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Biology
12th
grade
AP Biology: Unit 6 Gene Expression and Regulation REVIEW
85 questions
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- 1. Multiple Choice
In his transformation experiments, what did Griffith observe?
Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains.
- 2. Multiple Choice
What does transformation involve in bacteria?
the infection of cells by a phage DNA molecule
assimilation of external DNA into a cell
- 3. Multiple Choice
In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
DNA contains phosphorus, but protein does not.
DNA contains nitrogen, whereas protein does not.
- 4. Multiple Choice
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 wonʹt this experiment work?
Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive.
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
- 5. Multiple Choice
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?
12%
24%
31%
38%
- 6. Multiple Choice
Chargaffʹs analysis of the relative base composition of DNA was significant because he was able to show that
the relative proportion of each of the four bases differs within individuals of a species.
the amount of A is always equivalent to T, and C to G.
- 7. Multiple Choice
Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?
the diameter of the helix
the rate of replication
- 8. Multiple Choice
Why does the DNA double helix have a uniform diameter?
Purines pair with pyrimidines.
Deoxyribose sugars bind with ribose sugars.
- 9. Multiple Choice
What kind of chemical bond is found between paired bases of the DNA double helix?
hydrogen
ionic
covalent
- 10. Multiple Choice
In an analysis of the nucleotide composition of DNA, which of the following will be found?
A = G and C = T
A + C = G + T
- 11. Multiple Choice
Replication in prokaryotes differs from replication in eukaryotes for which of these reasons?
Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.
Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.
- 12. Multiple Choice
What is meant by the description ʺantiparallelʺ regarding the strands that make up DNA?
The 5ʹ to 3ʹ direction of one strand runs counter to the 5ʹ to 3ʹ direction of the other strand.
One strand is positively charged and the other is negatively charged.
- 13. Multiple Choice
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
One of the daughter cells, but not the other, would have radioactive DNA.
DNA in both daughter cells would be radioactive.
- 14. Multiple Choice
Which enzyme catalyzes the elongation of a DNA strand in the 5ʹ → 3ʹ direction?
primase
DNA ligase
DNA Polymerase
helicase
- 15. Multiple Choice
What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
the nucleotide sequence of the template strand
the primase used in the reaction
- 16. Multiple Choice
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
leading strands and Okazaki fragments
lagging strands and Okazaki fragments.
- 17. Multiple Choice
Which of the following separates the DNA strands during replication?
helicase
DNA polymerase
primase
- 18. Multiple Choice
Which of the following covalently connects segments of DNA?
helicase
DNA polymerase
ligase
- 19. Multiple Choice
Which of the following synthesizes short segments of RNA?
helicase
DNA polymerase
primase
- 20. Multiple Choice
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that
the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.
the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups.
- 21. Multiple Choice
The leading and the lagging strands differ in that
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.
the leading strand is synthesized by adding nucleotides to the 3ʹ end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5ʹ end.
- 22. Multiple Choice
A new DNA strand elongates only in the 5ʹ to 3ʹ direction because
DNA polymerase can only add nucleotides to the free 3ʹ end
Okazaki fragments prevent elongation in the 3ʹ to 5ʹ direction.
- 23. Multiple Choice
What is the function of topoisomerase?
relieving strain in the DNA ahead of the replication fork
elongation of new DNA at a replication fork by addition of nucleotides to the existing chain
- 24. Multiple Choice
Which would you expect of a eukaryotic cell lacking telomerase?
a reduction in chromosome length
production of Okazaki fragments
- 25. Multiple Choice
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?
methylation and phosphorylation of histone tails
nucleotide excision and reconstruction
- 26. Multiple Choice
Why do histones bind tightly to DNA?
Histones are positively charged, and DNA is negatively charged.
Histones are negatively charged, and DNA is positively charged.
- 27. Multiple Choice
Based your answer on the figure: A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?
an accumulation of A and no production of B and C
an accumulation of A and B and no production of C
- 28. Multiple Choice
The nitrogenous base adenine is found in all members of which group?
proteins, ATP, and DNA
ATP, RNA, and DNA
- 29. Multiple Choice
The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except
a gene from an organism could theoretically be expressed by any other organism.
all organisms have a common ancestor.
DNA was the first genetic material.
the same codons in different organisms usually translate into the same amino acids.
- 30. Multiple Choice
In which of the following actions does RNA polymerase differ from DNA polymerase?
RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.
RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to double-stranded DNA.
- 31. Multiple Choice
RNA polymerase moves in which direction along the DNA?
3ʹ → 5ʹ along the template strand
3ʹ → 5ʹ along the coding (sense) strand
- 32. Multiple Choice
What are the coding segments of a stretch of eukaryotic DNA called?
introns
exons
- 33. Multiple Choice
Introns are significant to biological evolution because
their presence allows exons to be shuffled.
they protect the mRNA from degeneration.
- 34. Multiple Choice
A mutation in which of the following parts of a gene is likely to be most damaging to a cell?
intron
exon
- 35. Multiple Choice
Alternative RNA splicing
is a mechanism for increasing the rate of transcription.
can allow the production of proteins of different sizes from a single mRNA
- 36. Multiple Choice
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
TTT
UUU
- 37. Multiple Choice
What type of bonding is responsible for maintaining the shape of the tRNA molecule?
covalent bonding between sulfur atoms
hydrogen bonding between base pairs
- 38. Multiple Choice
What is the most abundant type of RNA?
mRNA
tRNA
rRNA
- 39. Multiple Choice
When does translation begin in prokaryotic cells?
as soon as transcription has begun
once the pre-mRNA has been converted to mRNA
- 40. Multiple Choice
Why might a point mutation in DNA make a difference in the level of proteinʹs activity?
It might substitute an amino acid in the active site.
It might exchange one stop codon for another stop codon.
- 41. Multiple Choice
Sickle-cell disease is probably the result of which kind of mutation?
point
nondisjunction
- 42. Multiple Choice
A frameshift mutation could result from
a base insertion only.
either an insertion or a deletion of a base.
a base deletion only.
- 43. Multiple Choice
Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?
a base deletion near the end of the coding sequence, but not in the terminator codon
a base deletion near the start of a gene
- 44. Multiple Choice
What does the operon model attempt to explain?
the coordinated control of gene expression in bacteria
the mechanism of viral attachment to a host cell
- 45. Multiple Choice
The tryptophan operon is a repressible operon that is
turned off whenever tryptophan is added to the growth medium
turned on only when glucose is present in the growth medium.
- 46. Multiple Choice
When this is taken up by the cell, it binds to the repressor so that the repressor no longer binds to the operator:
inducer
repressor
- 47. Multiple Choice
Transcription of the structural genes in an inducible operon
occurs continuously in the cell.
starts when the pathwayʹs substrate is present.
- 48. Multiple Choice
Altering patterns of gene expression in prokaryotes would most likely serve the organismʹs survival in which of the following ways?
allowing the organism to adjust to changes in environmental conditions
organizing gene expression so that genes are expressed in a given order
allowing environmental changes to alter the prokaryoteʹs genome
- 49. Multiple Choice
Muscle cells and nerve cells in one species of animal owe their differences in structure to
having different genes.
having different genes expressed.
- 50. Multiple Choice
If you were to observe the activity of methylated DNA, you would expect it to
be unwinding in preparation for protein synthesis.
have turned off or slowed down the process of transcription.
- 51. Multiple Choice
This can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA:
enhancer
promoter
repressor
- 52. Multiple Choice
Steroid hormones produce their effects in cells by
binding to intracellular receptors and promoting transcription of specific genes.
activating key enzymes in metabolic pathways.
- 53. Multiple Choice
Which of the following best describes siRNA?
a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns
- 54. Multiple Choice
Which of the following statements is true about stem cells?
Stem cells can differentiate into specialized cells
Stem cells are found only in bone marrow.
- 55. Multiple Choice
What is considered to be the first evidence of differentiation in the cells of an embryo?
the occurrence of mRNAs for the production of tissue-specific proteins
changes in the size and shape of the cell
- 56. Multiple Choice
Which of the following statements describes proto-oncogenes?
They can code for proteins associated with cell growth.
They are introduced to a cell initially by retroviruses.
- 57. Multiple Choice
Which of the following is characteristic of the product of the p53 gene?
It is an activator for other genes.
It speeds up the cell cycle.
- 58. Multiple Choice
Tumor suppressor genes
can encode proteins that promote DNA repair or cell-cell adhesion
often encode proteins that stimulate the cell cycle.
- 59. Multiple Choice
The incidence of cancer increases dramatically in older humans because
as we age, normal cell division inhibitors cease to function
the longer we live, the more mutations we accumulate.
- 60. Multiple Choice
[Select all that apply] Which of the following can contribute to the development of cancer?
random spontaneous mutations
mutations caused by X-rays
chromosome translocations
- 61. Multiple Choice
One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Which of the following best describes this phenomenon?
inherited cancer taking a few years to be expressed
inherited inability to repair UV-induced mutation
- 62. Multiple Choice
Viral envelopes can best be analyzed with which of the following techniques?
antibodies against specific proteins not found in the host membranes
immunofluorescent tagging of capsid proteins
- 63. Multiple Choice
The host range of a virus is determined by
the proteins on its surface and that of the host.
whether its nucleic acid is DNA or RNA.
- 64. Multiple Choice
Which of the following molecules make up the viral envelope?
glycoproteins
carboproteins
- 65. Multiple Choice
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 life?
copies of the herpesvirus genome permanently maintained in host nuclei
copies of the herpesvirus genome permanently maintained in host cell cytoplasm
- 66. Multiple Choice
Which of the following is characteristic of the lytic cycle?
Viral DNA is incorporated into the host genome.
A large number of phages is released at a time.
- 67. Multiple Choice
Why do RNA viruses appear to have higher rates of mutation?
Replication of their genomes does not involve the proofreading steps of DNA replication.
RNA viruses replicate faster.
- 68. Multiple Choice
What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?
retroviruses
bacteriophages
- 69. Multiple Choice
What is the function of reverse transcriptase in retroviruses?
It uses viral RNA as a template for DNA synthesis.
It converts host cell RNA into viral DNA.
- 70. Multiple Choice
Which of the following can be effective in preventing viral infection in humans?
getting vaccinated
taking antibiotics
- 71. Multiple Choice
Which of the following series best reflects what we know about how the flu virus moves between species?
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.
A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans
- 72. Multiple Choice
Which enzyme was used to produce the molecule in the Figure?
ligase
a restriction enzyme
- 73. Multiple Choice
What is the enzymatic function of restriction enzymes?
to cleave nucleic acids at specific sites
to add new nucleotides to the growing strand of DNA
- 74. Multiple Choice
Bacteria containing recombinant plasmids are often identified by which process?
exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid
producing antibodies specific for each bacterium containing a recombinant plasmid
- 75. Multiple Choice
A principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that
prokaryotes use a different genetic code from that of eukaryotes.
bacteria cannot remove eukaryotic introns.
- 76. Multiple Choice
Which of the following separates molecules by movement due to size and electrical charge?
gel electrophoresis
gene cloning
- 77. Multiple Choice
Restriction fragments of DNA are typically separated from one another by which process?
gel electrophoresis
PCR
- 78. Multiple Choice
The segment of DNA shown in the figure 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?
- 79. Multiple Choice
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?
to raise the rate of production of a needed digestive enzyme
to decrease the production from a harmful gain-of-function mutated gene
- 80. Multiple Choice
Which of the following is most closely identical to the formation of identical twins?
use of adult stem cells
organismal cloning
- 81. Multiple Choice
In 1997, Dolly the sheep was cloned. Which of the following processes was used?
fusion of an adult cellʹs nucleus with an enucleated sheep egg, followed by incubation in a surrogate
replication and dedifferentiation of adult stem cells from sheep bone marrow
- 82. Multiple Choice
The DNA profiles in the figure represent four different individuals. Which of the following statements is consistent with the results?
B is the child of A and C.
C is the child of A and B.
- 83. Multiple Choice
Genetically engineered plants
include a transgenic rice plant that can help prevent vitamin A deficiency.
are banned throughout the world.
- 84. Multiple Choice
Which of the following is one of the technical reasons why gene therapy is problematic?
Transferred genes may not have appropriately controlled activity.
mRNA from transferred genes cannot be translated.
- 85. Multiple Choice
One possible use of transgenic plants is in the production of human proteins, such as vaccines. Which of the following is a possible hindrance that must be overcome?
prevention of transmission of plant allergens to the vaccine recipients
prevention of vaccine-containing plants being consumed by insects
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