Chapter 13
Student: _________________________________________________________
1. Assume DNA replication is NOT semi-conservative. Meselson and Stahl's replication experiment would have
shown different results. After growing the bacteria first on heavy 15N, centrifuged results would have shown one
band of heavy DNA. If then bacteria were allowed to grow on light 14N, the centrifuged results would have
shown:
A. one hybrid band and one light band.
B. one heavy band and one light band.
C. two heavy bands.
D. one hybrid band and one heavy band.
2. If a DNA sample contains 13% adenine, what percentage of the sample contains cytosine?
A. 13%
B. 37%
C. 26%
D. 74%
3. Which of the following is/are NOT true about mutations?
A. Damage to DNA can result after exposure to environmental factors such as sunlight or chemicals such as
pesticides.
B. Mutations can often be repaired by cellular enzymes.
C. Mutations to DNA always result in lethal effects and therefore death of a cell.
D. Variations in DNA and mutations are important for evolution to occur.
4. Which is NOT a major function of the genetic material?
A. store information
B. catalyze chemical reactions
C. replicate itself
D. undergo mutation
5. Nucleic acid was first discovered in pus cells in
A. 1824.
B. 1869.
C. 1912.
D. 1931.
E. 1953.
6. DNA was disregarded as a possible candidate for the genetic material because
A. with only four types of nucleotides, it was a very simple, repetitive molecule that could not account for 20
different amino acids.
B. it had been shown that proteins were more important in transferring genetic information than nucleic acids.
C. proteins and carbohydrates were of more interest.
D. it was thought that RNA was more likely to be the genetic material.
7. Transformation of bacteria was shown to occur when _______ bacteria were injected into mice and the mice
_______.
A. live, smooth; died
B. live, rough; didn't die
C. live, smooth and dead, rough; died
D. live, rough and dead, smooth; died
E. live, smooth and dead, rough; didn't die
8. The process of transformation in bacteria involves
A. transfer of genes for making a mucous capsule.
B. infection with a virus called a bacteriophage.
C. production of a cancer cell.
D. the mating of two different kinds of live bacteria.
9. DNA was first proven to be the transforming factor in bacterial cells by
A. Meischer.
B. Watson and Crick.
C. Griffith.
D. McClintock.
E. Avery.
10. Hershey and Chase experimented with radioactively labeled phosphorus and sulfur to determine that DNA
and not protein is the genetic material. Which of the following was essential to this confirming experiment?
A. Sulfur is present in amino acids in the protein coat of bacteria.
B. Phosphorus is present in high amounts in DNA.
C. Sulfur is not present in DNA.
D. Phosphorus is not present in amino acids in the protein coat of bacteria.
E. All were critical to demonstrating DNA is involved in the genetic material.
11. The term "bacteriophage" comes from the Greek root words for
A. disease-causing.
B. rod and to eat.
C. poison-containing.
D. germ and virus.
E. mutation-producing.
12. Which statement is NOT correct about the results of the Hershey-Chase experiment with T2 bacteriophage?
A. Radioactively labeled protein was found in the bacteria, not in the phage coats.
B. Radioactively labeled DNA was found in the bacteria, not in the phage coats.
C. DNA was labeled with radioactive phosphorus.
D. Protein was labeled with radioactive sulfur.
E. Two separate experiments were actually run, one with radioactive phosphorus and one with radioactive
sulfur.
13. DNA was proven to be the transforming substance when only the ______ enzymes could inhibit
transformation.
A. proteinase
B. RNase
C. DNase
D. lipase
14. One of Chargaff's rules states that
A. A + T = G + C.
B. A + G = T + C.
C. A = G, T = C.
D. A = C, T = G.
15. If a species contains 23% A in its DNA, what is the percentage of guanine it would contain?
A. 23%
B. 46%
C. 25%
D. 44%
E. 27%
16. The amount of adenine is always equal to the amount of _______ in DNA.
A. cytosine
B. uracil
C. guanine
D. thymine
E. ATP
17. Information from X-ray crystallographic data collected by _______ was used by Watson and Crick in their
development of the model of DNA.
A. Chargaff
B. Griffith
C. McClintock
D. Franklin
E. Hershey and Chase
18. The X-ray diffraction photography of Rosalind Franklin and Maurice Wilkins was critical evidence of
DNA,
A. indicating that DNA has a double helix structure.
B. showing equal numbers of purines and pyrimidines.
C. showing the bases of DNA were held together by hydrogen bonds.
D. revealing the structure of the deoxyribose sugar.
E. of the location of each adenine, guanine, cytosine, and thymine.
19. In the Watson and Crick model of DNA, the "steps" of the ladder are composed of
A. sugars.
B. a purine and a pyrimidine.
C. two purines.
D. two pyrimidines.
E. a sugar and a phosphate molecule.
20. Before Watson and Crick described DNA structure, Linus Pauling proposed a possible model with three
strands of support running down the middle and the bases extending out the sides. How close was his guess?
A. He missed the number of support strands which was two rather than three.
B. The support strands ran along the outside rather than down the center.
C. The bases were paired in the middle rather than sticking out the sides.
D. All of the choices varied from the real model.
21. Some chemotherapeutic drugs combat cancer by using
A. healthy cell templates to correct the resultant daughter cell DNA sequences that are cancerous.
B. analogs of one of the four nucleotides to prevent replication.
C. analogs of one of the four nucleotides to prevent unzipping of the DNA.
D. DNA polymerase to promote continuous or premature replication.
E. DNA repair enzymes to correct the genetic fault that causes cancer.
22. Which of the following statements about DNA replication is NOT correct?
A. Unwinding of the DNA molecule occurs as hydrogen bonds break.
B. Replication occurs as each base is paired with another exactly like it.
C. The process is known as semiconservative replication because one old strand is conserved in the new
molecule.
D. The enzyme that catalyzes DNA replication is DNA polymerase.
E. Complementary base pairs are held together with hydrogen bonds.
23. Because one original strand of the double-stranded helix is found in each daughter cell, the replication
process is called
A. proofreading.
B. semiconservative.
C. redundant.
D. freeing of DNA.
E. mutation positive.
24. Which does NOT describe a function of the DNA polymerase molecule?
A. recognize the free nucleotide that pairs with the base on the template strand of DNA
B. read the strand of template DNA and recognize the base there
C. proofread to ensure that the proper base has been incorporated
D. make the proper nucleotide to match with the base read on the template strand
E. cut out an improperly paired nucleotide and replace it with the proper one
25. In the Meselson and Stahl DNA replication experiment, "parent" bacteria were grown in a medium of heavy
nitrogen (15N) and then allowed to grow thereafter in light nitrogen (14N) media. Because replication is
conservative,
A. the next generation is mid-weight or hybrid (15N-14N) and the subsequent generation is 25% heavy, 50%
hybrid and 25% light nitrogen.
B. the second and all subsequent generations will be hybrid (15N-14N) strands.
C. the second generation will be hybrid (15N-14N) strands and all subsequent generations will regress toward
higher proportions of light nitrogen (14N).
D. the next generation will be all light (14N) because any heavy nitrogen will be corrected as a replication error.
26. In the Meselson and Stahl DNA replication experiment, "parent" bacteria were grown in a medium of heavy
nitrogen (15N) and then allowed to grow thereafter in light nitrogen (14N) media. The results were clear-cut.
Why was there no occasional variation in results due to crossing-over?
A. The experiment was conducted with bacteria with just one loop of DNA.
B. If crossing-over occurred in the proper organism, the original and complimentary strands would still produce
the same nitrogen isotope band results.
C. Variation is not observed because both the bacteria have one loop of DNA and crossing over between
original and complimentary strands produces the same results.
D. Crossing-over would cause variation in the Meselson and Stahl results; they just didn't run enough trials to
pick up the rare cases of crossing-over.
27. Which statement is NOT true about DNA replication?
A. It proceeds in a 5'-to-3' direction only.
B. One strand of new DNA is replicated faster than the other strand at the replication fork.
C. DNA can only replicate at one point on a chromosome at one time.
D. It occurs more rapidly in bacteria than in eukaryotes.
E. Replication can only begin at a special origin of replication.
28. Which statement is NOT true about DNA replication in prokaryotes?
A. Replication begins at a single origin of replication.
B. Replication is bidirectional from the origin(s).
C. Replication occurs at about 1 million base pairs per minute.
D. Since bacterial cells replicate so rapidly, a second round of replication may begin before the first has been
completed.
E. There are numerous different bacterial chromosomes, with replication occurring in each at the same time.
29. Which statement is NOT true about DNA replication in eukaryotes?
A. Replication of the entire genome takes about ten minutes.
B. A replication fork occurs at each growing point of the replicating chromosome(s).
C. Eukaryotes have numerous different chromosomes, with replication occurring in each at the same time.
D. Replication occurs at the rate of about 500-5000 base pairs per minute.
E. Multiple sites of replication are present on each chromosome.
30. Before the DNA repair enzymes complex has completed its function, approximately how many base-pairs
are still improperly matched?
A. 1 in 10,000
B. 1 in 100,000
C. 1 in 1,000,000
D. 1 in 10,000,000
E. 1 in a billion
31. After the DNA repair enzymes complex has completed its function, approximately how many base-pairs are
still improperly matched?
A. 1 in 10,000
B. 1 in 100,000
C. 1 in 1,000,000
D. 1 in 10,000,000
E. 1 in a billion
32. The evidence that transformation as described by Griffith's experiments was due to DNA
A. was found by Avery in the laboratory.
B. proved that neither enzymes that break down proteins or RNase that digests RNA could not prevent
transformation.
C. DNase caused digestion of the transforming substance.
D. All of the choices are correct.
33. If a species contains 40% guanine in its DNA, what is the percentage of cytosine that it would contain?
A. 60
B. 40
C. 27
D. 30
34. The model of DNA proposed by Watson and Crick
A. combined many of the findings of other researchers also studying DNA such as Rosalind Franklin and
Chargaff.
B. showed the double helix nature of the molecule.
C. presented a molecule with sugar-phosphate backbones on the outside and paired bases on the inside.
D. All of the choices are correct.
35. Replication of DNA is
A. semiconservative.
B. requires the unwinding of the double helix.
C. involves new complementary nucleotides forming base pairs and then joining to form new strands.
D. All of the choices are correct.
36. Genetic mutations are
A. common in bacteria due to their extremely rapid rate of DNA replication.
B. permanent changes in the base sequences of a gene in the DNA strand.
C. due to errors in DNA replication.
D. sometimes due to proofreading errors.
E. All of the choices apply.
37. Mutations are due to DNA damage. Environmental factors that cause mutations include all of the following
EXCEPT
A. UV radiation of sun light.
B. cigarette smoke.
C. free radicals.
D. phosphate detergents.
38. If the Hershey and Chase experiment had used a virus that has RNA for genetic material instead of a DNA
virus, their results would have been dramatically different.
True False
39. The only enzyme needed by the cell to replicate DNA is DNA polymerase.
True False
40. There are two kinds of nucleic acid, DNA and DNase.
True False
41. Bacterial transformation was first discovered using a pneumonia-causing bacterium called Streptococcus
pneumoniae.
True False
42. Chargaff's rules showed that different species contain differing base compositions.
True False
43. The complementary bases of DNA are located on the outside of the helix, with the sugar-phosphate
backbone on the inside.
True False
44. Complementary base pairing always pairs a purine with a pyrimidine.
True False
45. Growth at two replication forks arising from a single origin of replication produce a "bubble" as daughter
DNA molecules form.
True False
46. The Watson-Crick model of DNA was first described in 1961.
True False
47. Identical twins are human clones.
True False
48. During replication of DNA, DNA polymerase has to synthesize the daughter strand in the 5 prime to 3
prime direction because DNA polymerase can only join a 5 prime nucleotide to the free 3 prime end of another
nucleotide.
True False
49. Meselson and Stahl showed that DNA and not protein is the genetic material.
True False
USE THE FOLLOWING KEY (A-G) TO CLASSIFY THE EXPERIMENTAL RESULTS IN THE
FOLLOWING QUESTIONS: When Griffith injected mice with normally fatal S strain bacteria that had been
heat-killed, they did not die. However, if the heat-killed S strain bacteria were mixed with harmless live R strain
bacteria of the same species, the mice died and living S strain bacteria were recovered. Avery continued the
search for the substance that "transformed" the R strain into the S strain.
Hypothesis I: Genetic material or "transforming substance" is protein.
Hypothesis II: Genetic material or "transforming substance" is RNA.
Hypothesis III: Genetic material or "transforming substance" is DNA.
A. Supports Hypothesis I
B. Supports Hypothesis II
C. Supports Hypothesis III
D. Disproves Hypothesis I only.
E. Disproves Hypothesis II only.
F. Disproves Hypothesis III only.
G. Does not support any of these hypotheses.
50. Enzymes that degrade proteins cannot prevent transformation.
________________________________________
51. Enzyme digestion by DNase prevents transformation.
________________________________________
52. Neither heat-killed R strain or heat-killed S strain can kill the mice.
________________________________________
53. RNase fails to prevent transformation of the strain S to R strain.
________________________________________
54. DNA extracted from the S strain bacteria transforms R strain bacteria.
________________________________________
55. List and discuss the importance of the three basic functions of the genetic material.
56. Discuss why DNA composition retarded the discovery of DNA as the genetic material.
57. Describe the evidence that showed that the transforming substance in bacteria was DNA.
58. Describe the evidence that showed that the genetic material of bacteriophage viruses was DNA.
59. Explain Chargaff's rules and tell why they were important in the consideration of DNA as the genetic
material.
60. Explain what the DNA polymerase enzyme complex does.
61. Explain what is meant by "proofreading" by DNA polymerase.
62. The next generation of a bacterium contains half the original DNA strands of the "parent." Explain why the
cells in your body do not all contain one-half or one-fourth the original strands of DNA from your parents.
63. What are the major differences between prokaryotic and eukaryotic replication of DNA? Why do scientists
still consider that all life forms on earth have a common DNA origin?
64. In an earlier chapter, the amount of membrane lipid molecules was found to be approximately enough to
cover the cell volume twice, which is evidence that the membrane involves a lipid bilayer. What conclusions
can be drawn from the following quantitative measurements relative to the genetic function of cells?
-The amount of DNA in the cell nucleus of body cells is constant for an organism.
-The amount of DNA in the nucleus of sperm or eggs cells is constant for an organism and is one-half the value
for body cells.
-The amount of proteins in a cell varies widely for an organism.
Why does this discussion suggest but not prove that DNA is the genetic material?
Chapter 13 KEY
1. B
2. B
3. C
4. B
5. B
6. A
7. D
8. A
9. E
10. E
11. B
12. A
13. C
14. B
15. E
16. D
17. D
18. A
19. B
20. D
21. B
22. B
23. B
24. D
25. C
26. C
27. C
28. E
29. A
30. B
31. E
32. D
33. B
34. D
35. D
36. E
37. D
38. FALSE
39. FALSE
40. FALSE
41. TRUE
42. TRUE
43. FALSE
44. TRUE
45. TRUE
46. FALSE
47. TRUE
48. TRUE
49. FALSE
50. D
51. C
52. G
53. E
54. C
55. Answers will vary.
56. Answers will vary.
57. Answers will vary.
58. Answers will vary.
59. Answers will vary.
60. Answers will vary.
61. Answers will vary.
62. Answers will vary.
63. Answers will vary.
64. Answers will vary.