Genetics-EX2 CH-7

24. Which type of mutation is least likely to revert? A) deletion B) transition C) transversion D) insertion E) all are equally likely

A

19. Replacing an adenine nucleotide with a guanine is an example of a: A) translocation. B) transition. C) transversion. D) forward mutation. E) reversion or reverse mutation.

B

21. A mutation in which parts of two nonhomologous chromosomes change places is called a: A) translocation. B) transition. C) transversion. D) insertion. E) deletion.

A

46. In the Ames test for mutagenicity: A) auxotrophic bacteria are converted to prototrophs which survive. B) prototrophic bacteria are converted to auxotrophs which survive. C) cells are treated with mutagen and only those with no mutations survive. D) cells are treated with excess amino acids, killing cells that carry mutations. E) rat liver enzymes protect cells from mutation.

A

54. Shown below are the results of a series of coinfections using T4 rII- strains similar to those employed by Benzer. Each strain contains a different deletion mutation. Ability to produce wild-type progeny phage is indicated by (+), (o) indicates no wild-type progeny. A B C D E A o + o + + B + o + o o C o + o + + D o o + o + E + o + + o A) CADBE B) ACBDE C) ABCDE D) BEDCA E) CEADB

A

59. Shown below are the deletion maps of a series of rII- mutations. The deleted region is indicated as (......) and the intact region as ______. Note that strain 5 carries two different deletions. 1 ___________(...........)_______________ 2 _________________(...........)_________ 3 (.....................)_______________ ______ 4 ________________________(................) 5 _____(..........)________________(.........) A series of point mutations A-E is used in a coinfection experiment. Shown below are the results of those coinfections. Ability to produce wild-type progeny phage is indicated by (+), (o) indicates no wild type progeny. 1 2 3 4 5 A + + o + o B + o + + + C + + o + + D o + + + + E + + + o o Indicate the order that is most consistent with these data. A) CADBE B) DEBAC C) BADCE D) ABDEC E) CEADB

A

70. Consider the pathway for the synthesis of the amino acid arginine in Neurospora: ARG-E ARG-F ARG-H ornithine citrulline argininosuccinate arginine Mutant strains of Neurospora are grown in minimal media supplements as follows. Each mutant strain carries only a single mutation. Growth is shown by (+), no growth is shown by (o). Supplements mutant nothing ornitihine citrulline arginino- arginine strain succinate a o o o + + b o o + + + c o o o o + Indicate the correct strain / defective gene pairing. A) strain a / ARG-F B) strain a / ARG-H C) strain b / ARG-F D) strain c / ARG-E E) strain c / ARG-F

A

71. Consider the pathway for the synthesis of the amino acid arginine in Neurospora: ARG-E ARG-F ARG-H ornithine citrulline argininosuccinate arginine Mutant strains of Neurospora are grown in minimal media supplements as follows. Strains may carry more than one mutation. Growth is shown by (+) no growth is shown by (o). Supplements mutant nothing ornitihine citrulline arginino- arginine strain succinate a o o o o + Indicate the most accurate statement regarding strain A. A) There is a mutation in ARG-H, if citrulline accumulates, ARG-F is also defective. B) There is a mutation in ARG-H, if ornithine accumulates, ARG-F is also defective. C) There is a mutation in ARG-H, if argininosuccinate accumulates, ARG-F is also defective. D) There is a mutation in ARG-H, if citrulline accumulates, ARG-E is also defective. E) There is a mutation in ARG-E, if citrulline accumulates, ARG-F is also defective.

A

78. Choose the statement below that is not true regarding sickle-cell anemia. A) Individuals who are heterozygous for the sickle cell allele can not make hemoglobin. B) The sickle-cell hemoglobin molecule contains an amino acid substitution. C) The hemoglobin molecules of an individual with sickle cell anemia clump together. D) The red blood cells of an individual with sickle cell anemia distort and elongate. E) All of the above are true regarding sickle cell anemia.

A

83. Mutations that abolish the function encoded by the wild-type allele are known as: A) null mutations. B) hypomorphic mutations. C) hypermorphic mutations. D) conditional mutations. E) neomorphic mutations.

A

87. Examination of the rhodopsin gene family provides evidence for gene evolution by: A) duplication and divergence. B) accumulation of random mutations. C) convergent evolution. D) spontaneous generation. E) drift.

A

A null allele can be dominant to the fully functional wild-type allele due to: A) haploinsufficiency B) codominance C) incomplete dominance D) neomorphism E) not true, a null allele is always recessive to a fully functional wild-type allele

A

Gene evolution is best illustrated by: A) the rhodopsin gene family B) inborn errors of metabolism C) X-linked traits D) sickle cell anemia E) xeroderma pigmentosum

A

In an Ames test for mutagenicity, rat liver enzymes are accidentally excluded from the compound under test. What can you say about the results? A) the mutation rate will probably rise B) the mutation rate will probably decline C) the results are less relevant to mammals D) the results are less relevant to bacteria E) no mutations will form

A

48. Assume that a new low-calorie sweetener is developed. The structure is novel and is tested with the Ames test for mutagenicity. The following results are obtained: Sample Number of his+ revertent colonies distilled water 2 distilled water + rat liver enzymes 3 sweetener 6 sweetener + rat liver enzymes 65 What conclusion is most consistent with this data? A) The sweetener is not mutagenic. B) Rat liver enzymes are highly mutagenic. C) The sweetener is not mutagenic but can be converted into strong mutagens. D) The sweetener is mutagenic and can be converted into strong mutagens. E) The sweetener and its conversion products are equally mutagenic.

C

55. Shown below are the results of a series of coinfections using T4 rII- strains similar to those employed by Benzer. Each strain contains a different deletion mutation. Ability to produce wild-type progeny phage is indicated by (+), (o) indicates no wild-type progeny. A B C D E A o o + o + B o o + o + C + + o o o D o + o o + E + + o + o Indicate the order that is most consistent with these data. A) CADBE B) ACBDE C) BADCE D) BEDCA E) CEADB

C

56. Choose the statement that best distinguishes a complementation test and a recombination analysis when examining mutations in phage. A) Both tests require two different mutations. B) Recombination can only occur between two genes. C) Complementation results can be seen immediately, recombination requires a second infection. D) Recombination results can be seen immediately, complementation requires a second infection. E) Recombination can distinguish one gene with two alleles from two different genes.

C

61. How many progeny phage are released when a single E. coli cell is lysed by phage T4? A) between 1 and 10 B) between 10 and 100 C) between 100 and 1,000 D) about 10,000 E) about 100,000

C

62. Indicate which of the following is least important in doing a complementation test with coinfection of phage T4. A) Ensuring that sufficient phage of both strains are present. B) Recovering phage from the plaques after growth and lysis. C) Counting the plaques that are produced on E. coli K(). D) Control using both mutations in cis configuration and a wild type. E) All the above steps are essential for the experiment.

C

20. Assume that a wild-type sequence is 5'AGCCTAC3'. Indicate the sequence that might be produced by a transversion. A) 5'AGTCTAC3' B) 5'AGCCGCCGCCGCCTAC3' C) 5'AGCCCAC3' D) 5'ATCCTAC3' E) 5'AGCCTGC3'

D

23. Assume that the mutation rate for a given gene is 510-6 mutations per gene per generation. For that gene how many mutations would be expected if 10 million sperm are examined? A) none B) 510-6 C) 5 D) 50 E) 500

D

A conditional bacterial mutant is unable to methylate DNA at higher temperatures. What happens when you shift bacteria to these higher temperatures? A) the new DNA strand is more likely to contain errors B) the older DNA strand is more likely to contain errors C) the rate of mutation goes up D) a and c E) b and c

D

A stock of T4 phage is diluted by a factor of 10-7 and 0.1 ml of it is mixed with 0.1 ml of 108 E. coli/ml and 2.5 ml melted agar, and poured on the surface of an agar petri dish. The next day, 100 plaques are visible. What is the concentration (in plaque-forming units/ml) of T4 phages in the original T4 stock? A) 107 pfu (plaque-forming units)/ml B) 108 pfu/ml C) 109 pfu/ml D) 1010 pfu/ml E) 1011 pfu/ml

D

Assume 8 different strains of mouse have been isolated, each showing a recessive tail phenotype. Crosses are performed as follows; (+) indicates wild type, (0) indicates the behavioral trait. A B C D E F G H A 0 0 + + + + + + B 0 + + + + + + C 0 + 0 + 0 + D 0 + + + + E 0 + 0 + F 0 + + G 0 + H 0 Based on these crosses, how many different genes are present? A) 1 B) 3 C) 4 D) 5 E) 8

D

75. Choose the condition below that does not involve a defect in an enzyme pathway. A) alkaptonuria B) albinism C) sickle-cell anemia D) phenylketonuria (PKU) E) all of the above involve a defect in an enzyme pathway

C

An observable phenotype may arise from a change in: A) the amino acid sequence B) the control of protein expression C) the amino acid sequence of an interacting subunit D) all of the above E) a and c

D

17. A heritable change in DNA base sequence is called a: A) forward mutation. B) reversion. C) substitution. D) deletion. E) mutation.

E

Duplication of multiple three-nucleotide repeats is responsible for: A) sickle-cell anemia B) xeroderma pigmentosum C) alkaptonuria D) trisomy 21 E) fragile X syndrome

E

80. The structure of a polypeptide that is characterized by a three dimensional shape with a characteristic geometry at local regions maintained by hydrogen bonds is: A) primary structure. B) secondary structure. C) tertiary structure. D) quaternary structure. E) both tertiary and quaternary structure.

B

18. Replacing a thymine nucleotide with a guanine is an example of a: A) translocation. B) transition. C) transversion. D) forward mutation. E) reversion or reverse mutation.

C

27. The results of the Luria-Delbruck fluctuation experiment indicated that: A) bacteria are naturally resistant to phage. B) a low level of any bacteria population are naturally resistant to phage. C) bacteria become resistant to phage by mutation when exposed to phage. D) bacteria become resistant to phage by random spontaneous mutation. E) the phage mutate to produce large plaques with sharp edges.

D

45. Alkylating agents such as ethylmethane sulfate (EMS) function as mutagens to: A) promote deletions and insertions. B) remove amine groups. C) add oxygen free radicals to bases. D) add ethyl or methyl groups. E) fit between stacked bases and disrupt replication.

D

47. In the Ames test for mutagenicity, rat liver enzymes are included with the compound under test because: A) bacterial cell walls must be treated to permit uptake of the compounds. B) rat liver enzymes increase the sensitivity of the bacteria to mutagens. C) rat liver enzymes kill mutant cells and allow colonies to form. D) rat liver enzymes may modify or break down some compounds. E) the mutant strain of bacteria requires rat liver enzymes to digest nutrients for growth.

D

50. The size of the human genome in base-pairs is about: A) 210 million B) 100,000 C) 2.75 106 D) 2.75 109 E) 2.75 1010

D

52. Choose the statement that is most correct regarding the rII- strain of T4 that Benzer studied. A) Produces smaller plaques than wild type. B) Produces smaller plaques, grows in E. coli K(), not in E. coli B. C) Produces larger plaques, grows in E. coli K(), not in E. coli B. D) Produces larger plaques, grows in E. coli B, not in E. coli K(). E) Produces larger plaques, grows in both E. coli K() and in E. coli B.

D

An amino acid substitution in a protein can have: A) a large effect on protein structure B) a small effect on protein structure C) little to no effect on protein structure D) all of the above E) none of the above

D

Mutations that are in the same gene and do not complement each other are: A) a complementation group B) alleles C) deletions D) a and b E) none of the above

D

32. Thymine dimers are caused by: A) X-rays. B) free radicals such as oxygen. C) EMS or NSG. D) depurination. E) UV light.

E

39. If a man shows the premutation allele for fragile X syndrome, what is the probability that he will pass it on to his son? A) 100% B) 75% C) 50% D) 25% E) 0%

E

42. If a base analog such as 5-Bromouracil is used as a mutagen, how many generations will be required to mutate the codon for proline (CCC) into the codon for alanine (GCC)? A) one generation B) two generations C) three generations D) at lease two, but perhaps more due to chance E) it will not occur

E

44. Intercalating agents such as acridine orange function as mutagens to: A) promote transitions. B) remove amine groups. C) attach to purines causing distortions. D) add ethyl or methyl groups. E) fit between stacked bases and disrupt replication.

E

53. A plaque is: A) a colony of bacteria growing on a plate. B) a colony of bacteria that contain phage within them. C) a region on a plate where living bacteria survive phage infection. D) an area on a plate containing live phage-resistant bacteria. E) an area on a plate containing phage and dead or destroyed bacteria.

E

69. In the human genetic disorder alkaptonuria, urine turns black because of the presence of homogentisic acid in individuals with the trait. This is due to: A) the presence of large amounts of homogentisic acid in the diet. B) failure of individuals with alkaptonuria to manufacture enzymes involved in the synthesis of homogentisic acid. C) failure of wild-type individuals to manufacture enzymes involved in the synthesis of homogentisic acid. D) failure of the kidneys to remove homogentisic acid from the urine. E) failure of individuals with alkaptonuria to manufacture enzymes involved in the breakdown of homogentisic acid.

E

72. Consider the pathway for the synthesis of the amino acid arginine in Neurospora: ARG-E ARG-F ARG-H ornithine citrulline argininosuccinate arginine Mutant strains of Neurospora are grown in minimal media supplements as follows. The strains may carry more than one mutation. Growth is shown by (+) no growth is shown by (o). Supplements mutant nothing ornitihine citrulline arginino- arginine strain succinate a o o o + + b o o o + + Strain (a) accumulates citrulline, strain b does not. Indicate the statement that is most correct regarding these two strains. A) Strain a has a mutation in ARG-E only. B) Strain b has only one mutation. C) Strain a has mutations in ARG-F and ARG-H. D) Strain a has mutations in ARG-E, ARG-F and ARG-H. E) Strain a has a mutation in ARG-H only.

E

73. Indicate the false statement regarding amino acids. A) Every amino acid contains a carboxyl group. B) The side chain or R group differs for each amino acid. C) Amino acids are joined together by peptide bonds. D) The end of the polypeptide termed the N terminus contains a free amino group. E) All the above statements are correct.

E

82. Assume that a certain strain of bacteria carries a mutation that causes it to die at high temperature (37C), but grows normally at cooler temperatures. This mutation is termed: A) recessive. B) deletion. C) biochemical pathway mutant. D) conditional lethal that grows under restrictive conditions. E) conditional lethal that dies under restrictive conditions.

E

85. Assume that a transition mutation results in an amino acid substitution in the resulting polypeptide. What level of protein structure might be affected as a result? A) primary structure B) secondary structure C) tertiary structure D) quaternary structure E) all levels might be affected by a single amino acid substitution

E

90. The appearance of a novel phenotype resulting from the substitution of a single base pair might be due to: A) change in the amino acid sequence only. B) change in the amount of protein expressed. C) alteration in a gene that codes for a nontranslated RNA. D) change in the developmental time or location at which a gene is expressed. E) all of the above are possible consequences of a single base pair substitution.

E

94. Assume that for a given gene a mutation creates an allele that functions as a dominant negative. The gene codes for a protein that forms a trimer within the cell. If at least one of the subunits has the mutant structure the entire protein is inactivated. For a heterozygous individual, what percent of the trimers present in the cell will be inactive? A) 100% B) 25% C) 50% D) 6.25% E) 12.5%

E

29. The hydrolysis of a purine base from the deoxyribose-phosphate backbone is called: A) depurination. B) deamination. C) replica plating. D) excision repair. E) deletion.

A

34. The genetic condition xeroderma pigmentosum, which can lead to skin cancer, results from: A) inability to correct UV induced dimers. B) inability to process phenylamine. C) inability to produce functional hemoglobin. D) inability to correct transitions. E) breaks in the X chromosome.

A

41. Genes on the X chromosome of mammals and Drosophila are particularly suitable for genetic study because: A) males have only one X and most genes behave as haploids. B) females have only one X and most genes behave as haploids. C) the X chromosome is large and many more genes are located there. D) when present as Barr bodies they are exposed for electron microscopic examination. E) they behave as diploids in females.

A

43. Base analogs differ from other classes of mutagen in that they: A) only alter bases. B) can only cause transversions. C) only work during DNA replication or repair. D) can only cause forward mutations, nor reversions. E) will not function in bacterial cells.

C

37. Unequal crossing over results in: A) an exchange between nonhomologous chromosomes. B) a loss of genetic material. C) a repair of UV-induced damage. D) a production of eggs containing Y chromosomes. E) a creation of deletions and duplications.

E

25. Consider the following results. When 50 million sperm were examined for a specific mutation, 100 mutations were found. Indicate the mutation rate for that gene. A) 510-6 B) 5010-6 C) 210-6 D) 210-5 E) 510-5

C

51. A complementation group is: A) a group of mutations that produce the same phenotype. B) a group of mutations that are in the same gene and complement each other. C) a group of mutations that are in the same gene and do not complement each other. D) a group of mutations in two different genes that complement each other. E) a group of mutations in two different genes that do not complement each other.

C

16. The term mutation refers to: A) only changes in the DNA that result in new phenotypes. B) only changes in the DNA that result in novel proteins. C) any change in the DNA of a cell. D) a heritable change in the DNA of a cell. E) any change in the cell that changes its survival chances.

D

28. In the Luria-Delbruck fluctuation experiment, the bacteria + phage plates showed: A) all plates had some resistant colonies, some had very many. B) some plates had no resistant colonies, a few plates had very many resistant colonies. C) all plates had the same number of resistant colonies. D) some plates had no resistant colonies, the plates that had resistant colonies all had the same number of resistant colonies. E) phage caused mutations to occur in some of the plates but not in others.

B

30. Assume that in the organism under study the DNA polymerase has an error rate of 1 mistake in every 106 bases copied. However, the overall mutation rate is much lower. This is most likely because: A) the polymerase is more careful in replicating regions where genes exist. B) repair mechanisms correct errors made by the polymerase. C) not all mutations can be detected easily. D) the DNA polymerase has no proofreading function. E) mutations do not occur if mutagens are not present.

B

31. Excision repair corrects DNA by: A) removing a double-stranded fragment of damaged DNA. B) detecting, removing, and replacing a single stranded fragment of damaged DNA. C) excising the incorrect base from a nucleotide. D) removing extraneous groups such as methyl or oxygen added by mutagens. E) correcting A=T to C=G transitions.

B

49. The Ames test for mutagenicity is useful to identify potential carcinogens because: A) since bacteria do not get cancer they can survive lethal carcinogens. B) mutagens that affect bacterial DNA are likely to cause human mutation. C) bacteria thrive on substances that could cause cancer in humans. D) the same genes that cause cancer in humans can be mutated in bacteria. E) liver enzymes alter the bacteria so they will behave like mammal cells.

B

58. Shown below are the deletion maps of a series of rII- mutations. The deleted region is indicated as (......) and the intact region as ______. 1 ___________(...........)_______________ 2 _________________(...........)_________ 3 (.....................)_______________ ______ 4 ________________________(................) 5 _____(..........)______________________ A series of point mutations A-E is used in a coinfection experiment. Shown below are the results of those coinfections. Ability to produce wild-type progeny phage is indicated by (+), (o) indicates no wild type progeny. 1 2 3 4 5 A + o + + + B o + + + + C + + + o + D + + o + + E + + o + o Indicate the order that is most consistent with these data. A) CADBE B) DEBAC C) BADCE D) ABDEC E) CEADB

B

74. Indicate the false statement regarding amino acids. A) Several amino acids linked together are termed an oligopeptide. B) Amino acids are linked by peptide bonds that join two amino groups together. C) The C terminus of a polypeptide chain contains a free carboxylic acid group. D) Two amino acids joined together is termed a dipeptide. E) All the above statements are correct.

B

81. The structure of a protein that involves the interaction between two distinct polypeptide chains is: A) primary structure. B) secondary structure. C) tertiary structure. D) quaternary structure. E) both primary and secondary structure.

B

86. The photoreceptor protein rhodopsin: A) is found in cone cells and is sensitive to weak light at many wavelengths. B) is found in rod cells and is sensitive to weak light at many wavelengths. C) is found in cone cells and is responsible for blue and green color vision. D) is found in rod cells and is responsible for blue and green color vision. E) is missing in individuals who exhibit red-green colorblindness.

B

Assume four strains (A-D) of pure-breeding stippled lettuce have been isolated. Given the results of the following crosses: A X C = stippled A X B = wild type A X D = wild type B X C = wild type B X D = stippled C X D = wild type What are the complementation groups for genes A-D? A) A,B and D,C B) A,C and B, D C) A,D and C,B D) A,B,C and D E) A,C,D and B

B

Mutations that reduce the function encoded by the wild-type allele are known as ________, while mutations that eliminate all function are known as ________: A) null mutations; neomorphic mutations B) hypomorphic mutations; null mutations C) hypermorphic mutations; hypomorphic mutations D) conditional mutations; null mutations E) neomorphic mutations; null mutations

B

The hydrolysis of an -NH2 group from a base is called ________, while intercalating agents such as acridine orange function as mutagens by causing ________: A) deamination; transversions B) deamination; deletions or insertions C) excision repair; deletions or insertions D) excision repair; transversions E) deletion; transitions

B

22. Indicate the statement that is most accurate regarding mutations. A) Most mutations alter protein structure and phenotype. B) Only those mutations that alter protein structure will alter phenotype. C) Mutations altering a region that does not code for a protein may alter phenotype. D) All mutations that alter protein structure will alter phenotype. E) All altered phenotypes result from altered proteins.

C

35. The bacterial repair system that corrects mismatched bases after polymerization is able to discriminate between the old and newly made DNA strands because: A) the new strand will contain the incorrect base if a mismatch occurs. B) older DNA is more likely to contain errors. C) older DNA contains methyl groups at specific sequences. D) newer DNA contains methyl groups at specific sequences. E) the DNA polymerase is attached to the new strand.

C

36. The consequence to a bacterial cell of a mutation that inactivated the enzyme that methylates the A of the sequence GATC in newly made DNA would be: A) failure to carry out replication. B) failure to correct thymine dimers. C) failure to distinguish old and new DNA during mismatch repair. D) inactivation of certain metabolic genes. E) decrease in the mutation rate.

C

63. Assume that a researcher is studying coat color in voles. Three strains of white vole have been isolated: milky, blanc, and weiss. White is a recessive trait in each strain. Homozygous white voles are obtained for each strain. Consider the following crosses: milky blanc = all white progeny milky weiss = all brown (wild-type vole color) blanc weiss = all brown (wild-type vole color) The conclusion most consistent with these results is: A) all three strains have mutations in the same gene. B) all three strains have mutations in different genes. C) milky and blanc have mutations on the same gene, weiss has a mutation in a different gene. D) milky and weiss have mutations on the same gene, blanc has a mutation in a different gene. E) weiss and blanc have mutations on the same gene, milky has a mutation in a different gene.

C

66. Choose the statement that is most accurate concerning biochemical pathways. A) All enzymes in the pathway catalyze the same reaction. B) If an enzyme in a pathway is inactive, adding excessive amounts of its substrate will restore the normal phenotype. C) If an enzyme in a pathway is inactive, adding excessive amounts of its product will restore the normal phenotype. D) If the enzyme that catalyzes the final step in a pathway is inactive all the other enzymes will be inactivated as well. E) If the first enzyme in a pathway is inactivated, adding the final product will not restore the normal phenotype.

C

67. Assume 7 different strains of fly have been isolated, each shows a recessive white eye trait. Crosses are performed as follows; (w) indicates white-eyed progeny, (R) indicates wild-type red eyes. Based on these crosses, how many different genes are present? A) only one gene with several different alleles B) 2 C) 3 D) 4 E) 7

C

77. The condition sickle-cell anemia is due to: A) the insertion of an amino acid. B) the deletion of an amino acid. C) substitution of an amino acid. D) failure to synthesize a hemoglobin molecule. E) unequal recombination resulting in the deletion of the -chain hemoglobin gene.

C

84. A neomorphic mutation results in an allele that: A) produces no gene product. B) produces a nonfunctional gene product. C) produces novel proteins or cause inappropriate expression resulting in a new phenotype. D) produces proteins that aggregate with wild-type subunits, inactivating them. E) produces an altered protein that results in a wild-type phenotype.

C

Assume that for a given gene a mutation creates an allele that functions as a partially dominant negative as follows. The gene codes for a protein that forms a dimer within the cell. If one of the subunits has the mutant structure, the entire protein is 25% active. If both subunits are mutant, the enzyme is inactive. For a heterozygous individual, what percent of the normal activity is present in cells? A) 12.5% B) 25% C) 37.5% D) 50% E) 75%

C

Consider the pathway for the synthesis of the amino acid arginine in Neurospora: ARG-F ARG-G ARG-H ornithine → citrulline → succinate → arginine e e Mutant strains of Neurospora are grown in minimal media with supplements as follows. Each mutant strain carries only a single mutation. Growth is shown by (+), no growth is shown by (0). -------------------------------------------------------------------------------- Supplements -------------------------------------------------------------------------------- mutant strain nothing ornithine citrulline succinate arginine -------------------------------------------------------------------------------- a 0 0 0 0 + b 0 0 0 + + c 0 0 + + + -------------------------------------------------------------------------------- Indicate the correct strain / defective gene pairing. A) strain a / ARG-G B) strain a / ARG-F C) strain b / ARG-G D) strain c / ARG-H E) strain c / ARG-G

C

26. Assume that a researcher set out to duplicate the Luria-Delbruck fluctuation experiment. This researcher planted twenty small flasks with bacteria from the same colony and let them grow overnight. The next morning the researcher noticed that all but one of the flasks had come open and were ruined. Not wishing to redo the experiment the researcher took bacteria samples from the one remaining intact flask and placed them on twenty phage plates. What results would you expect to see when the twenty phage plates are examined, and how would these results compare with those of the original Luria-Delbruck fluctuation experiment? A) Identical to the Luria-Delbruck results, namely different numbers of resistant colonies. B) Identical to the Luria-Delbruck results, namely identical numbers of resistant colonies. C) Not like the Luria-Delbruck results, namely different numbers of resistant colonies. D) Not like the Luria-Delbruck results, namely identical numbers of resistant colonies. E) Identical to the Luria-Delbruck results, namely no resistant colonies.

D

33. UV light is a mutagen that can cause: A) depurination. B) deamination. C) alkylation. D) thymine dimers. E) oxidation.

D

40. The duplication of the triplet sequence CGG resulting in elongation or breakage of the X chromosome is termed: A) Barr-eyed. B) Huntington's disease. C) unequal crossing over. D) fragile X syndrome. E) Rhys syndrome.

D

57. Shown below are the deletion maps of a series of rII- mutations. The deleted region is indicated as (......) and the intact region as ______. 1 _____(..........)____________________ 2 _________________(..........)________ 3 (.........)__________________________ 4 ________________________(..............) 5 ___________(...........)______________ A series of point mutations A-E is used in a coinfection experiment. Shown below are the results of those coinfections. Ability to produce wild-type progeny phage is indicated by (+), (o) indicates no wild-type progeny. 1 2 3 4 5 A + + o + + B + + + + + C + + + o + D + + + + o E + o + + + Indicate the order that is most consistent with these data. A) CADBE B) ACBDE C) BADCE D) ABDEC E) CEADB

D

60. Indicate the correct order for one round of infection by bacteriophage T4. 1. Lysis of host cell. 2. Phage proteins and DNA synthesized, host DNA degraded. 3. Assembly of phage within host cell. 4. Phage body enters host cell. 5. Phage injects DNA into host cell. A) 4, 2, 3, 1 B) 1, 2, 3, 4, 5 C) 5, 1, 2, 3, D) 5, 2, 3, 1 E) 4, 5, 3, 1

D

64. Assume a researcher is studying the rII locus of phage T4. Three rII- strains are obtained: A, B, and C. When coinfections are performed in E. coli strain K() the following results are obtained: A B = plaques form A C = plaques form B C = no plaques form The conclusion most consistent with these data is: A) A, B, and C carry mutations in three different genes. B) A and B carry mutations in the same gene, C is on a different gene. C) A and C carry mutations in the same gene, B is on a different gene. D) B and C carry mutations in the same gene, A is on a different gene. E) A, B, and C carry mutations in the same gene.

D

65. Assume a researcher is studying the rII locus of phage T4. Four rII- strains are obtained: A, B, C and D. When coinfections are performed in E. coli strain K() the following results are obtained: A B = lysis A C = lysis B C = no lysis B D = no lysis C D = no lysis In a second experiment, coinfections are performed in E. coli strain B. When progeny phage are examined for their ability to form plaques in E. coli strain K(), the following results are obtained: A B = plaques B C = plaques C D = plaques B D = no plaques The conclusion most consistent with these data is: A) A carries a mutation in one gene, B, C and D are on a different gene, C and D both carry the same mutation. B) A and B carry mutations in the same gene, C and D are on a different gene. C) A carries a mutation in one gene, B, C and D are on a different gene, B and C both carry the same mutation. D) A carries a mutation in one gene, B, C and D are on a different gene, B and D both carry the same mutation. E) A, B, C and D carry mutations in the same gene.

D

68. Assume 8 different strains of fly have been isolated, each shows a recessive white eye trait. Crosses are performed as follows; (w) indicates white-eyed progeny, (R) indicates wild-type red eyes. Based on these crosses, how many different genes are present and what strains have mutations in the same gene as does strain A? A) 2, B, E, and H B) 3, B and C C) 3, B, C, and H D) 3, B, E, and H E) 4, B and H

D

79. Though sickle-cell anemia is frequently lethal for individuals who are homozygous for the sickle cell allele, natural selection seems to have maintained that allele in certain geographic locations. A likely explanation for this observation is: A) the forward mutation rate to sickle-cell is much higher in those regions. B) individuals with sickle-cell anemia live longer and have more children. C) reversion from sickle-cell to wild type is prevented in some populations. D) individuals who are heterozygous for the sickle-cell allele are protected from malaria. E) only certain populations have been tested for the presence of the sickle cell allele.

D

88. Red-green color blindness is more common in males than females because: A) the red pigment gene is on the X chromosome, the green is on an autosome. B) the green pigment gene is on the X chromosome, the red is on an autosome. C) rhodopsin gene is on the X chromosome. D) both the red and the green pigment genes are on the X chromosome. E) both the red and the green pigment genes are on an autosome.

D

89. Consider the gene for color in a particular flower. Three alleles exist: dark blue, white, and sky. Flowers homozygous for each allele produce the characteristic color. In heterozygotes, incomplete dominance occurs and intermediate colors are seen in a natural population. How many different color phenotypes are possible with these three alleles? A) 9 B) 2 C) 4 D) 6 E) 8

D

92. Assume that a series of compounds has been discovered in Neurospora. Compounds A-F appear to be members of an enzyme pathway. Several mutations have been identified and strains 1-4 each contains a single mutation. Shown below are 5 possible pathways. Choose the pathway that best fits the data presented. [growth in minimal media with supplements is shown by (+), no growth is shown by (o)] media supplement strain A B C D E F 1 o o o + + + 2 o o o o + + 3 o o o o + o 4 o o + + + + A) A B C D E F B) A B C F D E C) F B C D A E D) A B C D F E E) A B F E C D

D

93. The term fecundity refers to: A) ability to live a long life. B) ability to survive in several different conditions. C) ability to transcribe DNA. D) ability to produce offspring. E) ability to metabolize several different sugar molecules.

D

Assume that a new antidepressant is developed. The structure is novel and is tested using the Ames test for mutagenicity. The following results are obtained: -------------------------------------------------------------------------------- Sample Number of his+ revertant colonies -------------------------------------------------------------------------------- distilled water 2 distilled water + rat liver enzymes 3 antidepressant 37 antidepressant + rat liver enzymes 39 -------------------------------------------------------------------------------- What conclusion is most consistent with these data? A) the drug and its conversion products are not mutagenic. B) rat liver enzymes are mutagenic. C) the drug is not mutagenic but can be converted into strong mutagens. D) the drug is mutagenic and can be converted into strong mutagens. E) the drug and its conversion products are equally mutagenic.

D

What is the principal determinant of overall protein structure? A) the carboxyl group. B) the amino group C) peptide bonds D) amino acid sequence E) none of the above

D

Which type of mutation is most likely to revert? A) deletion B) translocation C) inversion D) transposition E) transition

D

38. The heritable disorder fragile X syndrome, a major cause of mental retardation, is caused by: A) production of enzymes that break the phosphate backbone. B) UV light. C) X-rays. D) presence of an extra X chromosome in the sperm or egg. E) duplication of multiple three-nucleotide repeats.

E

76. Choose the interaction listed below that is not involved in maintaining tertiary structure in protein molecules. A) covalent bond B) hydrogen bond C) hydrophobic/hydrophilic interactions D) ionic interactions E) all of the above may be involved in maintaining protein tertiary structure

E

91. Assume that a series of compounds has been discovered in Neurospora. Compounds A-F appear to be members of an enzyme pathway. Several mutations have been identified and strains 1-4 each contain a single mutation. Shown below are 5 possible pathways. Choose the pathway that best fits the data presented. [growth in minimal media with supplements is shown by (+), no growth is shown by (o)] media supplement strain A B C D E F 1 o o o + o o 2 o o o o o + 3 o o o o + + 4 o o + o o o A) A B C D E F B) A B C F E D C) A B C D E F D) A B C D E F E) A B C D E F

E

95. A neomorphic dominant mutation in the Antennapedia (Antp) gene of Drosophila causes: A) kinks to form in their tails. B) shortened tails. C) total loss of color vision. D) failure to assemble microtubules during mitosis. E) growth of leg from the head region.

E