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Flashcards in test questions - 3/5 Deck (140):
1

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.

E) bind to the repressor protein and activate it.

2

the tryptophan operon is a répressible opéron 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.

E) turned off whenever tryptophan is added to the growth medium

3

Which of the following is a protein produced by a regulatory gene?
A) operon
B) inducer
C) promoter
D) repressor
E) corepressor

Answer: D

4

A lack of which molecule would result in the cell's inability to "turn off" genes?
A) operon
B) inducer
C) promoter
D) ubiquitin
E) corepressor

Answer: E

5

Which of the following, when taken up by the cell, binds to the repressor so that the repressor no
longer binds to the operator?
A) ubiquitin
B) inducer
C) promoter
D) repressor
E) corepressor

B) inducer 

6

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its
conformation?
A) inducer
B) promoter
C) RNA polymerase
D) transcription factor
E) cAMP

Answer: A

7

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 by alteration of its active site.
E) continuous translation of the mRNA because of alteration of its structure.

Answer: A - a continuous transcription of the structural gene controlled by that regulator

8

The lactose operon is likely to be transcribed when
A) there is more glucose in the cell than lactose.
B) the cyclic AMP levels are low.
C) there is glucose but no lactose in the cell.
D) the cyclic AMP and lactose levels are both high within the cell.
E) the cAMP level is high and the lactose level is low.

Answer: D - the cyclic amp and lactose levels are both high within the cell

9

Transcription of the structural genes in an inducible operon
A) occurs continuously in the cell.
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 result in the production of enzymes.

Answer: B - starts when the pathway’s substrate is present

10

For a repressible operon to be transcribed, which of the following must occur?
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.

Answer: C - rna polymerase must bind to the promoter, and the repressor must be inactive

11

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is
presented for the first time with the sugar lactose (containing allolactose) as a potential food source.
Which of the following occurs when the lactose enters the cell?
A) The repressor protein attaches to the regulator.
B) Allolactose binds to the repressor protein.
C) Allolactose binds to the regulator gene.
D) The repressor protein and allolactose bind to RNA polymerase.
E) RNA polymerase attaches to the regulator.

B) allolactose binds to the repressor protein

12

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival
in which of the following ways?
A) organizing gene expression so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing the organism to adjust to changes in environmental conditions
D) allowing young organisms to respond differently from more mature organisms
E) allowing environmental changes to alter the prokaryote's genome

C) allowing the organism to adjust to changes in environmental conditions

13

In response to chemical signals, prokaryotes can do which of the following?
A) turn off translation of their mRNA
B) alter the level of production of various enzymes
C) increase the number and responsiveness of their ribosomes
D) inactivate their mRNA molecules
E) alter the sequence of amino acids in certain proteins

B) alter the level of production of various enzymes

14

If glucose is available in the environment of E. coli, the cell responds with a very low concentration
of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would
you expect to be a measurable effect?
A) decreased concentration of the lac enzymes
B) increased concentration of the trp enzymes
C) decreased binding of the RNA polymerase to sugar metabolism-related promoters
D) decreased concentration of alternative sugars in the cell
E) increased concentrations of sugars such as arabinose in the cell

E) increased concentrations of sugars such as arabinose in the cell

15

In positive control of several sugar-metabolism- related operons, the catabolite activator protein
(CAP) binds to DNA to stimulate transcription. What causes an increase in CAP?
A) increase in glucose and increase in cAMP
B) decrease in glucose and increase in cAMP
C) increase in glucose and decrease in cAMP
D) decrease in glucose and increase in repressor
E) decrease in glucose and decrease in repressor

B) decrease in glucose and increase in cAMP

16

There is a mutation in the repressor that results in a molecule known as a super-repressor because it
represses the lac operon permanently. Which of these would characterize such a mutant?
A) It cannot bind to the operator.
B) It cannot make a functional repressor.
C) It cannot bind to the inducer.
D) It makes molecules that bind to one another.
E) It makes a repressor that binds CAP.

C) It cannot bind to the inducer.

17

Which of the following mechanisms is (are) used to coordinate the expression of multiple, related
genes in eukaryotic cells?
A) Genes are organized into clusters, with local chromatin structures influencing the expression of all
the genes at once.
B) The genes share a common intragenic sequence, and allow several activators to turn on their
transcription, regardless of location.
C) The genes are organized into large operons, allowing them to be transcribed as a single unit.
D) A single repressor is able to turn off several related genes.
E) Environmental signals enter the cell and bind directly to promoters.

A) Genes are organized into clusters, with local chromatin structures influencing the expression of all the genes at once.

18

If you were to observe the activity of methylated DNA, you would expect it to
A) be replicating nearly continuously.
B) be unwinding in preparation for protein synthesis.
C) have turned off or slowed down the process of transcription.
D) be very actively transcribed and translated.
E) induce protein synthesis by not allowing repressors to bind to it.

C) have turned off or slowed down the process of transcription.

19

Genomic imprinting, DNA methylation, and histone acetylation are all examples of
A) genetic mutation.
B) chromosomal rearrangements.
C) karyotypes.
D) epigenetic phenomena.
E) translocation.

D) epigenetic phenomena.

20

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact
with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin
must constantly alter its structure. Which processes contribute to this dynamic activity?
A) DNA supercoiling at or around H1
B) methylation and phosphorylation of histone tails
C) hydrolysis of DNA molecules where they are wrapped around the nucleosome core
D) accessibility of heterochromatin to phosphorylating enzymes
E) nucleotide excision and reconstruction

B) methylation and phosphorylation of histone tails

21

Two potential devices that eukaryotic cells use to regulate transcription are
A) DNA methylation and histone amplification.
B) DNA amplification and histone methylation.
C) DNA acetylation and methylation.
D) DNA methylation and histone modification.
E) histone amplification and DNA acetylation.

D) DNA methylation and histone modification.

22

During DNA replication,
A) all methylation of the DNA is lost at the first round of replication.
B) DNA polymerase is blocked by methyl groups, and methylated regions of the genome are therefore
left uncopied.
C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one
strand is already methylated and thus correctly methylates daughter strands after replication.
D) methylation of the DNA is maintained because DNA polymerase directly incorporates methylated
nucleotides into the new strand opposite any methylated nucleotides in the template.
E) methylated DNA is copied in the cytoplasm, and unmethylated DNA is copied in the nucleus.

C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication.

23

In eukaryotes, general transcription factors
A) are required for the expression of specific protein-encoding genes.
B) bind to other proteins or to a sequence element within the promoter called the TATA box.
C) inhibit RNA polymerase binding to the promoter and begin transcribing.
D) usually lead to a high level of transcription even without additional specific transcription factors.
E) bind to sequences just after the start site of transcription.

B) bind to other proteins or to a sequence element within the promoter called the TATA box.

24

Transcription factors in eukaryotes usually have DNA binding domains as well as other domains
that are also specific for binding. In general, which of the following would you expect many of them to
be able to bind?
A) repressors
B) ATP
C) protein-based hormones
D) other transcription factors
E) tRNA

D) other transcription factors

25

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather
than prokaryotes because of which of the following?
A) Eukaryotic mRNAs get 5' caps and 3' tails.
B) Prokaryotic genes are expressed as mRNA, which is more stable in the cell.
C) Eukaryotic exons may be spliced in alternative patterns.
D) Prokaryotes use ribosomes of different structure and size.
E) Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.

C) Eukaryotic exons may be spliced in alternative patterns.

26

Which of the following experimental procedures is most likely to hasten mRNA degradation in a
eukaryotic cell?
A) enzymatic shortening of the poly-A tail
B) removal of the 5' cap
C) methylation of C nucleotides
D) methylation of histones
E) removal of one or more exons

B) removal of the 5' cap

27

Which of the following is most likely to have a small protein called ubiquitin attached to it?
A) a cyclin that usually acts in G1, now that the cell is in G2
B) a cell surface protein that requires transport from the ER
C) an mRNA that is leaving the nucleus to be translated
D) a regulatory protein that requires sugar residues to be attached
E) an mRNA produced by an egg cell that will be retained until after fertilization

A) a cyclin that usually acts in G1, now that the cell is in G2

28

In prophase I of meiosis in female Drosophila, studies have shown that there is phosphorylation of
an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process
results in sterility. Which of the following is the most likely hypothesis?
A) These oocytes have no histones.
B) Any mutation during oogenesis results in sterility.
C) All proteins in the cell must be phosphorylated.
D) Histone tail phosphorylation prohibits chromosome condensation.
E) Histone tails must be removed from the rest of the histones.

D) Histone tail phosphorylation prohibits chromosome condensation.

29

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.

A) RNA interference.

30

At the beginning of this century there was a general announcement regarding the sequencing of the
human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed
by many that the number of protein-coding sequences was much smaller than they had expected. Which
of the following could account for most of the rest?
A) "junk" DNA that serves no possible purpose
B) rRNA and tRNA coding sequences
C) DNA that is translated directly without being transcribed
D) non-protein- coding DNA that is transcribed into several kinds of small RNAs with biological
function
E) non-protein- coding DNA that is transcribed into several kinds of small RNAs without biological function

D) non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function

31

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns
during gamete formation and block expression of some transposons. These are known as
A) miRNA.
B) piRNA.
C) snRNA.
D) siRNA.
E) RNAi.

B) piRNA.

32

Which of the following best describes siRNA?
A) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of
mRNA
B) a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf
patterns
C) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor
D) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small
subunits
E) a molecule, known as Dicer, that can degrade other mRNA sequences

A) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

33

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the
possibilities for their use in medicine. Of the following scenarios for future research, which would you
expect to gain most from RNAs?
A) exploring a way to turn on the expression of pseudogenes
B) targeting siRNAs to disable the expression of an allele associated with autosomal recessive disease
C) targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease
D) creating knock-out organisms that can be useful for pharmaceutical drug design
E) looking for a way to prevent viral DNA from causing infection in humans

C) targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease

34

Which of the following describes the function of an enzyme known as Dicer?
A) It degrades single-stranded DNA.
B) It degrades single-stranded mRNA.
C) It degrades mRNA with no poly-A tail.
D) It trims small double-stranded RNAs into molecules that can block translation.
E) It chops up single-stranded DNAs from infecting viruses.

D) It trims small double-stranded RNAs into molecules that can block translation.

35

In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates
so that the centromere is abnormally formed from chromatin. Which of the following is most likely to
occur?
A) The usual mRNAs transcribed from centromeric DNA will be missing from the cells.
B) Tetrads will no longer be able to form during meiosis I.
C) Centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture.
D) The cells will no longer be able to resist bacterial contamination.
E) The DNA of the centromeres will no longer be able to replicate.

C) Centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture.

36

Since Watson and Crick described DNA in 1953, which of the following might best explain why the
function of small RNAs is still being explained?
A) As RNAs have evolved since that time, they have taken on new functions.
B) Watson and Crick described DNA but did not predict any function for RNA.
C) The functions of small RNAs could not be approached until the entire human genome was
sequenced.
D) Ethical considerations prevented scientists from exploring this material until recently.
E) Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible 

E) Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible.

37

You are given an experimental problem involving control of a gene's expression in the embryo of a
particular species. One of your first questions is whether the gene's expression is controlled at the level
of transcription or translation. Which of the following might best give you an answer?
A) You explore whether there has been alternative splicing by examining amino acid sequences of very
similar proteins.
B) You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the
same.
C) You assess the position and sequence of the promoter and enhancer for this gene.
D) An analysis of amino acid production by the cell shows you that there is an increase at this stage of
embryonic life.
E) You use an antibiotic known to prevent translation.

B) You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same.

38

42) What is considered to be the first evidence of differentiation in the cells of an embryo?
A) cell division occurring after fertilization
B) the occurrence of mRNAs for the production of tissue-specific proteins
C) determination of specific cells for certain functions
D) changes in the size and shape of the cell
E) changes resulting from induction

B) the occurrence of mRNAs for the production of tissue-specific proteins

39

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. 

If she moves the repressor gene (lac I), along with its promoter, to a position at some several
thousand base pairs away from its normal position, which will you expect to occur?
A) The repressor will no longer be made.
B) The repressor will no longer bind to the operator.
C) The repressor will no longer bind to the inducer.
D) The lac operon will be expressed continuously.
E) The lac operon will function normally.

E) The lac operon will function normally.

40

67) If she moves the operator to a position upstream from the promoter, what would occur?
A) The lac operon will function normally.
B) The lac operon will be expressed continuously.
C) The repressor will not be able to bind to the operator.
D) The repressor will bind to the promoter.
E) The repressor will no longer be made.

B) The lac operon will be expressed continuously.

41

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. 

In one set of experiments using this procedure in Drosophila, she was readily successful in
increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of
the following results would she most likely see?
A) increased chromatin condensation
B) decreased chromatin condensation
C) abnormalities of mouse embryos
D) decreased binding of transcription factors
E) inactivation of the selected genes

B) decreased chromatin condensation

42

In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the
following results would she most likely see?
A) increased chromatin condensation
B) decreased chromatin condensation
C) abnormalities of mouse embryos
D) decreased binding of transcription factors
E) inactivation of the selected genes

A) increased chromatin condensation

43

One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian
system. Which of the following results would she most likely see?
A) increased chromatin condensation
B) decreased chromatin condensation
C) abnormalities of mouse embryos
D) decreased binding of transcription factors
E) inactivation of the selected genes

E) inactivation of the selected genes

44

Muscle cells differ from nerve cells mainly because they
A) express different genes.
B) contain different genes.
C) use different genetic codes.
D) have unique ribosomes.
E) have different chromosomes.

A) express different genes.

45

The functioning of enhancers is an example of
A) transcriptional control of gene expression.
B) a post-transcriptional mechanism to regulate mRNA.
C) the stimulation of translation by initiation factors.
D) post-translational control that activates certain proteins.
E) a eukaryotic equivalent of prokaryotic promoter functioning.

A) transcriptional control of gene expression.

46

Cell differentiation always involves
A) the production of tissue-specific proteins, such as muscle actin.
B) the movement of cells.
C) the transcription of the myoD gene.
D) the selective loss of certain genes from the genome.
E) the cell's sensitivity to environmental cues, such as light or heat.

A) the production of tissue-specific proteins, such as muscle actin.

47

Which of the following is an example of post-transcriptional control of gene expression?
A) the addition of methyl groups to cytosine bases of DNA
B) the binding of transcription factors to a promoter
C) the removal of introns and alternative splicing of exons
D) gene amplification contributing to cancer
E) the folding of DNA to form heterochromatin

C) the removal of introns and alternative splicing of exons

48

What would occur if the repressor of an inducible operon were mutated so it could not bind the
operator?
A) irreversible binding of the repressor to the promoter
B) reduced transcription of the operon's genes
C) buildup of a substrate for the pathway controlled by the operon
D) continuous transcription of the operon's genes
E) overproduction of catabolite activator protein (CAP)

D) continuous transcription of the operon's genes

49

Which of the following statements about the DNA in one of your brain cells is true?
A) Most of the DNA codes for protein.
B) The majority of genes are likely to be transcribed.
C) Each gene lies immediately adjacent to an enhancer.
D) Many genes are grouped into operon-like clusters.
E) It is the same as the DNA in one of your heart cells.

E) It is the same as the DNA in one of your heart cells.

50

Within a cell, the amount of protein made using a given mRNA molecule depends partly on
A) the degree of DNA methylation.
B) the rate at which the mRNA is degraded.
C) the presence of certain transcription factors.
D) the number of introns present in the mRNA.
E) the types of ribosomes present in the cytoplasm.

B) the rate at which the mRNA is degraded.

51

Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which
of the following viral features is most apt to correlate with the size of the genome?
A) size of the viral capsomeres
B) RNA versus DNA genome
C) double- versus single-strand genomes
D) size and shape of the capsid
E) glycoproteins of the envelope

D) size and shape of the capsid

52

Viral envelopes can best be analyzed with which of the following techniques?
A) transmission electron microscopy
B) antibodies against specific proteins not found in the host membranes
C) staining and visualization with the light microscope
D) use of plaque assays for quantitative measurement of viral titer
E) immunofluorescent tagging of capsid proteins

B) antibodies against specific proteins not found in the host membranes

53

The host range of a virus is determined by
A) the enzymes carried by the virus.
B) whether its nucleic acid is DNA or RNA.
C) the proteins in the host's cytoplasm.
D) the enzymes produced by the virus before it infects the cell.
E) the proteins on its surface and that of the host.

E) the proteins on its surface and that of the host.

54

In many ways, the regulation of the genes of a particular group of viruses will be similar to the
regulation of the host genes. Therefore, which of the following would you expect of the genes of the
bacteriophage?
A) regulation via acetylation of histones
B) positive control mechanisms rather than negative
C) control of more than one gene in an operon
D) reliance on transcription activators
E) utilization of eukaryotic polymerases

C) control of more than one gene in an operon

55

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.

D) A large number of phages are released at a time.

56

Which of the following statements describes the lysogenic cycle of lambda (λ) phage?
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 activated 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 lytic
to the lysogenic.
E) The phage DNA is incorporated by crossing over into any nonspecific site on the host cell's DNA.

C) The phage genome replicates along with the host genome.

57

Why do RNA viruses appear to have higher rates of mutation?
A) RNA nucleotides are more unstable than DNA nucleotides.
B) Replication of their genomes does not involve proofreading.
C) RNA viruses replicate faster.
D) RNA viruses can incorporate a variety of nonstandard bases.
E) RNA viruses are more sensitive to mutagens.

B) Replication of their genomes does not involve proofreading.

58

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid.
Which of the following observations supports this theory?
A) Viruses contain either DNA or RNA.
B) Viruses are enclosed in protein capsids rather than plasma membranes.
C) Viruses can reproduce only inside host cells.
D) Viruses can infect both prokaryotic and eukaryotic cells.
E) Viral genomes are usually similar to the genome of the host cell.

E) Viral genomes are usually similar to the genome of the host cell.

59

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic
virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is
sprayed on tobacco plants. Which of the following would be expected to occur?
A) The plants would develop some but not all of the symptoms of the TMV infection.
B) The plants would develop symptoms typically produced by viroids.
C) The plants would develop the typical symptoms of TMV infection.
D) The plants would not show any disease symptoms.
E) The plants would become infected, but the sap from these plants would be unable to infect other
plants.

C) The plants would develop the typical symptoms of TMV infection.

60

Which viruses have single-stranded RNA that acts as a template for DNA synthesis?
A) lytic phages
B) proviruses
C) viroids
D) bacteriophages
E) retroviruses

E) retroviruses

61

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.

B) It uses viral RNA as a template for DNA synthesis.

62

Which of the following can be effective in preventing the onset of viral infection in humans?
A) taking vitamins
B) getting vaccinated
C) taking antibiotics
D) applying antiseptics
E) taking nucleoside analogs that inhibit transcription

B) getting vaccinated

63

Which of the following describes plant virus infections?
A) They can be controlled by the use of antibiotics.
B) They are spread via the plasmodesmata.
C) They have little effect on plant growth.
D) They are seldom spread by insects.
E) They can never be passed vertically.

B) They are spread via the plasmodesmata.

64

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, whereas 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, whereas viroids can.

B) Viruses have capsids composed of protein, whereas viroids have no capsids.

65

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

A) vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.

66

Which of the following is the best predictor of how much damage a virus causes?
A) ability of the infected cell to undergo normal cell division
B) ability of the infected cell to carry on translation
C) whether the infected cell produces viral protein
D) whether the viral mRNA can be transcribed
E) how much toxin the virus produces

A) ability of the infected cell to undergo normal cell division

67

Antiviral drugs that have become useful are usually associated with which of the following
properties?
A) ability to remove all viruses from the infected host
B) interference with viral replication
C) prevention of the host from becoming infected
D) removal of viral proteins
E) removal of viral mRNAs

B) interference with viral replication

68

Which of the following is the most probable fate of a newly emerging virus that causes high
mortality in its host?
A) It is able to spread to a large number of new hosts quickly because the new hosts have no
immunological memory of them.
B) The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts.
C) A change in environmental conditions such as weather patterns quickly forces the new virus to
invade new areas.
D) Sporadic outbreaks will be followed almost immediately by a widespread pandemic.
E) The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

E) The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

69

Which of the three types of viruses shown above would you expect to include glycoproteins?
A) I only
B) II only
C) III only
D) I and II only
E) all three

Q image thumb

D) I and II only

70

Which of the three types of viruses shown above would you expect to include a capsid(s)?
A) I only
B) II only
C) III only
D) I and II only
E) all three

E) all three

71

25) In the figure, at the arrow marked II, what enzyme(s) are being utilized?
A) reverse transcriptase
B) viral DNA polymerase
C) host cell DNA polymerase
D) host cell RNA polymerase
E) host cell DNA and RNA polymerases

 

 

C) host cell DNA polymerase

72

In the figure, when new viruses are being assembled (IV), what mediates the assembly?
A) host cell chaperones
B) assembly proteins coded for by the host nucleus
C) assembly proteins coded for by the viral genes
D) viral RNA intermediates
E) nothing; they self-assemble

 

 

 

E) nothing; they self-assemble

73

27) A linear piece of viral DNA of 8 kb can be cut with either of two restriction enzymes (X or Y). These are subjected to electrophoresis and produce the following bands:

Cutting the same 8 kb piece with both enzymes together results in bands at 4.0, 2.5, 1.0, and 0.5.

Of the possible arrangements of the sites given below, which one is most likely?

Q image thumb

A image thumb
74

Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets.

30) If this virus has a positive RNA strand as its genome, it begins the infection by using this strand as
mRNA. Therefore, which of the following do you expect to be able to measure?
A) replication rate
B) transcription rate
C) translation rate
D) accumulation of new ribosomes
E) formation of new transcription factors

 

 

C) translation rate

75

In a cell-free system, what other components would you have to provide for this virus to express its
genes?
A) ribosomes, tRNAs and amino acids
B) ribosomes, tRNAs, amino acids, and GTP
C) RNA nucleotides and GTP
D) RNA nucleotides, RNA polymerase, and GTP
E) bean cell enzymes

 

 

B) ribosomes, tRNAs, amino acids, and GTP

76

Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides.

32) What part of the poliovirus would first interact with host cell ribosomes to mediate translation?
A) the poly-A tail
B) the leader sequence
C) the VPg protein
D) the AUG in the leader sequence
E) the AUG at the start of the coding sequence

 

C) the VPg protein

77

33) What conclusion is most consistent with the results of the radioactive labeling experiment?
A) The host cell cannot translate viral protein with the amino acid analogues.
B) Host cell ribosomes only translate the viral code into short polypeptides.
C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.
D) The RNA is translated into short polypeptides, which are subsequently assembled into large ones.
E) The large radioactive polypeptides are coded by the host, whereas the short ones are coded for by the
virus.

 

C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.

78

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
37) Which treatment could definitively determine whether or not the component is a viroid?
A) I
B) II
C) III
D) IV
E) first II and then III

38) 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

39) 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

      37 -     A) I

38 - C) III

39 -    D) IV    

79

The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.

40) If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection?A)vaccination of all persons with preexisting cases
B) interference with new viral replication in preexisting cases
C) treatment of the HSV lesions to shorten the breakout
D) medication that destroys surface HSV before it gets to neurons
E) education about avoiding sources of infection

B) interference with new viral replication in preexisting cases

80

In order to be able to remain latent in an infected live cell, HSV must be able to shut down what
process?
A) DNA replication
B) transcription of viral genes
C) apoptosis of a virally infected cell
D) all immune responses
E) interaction with histones

C) apoptosis of a virally infected cell

81

Which of the following characteristics, structures, or processes is common to both bacteria and
viruses?
A) metabolism
B) ribosomes
C) genetic material composed of nucleic acid
D) cell division
E) independent existence

C) genetic material composed of nucleic acid

82

Emerging viruses arise by
A) mutation of existing viruses.
B) the spread of existing viruses to new host species.
C) the spread of existing viruses more widely within their host species.
D) mutation of existing viruses, the spread of existing viruses to new host species, and the spread of
existing viruses more widely within their host species.
E) none of these.

 

 

D) mutation of existing viruses, the spread of existing viruses to new host species, and the spread of existing viruses more widely within their host species.

83

To cause a human pandemic, the H5N1 avian flu virus would have to
A) spread to primates such as chimpanzees.
B) develop into a virus with a different host range.
C) become capable of human-to- human transmission.
D) arise independently in chickens in North and South America.
E) become much more pathogenic.

C) become capable of human-to-human transmission.

84

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage
protein coat and T4 phage DNA. The new phages produced would have
A) T2 protein and T4 DNA.
B) T2 protein and T2 DNA.
C) a mixture of the DNA and proteins of both phages.
D) T4 protein and T4 DNA.
E) T4 protein and T2 DNA.

D) T4 protein and T4 DNA.

85

RNA viruses require their own supply of certain enzymes because
A) host cells rapidly destroy the viruses.
B) host cells lack enzymes that can replicate the viral genome.
C) these enzymes translate viral mRNA into proteins.
D) these enzymes penetrate host cell membranes.
E) these enzymes cannot be made in host cells.

 

B) host cells lack enzymes that can replicate the viral genome.

86

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 restriction enzyme X directly into the plasmid without cutting the
plasmid.
B) cut the plasmid with restriction enzyme X and insert the fragments cut with restriction enzyme 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 restriction enzyme X and then insert the gene into the plasmid.

 

 

C) cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

87

How does a bacterial cell protect its own DNA from restriction enzymes?
A) by adding methyl groups to adenines and cytosines
B) by using DNA ligase to seal the bacterial DNA into a closed circle
C) by adding histones to protect the double-stranded DNA
D) by forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching
E) by reinforcing the bacterial DNA structure with covalent phosphodiester bonds

 

A) by adding methyl groups to adenines and cytosines

88

 What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the
plasmid into a bacterium?
I. Transform bacteria with a recombinant DNA molecule.
II. Cut the plasmid DNA using restriction enzymes.
III. Extract plasmid DNA from bacterial cells.
IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.
V. Use ligase to seal plasmid DNA to nonplasmid DNA.
A) I, II, IV, III, V
B) II, III, V, IV, I
C) III, II, IV, V, I
D) III, IV, V, I, II
E) IV, V, I, II, III

C) III, II, IV, V, I

89

A principal problem with inserting an unmodified mammalian gene into a BAC, 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.

 

C) bacteria cannot remove eukaryotic introns.

90

A gene that contains introns can be made shorter (but remain functional) for genetic engineering
purposes by using
A) RNA polymerase to transcribe the gene.
B) a restriction enzyme to cut the gene into shorter pieces.
C) reverse transcriptase to reconstruct the gene from its mRNA.
D) DNA polymerase to reconstruct the gene from its polypeptide product.
E) DNA ligase to put together fragments of the DNA that code for a particular polypeptide.

 

 

C) reverse transcriptase to reconstruct the gene from its mRNA.

91

Why are yeast cells frequently used as hosts for cloning?
A) They easily form colonies.
B) They can remove exons from mRNA.
C) They do not have plasmids.
D) They are eukaryotic cells.
E) Only yeast cells allow the gene to be cloned.                     

 

D) They are eukaryotic cells.

92

Yeast artificial chromosomes contain which of the following elements?
A) centromeres only
B) telomeres only
C) origin of replication only
D) centromeres and telomeres only
E) centromeres, telomeres, and an origin of replication

 

 

E) centromeres, telomeres, and an origin of replication

93

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

 

 

A) 2, 1, 4

94

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because
A) it allows researchers to use the sequence to build a "better" nematode, which is resistant to disease.
B) it allows research on a group of organisms we do not usually care much about.
C) the nematode is a good animal model for trying out cures for viral illness.
D) a sequence that is found to have a particular function in the nematode is likely to have a closely
related function in vertebrates.
E) a sequence that is found to have no introns in the nematode genome is likely to have acquired the
introns from higher organisms.

 

D) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

95

Which of the following is used to make complementary DNA (cDNA) from RNA?
A) restriction enzymes
B) gene cloning
C) DNA ligase
D) gel electrophoresis
E) reverse transcriptase

 

 

E) reverse transcriptase

96

Why is it so important to be able to amplify DNA fragments when studying genes?
A) DNA fragments are too small to use individually.
B) A gene may represent only a millionth of the cell's DNA.
C) Restriction enzymes cut DNA into fragments that are too small.
D) A clone requires multiple copies of each gene per clone.
E) It is important to have multiple copies of DNA in the case of laboratory error.

 

 

B) A gene may represent only a millionth of the cell's DNA.

97

The reason for using Taq polymerase for PCR is that
A) it is heat stable and can withstand the temperature changes of the cycler.
B) only minute amounts are needed for each cycle of PCR.
C) it binds more readily than other polymerases to primer.
D) it has regions that are complementary to primers.
E) All of these are correct.

 

 

A) it is heat stable and can withstand the temperature changes of the cycler.

98

Why might a laboratory be using dideoxy nucleotides?
A) to separate DNA fragments
B) to clone the breakpoints of cut DNA
C) to produce cDNA from mRNA
D) to sequence a DNA fragment
E) to visualize DNA expression

 

 

D) to sequence a DNA fragment

99

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) The fragments must be separated by electrophoresis and the fragments must be treated with heat or
chemicals to separate the strands of the double helix.
E) The fragments must be separated by electrophoresis, the fragments must be treated with heat or
chemicals to separate the strands of the double helix, and the probe must be hybridized with the
fragment.

 

E) The fragments must be separated by electrophoresis, the fragments must be treated with heat or chemicals to separate the strands of the double helix, and the probe must be hybridized with the fragment.

100

Which of the following modifications is least likely to alter the rate at which a DNA fragment moves
through a gel during electrophoresis?
A) altering the nucleotide sequence of the DNA fragment
B) methylating the cytosine bases within the DNA fragment
C) increasing the length of the DNA fragment
D) decreasing the length of the DNA fragment
E) neutralizing the negative charges within the DNA fragment

 

 

A) altering the nucleotide sequence of the DNA fragment

101

DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called
Southern blotting. What is the purpose of transferring the DNA from a gel to a nitrocellulose paper?
A) to attach the DNA fragments to a permanent substrate
B) to separate the two complementary DNA strands
C) to transfer only the DNA that is of interest
D) to prepare the DNA for digestion with restriction enzymes
E) to separate out the PCRs

 

 

A) to attach the DNA fragments to a permanent substrate

102

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.

 

C) allow the expression of many or even all of the genes in the genome to be compared at once

103

RNAi methodology uses double-stranded pieces of RNA to trigger a breakdown or blocking of
mRNA. For which of the following might it more possibly be useful?
A) to raise the rate of production of a needed digestive enzyme
B) to decrease the production from a harmful gain-of- function mutated gene
C) to destroy an unwanted allele in a homozygous individual
D) to form a knockout organism that will not pass the deleted sequence to its progeny
E) to raise the concentration of a desired protein

 


 

B) to decrease the production from a harmful gain-of-function mutated gene

104

A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted this into
a cell. In order to have the mutated sequence disable the function of the gene, what must then occur?
A) recombination resulting in replacement of the wild type with the mutated gene
B) use of a microarray to verify continued expression of the original gene
C) replication of the cloned gene using a bacterial plasmid
D) transcription of the cloned gene using a BAC
E) attachment of the mutated gene to an existing mRNA to be translated

 

 

A) recombination resulting in replacement of the wild type with the mutated gene

105

Which of the following techniques used to analyze gene function depends on the specificity of DNA
base complementarity?
A) Northern blotting
B) use of RNAi
C) in vitro mutagenesis
D) in situ hybridization
E) restriction fragment analysis

 

C) in vitro mutagenesis

106

Silencing of selected genes is often done using RNA interference (RNAi). Which of the following
questions would not be answered with this process?
A) What is the function of gene 432 in this species of annelid?
B) What will happen in this insect's digestion if gene 173 is not able to be translated?
C) Is gene HA292 responsible for this disorder in humans?
D) Will the disabling of this gene in Drosophila and in a mouse cause similar results?
E) Is the gene on Drosophila chromosome 2L at this locus responsible for part of its production of
nitrogen waste?

 

 

C) Is gene HA292 responsible for this disorder in humans?

107

In large scale, genome-wide association studies in humans, correlation is sought between
A) lengthy sequences that might be shared by most members of a population.
B) single nucleotide polymorphisms found only in persons with a particular disorder.
C) single nucleotide polymorphisms found in families with a particular introns sequence.
D) single nucleotide polymorphisms in two or more adjacent genes.
E) large inversions that displace the centromere.

 

B) single nucleotide polymorphisms found only in persons with a particular disorder.

108

For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen
patients' breast tumor biopsies. The researchers will be looking for
A) a particular gene that is amplified in all or most of the patient samples.
B) a pattern of fluorescence that indicates which cells are overproliferating.
C) a pattern shared among some or all of the samples that indicates gene expression differing from
control samples.
D) a group of cDNAs that act differently from those on the rest of the grid.
E) a group of cDNAs that match those in non-breast cancer control samples from the same population.

 

 

C) a pattern shared among some or all of the samples that indicates gene expression differing from control samples.

109

Which of the following is most closely identical to the formation of twins?
A) cell cloning
B) therapeutic cloning
C) use of adult stem cells
D) embryo transfer
E) organismal cloning

 

 

E) organismal cloning

110

In 1997, Dolly the sheep was cloned. Which of the following processes was used?
A) use of mitochondrial DNA from adult female cells of another ewe
B) replication and dedifferentiation of adult stem cells from sheep bone marrow
C) separation of an early stage sheep blastula into separate cells, one of which was incubated in a
surrogate ewe
D) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate
E) isolation of stem cells from a lamb embryo and production of a zygote equivalent

 

 

D) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate

111

Which of the following problems with animal cloning might result in premature death of the clones?
A) use of pluripotent instead of totipotent stem cells
B) use of nuclear DNA as well as mtDNA
C) abnormal regulation due to variant methylation
D) the indefinite replication of totipotent stem cells
E) abnormal immune function due to bone marrow dysfunction

 

 

C) abnormal regulation due to variant methylation

112

Which of the following is true of embryonic stem cells but not of adult stem cells?
A) They can differentiate into many cell types.
B) They make up the majority of cells of the tissue from which they are derived.
C) They can continue to replicate for an indefinite period.
D) They can provide enormous amounts of information about the process of gene regulation.
E) One aim of using them is to provide cells for repair of diseased tissue.

 

 

B) They make up the majority of cells of the tissue from which they are derived.

113

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue.
Which of the following is a likely finding?
A) The cells from the two sources exhibit different patterns of DNA methylation.
B) Adult stem cells have more DNA nucleotides than their counterparts.
C) The two kinds of cells have virtually identical gene expression patterns in microarrays.
D) The nonstem cells have fewer repressed genes.
E) The nonstem cells have lost the promoters for more genes.

 

 

A) The cells from the two sources exhibit different patterns of DNA methylation.

114

In animals, what is the difference between reproductive cloning and therapeutic cloning?
A) Reproductive cloning uses totipotent cells, whereas therapeutic cloning does not.
B) Reproductive cloning uses embryonic stem cells, whereas therapeutic cloning does not.
C) Therapeutic cloning uses nuclei of adult cells transplanted into enucleated nonfertilized eggs.
D) Therapeutic cloning supplies cells for repair of diseased or injured organs.

 

 

D) Therapeutic cloning supplies cells for repair of diseased or injured organs.

115

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells
(iPS). In order to make this conversion, what has been done to the adult cells?
A) A retrovirus is used to introduce four specific regulatory genes.
B) The adult stem cells must be fused with embryonic cells.
C) Cytoplasm from embryonic cells is injected into the adult cells.
D) An adenovirus vector is used to transfer embryonic gene products into adult cells.
E) The nucleus of an embryonic cell is used to replace the nucleus of an adult cell.

 

A) A retrovirus is used to introduce four specific regulatory genes.

116

42) Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for
replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the
following could still be problems?
I. the possibility that, once introduced into the patient, the iPS cells produce nonpancreatic cells
II. the failure of the iPS cells to take up residence in the pancreas
III. the inability of the iPS cells to respond to appropriate regulatory signals
A) I only
B) II only
C) III only
D) I and II
E) all of them

E) all of them

117

Which of the following is one of the technical reasons why gene therapy is problematic?
A) Most cells with an engineered gene do not produce gene product.
B) Most cells with engineered genes overwhelm other cells in a tissue.
C) Cells with transferred genes are unlikely to replicate.
D) Transferred genes may not have appropriately controlled activity.
E) mRNA from transferred genes cannot be translated.

 

D) Transferred genes may not have appropriately controlled activity.

118

As genetic technology makes testing for a wide variety of genotypes possible, which of the
following is likely to be an increasingly troublesome issue?
A) use of genotype information to provide positive identification of criminals
B) using technology to identify genes that cause criminal behaviors
C) the need to legislate for the protection of the privacy of genetic information
D) discrimination against certain racial groups because of major genetic differences
E) alteration of human phenotypes to prevent early disease

 

C) the need to legislate for the protection of the privacy of genetic information

119

Which enzyme was used to produce the molecule in Figure 20.1?
A) ligase
B) transcriptase
C) a restriction enzyme
D) RNA polymerase
E) DNA polymerase
 

Q image thumb

C) a restriction enzyme

120

The segment of DNA shown in Figure 20.2 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?

Q image thumb

A image thumb
121

51) 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.

52) Which of the following statements is most likely true?
A) D is the child of A and C.
B) D is the child of A and B.
C) D is the child of B and C.
D) A is the child of C and D.
E) B is the child of A and C.

53) 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

 

Q image thumb

51 - B) C is the child of A and B.

52 - B) D is the child of A and B.

53 - D) C and D

122

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.

54) Bacteria that contain the plasmid, but not the eukaryotic gene, would grow
A) in the nutrient broth plus ampicillin, but not in the broth containing tetracycline.
B) only in the broth containing both antibiotics.
C) in the broth containing tetracycline, but not in the broth containing ampicillin.
D) in all four types of broth.
E) in the nutrient broth without antibiotics only.

 

D) in all four types of broth.

123

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.

 

 

E) the ampicillin broth and the nutrient broth.

124

Bacteria that do not take up any plasmids would grow on which media?
A) the nutrient broth only
B) the nutrient broth and the tetracycline broth
C) the nutrient broth and the ampicillin broth
D) the tetracycline broth and the ampicillin broth
E) all three broths

 

 

A) the nutrient broth only

125

A group of six students has taken samples of their own cheek cells, purified the DNA, and used a restriction enzyme known to cut at zero, one, or two sites in a particular gene of interest.

57) Why might they be conducting such an experiment?
A) to find the location of this gene in the human genome
B) to prepare to isolate the chromosome on which the gene of interest is found
C) to find which of the students has which alleles
D) to collect population data that can be used to assess natural selection
E) to collect population data that can be used to study genetic drift

 

C) to find which of the students has which alleles

126

Their next two steps, in order, should be
A) use of a fluorescent probe for the gene sequence, then electrophoresis.
B) electrophoresis of the fragments followed by autoradiography.
C) electrophoresis of the fragments, followed by the use of a probe.
D) use of a ligase that will anneal the pieces, followed by Southern blotting.
E) use of reverse transcriptase to make cDNA, followed by electrophoresis.

 

C) electrophoresis of the fragments, followed by the use of a probe.

127

Analysis of the data obtained shows that two students each have two fragments, two students each
have three fragments, and two students each have one only. What does this demonstrate?
A) Each pair of students has a different gene for this function.
B) The two students who have two fragments have one restriction site in this region.
C) The two students who have two fragments have two restriction sites within this gene.
D) The students with three fragments are said to have "fragile sites."
E) Each of these students is heterozygous for this gene.

 

 

B) The two students who have two fragments have one restriction site in this region.

128

Which of the following tools of recombinant DNA technology is incorrectly paired with its use?
A) restriction enzyme analysis of RFLPs
B) DNA ligase cutting DNA, creating sticky ends of restriction fragments
C) DNA polymerase polymerase chain reaction to amplify sections of DNA
D) reverse transcriptase production of cDNA from mRNA
E) electrophoresis separation of DNA fragments

B) DNA ligase cutting DNA, creating sticky ends of restriction fragments

129

Plants are more readily manipulated by genetic engineering than are animals because
A) plant genes do not contain introns.
B) more vectors are available for transferring recombinant DNA into plant cells.
C) a somatic plant cell can often give rise to a complete plant.
D) genes can be inserted into plant cells by microinjection.
E) plant cells have larger nuclei.

 

C) a somatic plant cell can often give rise to a complete plant.

130

A paleontologist has recovered a bit of tissue from the 400-year- old preserved skin of an extinct
dodo (a bird). To compare a specific region of the DNA from the sample with DNA from living birds,
which of the following would be most useful for increasing the amount of dodo DNA available for
testing?
A) RFLP analysis
B) polymerase chain reaction (PCR)
C) electroporation
D) gel electrophoresis
E) Southern blotting

 

 

B) polymerase chain reaction (PCR)

131

DNA technology has many medical applications. Which of the following is not done routinely at
present?
A) production of hormones for treating diabetes and dwarfism
B) production of microbes that can metabolize toxins
C) introduction of genetically engineered genes into human gametes
D) prenatal identification of genetic disease alleles
E) genetic testing for carriers of harmful alleles

 

 

C) introduction of genetically engineered genes into human gametes

132

In recombinant DNA methods, the term vector can refer to
A) the enzyme that cuts DNA into restriction fragments.
B) the sticky end of a DNA fragment.
C) a SNP marker.
D) a plasmid used to transfer DNA into a living cell.
E) a DNA probe used to identify a particular gene.

 

 

D) a plasmid used to transfer DNA into a living cell.

133

Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of
mRNA and reverse transcriptase is part of a strategy to solve the problem of
A) post-transcriptional processing.
B) electroporation.
C) post-translational processing.
D) nucleic acid hybridization.
E) restriction fragment ligation.

 

 

A) post-transcriptional processing.

134

Which of the following sequences in double-stranded DNA is most likely to be recognized as a
cutting site for a restriction enzyme?
A) AAGG
TTCC
B) AGTC
TCAG
C) GGCC
CCGG
D) ACCA
TGGT
E) AAAA
TTTT

C)            GGCC

                CCGG

135

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.

D) binding to intracellular receptors and promoting transcription of specific genes.

136

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the
trp operon, then
A) the amino acid inactivates the repressor.
B) the enzymes produced are called inducible enzymes.
C) the repressor is active in the absence of the amino acid.
D) the amino acid acts as a corepressor.
E) the amino acid turns on transcription of the operon.

D) the amino acid acts as a corepressor.

137

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a
disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral
mutation. Which of the following is the best example of a zoonosis?
A) rabies
B) herpesvirus
C) smallpox
D) HIV
E) hepatitis virus

A) rabies

138

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or
genital sore getting flare-ups for the rest of his or her life?
A) re-infection by a closely related herpesvirus of a different strain
B) re-infection by the same herpesvirus strain
C) co-infection with an unrelated virus that causes the same symptoms
D) copies of the herpesvirus genome permanently maintained in host nuclei
E) copies of the herpesvirus genome permanently maintained in host cell cytoplasm

D) copies of the herpesvirus genome permanently maintained in host nuclei

139

Which of the following series best reflects what we know about how the flu virus moves between
species?
A) An avian flu virus undergoes several mutations and rearrangements such that it is able to be
transmitted to other birds and then to humans.
B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the
pig products can be infected.
C) A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently
and then pass it back to humans.
D) An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this
enables it to be transmitted to a human host.
E) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new
virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to
humans.

E) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new
virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to
humans.

140

In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell
surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with
nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best
fits these observations?
A) Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus.
B) The viral envelope is not required for infectivity, since the envelope does not enter the nucleus.
C) Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the
genome of a phage.
D) The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the
genome is all that enters the nucleus.
E) The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it
may or may not replicate.

D) The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the
genome is all that enters the nucleus.