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Unformatted text preview: Answers to Questions on CH 22‐26 To Be Covered During Lecture or in Exam 3 Review 1. During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard‐ cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection? a. Small birds gaining larger beaks by exercising their mouth parts. b. Small birds mutating their beak genes with the result that later‐generation offspring have larger beaks. c. Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks. d. More small‐beaked birds dying than larger‐beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks. e. Larger birds eating less so smaller birds can survive. ANSWER: “D” 2. The indigenous plants and animals of the Galapagos Islands and Cape Verde Islands: a. are the same species as those found on the nearby mainland. b. are the same species on the two islands, but are different from those on the mainland. c. are the same species on the two islands and on the mainland. d. are similar to one another, but quite different from either adjacent mainland. e. resemble the nearest mainland species, but have evolved into new species. ANSWER: “E” 3. A newly evolved species may take over an ecological role or ecological niche that is already occupied if the new species has a. the ability to alter or change the environmental parameters. b. the ability to evolve through natural selection, whereas the original occupant cannot continue to evolve. c. the ability to grow to a larger size, thus providing it with a selective advantage. d. features that make it competitively superior to the original occupant of that niche. ANSWER: “D” 4. Which of the following is not an observation or inference on which natural selection is based? a. There is heritable variation among individuals. b. Poorly adapted individuals never produce offspring. c. Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characters are less well suited. d. There is a struggle for limited resources, and only a fraction of offspring survive ANSWER: “B” 5. Within a few weeks of treatment with the drug 3TC, a patient’s HIV population consists entirely of 3TC‐ resistant viruses. How can this result best be explained? a. The drug caused the HIV RNA to change b. A few drug‐resistant viruses were present at the start of treatment, and natural selection increased their frequency. c. HIV began making drug‐resistant versions of reverse transcriptase in response to the drug. ANSWER: B 2 6. A population evolves when a. environmentally‐induced variation is constant between generations. b. individuals with different genotypes survive or reproduce at different rates. c. the Hardy‐Weinberg equation is equal to one. d. members reproduce by cloning. ANSWER: “B” e. there is no migration between populations of the same species. 7. Genetic equilibrium (i.e., Hardy‐Weinberg equilibrium) in a population a. refers to equal numbers of dominant and recessive alleles. b. refers to equal numbers of females and males. c. refers to unchanging allele frequencies in successive generations. d. occurs due to nonrandom mating. ANSWER: “C” e. occurs as a result of a bottleneck event. 8. _______ selection occurs when the extremes of a population contribute relatively few offspring to the next generation as compared to average members of the population. a. Disruptive b. Directional c. Stabilizing d. Sexual ANSWER: “C” 9. In a population of 200 individuals in Hardy‐Weinberg equilibrium, 72 are homozygous recessive for the character of eye color (cc). Answer the following questions. a. What is the frequency of the dominant phenotype in the population? A) 0.80 B) 0.36 C) 0.64 D) 0.48 E) 0.60 ANSWER: “C” b. What is the frequency of the dominant allele? A) 0.16. B) 0.36. C) 0.40. D) 0.48. E) 0.60. ANSWER: “C” c. What the frequency of heterozygotes? A) 0.16. B) 0.36. C) 0.40. D) 0.48. E) 0.60. ANSWER: “D” 10. Six squirrels with different tail spotting patterns live in eastern Mexico. Five of them can interbreed and produce fertile offspring. One of them cannot interbreed with the other five. What can you conclude about these squirrels? a. They all belong to the same biological species. b. They each are a different biological species. c. There are two biological species in the example above. d. There is not enough data given to draw a conclusion. e. There are six biological species in the example above. ANSWER: “C” 3 11. Which of the following would not result in reproductive isolation between two populations that are reunited following isolation? a. The two populations have different breeding seasons. b. There are physiological differences between the two populations so that they cannot produce viable offspring. c. Members of one population do not find members of the other population attractive as mating partners. d. The two populations have different courtship behaviors. e. The two populations produce successful hybrids. ANSWER: “E” 12. Two species of Japanese ladybird beetles occur in the same area. Epilachnea niponica feeds on thistles, and Epilachnea yasutomii feeds on other plants that grow among thistles. Adults of both species feed and mate on their own host plant. The two species hybridize in the laboratory, but not in nature. In this scenario, it is likely the two separate species are a result of: a. Allopatric speciation b. Sympatric speciation ANSWER: “B” 13. What process refers to dramatic phenotypic changes that some‐times occur in evolution, such as the appearance of feathered wings during the evolution of birds? a. Paedomorphosis b. Macroevolution c. Allopolyploidy d. Microevolution ANSWER: “B” 14. In a comparison of humans, chimps, dogs and cats, an ancestral trait for all four would be a. hands specialized for grasping. b. presence of body hair. c. standing on two legs. d. lack of a tail. e. poor sense of smell. ANSWER: “B” 15. The excellent fossil record of horses shows that modern horses, which have one toe on each foot, evolved from ancestors that had multiple toes. A trait that differs from the ancestral trait in the lineage is called a(n) ___________ trait. a. derived b. ancestral c. morphological d. biochemical e. fundamental ANSWER: “A” 4 16. Shown to the right is a phylogenetic tree comparing the evolutionary histories of organisms E, F,G, H, and I, which are current living organisms. The most recent common ancestor is shared by: a. H and I b. G, H, and I c. E and F d. E, F, G, H, and I E B F G H I D C A
ANSWER: “C” 17. Which of the following statements is false concerning the organisms in this phylogenetic tree? a. Organisms E, F, G, H, and I could belong to the same family; H and I to the same class. b. Organism F has the youngest evolutionary history compared to G, H and I. c. Organisms E, F, G, H, and I could belong to the same phylum; G, H and I to the same class. d. All (A‐D) are false statements. ANSWER: “A” (family is a smaller taxon than class) ...
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- Spring '08