genetics test - 42. Which of the following statements is...

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Unformatted text preview: 42. Which of the following statements is fl0_t true about p16'NK4a? A) It is a tumour suppressor. B) p16INK4a from mutant alleles have decreased affinity for CDK4. C) Missense mutations in the gene that encodes this protein result in dominant predisposition to melanoma. D) It contains ankyrin repeats. E) A mutation in the 5' untranslated region of the CDKNZA gene generates a new transcription initiation site. 43. Which of the following is m an indicator that a disease has a genetic cause? A) The disease has a specific age of onset. B) A high level of concordance among monozygotic twins. C) The disease occurs in individuals that are exposed to the same environment. D) The disease is similarto a known genetic disease in an animal such as a mouse. E) Different populations have different frequencies of the disease. ‘ 44. Rett syndrome is caused by point mutations in the MECP2 gene, at Xq28; which of the following statements is false with respect to this syndrome? A) Point mutations occur mainly in sperm, so male offspring don’t inherit the defective gene B) In the rare familial cases, mothers are often non-penetrant carriers due to skewed X-inactivation. C) Expressivity varies due to the percentage of cells with the normal copy of the gene on the inactivated X-chromosome. D) More boys than girls are born with this childhood neurodevelopmental disorder. E) Loss of function of MECP2 leads to abnormal expression of other genes. 45. Establishment of the dorsal—ventral axis of the Drosophila embryo: A) involves the production of localized DL mRNA on the ventral side of the developing embryo. B) occurs via at least two paracrine signals transmitted between the developing oocyte and the surrounding somatic follicle cells. C) involves the zygotically expressed DL morphogen. D) depends on the activity of anterior-posterior morphogens, such as BCD or HB-M. E) involves anchoring of maternal mRNA at the + end of microtubules. Page 12 of21 46. Suppose that a Drosophila geneticist examined a fruit fly pedigree that included bicoid mutant (bcd) individuals. Use this pedigree to predict the genotype (for the bed locus), if possible, for IA. I O—EI , . A B = Female with two posterior H O = Wild-tVDe female A B C l = Male with two posterior “I C] = Wild-tvoe male A B C D A) bcd*/-- B) bcd+/ bcd + C) bcd+ bcd ' D) bcd/ bcd ' E) the genotype cannot be determined 47. If you observed a fruit fly with two additional thoracic segments and two fewer abdominal segment, in what type of gene did the mutation likely occur? A) maternal-effect gene B) gap gene C) segment polarity gene D) pair-rule gene E) homeotic gene 48. Why are recessive mutations in the 8x! gene in Drosophila lethal in XX females? A) because le activates the transcription of cell survival genes. B) because recessive mutations indicate an increase in 8x! activity. C) because these mutations are the result of a loss of both X chromosomes. D) because le functions as a repressor of a male-specific dosage compensation genes. E) because le is required for transcription of male-specific genes. 49. Which of'the below is m; true about the pattern of gap gene expression in early Drosophila development? A) It is dependent upon previous expression of the segment polarity genes. B) It is determined by the activity of the anterior-posterior morphogens BCD and HB-M. C) It determines the pattern of expression of the pair-rule genes. D) it determines the pattern of expression of the homeotic genes. E) It forms asymmetric bands of expression. Page 13 of21 50. Which of the following statements is true? A) BCD protein is repressed by the NOS protein. B) The translation of hb-m mRNA is inhibited by the NOS protein. C) Bcd and Nos mRNA both contain localization signals in their 5’ UTR regions. D) SPZ protein is held inactive in the cytoplasm by being bound to a CACT protein. E)Activated DL protein turns on genes that establish the dorsal cell fate. 51. How does the cytoskeleton contribute to the establishment of the Drosophila anterior-posterior axis? A) Through microtubule control of the orientation of mitotic cleavages B) Through microfilament control of the orientation of mitotic cleavages C) Through microfilament-directed asymmetric cell divisions D) Through microtubule-directed tethering of localized transcription factor mRNAs E) None of the above. 52. Pole cells are responsible for forming what structures in an adult organism? A) external sexual organs B) gametes C) head structures D) posterior structures E) abdominal hairs 53. Which of the following statements about positional information in Drosophila is false? A) Morphogens are a type of molecule that conveys positional information. B) When a morphogen is secreted, it must bind to cell surface receptors to elicit its effects. . C) The anterior pole is determined by the site of sperm entry. D) The body pattern relies initially on the spatial location of maternal gene products. E) Morphogens define different cell fates in a concentration-dependent manner. 54. In XY humans, what would be the effect of a loss-of—function mutation in AMH (anti- Mullerian hormone)? A) The testes would not form, resulting in a normal female phenotype. B) The testes would form, but the individual would develop as a sterile female with non-functional internal sexual organs. C) The individual would develop as a normal male, though with feminized secondary sexual characteristics. D) The testes would not form, resulting in a sterile male phenotype. E) The testes would form, but these males would be infertile with internal female sexual organs. Page 14 of21 55. In a population in Hardy-Weinberg equilibrium, what will be the proportion of matings between homozygotes? A) p: + 2m B) p C) p4 + q“ D) ID4 + q“ + 2:326)2 E) 4pzq2 56. An RFLP probe shows four different morphs in a population of butterflies, how many different genotypes will there be in this population with regard to this RFLP? A)3 B)4 C)6 D)10 E)16 57.(2 marks) The gene for coat colour in rabbits can exist in four alleles termed C (full coat colour , cc" (chinchilla), c” (Himalayan) and c (albino), with a dominance series of C > cc" > c > c. In a population of rabbits in Hardy-Weinberg equilibrium, the allele frequencies are: C = 0.34; cc" = 0.17; c" = 0.44; and c = 0.05. Among 1000 rabbits, how many would you expect to have a Himalayan coat colour? A) 44 B) 194 C) 240 D) 387 E) 492 58. (2 marks) Human albinism is an autosomal recessive trait. Suppose that you find a village in the Andes where 1/4 of the population is albino. If the population size is 1000 and the population is in Hardy—Weinberg equilibrium with respect to this trait, how many individuals are expected to be heterozygotes? A) 50 B) 250 C) 300 D) 500 E) 750 Page 15 of21 59. Inbreeding in populations that are normally outbreeding leads to which of the following? A) A smaller population B) A higher rate of mutation C) A higher rate of genetic drift D) An increase in the frequency of heterozygotes E) More individuals affected by rare diseases 60. In a given population of Drosophila, curly wings (c) is recessive to the wild-type condition of straight wings (6‘). You isolate a population of 35 curly winged flies, 70 flies that are heterozygous for straight wings and 45 that are homozygous for straight wings. What is the frequency of alleles in this population? A) 35% c; 45% c'r B) 47% c; 53% c+ C) 50% c; 50% c+ D) 55% c; 45% c+ E) 70% c; 30% c+ 61. (2 marks) Suppose that two first cousins (i.e. they have the same grandparents on one side) marry. What is the chance that they will have a child with cystic fibrosis, considering that the carrier frequency is 1/25? A) 0.0256 B) 0.0050 C) 0.00125 D) 0.00040 E) 0.000525 62. (2 marks) This is one line from the table giving frequencies of gametic types for the MNS system in various human populations: —_G_a_nLictvpe____ Population MS Ms NS Ns English 0.247 0.283 0.080 0.290 Calculate the allelelic heterozygosity (H) for this English population. A) 0.938 B) 0.700 C) 0.469 D) 0.250 E) 0.235 Page 16 of21 63. Which of the following will alter the frequency of alleles in the population the least? A) mutation B) natural selection C) genetic drift D) migration E) all of the answers are equal 64. Which of the following is [Lot correct concerning events such as natural disasters and habitat destruction? A) They have a greater impact on small populations. B) They are examples of genetic drift. C) They eliminate members of a population without regards to genotype. D) The resulting population has a different genetic makeup from the starting population. E) They promote genetic diversity in large populations. 65. Which of the following is true regarding a balanced polymorphism? A) The frequency of alleles is not changing over time. B) The homozygous condition for the alleles is not advantageous to the organism. C) The population (or species) occupies a heterogeneous environment. D) An example in humans is sickle-cell anemia. E) All of the answers are correct 66. If mating occurs solely between relatives, eventually what will happen to the population? A) It will become completely heterozygous. B) it will remain in equilibrium. C) It will become polymorphic for all shared traits. D) It will become completely homozygous. E) The individuals in the population will have more dominant alleles. 67. (2 marks) In a donor population, the allele frequencies for the normal (HbA) and sickle-cell alleles (Hbs) are 0.9 and 0.1, respectively. A group of 550 individuals migrates to a new population containing 10,000 individuals; in the recipient population, the allele frequencies are HbA = 0.99 and Hbs = 0.01 (before the new group arrives). What will be the frequency of the Hbs allele in the new combined population? A) 0.015 B) 0.0095 C) 0.0047 ' D) 0.00062 E) 0.0002 Page 17 of21 68. (3 marks) The colouration of B. betu/aria (a moth) affects the probability that birds will see and eat them. Thus, the dark form has a selective advantage in industrialized areas. The dark allele (D) is dominant to the light allele (d). In one such area, the frequency of D = 0.7 and the frequency of d = 0.3. The fitness of the dark moth is 1.0 compared to 0.47 for the light moth. What would be the frequency of the light allele after one generation of selection? A) 0.42 B) 0.29 C) 0.27 D) 0.045 E) 0.042 69. A heritability value of 0.997 indicates which of the following? A) The majority of the phenotypic variation has a genetic basis. B) The majority of the phenotypic variation has an environmental basis. C) The trait is polygenic. D) There is a significant difference between the two strains. E) none of the answers are correct 70. (2 marks) In a natural population of outbreeding annual plants, the variance of the total number of seeds per plant is 16. From the natural population, 20 plants are taken into the laboratory and each is selfed for 10 generations. The average variance in the tenth generation of each of the 20 sets is about equal, and averages 5.8 across all the sets. Estimate the broad-sense heritability (H2) of seed number in this population. A) 0.18 B) 0.32 C) 0.82 D) 0.75 E) 0.68 Page 18 of21 71. Which of the following statements regarding heritability and continuous variation is true? A) Heritability measures the degree to which genes determine phenotype. B) As the number of gene loci that affect a trait increases, the proportion of extreme version of the trait also increases. C) Heritability may be calculated as genetic variance divided by environmental vanance D) Heritability applies to a specific population raised in a particular environment. E) A heritability value of 1.0 means that the environment is unimportant in the outcome of the trait. 72. (2 marks) Assume a situation where genes A, B, C, and D have identical and additive effects and are inherited independently. Each dominant allele of these genes contributes 3 cm to height to the organism. In addition, a gene L, is always present in the homozygous state, contributes a constant 40 cm of height. An organism that is A/A; B/B; C/C; D/D; UL would be 64 cm high, and one that is a/a; b/b; c/c; d/d; L/L would be 40 cm high. A cross was made between A/A; b/b; C/C; D/D; UL and a/a; B/B; c/c; D/D; UL and wascarried into the F2. Which of the following is n_ot correct? A) The heights of the two parents would be 58 cm and 52 cm, respectively, with the F1 being intermediate in height. B) The F2 individuals will have an average height of 55 cm. C) The F2 will show a greater variability in height than the F1. D) There will be 16 phenotypic classes in the F2. E) Interbreeding the F2 individuals of the shortest height will lead to an F3 with a reduced variability compared to the F2. ‘ 73. For the situation described in question 72, what is the expected frequency of the tallest class in the F2? A) 1/16 B) 1/32 C) 1/64 D) 1/256 E) 1/1024 Page 19 of21 74. To establish that evolution by naturalselection is operating in a population, one must demonstrate variability for a trait, heritability of that trait, differential reproductive success based on that trait, and what else? A) continuous change in the environment. B) progress. C) random mating D) increased complexity of the organism. E) nothing else. 75. Studies have shown that 85% of the total genetic diversity among humans can be found in all populations, whereas only 15% is specific to individual populations. Which of the following evolutionary forces is probably responsible for this pattern? A) Migration B) Mutation C) Inbreeding D) Directional selection E) Genetic drift ' 76. Which of the following reduces heterozygosity? A) Migration B) Mutation C) Directional selection D) Balancing selection E) Large population size 77. Which of the following is an exampleof post-zygotic isolation in speciation? A) Different species of flowering plants flower at different times. B) Insects produce specific pheromones to attract males of the same group. C) Some plants do not open their flowers until self fertilization is complete. D) When a bee visits a flower with many types of pollen, biochemical signals from the plant allow pollen only from the same species to fertilize. E) Tetraploid strawberry hybridizes with a diploid strawberry to give a triploid offspring with greatly reduced fertility. Page 20 of 21 78. If the sequence of a gene from one species is similar to a gene from another species, it is often assumed that they have the same function. Which of the following statements must be true for this assumption to be correct? A) All species have descended from a single ancestor. B) The molecular clock must be accurate. C) The mutation rate is similar for all genes and in all species. D) Nonsynonymous substitutions must be neutral. E) The rate of synonymous substitution must equal the rate of non-synonymous substitution. For 79 and 80: The rate of change is not identical for all genes. The following graph shows the rate of change of four hypothetical human proteins (A-D). Use this graph to answer the following two questions. A 100 EB # of amino 75 acid subs. C per 100 50 residues 25 O 375 750 1125 1500 Millions of years since divergence 79. Which evolutionary force plays the biggest role in causing the observed difference in the rate of change between proteins A-D? A) Migration B) Mutation C) Selection D) Genetic drift E) Balanced polymorphism 80. If you were going to use one of the proteins to build a phylogenetic tree of various plant species (which diverged during the past 500 million years), which protein sequence would be most useful? A) A B) B C) C. D) D E) All proteins are equally useful Page 21 of21 ...
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genetics test - 42. Which of the following statements is...

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