
d.
The inner part of the vulva would develop, but the outer part would not.
e.
Only the posterior part of the vulva would develop.
 

 250. 
In vertebrates, programmed cell death is essential for all of the following except
a.
normal development of the nervous system.
b.
normal operation of the immune system.
c.
normal morphogenesis of human feet.
d.
normal removal of damaged cells.
e.
normal triggering of the signal transduction pathways.
 



 
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