BioSc 231 General Genetics Exam 3 Name Multiple Choice 2 points each C Recombination frequencies A are the same for all genes B arise from specific genetic exchange C are the same for cis and trans heterozygotes D decrease with distance B A plant of genotype C C d d is crossed to c c D D and an F1 testcrossed to c c d d If the genes are linked and 40 map units apart the percentage of c c d d recombinants will be A 10 B 20 C 30 D 40 E 50 C The maximum recombination frequency between two genes is A 100 B 80 C 50 D 10 E 1 B In Drosophila the two genes w and sn are X linked and 25 map units apart A female fly of genotype w sn w sn is crossed to a male from a wild type line What percentage of male progeny will be w sn A 0 B 12 5 C 25 D 37 5 E 50 C The maize genes sh and bz are linked 40 map units apart If a plant sh bz sh bz is selfed what proportion of the progeny will be sh bz sh bz A 0 04 B 0 10 C 0 20 D 0 40 A In maize two plants that are both heterozygous for the recessive alleles a and b are crossed What frequency of double mutant progeny will appear if a and b are 7 2 map units apart and both parents carry a and b in trans A 0 036 B 0 0625 C 0 001296 D 0 005184 E 0 072 D In crossing over A Genetic exchange occurs before chromosome replication B The probability of its occurrence decreases with increasing distance between the genes exchanged C Occurs between two loci very close together D The reciprocal exchange between homologous chromosomes is random A The F G and H loci are linked in the order written There are 30 map units between F and G and 30 map units between G and H If a plant F G h f g H is testcrossed what proportion of the progeny plants will be f g h f g h if there is complete interference A 0 15 B 0 21 C 0 245 D 0 3 E 0 7 C Out of 800 progeny of a three point testcross there were 24 double crossover recombinants whereas 30 had been expected on the basis of no interference The interference is A 0 05 B 0 10 C 0 20 D 0 50 E 0 80 B In a four point testcross the number of phenotypic classes of progeny expected is A 4 B 8 C 16 D 32 E depends on the gene linkage of the tetrahybrid B In a cross of two yeast strains of genotypes c a X c a the progeny were 42 c a 46 c a 5 c a 7 c a The frequency of recombination is A 11 B 12 C 24 D 50 E 76 D Two genes with a 50 recombination frequency are A Present on homologous chromosomes B Located close by C Linked D Far apart on a single chromosome E In testcross experiments the frequency of recombination between genes a and b is 0 3 between b and c 0 2 between c and d 0 1 between a and c 0 5 and between b and d 0 3 What is the order of the three genes A c b d a B d c a b C a d c b D b a c d E a b c d A Three point test crosses A Detect double crossing over events B Require heterozygous gametes C Cannot determine gene order on a chromosome D Determine goodness of fit B Genes ho and dp are 9 0 map units apart and genes dp and da are 26 3 map units apart What is the probability of a double crossover in these regions A 1 3 B 2 3 C 3 4 D 4 5 E 5 6 A In Drosophila the genes r and s are linked Flies of genotype r s r s and r s r s are crossed and an F1 obtained The F1 allele arrangement is called A cis B trans C recombinant D complementary E crossover C The Drosophila genes for white eyes w tan body t and vestigial wings vg lie at map positions 2 22 and 52 respectively Out of 500 progeny 21 exhibited double crossovers What is the degree of interference A 0 10 B 0 20 C 0 30 D 0 40 A One Drosophila genotype P m P m is crossed with another genotype p m p m If the genes are closely linked A All progeny will be phenotypically Pm B All progeny will be phenotypically pm C 50 of the progeny will be phenotypically Pm and 50 phenotypically pm D None of the above B A plant of genotype C C D D is crossed to c c d d and an F1 testcrossed to c c d d If the genes are unlinked the percentage of c c d d recombinants will be A 10 B 25 C 30 D 40 E 50 D Which of the following statements is true regarding recombination between genes on homologous chromosomes A Equivalent ratios 1 1 1 1 are found in progeny from homozygous dihybrid crosses B Recombination frequencies are greater than 50 C 25 of each genotype will appear among the progeny from dihybrid crosses D Exchange of the middle pair of alleles occurs in double crossovers Problems variable points each Two point testcrosses revealed the following map results am pm 23 map units pm nn 16 map units A Draw the two possible maps for these loci 2 am 23 pm 16 nn or am 7 nn 16 pm B What cross would resolve the two possible maps and what are the possible outcomes of that cross 1 A two point testcross to map the distance between am and nn If the first map is correct the distance would be 39 mu and if the second map is correct the distance would be 7 mu You could also do a three factor test cross and low recombination freq would indicate which gene is in the middle Consider a fully heterozygous flowering plant with normal blue flowers and round seeds This plant when crossed with one that has red flowers and oval seeds results in the following progeny 91 blue round 94 red round 93 blue oval 92 red oval A What is the recombination frequency 2 50 B Are these genes linked 1 NO What gametes are produced by an individual with the genotype kL Kl if the genes are A linked no crossing over and B unlinked 2 Linked kL and Kl unlinked kL kl KL Kl Several testcrosses have revealed the rate of recombination for the following genes k m 0 06 k l 0 08 l m 0 13 A What is the order of the three genes 2 …