Chapter 25 Population and Evolutionary Genetics1) What term is given to the total genetic information carried by all members of a population?A) gene poolB) genomeC) chromosome complementD) breeding unitE) raceAnswer: ASection: 25.12) In a population of 100 individuals, 49% are of the NN blood type. What percentage is expected to be MN assuming Hardy—Weinberg equilibrium conditions?A) 9%B) 21%C) 42%D) 51%E) There is insufficient information to answer this questionAnswer: CSection: 25.23) Albinism is an autosomal recessive trait in humans. Assume that there are 100 albinos (aa) in a population of 1 million. How many individuals would be expected to be homozygous normal (AA) under equilibrium conditions?A) 100B) 10,000C) 19,800D) 980,100E) 999,900Answer: DSection: 25.24) In small isolated populations, gene frequencies can fluctuate considerably. The term that applies to this circumstance is ________.A) genetic isolationB) allelic separationC) natural selectionD) stabilizing selectionE) genetic driftAnswer: ESection: 25.71Copyright © 2012 Pearson Education, Inc.5) The discipline within evolutionary biology that studies changes in allele frequencies is known as ________.A) population geneticsB) consanguinityC) hybrid vigorD) geneticsE) cytogeneticsAnswer: ASection: Introduction6) A number of mechanisms operate to maintain genetic diversity in a population. Why is such diversity favored?A) Homozygosity is an evolutionary advantage.B) Diversity leads to inbreeding advantages.C) Genetic diversity may better adapt a population to inevitable changes in the environment.D) Greater genetic diversity increases the chances of haploidy.E) Genetic diversity helps populations avoid diploidy.Answer: CSection: 25.17) Which method is often used to analyze proteins and nucleic acids by physical separation whenestimating genetic variation in populations?A) electrophoresisB) centrifugationC) absorption spectrophotometryD) fluorometryE) in situ hybridizationAnswer: ASection: 25.38) Which general term is used to group various biological and behavioral properties of organismsthat act to prevent or reduce interbreeding?A) phyletic evolutionB) allopatric speciationC) reproductive isolating mechanismsD) inbreedingE) genetic divergenceAnswer: CSection: 25.99) Assume that a trait is caused by the homozygous state of a gene that is recessive and autosomal. Nine percent of the individuals in a given population express the phenotype caused by this gene. What percentage of the individuals would be heterozygous for the gene? Assume that the population is in Hardy-Weinberg equilibrium.Answer: 42%Section: 25.22Copyright © 2012 Pearson Education, Inc.10) In a population that meets the Hardy-Weinberg equilibrium assumptions, 81% of the individuals are homozygous for a recessive allele. What percentage of the individuals would be expected to be heterozygous for this locus in the next generation?Answer: 18%Section: 25.211) In a population of cattle, the following color distribution was noted: 36% red (RR), 48% roan(Rr), and 16% white (rr). Is this population in a Hardy-Weinberg equilibrium? What will be the distribution of genotypes in the next generation if the Hardy-Weinberg assumptions are met?Answer: Yes, it is in equilibrium. The distribution will be the same in the next generation.Section: 25.212) List at least three factors that change gene frequencies in populations.Answer: mutation, migration, selection, genetic driftSection: 25.4, 25.5, 25.6, 25.713) List and briefly describe three factors that contribute to the phenomenon of natural selection.Answer: genetic variation among members of a species, overpopulation, and competition for mates and survivalSection: 25.414) List at least five of the assumptions that pertain to a population in a Hardy-Weinberg equilibrium.Answer: infinitely large population; random mating; no selective advantage of one genotype; and no migration, mutation, or genetic driftSection: 25.215) Assume that in a Hardy-Weinberg population, 9% of the individuals are of the homozygous recessive phenotype. What percentage are homozygous dominant?Answer: 49%Section: 25.216) Define the term fitness and relate it to the meaning of selection coefficient.Answer: Fitness is a measure of the proportion of offspring that a particular phenotype will contribute to the next generation; the selection coefficient is the mathematical difference betweenthe actual fitness of a given genotype and the optimal fitness for an individual in a given population.Section: 25.917) Contrast directional and stabilizing forms of selection.Answer: In directional selection, a particular phenotypic extreme is selected for; in stabilizing selection, both extreme phenotypes are selected against.Section: 25.43Copyright © 2012 Pearson Education, Inc.18) In a population of 10,000 individuals, where 3600 are MM, 1600 are NN, and 4800 are MN, what are the frequencies of the M alleles and the N alleles?Answer: M = 0.6; N = 0.4Section: 25.219) One of the Hardy-Weinberg assumptions states that the population is infinitely large. What influence might a small population size have on a Hardy-Weinberg equilibrium?Answer: Sampling error would cause random and possibly significant fluctuations in gene frequencies.Section: 25.720) One of the Hardy-Weinberg assumptions states that all genotypes in the population are free of selective advantage. What influence might a selective advantage of a genotype have on a Hardy-Weinberg equilibrium?Answer: Certain alleles will reach the next generation on a nonrandom basis, thus upsetting the equilibrium.Section: 25.421) What is meant by the equation p + q = 1.0?Answer: The sum of the relevant individual alleles in a population is equal to 100 % of those alleles.Section: 25.222) What does the variable 2pq represent?Answer: the expected frequency of heterozygotes in a population in Hardy-Weinberg equilibriumSection: 25.223) Assuming that p = 0.3 for a population in Hardy-Weinberg equilibrium, what would be the expected frequency of heterozygotes for the involved allelic pair?Answer: 0.42Section: 25.224) Give a brief definition of the term genetic equilibrium.Answer: a condition for a population in which the frequency of a given gene remains constant from generation to generationSection: 25.225) A certain form of albinism in humans is recessive and autosomal. Assume that 1% of the individuals in a given population are albino. Assuming that the population