IB 201 Spring 2005 Exam 1 March 8 2005 Name Lab Section TA In the following numbered questions on the left chose from the possible answers given by the letters on the right Not all answers are necessarily used and some answers might be used more than once 1 a h uncovers a recessive allele it is said to cause pseudodominance 2 p is an accident of cell division in which the homologous chromosomes fail to separate and migrate to opposite poles responsible for monosomy and trisomy 3 A map unit is equivalent to the physical distance along a chromosome which will experience 1 crossover event in every c meiotic divisions 4 p is an accident of cell division in which the homologous chromosomes fail to separate and migrate to opposite poles responsible for monosomy and trisom 5 A polyploid individual in which sets of chromosomes are derived from different species is an e 6 A chromosomal inversion that does not include the centromere is a r inversion 7 m results because the occurrence of crossing over in a chromosomal region is not independent of the occurrence of crossing over in nearby regions 8 k causes the proportion of homozygotes to increase above that expected under Hardy Weinberg equilibrium 9 j causes random allele frequency change from generation to generation but does not usually lead to significant deviations from Hardy Weinberg proportion within generations 10 k does not change allele frequencies but leads to an excess of homozygotes within populations 1 a b c d e f g h i j k l m n o p q r s t u v w 1 10 50 100 allopolyploid autopolyploid coefficient of coincidence deletion duplication genetic drift inbreeding inversion interference migration mutation nondisjunction nonrandom mating paracentric pericentric selection sex limited sex linked translocation 1 Pick the most accurate term from the following list to fill in the blank in this statement a locus with two alleles in which the phenotypic effects of both alleles are expressed in the heterozygote is an example of a overdominance b epistasis c pleiotropy d codominance e incomplete dominance 2 You find phenotypic variation in body color in a species of earthworm You cross a pure breeding red worm with a pure breeding yellow worm The F1 offspring from this cross are all red You self fertilize one of these F1 offspring and you see the following phenotypic ratios in the offspring 207 red 68 brown 93 yellow Which of the following mechanisms do you think controls skin color in this species a two genes complete dominance b one gene normal dominance c one gene epistasis d two genes incomplete dominance e two genes epistasis 3 Two Manx cats are mated In a large litter two thirds of the kittens are Manx and one third have normal tails Which symbols below most accurately describe the genotypes of the parental cats a M and b M M and c M and M d M and e M M and M 4 In some plants a red pigment cyanidine is synthesized from a colorless precursor The addition of a hydroxyl group to the cyanidine molecule causes it to become purple In a cross between two purple plants the following results are obtained 94 purple 31 red 43 colorless Of the following list what were the most likely genotypes of the parental purple plants a Aa and Aa b AA and aa c Aa and aa d Aa Bb and Aa Bb e AABB and aabb 5 Black and orange pigments in the coats of cats are determined by an X linked pair of alleles cb black and co orange Females are either black cb cb orange co co or tortoiseshell with patches of black and patches of orange cb co Males are either black cb Y or orange co Y What genotypes and phenotypes would be expected among the offspring of a cross between a black female and an orange male a all orange males all black females b all black males all orange females c all orange males all tortoiseshell females 2 d all black males all tortoiseshell females e all tortoiseshell males all black females 6 Fragile X syndrome is caused by expansion of the number of CGG repeats in a region immediately adjacent to the FMR 1 gene Expansion occurs from the normal range 6 to 50 repeats to the permutation range 55 to 230 repeats to the full mutation range 230 repeats Expansion to the full mutation tends to occur in the offspring of individuals with permutations but not in the offspring of individuals within the normal range This condition is an example of a kind of inheritance called a incomplete penetrance b genotype environment interaction c genetic anticipation d recessive X linked inheritance e dominant X linked inheritance 7 An individual that is heterozygous for a pericentric inversion will produce a all abnormal gametes b 50 normal gametes and 50 gametes containing deletions and duplications c as above but only if crossing over occurs within the inversion d 50 normal gametes 25 gametes containing dicentric chromosomes 25 gametes containing acentric chromosomes e as above but only if crossing over occurs within the inversion 8 Assume that a chiasma forms between genes A and B in 12 of the meioses of an individual of genotype AB ab The represent two homologous chromosomes that contain the A and B genes one homolog contains the A and B alleles and the other contains the a and b alleles You cross this individual to an ab ab individual and examine resulting progeny What proportion of the testcross progeny will be Ab ab a 0 b 3 c 6 d 12 e 24 9 In Drosophila a heterozygous female for the X linked recessive traits a b and c was crossed to a male that phenotypically expressed a b and c The offspring occurred in the phenotypic ratios given below The next two questions refer to this data b c 460 a 450 a b c 32 38 a c 11 b 9 c 0 a b 0 3 What is the order and correct linkage pattern of the alleles in the heterozygous female parent a b c a b a c b c a c b d c b a e a c b 10 What pair of map distances below represents the correct map distances between linked genes for this problem a 11 9 b 14 4 c 38 11 d 70 20 e 7 2 11 What is the interference in the above cross a 0 b 0 2 c 0 4 d 0 8 e 1 0 12 In a large randomly mating population of peas the pod color alleles G green and g yellow are at frequencies of 0 75 and 0 25 respectively and green is dominant to yellow You sample peas from 400 plants in this population By doing a series of test crosses you discover that 220 plants have genotype GG 155 have genotype Gg and 25 have genotype gg Can you reject the hypothesis that this population is in HardyWeinberg equilibrium and what is the value of the …