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Population genetics and mendelian genetics




BIS 2B;Mendelian genetics practice questions 2014;1. You breed black labs. Labs exhibit epistasis for coat color. Dad is BbEe and mom is;BbEe, where B_ codes for black, and bb results in brown coat color. The E locus is;epistatic for coat color where ee pups are yellow. What colors are the parents? What is;the chance that a pup of the litter will be brown?;2. List the possible gamete genotypes produced by individuals of the following;genotypes. Start out by assuming that the A, B and C loci are unlinked.;a. Aa;b. AaBb;c. AAbbcc;d. AaBBCc;e. AaBbCc;List the possible genotypes that emerge from a test cross between an;individual of each of these genotypes with a homozygous recessive individual.;List all the possible phenotypes that could emerge from these test crosses if all;traits were strictly dominant? What are their frequencies?;List all the possible phenotypes that could emerge from these test crosses if all;traits were co-dominant? What are these frequencies?;3. You conduct a dihybrid cross of two parents that are both homozygous for both traits;to get an F1 generation where all individuals are heterozygous for both traits. Both traits;exhibit co-dominance.;You expect to observe how many different phenotypes in the F2 generation?;You expect to observe how many different genotypes in the F2 generation?;4. A mother with type A blood and a father with type B have children with type AB, type O;and type B. This pedigree can be explained by;A. Epistasis;B. Independent assortment;C. Pleiotropy;D. Segregation;E. Sex linkage;5. A flower color gene has two possible alleles (P, p). P is dominant to p, where PP and Pp are;purple and pp is white. Flower shape is referred to as Spurred (SS), partially spurred (Ss) and not;spurred (ss). The plant is self-compatible. The S and P loci are unlinked.;You start with a true breeding purple and spurred individual, and a true;breeding white and not spurred individual. You cross them. What kind(s) of;offspring do you get in the F1? What are the phenoptype(s) and genotype(s)?;Now you will cross the F1 offspring to get an F2 generation. What does the;Punnett Square that shows the possible outcomes of this cross look like?;How many different phenotypes can emerge from this cross?;What are the expected frequencies of phenotypes?;6. In peas, pink flower color depends upon anthocyanin synthesis. The C gene controls the;production of an anthocyanin precursor, and the P gene controls the conversion of that;precursor to anthocyanin. In plants homozygous for the recessive c allele at C, no;precursor is made, and therefore no anthocyanin pigment. In plants homozygous for the;recessive pp locus at P, precursor cannot be converted to anthocyanin pigment. Thus;unlinked.;If you make a cross between two CcPp heterozygote;parents, what will be the frequency of white-;flowered plants in the progeny? (Hint: the Punnett;square is your friend, but you may not need to fill in;all of the cells.);A. 1/16;B. 3/16;C. 4/16;D. 7/16;E. 9/16;7. In progeny of a cross between genotypes AaBb and aabb, you observe the following;genotype frequencies: AaBb 6/16, Aabb 2/16, aaBb 2/16, aabb 6/16.;The best explanation for these results is;A. Epistasis;B. Independent assortment;C. Linkage;D. Pleiotropy;E. Segregation;19. A test cross between genotypes AaBb and aabb reveals the following gamete;frequencies: 25%AB, 25%Ab, 25%aB, 25%ab. An AaCc x aacc test cross reveals gamete;frequencies of 39% AB, 11% Ab, 9% aB, and 41% ab.;Which of the following is true?;A. A, B, and C are unlinked, and assort independently;B. A and C assort independently, but A and B are linked.;C. A, B, and C are linked, but A and C are closer together than A and B;D. A, B, and C are linked, but A and B are closer together than A and C;E. A and B assort independently, but A and C are linked;View Full Attachment;Population Genetics.pdf Download Attachment;Population genetics practice questions 2014 (Schmitt);1. Given the following genotype frequencies, is each of these populations in Hardy-;Weinberg equilibrium? If not, determine which observed genotype frequencies > expected;and which observed genotype frequencies < expected.;A. AA = 0.01, Aa = 0.18, aa = 0.81;B. AA = 0.25, Aa = 0.50, aa = 0.25;C. AA = 0.36, Aa = 0.60, aa = 0.04;D. AA = 0.09, Aa = 0.42, aa = 0.49;E. AA = 0.64, Aa = 0.20, aa = 0.16;2. Which of the following phenomena is LEAST likely to cause changes in allele frequencies;over time within populations?;A. Assortative mating;B. Founder effects;C. Gene flow;D. Directional selection;E. Population bottlenecks;3. Rare deleterious recessive alleles are slow to be completely eliminated by natural;selection because;A. The fitness of homozygotes increases with declining allele frequency in the;population;B. Genetic drift becomes more important when the recessive allele is very rare.;C. When a recessive allele is rare, it occurs mostly in heterozygous individuals;where it does not affect relative fitness.;D. New mutations arise faster than natural selection can eliminate them from the;population.;E. Gene flow from other populations balances out the effects of natural selection.;4. Which of the following is NOT a possible mechanism for maintaining genetic variation;within populations?;A. Heterozygote advantage;B. Frequency-dependent selection;C. Gene flow;D. Population bottlenecks;E. Balancing selection;5. The most likely explanation for the frequent observation of multiple gametophytic self-;incompatibility alleles within plant populations is;A. Disruptive selection;B. Assortative mating;C. Gene flow;D. Epistasis;E. Negative frequency-dependent selection;6. Orange coat color in cats is caused by the X-linked codominant allele O. Suppose;that 20% of the male kittens in a feral population are orange. Assume that the;population is in Hardy-Weinberg equilibrium.;a. What is the frequency of the O allele in the population (2 points)?;b. Among females, what is;-- the predicted frequency of pure orange coats (2 points)?;-- the predicted frequency of calico (half orange) coats (2 points)?;7. You sample a population of butterflies at the end of the flying season, and score;them for their genotype for the enzyme PGI. In this population, there are two PGI;alleles: P1 and P2. You observe the following genotype frequencies: P1P1: 0.20;P1P2: 0.60, P2P2: 0.20;a. (2 points) What is the allele frequency for P1? ____ For P2?;b. 2 points) What is the expected frequency of each genotype under Hardy-;Weinberg equilibrium? P1P1:_______ P1P2 _________ P2P2;c. (4 points) Suggest two processes that could produce the observed pattern of;genotype frequencies;1;2;8. In a population exhibiting variation in two traits, where each trait has three;alleles, you measure allele frequencies of trait A to be: p = 0.2, q = 0.3, r =.5 and A3;(r) is recessive to A1(p) and A2 (q). For trait B, frequencies are, coincidentally, the;same as in A. Similarly B3 is recessive to B1 and B2. At Hardy Weinberg equilibrium;you predict that the population will contain what fraction of individuals that exhibit;both A3 and B3 recessive traits?;9. You use genetic sequencing to genotype a population of one of New Zealand;native mammals. You find that for the eye color allele (A is dominant for red eyes, a;is recessive for green eyes). However, there is an epistatic effect and a second locus;codes for eye pigment. The Allele for eye pigment (B) is dominant and at a;frequency of 0.6.The _____s that lack the eye pigment allele (bb) have yellow eyes.;What fraction of individuals do you expect to have yellow eyes?;Among just the individuals that have eye pigment (red or green), you;observe that 75% have red eyes and 25% of the population have green;eyes. Noticing historical notes of this species in the 1920s reporting the;same frequencies of eye color, you assume the population to be at Hardy-;Weinberg Equilibrium. What do you estimate to be the frequency of the A;allele in this population?;What is the expected frequency of Aa heterozygotes in the population?;What is the expected frequency of Aa heterozygotes among the yellow-;eyed individuals?;If both alleles are at Hardy Weinberg equilibrium, what proportion of the;entire population do you expect to have green eyes?;You discover a sub-population on an outlying island that has positive;assortative mating by eye color, but there remains no selective advantage;by eye color. Do you expect the frequency of individuals that are;heterozygous for red eyes to increase, decrease or have no effect?


Paper#15078 | Written in 18-Jul-2015

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