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Test 2
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Question 1 Your answer is CORRECT. The graph below shows the change in allele frequency, p, over 100 generations of selection. At generation 0, p=0.1. The red and blue lines represent evolution in two populations experiencing two different selective scenarios. Which statement best describes the difference between the red and blue scenarios? a) The red line shows a deleterious recessive allele; the blue line shows a deleterious dominant allele. b) The red line shows heterozygote advantage; the blue line shows a beneficial recessive allele. c) The absolute fitnesses in the blue population are higher than the absolute fitnesses in the red population. d) The blue line shows a stable equilibrium; the red line shows an unstable equilibrium. e) The blue line shows the effects of natural selection; the red line shows the effects of genetic drift. Question 2 Your answer is CORRECT.
The graph below shows the change in allele frequency, p, over 100 generations. Each color represents an independent population. At generation 0, p=0.5. Which of the following statements most accurately describes processes occurring in these populations? a) Genetic drift is randomly changing allele frequencies. b) Some populations are experiencing natural selection and others are experiencing genetic drift. c) Heterozygotes have the highest fitness. d) Natural selection is driving some alleles to fixation and others to loss. e) These populations are becoming adapted to their current environment. Question 3 Your answer is CORRECT. Flower color in morning glories (Ipomoea purpurea) is determined by two alleles at a locus. The allele for purple color is dominant to the allele for white color. In a population that is in Hardy-Weinberg equilibrium, we count 32 out of 200 individuals that have white flowers. What percentage of the population is expected to be heterozygous for flower color? a) 48% b) 16% c) 50%
dominant. a) X: beneficial dominant; Y: deleterious recessive; Z: beneficial dominant. b) X: deleterious recessive; Y: heterozygote advantage; Z: beneficial semi-dominant. c) X: beneficial recessive; Y: heterozygote advantage; Z: heterozygote disadvantage. d) X: beneficial recessive; Y: deleterious semi-dominant; Z: heterozygote disadvantage. e) X: deleterious recessive; Y: deleterious recessive; Z: beneficial dominant. Question 7 Your answer is CORRECT. 5% of Quarter horses in the United States are heterozygous for the recessive lethal allele that causes glycogen branching enzyme deficiency (GBED). Assuming that Quarter horses are randomly mated and that the GBED allele is maintained in the population by mutation-selection balance, what is the mutation rate to the disease allele? a) 0. b) 0. c) 0. d) 0. e) 0. Question 8 Your answer is CORRECT.
There are two alleles of alcohol dehydrogenase (Adh) in a population of Drosophila melanogaster, F and S. In laboratory experiments, the three genotypes are shown to have the following viabilities (probability of survival from egg to adult): 68% FF, 44% FS, 43% SS. The frequency of F in the population is p = 0.528. What is the mean fitness of the population? a) 0. b) 0. c) 0. d) 0. e) 0. Question 9 Your answer is CORRECT. Which of the following can lead to adaptation? a) Genetic Drift b) Natural Selection c) Inbreeding d) Migration e) All of the above Question 10 Your answer is CORRECT. Which of the following types of sequence are most likely to evolve at the fastest rate? a) Two-fold degenerate sites b) Pseudogenes c) Nonsynonymous sites d) RNA coding genes e) Protein coding genes Question 11 Your answer is CORRECT.
e) 0. Question 14 Your answer is CORRECT. A population of the land snail Cepaea nemoralis shows variation in the intensity of its shell pigmentation determined by one locus with two alleles, N and n: NN individuals have dark shells, nn individuals have light shells, and Nn individuals have an intermediate phenotype. Dark shells absorb solar energy more efficiently than light shells, so that individuals with dark shells have a fitness 1.4% higher than those with light shells (i.e. s=0.014). What is the maximum possible effective population size consistent with the N allele being effectively neutral? a)^71 b)^36 c)^8 d)^50 e) 0. Question 15 Your answer is CORRECT. Pairs of human-mouse homologous genes were examined for their patterns of sequence evolution. Synonymous substitutions per synonymous site (ds) and nonsynonymous substitutions per nonsynonymous site (dn) are reported below. Which of the following statements accurately reflects the data? a) Gene 1 is evolving the slowest and gene 3 has the highest mutation rate. b) Gene 3 has experienced the strongest negative/purifying selection and none of the genes have experienced positive selection. c) Synonymous substitutions in gene 3 are less deleterious than those in genes 1 and 2.
d) Gene 1 has experienced the strongest negative/purifying selection and gene 2 has experienced positive selection. e) All of these genes are evolving neutrally. Question 16 Your answer is CORRECT. Consider a completely selfing population, F = 0.5, with heterozygosity, H = 0.64. What will be the frequency of heterozygotes in the next generation? a) 0. b)^0 c) 0. d) 0. e) 0. Question 17 Your answer is CORRECT. Why is the substitution rate at four-fold degenerate sites (3rd codon positions) less than the substitution rate in pseudogenes? a) Positive selection for increased rate of translation is stronger at four-fold degenerate sites than in pseudogenes. b) Mutations at four-fold degenerate sites can be either neutral or nearly neutral; mutations in pseudogenes are only neutral. c) Pseudogenes have a higher rate of mutation than four-fold degenerate sites. d) The substitution rate at four-fold degenerate sites is not less than in pseudogenes. e) Mutations at four-fold degenerate sites can experience negative selection to maintain translational efficiency. Question 18 Your answer is CORRECT. Scientists have found a perplexing lack of correlation between genome size (as measured by chromosome number, number of nucleotides, or number of genes) and organismal complexity. One explanation for this observation is that genome size increases due to neutral mutations. Which of the following pieces of data would support this neutralist hypothesis? a) More beneficial mutations in less complex organisms.
