BIOL 3301 Genetics Exam 1 Key (GRADE A) Questions and Answer Solutions.

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BIOL 3301 Genetics Exam 1 Key (GRADE A) Questions and Answer Solutions. Biol 3301 Exam #1 There are a total of 11 pages in this exam. This exam consists of 33 questions worth a total of 100 poin... ts. All questions are multiple choice and there is one best answer for each question. Record your answers on the scantron sheet, and answer only once for each question or you will be automatically marked wrong. Use a #2 pencil. Name ID# 1) Recombinant chromatids arise from a. reciprocal exchange of DNA between homologs during prophase II b. reciprocal exchange of DNA between homologs during prophase I c. the alignment of chromosomes at metaphase II d. reciprocal exchange of DNA between sister chromatids during prophase e. the primordial ooze 2) Sister chromatids separate during a. anaphase in mitosis and anaphase II in meiosis b. mitosis, but not in meiosis c. in meiosis, but not in mitosis d. at anaphase II in mitosis and anaphase in meiosis e. half time Question 3 – 6 refer to the following pedigree segregating a dominant trait and a microsatellite with three morphs (M1, M2, and M3): 3) What is the probability that in generation III, any three children of the seven children would have the trait? a. 0.5 b. 35 X [(0.5)3x(0.5)4] c. (0.5)3x(0.5)4 d. (0.25)3x(0.75)4 e. 10 X (0.5)7 4) If II-1 would have another child, what is the probability that this progeny would inherit the dominant trait? a. 0.05 b. (0.5)7 c. 0.25 d. 0.50 e. 0.75 5) In Generation III, there are a. 7 parental type progeny b. 6 parental type and 1 recombinant type progeny c. 5 parental type and 2 recombinant type progeny d. 2 parental type and 5 recombinant type progeny e. Not enough data 6) Assuming the microsatellite is linked to the dominant trait and you wish to test a recombination frequency of 0.2, the ratio of RF = 0.2 to that independent assortment is: a. (0.25)5 b. 35 X (0.1)3 X (0.4)4 c. [(0.2)2 X (0.8)5]/(0.5)7 d. [(0.2)3 X (0.8)4] /(0.25)75 e. [(0.1)2 X (0.4)5] /(0.25)7 ] 7) Which of the following does NOT add to phenotypic variability of a single trait: a. Genetic recombination b. Developmental noise c. Genotype-Environmental interaction d. Allelic changes in genotypes e. None of the above. Question 8-11: you have performed the following dihybrid cross in Drosophila using the black body color (b) and vestigial wings (vg) mutations. The b+ (grey body) and vg+ (normal wing) are dominant wild type alleles. These genes are autosomal. Female ♀ b+ vg+ X male ♂ b vg b vg b vg Progeny: Phenotype # of Progeny Grey body normal wing 467 Black body vestigial wing 466 Grey body vestigial wing 97 Black body normal wing 90 Total 1120 8) Assuming independent segregation what is the value for χ2? a. 3 b. 497 c. 650.9 d. 706.3 e. 0.05 9) How many degrees of freedom for this chi square test? a. 1 b. 2 c. 3 d. 4 e. 0 10) Referring to the χ2 table below, which of the following statements is true: a. The probability of having a χ2 value this large is greater than or equal 0.05 b. The data supports independent segregation c. In this experiment, any χ2 value equal to or greater than 5.024 is significant and the hypothesis is rejected d. The χ value proves linkage significant and the hypothesis is rejected 2 e. In this experiment, any χ value equal to or greater than 7.815 is 11) Which of the following statements regarding the genetic distance between black and vestigial in this data set is true. a. The genetic distance of 20.3 cM derived using Haldane’s mapping function is more accurate than recombination frequency as it includes an estimate of the number of double recombination events. b. The genetic distance of 25.5 cM derived using Haldane’s mapping function is more accurate than recombination frequency as it includes an estimate of interference. c. The genetic distance of 16.9 cM derived using Haldane’s mapping function is more accurate than recombination frequency as it includes an estimate of interference. d. The genetic distance of 25.5 cM derived using Haldane’s mapping function is more accurate than recombination frequency as it includes an estimate of the number of double recombination events. e. Since there are zero double recombinants, the recombination frequency is the most accurate measure of genetic distance. 12) Which of the following statements is not true? a. Genes are capable of existing in several states (alleles), each having detectable effects. The change from one such state to another is known as mutation. b. The order of genes along a chromosome is altered through the process of recombination. c. Each chromosome has many genes, and these are arranged in a linear order. d. Every gamete receives one chromosome of each homologous pair. This distribution of chromosomes to the gametes is a matter of chance. e. The distribution to the gametes of the chromosomes of one homologous pair has no effect on the distribution of the chromosomes of the other are true pairs. 13) If you self a tetra-hybrid (B1b1 B2b2 B3b3 B4b4), how many different phenotypic classes would you expect to find in the resulting progeny? a. 27 b. 8 c. 4 d. 9 e. 16 14) In Meiosis, the stages of Prophase I are: a. Leptotene, Zygotene, Pachytene, Diplosomia, Telekinesis b. Leptin, Zygotes, Polydactyl, Diplosomia, Diakinesis c. Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis d. Leptin, Zygotes, Pachytene, Diplosomia, Diakinesis e. Leptotene, Zygosis, Polydactyl, Diplotene, Diakinesis 15) What is the most likely inheritance pattern in the following pedigree? a. Autosomal Recessive b. Autosomal Dominant c. Sex-linked recessive d. Sex-influenced autosomal e. Cytoplasmic 16) Cohesions: a. Are proteins that hold sister chromatids together during meiosis b. Are present only during prophase II c. Are only found at centromeres d. Are found within recombination nodules e. A, B, & D Questions 17-20: You have performed the following trihybrid test cross in Arabidopsis with the ethylene insensitive 2 (ein2), flowering tTime (fy) loci and gibberellin-responsive dwarf (ga3) loci. You need to figure out the map order (order of genes along the chromosome) and the distance between the loci. EIN2ein2, FYfy, GA3ga3 X ein2ein2, fyfy, ga3ga3 (tester) Ethylene sensitive seedlings Ethylene insensitive seedlings Normal flowering Delayed flowering Normal height short plant, reversible by adding gibberellic acid. The resulting progeny phenotype classes are shown below: Phenotype Class # of Progeny 51 49 1,048 1,039 3,469 3,481 427 436 Total 10,000 17) Which of the following gamete genotypes is a parental (non-recombinant) class of the Trihybrid parent: a. ein2 FY ga3 b. ein2 fy ga3 c. EIN2 FY ga3 d. ein2 FY GA3 e. None of the above 18) Which of the following gametes represents a double recombinant event: a. ein2 FY ga3 b. ein2 fy ga3 c. EIN2 FY ga3 d. ein2 FY GA3 e. None of the above 19) Assuming that the expected frequency of double recombinants is 0.015, what is the Interference for this three-point test cross? a. 0.01 b. 0.0081 c. 0.667 d. 0.333 e. 0.99 20) Which of the following maps is the most accurate for this trihybrid cross: The Answer is b. 21) In a three-point test cross with genes A-B-C. The B gene is located between genes A and C. You find there is interference between the A and C. Which of the following is correct: a. Recombination events between A and B are not independent of recombination events between B and C. b. Recombination events between A and B are independent of recombination events between B and C. c. The coefficient of coincidence is less than 1. d. Both b. and c. e. Both a. and c. 22) A lod score is a statistical value that represents the probability of genetic linkage between human genes. Assume that you find a LOD score of 3 for a recombination frequency of 0.05 between a rare disease and an RFLP. Which of the following statements best characterizes your analysis? a. The probability of linkage at 5 cM is 1000 times higher than the probability of independent assortment b. There is not enough evidence to accept the hypothesis of linkage between the disease train and the RFLP. c. The probability of linkage at 5 cM is 3 times higher than the probability of independent assortment. d. None of the previous statements are true. 23) You purchase two true breeding carnation strains. One strain has white flowers, and the other strain has red flowers. When you cross the two strains, you discover that all of the progeny have pink flowers. You then cross the F1 generation and produce 40 offspring. Of those 40 offspring, 10 have red flowers, 10 have white flowers, and 20 have pink flowers. How can you explain this result? a. The red allele is completely dominant to the white allele. b. The pink allele is dominant to the white allele. c. There is incomplete dominance between the red and white alleles. d. The red allele is epistatic to the white allele. e. The red allele is homozygous lethal. 24) When flies carrying a dominant mutation in the Ts gene are raised at 25 Celsius they appear wild-type, but when they are raised at 30 Celsius they have small wings. If you cross Ts mutant heterozygotes and raise the offspring at 25 Celsius, what ratio of wild-type:small-winged flies do you expect? a. 1:1 b. 1:3 c. All small-winged d. All wild-type e. All flies will die because Ts is dominant. 25) A gene that controls a plant’s ability to grow in dry conditions also affects flower color. How would you describe the gene? a. incompletely penetrant b. pleiotropic c. codominant d. epistatic e. heterozygous 26) Mice that are heterozygous for a mutation in the S gene have short legs. You cross two heterozygous mice and observe a 2:1 ratio of shortlegs:normal-legs progeny. How can you explain this result? a. The wild-type allele is dominant to the short legs allele. b. The short legs allele is epistatic to the wild-type allele. c. There is incomplete dominance. d. The wild-type allele is homozygous lethal. e. The short legs allele is homozygous lethal. 27) Genes B and R are part of a flower color pathway, and b and r are recessive mutations of each gene. Wild-type plants have purple flowers because the B gene product produces a blue pigment, and the R product converts that blue pigment into purple. Homozygotes for the b mutation have white flowers regardless of their genotype at the R gene. Homozygotes for the r allele have blue flowers if they have a wild-type copy of B. If you cross BbRr heterozygotes, what ratio of purple:blue:white flowers do you expect in progeny? a. 9:3:4 b. 9:6:1 c. 13:2:1 d. 12:3:1 e. 1:1:1 28) You discover a mutation that prevents bacteria from growing in a minimal medium. If you supplement the media with glycine, the bacteria grow well. What can explain your result? a. The mutation prevents the bacteria from uptaking glycine. b. The mutation is in a gene that converts glycine into something else. c. The mutation is in a gene that is part of the glycine synthesis pathway. d. Glycine should accumulate in the mutant bacteria. e. Wild-type bacteria need glycine in their media to grow. 29) You discover two mutations, shorty and midget, that cause oak trees to grow to only 5 feet tall. You cross true breeding shorty trees with true breeding midget trees and get all normal height (tall) oak trees. What best explains your result? a. The two mutations are in different genes. b. The two mutations are in the same gene. c. The mutations are incompletely penetrant. d. One mutation is dominant to the other. e. The mutations are incompletely dominant. 30) Thomas Jefferson is believed to have fathered six children with Sally Hemings, a slave at Jefferson’s plantation. A historian would like to identify modern descendants of the children Hemings had with Jefferson, and the historian solicits your expertise as a geneticist to assist in the search. You are able to isolate and sequence a small fragment of mitochondrial DNA from Hemings’ remains, Jefferson’s remains, and living individuals who believe they descend from Hemings and Jefferson. What relationship(s) will you be able to establish with these data? a. Verify that males and females are descended from both Jefferson and Hemings b. Verify that males and females are descended from Jefferson c. Verify that males and females are descended from Hemings d. Verify that females, not males, are descended from Hemings e. None of the above 31) You discover a mutation that causes mice to have trouble walking. You cross a male mouse that has trouble walking with a wild-type female mouse, and all of the progeny are wild-type. You then do the reciprocal cross—nonwalking female with wild-type male—and all of the progeny have trouble walking. When you cross one of the non-walking female progeny to a wildtype male, all of the progeny cannot walk. However, the sons who cannot walk have entirely wild-type offspring when crossed to a wild-type female. How is this trait inherited? a. X-linked gene b. Y-linked gene c. Autosomal gene d. Mitochondrial gene e. Chloroplast gene 32) Which of the following is NOT true about organelles? a. The mitochondria arose when a cell engulfed an α-proteobacterium. b. The chloroplast arose when a cell engulfed a cyanobacteria. c. All eukaryotic cells have chloroplasts. d. Humans have mitochondria. e. Mitochondria and chloroplasts have their own genomes. 33) Please Answer a. a. b. c. d. e. [Show More]

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