7e Biology, (Campbell)
Chapter 16: The Molecular Basis of Inheritance
Chapter Questions
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.
Answer: D
Topic: Concept 16.1
Skill: Comprehension
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.
Answer: B
Topic: Concept 16.1
Skill: Knowledge
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
Answer: E
Topic: Concept 16.1
Skill: Knowledge
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
Answer: A
Topic: Concept 16.1
Skill: Knowledge
1
5) Tobacco mosaic virus has RNA rather than DNA as its genetic material. In a hypothetical situation
where RNA from a tobacco mosaic virus is mixed with proteins from a related DNA virus, the result could
be a hybrid virus. If that virus were to infect a cell and reproduce, what would the resulting "offspring"
viruses be like?
A) tobacco mosaic virus
B) the related DNA virus
C) a hybrid: tobacco mosaic virus RNA and protein from the DNA virus
D) a hybrid: tobacco mosaic virus protein and nucleic acid from the DNA virus
E) a virus with a double helix made up of one strand of DNA complementary to a strand of RNA
surrounded by viral protein
Answer: A
Topic: Concept 16.1
Skill: Application
6) 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.
II.
III.
IV.
V.
Avery, McCarty, and MacLeod
Griffith
Hershey and Chase
Meselson and Stahl
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
Answer: B
Topic: Concept 16.1
Skill: Knowledge
7) 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.
Answer: D
Topic: Concept 16.1
Skill: Application
8) In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of
which of the following facts?
A) DNA does not contain sulfur, whereas protein does.
B) DNA contains phosphorus, but protein does not.
C) DNA contains nitrogen, whereas protein does not.
D) A and B only
E) A, B, and C
Answer: D
Topic: Concept 16.1
Skill: Knowledge
2
9) 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.
Answer: E
Topic: Concept 16.1
Skill: Comprehension
Match the investigator(s) to the appropriate discovery of about the nature of genes.
A.
B.
C.
D.
E.
Frederick Griffith
Alfred Hershey and Martha Chase
Oswald Avery, Maclyn McCarty, and Colin MacLeod
Erwin Chargaff
Matthew Meselson and Franklin Stahl
10) 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.
Answer: C
Topic: Concept 16.1
Skill: Knowledge
11) 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.
Answer: B
Topic: Concept 16.1
Skill: Knowledge
12) In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of
guanine equals the amount of cytosine.
Answer: D
Topic: Concept 16.1
Skill: Knowledge
13) 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
Answer: B
Topic: Concept 16.1
Skill: Comprehension
3
14) 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.
Answer: A
Topic: Concept 16.1
Skill: Application
15) 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
Answer: D
Topic: Concept 16.1
Skill: Knowledge
16) 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.
Answer: C
Topic: Concept 16.1
Skill: Knowledge
17) 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
Answer: A
Topic: Concept 16.1
Skill: Knowledge
18) 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
Answer: A
Topic: Concept 16.1
Skill: Knowledge
4
19) Which of the following statements does not apply to the Watson and Crick model of DNA?
A) The two strands of the DNA form a double helix.
B) The distance between the strands of the helix is uniform.
C) The framework of the helix consists of sugar-phosphate units of the nucleotides.
D) The two strands of the helix are held together by covalent bonds.
E) The purines form hydrogen bonds with pyrimidines.
Answer: D
Topic: Concept 16.1
Skill: Knowledge
20) 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.
Answer: A
Topic: Concept 16.1
Skill: Knowledge
21) 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
Answer: E
Topic: Concept 16.1
Skill: Comprehension
22) 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.
Answer: D
Topic: Concept 16.2
Skill: Knowledge
23) 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.
Answer: B
Topic: Concept 16.2
Skill: Knowledge
5
24) Suppose one were provided with an actively dividing culture of E. coli bacteria to which radioactive
thymine had been added. What would happen if a cell replicated once in the presence of this radioactive
base?
A) One of the daughter cells, but not the other, would have radioactive DNA.
B) Neither of the two daughter cells would be radioactive.
C) All four bases of the DNA would be radioactive.
D) Radioactive thymine would pair with nonradioactive guanine.
E) DNA in both daughter cells would be radioactive.
Answer: E
Topic: Concept 16.2
Skill: Comprehension
Use Figure 16.1 to answer the following questions.
Figure 16.1
25) 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 Figure 16.1 would be
expected after one DNA replication in the presence of 14N?
Answer: D
Topic: Concept 16.2
Skill: Comprehension
26) 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 Figure 16.1 would you expect if the DNA was
replicated in a conservative manner?
Answer: B
Topic: Concept 16.2
Skill: Application
27) Which enzyme catalyzes the elongation of a DNA strand in the 5' 3' direction?
A) primase
B) DNA ligase
C) DNA polymerase
D) topoisomerase
E) helicase
Answer: C
Topic: Concept 16.2
Skill: Knowledge
6
28) What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
A) the particular DNA polymerase catalyzing the reaction
B) the relative amounts of the four nucleoside triphosphates in the cell
C) the nucleotide sequence of the template strand
D) the primase used in the reaction
E) both A and D
Answer: C
Topic: Concept 16.2
Skill: Knowledge
29) What is the function of DNA polymerase?
A) to unwind the DNA helix during replication
B) to seal together the broken ends of DNA strands
C) to add nucleotides to the end of a growing DNA strand
D) to degrade damaged DNA molecules
E) to rejoin the two DNA strands (one new and one old) after replication
Answer: C
Topic: Concept 16.2
Skill: Knowledge
30) 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
Answer: C
Topic: Concept 16.2
Skill: Comprehension
31) 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 DNA of
labeled 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.
Answer: A
Topic: Concept 16.2
Skill: Application
7
Refer to the following list of enzymes to answer the following questions. The answers may be used once,
more than once, or not at all.
A.
B.
C.
D.
E.
helicase
nuclease
ligase
DNA polymerase I
primase
32) removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of
Okazaki fragments
Answer: D
Topic: Concept 16.2
Skill: Knowledge
33) separates the DNA strands during replication
Answer: A
Topic: Concept 16.2
Skill: Knowledge
34) covalently connects segments of DNA
Answer: C
Topic: Concept 16.2
Skill: Knowledge
35) synthesizes short segments of RNA
Answer: E
Topic: Concept 16.2
Skill: Knowledge
36) DNA-cutting enzymes used in the repair of DNA damage
Answer: B
Topic: Concept 16.2
Skill: Knowledge
37) The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that
A) the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.
B) the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups.
C) ATP contains three high-energy bonds; the nucleoside triphosphates have two.
D) ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells.
E) triphosphate monomers are active in the nucleoside triphosphates, but not in ATP.
Answer: A
Topic: Concept 16.2
Skill: Knowledge
38) 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.
Answer: A
Topic: Concept 16.2
Skill: Knowledge
8
39) 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
Answer: E
Topic: Concept 16.2
Skill: Comprehension
40) 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.
Answer: B
Topic: Concept 16.2
Skill: Knowledge
41) 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.
Answer: E
Topic: Concept 16.2
Skill: Comprehension
42) Replicating the lagging strand of DNA-that is, adding bases in the 3' 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
Answer: E
Topic: Concept 16.2
Skill: Knowledge
43) 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
Answer: A
Topic: Concept 16.2
Skill: Knowledge
9
44) 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
Answer: A
Topic: Concept 16.2
Skill: Knowledge
45) 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
Answer: C
Topic: Concept 16.2
Skill: Knowledge
46) 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
Answer: D
Topic: Concept 16.2
Skill: Knowledge
47) 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
Answer: D
Topic: Concept 16.2
Skill: Knowledge
48) 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
Answer: E
Topic: Concept 16.2
Skill: Knowledge
10
49) Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight because their cells
have an impaired ability to
A) replicate DNA.
B) undergo mitosis.
C) exchange DNA with other cells.
D) repair thymine dimers.
E) recombine homologous chromosomes during meiosis.
Answer: D
Topic: Concept 16.2
Skill: Knowledge
50) 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
Answer: B
Topic: Concept 16.2
Skill: Application
51) A eukaryotic cell lacking telomerase would
A) have a high probability of becoming cancerous.
B) produce Okazaki fragments.
C) be unable to repair thymine dimers.
D) undergo a reduction in chromosome length.
E) be highly sensitive to sunlight.
Answer: D
Topic: Concept 16.2
Skill: Comprehension
52) 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
Answer: E
Topic: Concept 16.2
Skill: Knowledge
11
Media Activity Questions
53) Hershey and Chase used ________ to radioactively label the T2 phage's proteins.
A) 35S
B) 14C
C) 222Ra
D) 32P
E) 92U
Answer: A
Topic: Web/CD Activity: The Hershey-Chase Experiment
54) Which of these is a difference between a DNA and an RNA molecule?
A) DNA contains uracil, whereas RNA contains thymine.
B) DNA is a polymer composed of nucleotides, whereas RNA is a polymer composed of nucleic acids.
C) DNA is double-stranded, whereas RNA is single-stranded.
D) DNA contains five-carbon sugars, whereas RNA contains six-carbon sugars.
E) DNA contains nitrogenous bases, whereas RNA contains phosphate groups.
Answer: C
Topic: Web/CD Activity: DNA and RNA Structure
55) In a nucleotide, the nitrogenous base is attached to the sugar's ________ carbon and the phosphate
group is attached to the sugar's ________ carbon.
A) 1'; 2'
B) 1'; 5'
C) 2'; 3'
D) 1'; 3'
E) 2'; 1'
Answer: B
Topic: Web/CD Activity: DNA and RNA Structure
56) After DNA replication is completed,
A) each new DNA double helix consists of one old DNA strand and one new DNA strand.
B) each new DNA double helix consists of two new strands.
C) one DNA double helix consists of two old strands and one DNA double helix consists of two new
strands.
D) each of the four DNA strands consists of some old strand parts and some new strand parts.
E) there are four double helices.
Answer: A
Topic: Web/CD Activity: DNA Replication: An Overview
57) Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
A) the replication forks block the formation of longer strands
B) DNA polymerase can assemble DNA only in the 3' to 5' direction
C) DNA polymerase can assemble DNA only in the 5' to 3' direction
D) it is more efficient than assembling complete new strands
E) only short DNA sequences can extend off the RNA primers
Answer: C
Topic: Web/CD Activity: DNA Replication: A Closer Look
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Self-Quiz Questions
58) In his work with pneumonia-causing bacteria and mice, Griffith found that
A) the protein coat from pathogenic cells was able to transform nonpathogenic cells.
B) heat-killed pathogenic cells caused pneumonia.
C) some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.
D) the polysaccharide coat of bacteria caused pneumonia.
E) bacteriophages injected DNA into bacteria.
Answer: C
59) E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more
generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density
distribution of DNA would you expect in this experiment?
A) one high-density and one low-density band
B) one intermediate-density band
C) one high-density and one intermediate-density band
D) one low-density and one intermediate-density band
E) one low-density band
Answer: D
60) A biochemist isolates and purifies various molecules needed for DNA replication. When she adds
some DNA, replication occurs, but each DNA consists of a normal DNA strand paired with numerous
segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?
A) DNA polymerase
B) DNA ligase
C) nucleotides
D) Okazaki fragments
E) primase
Answer: B
61) What is the basis for the difference in how the leading and lagging strands of DNA molecules are
synthesized?
A) The origins of replication occur only at the 5' end.
B) Helicases and single-strand binding proteins work at the 5' end.
C) DNA polymerase can join new nucleotides only to the 3' end of a growing strand.
D) DNA ligase works only in the 3' 5' direction.
E) Polymerase can only work on one strand at a time.
Answer: C
62) In analyzing the number of different bases in a DNA sample, which result would be consistent with the
base-pairing rules?
A) A = G
B) A + G = C + T
C) A + T = G + T
D) A = C
E) G = T
Answer: B
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63) Synthesis of a new DNA strand usually begins with
A) an RNA primer.
B) a DNA primer.
C) an Okazaki fragment.
D) DNA ligase.
E) a thymine dimer.
Answer: A
64) A eukaryotic cell lacking active telomerase would
A) be unable to take up DNA from the surrounding solution.
B) be unable to identify and correct mismatched nucleotides.
C) experience a gradual reduction of chromosome length with each replication cycle.
D) have a greater potential to become cancerous.
E) be unable to connect Okazaki fragments.
Answer: C
65) The elongation of the leading strand during DNA synthesis
A) progresses away from the replication fork.
B) occurs in the 3' 5' direction.
C) produces Okazaki fragments.
D) depends on the action of DNA polymerase.
E) does not require a template strand.
Answer: D
66) The spontaneous loss of amino groups from adenine results in hypoxanthine, an unnatural base,
opposite thymine. What combination of molecules could the cell use to repair such damage?
A) nuclease, DNA polymerase, DNA ligase
B) telomerase, primase, DNA polymerase
C) telomerase, helicase, single-strand binding protein
D) DNA ligase, replication fork proteins, adenylyl cyclase
E) nuclease, telomerase, primase
Answer: A
67) The most reasonable inference from the observation that defects in DNA repair enzymes contribute to
some cancers is that
A) cancer is generally inherited.
B) uncorrected changes in DNA can lead to cancer.
C) cancer cannot occur when repair enzymes work properly.
D) mutations generally lead to cancer.
E) cancer is caused by environmental factors that damage DNA repair enzymes.
Answer: B
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