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This Document Contains Chapters 19 to 20 Chapter 19: Descent with Modification 19.1 Multiple-Choice Questions 1) Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier's attempt to explain the existence of A) evolution. B) the fossil record. C) uniformitarianism. D) the origin of new species. E) natural selection. Answer: B 2) What was the prevailing belief prior to the time of Lyell and Darwin? A) Earth is a few thousand years old, and populations are unchanging. B) Earth is a few thousand years old, and populations gradually change. C) Earth is millions of years old, and populations rapidly change. D) Earth is millions of years old, and populations are unchanging. E) Earth is millions of years old, and populations gradually change. Answer: A 3) During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception? A) Characteristics acquired during an organism's life are generally not passed on through genes. B) Spontaneous mutations can result in the appearance of new traits. C) Only favorable adaptations have survival value. D) Disuse of an organ may lead to its eventual disappearance. E) If the giraffes did not have to compete with each other, longer necks would not have been passed on to the next generation. Answer: A 4) Which of the following is the most accurate summary of Cuvier's consideration of fossils found in the vicinity of Paris? A) extinction of species yes; evolution of new species yes B) extinction of species no; evolution of new species yes C) extinction of species yes; evolution of new species no D) extinction of species no; evolution of new species no Answer: C 5) In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of A) Cuvier. B) Hutton. C) Lamarck. D) Darwin. E) Lyell. Answer: C 6) Charles Darwin was the first person to propose A) that evolution occurs. B) a mechanism for how evolution occurs. C) that Earth is older than a few thousand years. D) a mechanism for evolution that was supported by evidence. E) that population growth can outpace the growth of food resources. Answer: D 7) Which of these conditions should completely prevent the occurrence of natural selection in a population over time? A) All variation between individuals is due only to environmental factors. B) The environment is changing at a relatively slow rate. C) The population size is large. D) The population lives in a habitat where there are no competing species present. Answer: A 8) Natural selection is based on all of the following except A) genetic variation exists within populations. B) the best-adapted individuals tend to leave the most offspring. C) individuals who survive longer tend to leave more offspring than those who die young. D) populations tend to produce more individuals than the environment can support. E) individuals adapt to their environments, and thereby evolve. Answer: E 9) Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus? A) Technological innovation in agricultural practices will permit exponential growth of the human population into the foreseeable future. B) Populations tend to increase at a faster rate than their food supply normally allows. C) Earth changed over the years through a series of catastrophic upheavals. D) The environment is responsible for natural selection. E) Earth is more than 10,000 years old. Answer: B 10) Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship. A) 2 → 4 → 1 → 3 B) 4 → 2 → 1 → 3 C) 4 → 1 → 2 → 3 D) 4 → 2 → 3 → 1 E) 2 → 4 → 3 → 1 Answer: A 11) A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true? A) The amount of available food may have increased. B) The parental generation of squirrels developed better eyesight due to improved diet; the subsequent squirrel generation inherited better eyesight. C) The number of predators that prey upon squirrels may have decreased. D) A and C could be true. E) A, B, and C could be true. Answer: D 12) Which of the following must exist in a population before natural selection can act upon that population? A) genetic variation among individuals B) variation among individuals caused by environmental factors C) sexual reproduction D) Three of the responses are correct. E) Two of the responses are correct. Answer: A 13) Which of Darwin's ideas had the strongest connection to Darwin having read Malthus's essay on human population growth? A) descent with modification B) variation among individuals in a population C) struggle for existence D) the ability of related species to be conceptualized in "tree thinking" E) that the ancestors of the Galápagos finches had come from the South American mainland Answer: C 14) If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement? A) If natural selection can change one gene's frequency in a population over the course of generations, then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones. B) If an individual's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring. C) If an individual acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will be the result. D) A single mutation in a single gene in a single gamete will, if perpetuated, produce a new species within just two generations. Answer: A 15) The role that humans play in artificial selection is to A) determine who lives and who dies. B) create the genetic variants, which nature then selects. C) choose which organisms breed, and which do not. D) train organisms to breed more successfully. E) perform artificial insemination. Answer: C 16) In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations? A) selection for drab coloration of the algae-eaters B) selection for nocturnal algae-eaters (active only at night) C) selection for larger female algae-eaters, bearing broods composed of more, and larger, young D) selection for algae-eaters that become sexually mature at smaller overall body sizes E) selection for algae-eaters that are faster swimmers Answer: C 17) DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run? A) Larger doses of DDT should have been applied. B) All habitats should have received applications of DDT at about the same time. C) The frequency of DDT application should have been higher. D) None of the individual insects should have possessed genomes that made them resistant to DDT. E) DDT application should have been continual. Answer: D 18) Which of the following statements best describes theories? A) They are nearly the same things as hypotheses. B) They are supported by, and make sense of, many observations. C) They cannot be tested because the described events occurred only once. D) They are predictions of future events. Answer: B 19) Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true? A) Species X and Y are not related to species Z. B) Species X and Y share a greater number of homologies with each other than either does with species Z. C) Species X and Y share a common ancestor that is still extant (in other words, not yet extinct). D) Species X and Y are the result of artificial selection from an ancestral species Z. E) Species X, Y, and Z share a common ancestor, but nothing more can be claimed than this. Answer: B 20) The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because A) humans purposefully raise MRSA in large fermenters in an attempt to make the bacteria ever-more resistant. B) S. aureus is cultivated by humans to replenish the soil with nutrients. C) humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin. D) Humans are becoming resistant to bacteria by taking methicillin. Answer: C 21) Two plant species live in the same biome but on different continents. Although the two species are not at all closely related, they may appear quite similar as a result of A) parallel evolution. B) convergent evolution. C) allopatric speciation. D) introgression. E) gene flow. Answer: B 22) If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing? A) These genes should continue to be maintained in case the antibiotics ever appear. B) These bacteria should be outcompeted and replaced by bacteria that have lost these genes. C) The bacteria should try to make the cost worthwhile by locating, and migrating to, microenvironments where traces of antibiotics are present. D) The bacteria should start making and secreting their own antibiotics. Answer: B 23) Of the following anatomical structures, which is homologous to the bones in the wing of a bird? A) cartilage in the dorsal fin of a shark B) bones in the hind limb of a kangaroo C) chitinous struts in the wing of a butterfly D) bony rays in the tail fin of a flying fish E) bones in the flipper of a whale Answer: E 24) If two modern organisms are distantly related in an evolutionary sense, then one should expect that A) they live in very different habitats. B) they should share fewer homologous structures than two more closely related organisms. C) their chromosomes should be very similar. D) they shared a common ancestor relatively recently. E) they should be members of the same genus. Answer: B 25) Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities? A) by identifying the bones as being homologous structures B) by the principle of convergent evolution C) by proposing that humans, bats, and dolphins share a common ancestor D) Three of the statements above are correct. E) Two of the statements above are correct. Answer: E 26) Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses? A) Natural selection cannot account for losses, only for innovations. B) Natural selection accounts for these losses by the principle of use and disuse. C) Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits. D) The ancestors of these organisms experienced harmful mutations that forced them to find new habitats that these species had not previously used. Answer: C 27) Which of the following pieces of evidence most strongly supports the common origin of all life on Earth? A) All organisms require energy. B) All organisms use essentially the same genetic code. C) All organisms reproduce. D) All organisms show heritable variation. E) All organisms have undergone evolution. Answer: B 28) Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree? A) None of the organisms depicted by the tree ate the same foods. B) Some of the organisms depicted by the tree had lived in different habitats. C) The skeletal remains of the organisms depicted by the tree were incomplete (in other words, some bones were missing). D) Transitional fossils had not been found. E) Relationships between DNA sequences among the species did not match relationships between skeletal patterns. Answer: E 29) Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ? A) The appendix can be surgically removed with no immediate ill effects. B) The appendix might have been larger in fossil hominids. C) The appendix has a substantial amount of defensive lymphatic tissue. D) Individuals with a larger-than-average appendix leave fewer offspring than those with a below-average-sized appendix. E) In a million years, the human species might completely lack an appendix. Answer: C 30) Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution? A) The two species live at great distance from each other. B) The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical. C) The sizes of the structures in adult members of both species are similar. D) Both species are well adapted to their particular environments. Answer: B 31) Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are A) homologous. B) examples of convergent evolution. C) adaptations to a common environment. D) Three of the responses above are correct. E) Two of the responses above are correct. Answer: E 32) Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals? A) homologous; homologous B) analogous; homologous C) homologous; analogous D) analogous; analogous Answer: C 33) What must be true of any organ that is described as vestigial? A) It must be analogous to some feature in an ancestor. B) It must be homologous to some feature in an ancestor. C) It must be both homologous and analogous to some feature in an ancestor. D) It need be neither homologous nor analogous to some feature in an ancestor. Answer: B 34) What is true of pseudogenes? A) They are composed of RNA, rather than DNA. B) They are the same things as introns. C) They are unrelated genes that code for the same gene product. D) They are vestigial genes. Answer: D 35) It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that A) island forms and mainland forms descended from common ancestors. B) common environments are inhabited by the same organisms. C) the islands were originally part of the continent. D) the island forms and mainland forms are converging. E) island forms and mainland forms have identical gene pools. Answer: A 36) If one wanted to find the largest number of endemic species, one should visit which of the following geological features (assuming each has existed for several millions of years)? A) an isolated ocean island in the tropics B) an extensive mountain range C) a midcontinental grassland with extreme climatic conditions D) a shallow estuary on a warm-water coast Answer: A 37) A high degree of endemism is most likely in environments that are A) easily reached and heterogeneous. B) isolated and heterogeneous. C) isolated and homogeneous. D) isolated and extremely cold. E) easily reached and homogeneous. Answer: B 19.2 Art Questions The following questions refer to Figure 19.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Figure 19.1 1) If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum? A) A B) B C) C D) D Answer: C 2) If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata? A) one stratum B) two strata C) three strata D) four strata Answer: B 3) Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta and a third species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree? A) B) C) D) E) Answer: D The following questions refer to the evolutionary tree in Figure 19.2. The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Figure 19.2 4) Which pair would probably have agreed with the process that is depicted by this tree? A) Cuvier and Lamarck B) Lamarck and Wallace C) Aristotle and Lyell D) Wallace and Linnaeus E) Linnaeus and Lamarck Answer: B 5) How many separate species, both extant and extinct, are depicted in this tree? A) two B) three C) four D) five E) six Answer: E 6) According to this tree, what percent of the species seem to be extant (in other words, not extinct)? A) 25% B) 33% C) 50% D) 66% E) 75% Answer: D 7) Which of the five common ancestors, labeled V-Z, has given rise to the greatest number of species, both extant and extinct? A) V B) W C) Z D) Both W and Z can be considered to have given rise to the greatest number of extant and extinct species. E) Both X and Y can be considered to have given rise to the greatest number of extant and extinct species. Answer: E 8) Which of the five common ancestors, labeled V-Z, has been least successful in terms of the percent of its derived species that are extant? A) V B) W C) X D) Y E) Z Answer: B 9) Which of the five common ancestors, labeled V-Z, has been most successful in terms of the percent of its derived species that are extant? A) V B) W C) X D) Y E) Z Answer: E 10) Evolutionary trees such as this are properly understood by scientists to be A) theories. B) hypotheses. C) guesses. D) dogmas. E) facts. Answer: B 19.3 Scenario Questions About 13 different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the 13 species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). 1) If the six ground finch species have evolved most recently, then which of these is the most logical prediction? A) They should be limited to the six islands that most recently emerged from the sea. B) Their genomes should be more similar to each other than are the genomes of the five tree finch species. C) They should share fewer anatomical homologies with each other than they share with the tree finches. D) The chances of hybridization between two ground finch species should be less than the chances of hybridization between two tree finch species. Answer: B 2) According to a 1999 study, the vegetarian finch is genetically no more similar to the tree finches than it is to the ground finches, despite the fact that it is placed in the same genus as the tree finches. Based on this finding, it is reasonable to conclude that the vegetarian finch A) is no more closely related to the tree finches than it is to the ground finches, despite its classification. B) should be re-classified as a warbler finch. C) is not truly a descendent of the original ancestral finch. D) is a hybrid species, resulting from a cross between a ground finch and a tree finch. Answer: A 19.4 End-of-Chapter Questions 1) 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) Species produce more offspring than the environment can support. D) Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characteristics are less well suited. E) Only a fraction of an individual’s offspring may survive. Answer: B 2) Which of the following observations helped Darwin shape his concept of descent with modification? A) Species diversity declines farther from the equator. B) Fewer species live on islands than on the nearest continents. C) Birds live on islands located farther from the mainland than the birds’ maximum nonstop flight distance. D) South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe. E) Earthquakes reshape life by causing mass extinctions. Answer: D 3) Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained? A) S. aureus can resist vaccines. B) A patient must have become infected with MRSA from another community. C) In response to the drug, S. aureus began making drugresistant versions of the protein targeted by the drug. D) Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency. E) The drug caused the S. aureus DNA to change. Answer: D 4) The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data? A) Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms. B) Forelimb evolution was adaptive in people and bats, but not in whales. C) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy. D) Genes mutate faster in whales than in humans or bats. E) Whales are not properly classified as mammals. Answer: C 5) DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that A) humans and chimpanzees share a relatively recent common ancestor. B) humans evolved from chimpanzees. C) chimpanzees evolved from humans. D) convergent evolution led to the DNA similarities. E) humans and chimpanzees are not closely related. Answer: A Chapter 20: Phylogeny 20.1 Multiple-Choice Questions 1) The legless condition that is observed in several groups of extant reptiles is the result of A) their common ancestor having been legless. B) a shared adaptation to an arboreal (living in trees) lifestyle. C) several instances of the legless condition arising independently of each other. D) individual lizards adapting to a fossorial (living in burrows) lifestyle during their lifetimes. Answer: C 2) The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical classification system differ from each other on the basis of A) how widely the organisms assigned to each are distributed throughout the environment. B) their inclusiveness. C) the relative genome sizes of the organisms assigned to each. D) morphological characters that are applicable to all organisms. Answer: B 3) If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology? A) A and B B) A and C C) B and D D) C and F E) D and F Answer: E 4) Linnaeus was a "fixist" who believed that species remained fixed in the form in which they had been created. Linnaeus would have been uncomfortable with A) classifying organisms using the morphospecies concept. B) the scientific discipline known as taxonomy. C) phylogenies. D) nested, ever-more inclusive categories of organisms. E) a hierarchical classification scheme. Answer: C 5) The best classification system is that which most closely A) unites organisms that possess similar morphologies. B) conforms to traditional, Linnaean taxonomic practices. C) reflects evolutionary history. D) reflects the basic separation of prokaryotes from eukaryotes. Answer: C 6) The term homoplasy is most applicable to which of the following features? A) the legless condition found in various lineages of extant lizards B) the five-digit condition of human hands and bat wings C) the β hemoglobin genes of mice and of humans D) the fur that covers Australian moles and North American moles E) the bones of bat forelimbs and the bones of bird forelimbs Answer: A 7) If, someday, an archaean cell is discovered whose rRNA sequence is more similar to that of humans than the sequence of mouse rRNA is to that of humans, the best explanation for this apparent discrepancy would be A) homology. B) homoplasy. C) common ancestry. D) retro-evolution by humans. E) coevolution of humans and that archaean. Answer: B 8) Which of the following are the best examples of homologous structures? A) bones in the bat wing and bones in the human forelimb B) owl wing and hornet wing C) bat wing and bird wing D) eyelessness in the Australian mole and eyelessness in the North American mole Answer: A 9) Some molecular data place the giant panda in the bear family (Ursidae) but place the lesser panda in the raccoon family (Procyonidae). Consequently, the morphological similarities of these two species are probably due to A) inheritance of acquired characteristics. B) sexual selection. C) inheritance of shared derived characters. D) possession of analogous structures. E) possession of shared primitive characters. Answer: D 10) The importance of computers and of computer software to modern cladistics is most closely linked to advances in A) light microscopy. B) radiometric dating. C) fossil discovery techniques. D) Linnaean classification. E) molecular genetics. Answer: E 11) The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds and mammals are best described as A) structural homologies. B) vestiges. C) homoplasies. D) the result of shared ancestry. E) molecular homologies. Answer: C 12) A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on the primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged? A) Among themselves, they should share relatively few ancestral traits, especially those that enabled ancestral forms to adapt to extreme conditions. B) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans. C) They should contain genes that originated in eukaryotes that are the hosts for numerous species of bacteria. D) They should currently be undergoing a high level of horizontal gene transfer with non-extremophilic archaeans. Answer: B 13) Which of the following is (are) problematic when the goal is to construct phylogenies that accurately reflect evolutionary history? A) polyphyletic taxa B) paraphyletic taxa C) monophyletic taxa D) polyphyletic taxa and monophyletic taxa E) polyphyletic taxa and paraphyletic taxa F) All of the choices are correct. Answer: D 14) Which of the following is true of all horizontally oriented phylogenetic trees, where time advances to the right? A) Each branch point represents a point in absolute time. B) Organisms represented at the base of such trees are descendants of those represented at higher levels. C) The fewer branch points that occur between two taxa, the more divergent their DNA sequences should be. D) The common ancestor represented by the rightmost branch point existed more recently in time than the common ancestors represented at branch points located to the left. E) The more branch points there are, the fewer taxa are likely to be represented. Answer: D 15) When using a cladistic approach to systematics, which of the following is considered most important for classification? A) shared primitive characters B) analogous primitive characters C) shared derived characters D) the number of homoplasies E) overall phenotypic similarity Answer: C 16) Cladograms (a type of phylogenetic tree) constructed from evidence from molecular systematics are based on similarities in A) morphology. B) the pattern of embryological development. C) biochemical pathways. D) habitat and lifestyle choices. E) mutations to homologous genes. Answer: E 17) There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then what can be properly said of hair? A) It is a shared derived character of mammals, even if cynodonts continue to be classified as reptiles. B) It is a shared derived character of the amniote clade, and not of the mammal clade. C) It is a shared ancestral character of the amniote clade, but only if cynodonts are reclassified as mammals. D) It is a shared derived character of the mammals, but only if cynodonts are reclassified as mammals. Answer: D 18) A phylogenetic tree constructed using sequence differences in mitochondrial DNA would be most valid for discerning the evolutionary relatedness of A) archaeans and bacteria. B) fungi and animals. C) chimpanzees and humans. D) sharks and dolphins. E) mosses and ferns. Answer: C 19) The most important feature that permits a gene to act as a molecular clock is A) having a large number of base pairs. B) having a larger proportion of exonic DNA than of intronic DNA. C) having a reliable average rate of mutation. D) its recent origin by a gene-duplication event. E) its being acted upon by natural selection. Answer: C 20) Neutral theory proposes that A) molecular clocks are more reliable when the surrounding pH is close to 7.0. B) most mutations of highly conserved DNA sequences should have no functional effect. C) DNA is less susceptible to mutation when it codes for amino acid sequences whose side groups (or R groups) have a neutral pH. D) DNA is less susceptible to mutation when it codes for amino acid sequences whose side groups (or R groups) have a neutral electrical charge. E) a significant proportion of mutations are not acted upon by natural selection. Answer: E 21) When it acts upon a gene, which of the following processes consequently makes that gene an accurate molecular clock? A) transcription B) directional natural selection C) mutation D) proofreading E) reverse transcription Answer: C 22) Which of these would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock? A) neutral mutations B) genetic drift C) mutations within introns D) natural selection E) most substitution mutations involving an exonic codon's third position Answer: D 23) Which kind of DNA should provide the best molecular clock for determining the evolutionary relatedness of several species whose common ancestor became extinct billions of years ago? A) that coding for ribosomal RNA B) intronic DNA belonging to a gene whose product performs a crucial function C) paralogous DNA that has lost its function (i.e., no longer codes for functional gene product) D) mitochondrial DNA E) exonic DNA that codes for a noncrucial part of a polypeptide Answer: A 24) What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom? A) molecular B) behavioral C) nutritional D) anatomical E) ecological Answer: A 25) Which kingdom has been replaced with two domains? A) Plantae B) Fungi C) Animalia D) Protista E) Monera Answer: E 26) Which eukaryotic kingdom is polyphyletic, and therefore unacceptable, based on cladistics? A) Plantae B) Fungi C) Animalia D) Protista E) Monera Answer: D 20.2 Art Questions Use Figure 20.1 to answer the following questions. Figure 20.1 1) Which extinct species should be the best candidate to serve as the outgroup for the clade whose common ancestor occurs at position 2 in Figure 20.1? A) A B) B C) C D) D E) E Answer: A 2) If Figure 20.1 is an accurate depiction of relatedness, then which of the following should be correct? 1. The entire tree is based on maximum parsimony. 2. If all species depicted here make up a taxon, this taxon is monophyletic. 3. The last common ancestor of species B and C occurred more recently than the last common ancestor of species D and E. 4. Species A is the direct ancestor of both species B and species C. 5. The species present at position 3 is ancestral to C, D, and E. A) 1 and 3 B) 3 and 4 C) 2, 3, and 4 D) 1, 2, and 3 Answer: D Traditionally, whales and hippopotamuses have been classified in different orders, the Cetacea and the Artiodactyla, respectively. Recent molecular evidence, however, indicates that the whales' closest living relatives are the hippos. This has caused some zoologists to lump the two orders together into a single clade, the Cetartiodactyla. There is no consensus on whether the Cetartiodactyla should be accorded order status or superorder status. This is because it remains unclear whether the whale lineage diverged from the lineage leading to the hippos before or after the other members of the order Artiodactyla (pigs, camels, etc.) diverged (see Figure 20.2). Figure 20.2 contrasts the "Within the artiodactyls" origin of the whale lineage with the "Without the artiodactyls" origin of the whale lineage. 3) What can be properly inferred from Figure 20.2? A) In the "Without" tree, pigs are more distantly related to hippos than is depicted in the "Within" tree. B) In the "Without" tree, pigs are more closely related to hippos than are whales. C) In the "Within" tree, pigs are more closely related to whales than they are to hippos. D) The "Without" tree is more consistent with molecular evidence than is the "Within" tree. E) In the "Within" tree, all artiodactyls, including hippos, are more closely related to each other than any are to the whales. Answer: B 4) Placing whales and hippos in the same clade means that A) these organisms are phenotypically more similar to each other than to any others shown on the trees in Figure 20.2. B) their morphological similarities are probably homoplasies. C) they had a common ancestor. D) all three of the responses are correct. E) two of the responses are correct. Answer: C 5) If it turns out that the whale lineage diverged from the lineage leading to hippos after the divergence of the lineage leading to the pigs and other artiodactyls, and if the whales continue to be classified in the order Cetacea, then what becomes true of the order Artiodactyla? A) It becomes monophyletic. B) It becomes paraphyletic. C) It becomes polyphyletic. D) It is incorporated into the order Cetacea. Answer: B 6) If it turns out that the whale lineage diverged from the lineage leading to hippos after the divergence of the lineage leading to the pigs and other artiodactyls, and if the whales continue to be classified in the order Cetacea, then what becomes true of the taxon Cetartiodactyla? A) It should be considered as one monophyletic superorder. B) It should be considered a superorder that consists of two monophyletic orders. C) It should be established as a paraphyletic order. D) It should be thrown out or modified by taxonomists if classification is to reflect evolutionary history. Answer: A 7) One morphological feature of modern cetaceans is a vestigial pelvic girdle. If it is determined that cetacean lineage diverged from the artiodactyls' lineage after the divergence of pigs and other artiodactyla, then what should be true of the vestigial pelvic girdle of cetaceans? A) It should be considered a shared ancestral character of the cetartiodactyls. B) It should be considered a shared derived character of the cetartiodactyls. C) It should be considered a shared ancestral character of the cetaceans. D) It should be considered a shared derived character of the cetaceans. Answer: D 8) If cetaceans are determined to have diverged from the lineage leading to the artiodactyls before the divergence of lineages leading to the modern artiodactyls (including hippos), then the cetaceans can be considered 1. a sister order to the order Artiodactyla. 2. an ingroup of the order Artiodactyla. 3. the common ancestor of the order Artiodactyla. A) 1 only B) 3 only C) 1 and 2 D) 1 and 3 E) 2 and 3 Answer: A 9) It was once thought that cetaceans had evolved from an extinct group of mammals called the mesonychids. If, in the future, it is determined that some organisms currently classified as cetaceans did actually evolve from mesonychids, whereas other cetaceans evolved from artiodactyl stock, then what will be true of the order Cetacea? A) It will be paraphyletic. B) It will be polyphyletic. C) It will need to be modified if classification is to reflect evolutionary history. D) A and C E) B and C Answer: D The following questions refer to the phylogenetic tree in Figure 20.3, depicting the origins of life and of the three domains. Horizontal lines indicate instances of gene or genome transfer. Figure 20.3 A possible phylogenetic tree for the three domains of life. 10) If the early history of life on Earth is accurately depicted by Figure 20.3, then which statement is least in agreement with the hypothesis proposed by this tree? A) The last universal common ancestor of all extant species is better described as a community of organisms, rather than an individual species. B) The origin of the three domains appears as a polytomy. C) Archaean genomes should contain genes that originated in bacteria, and vice versa. D) Eukaryotes are more closely related to archaeans than to bacteria. Answer: D 11) Which of these processes can be included among those responsible for the horizontal components of Figure 20.3? A) endosymbiosis B) mitosis C) binary fission D) point mutations E) S phase of the cell cycle Answer: A 12) Which portion of Figure 20.3 may ultimately be better depicted as a "ring"? A) the bacterial lineage B) the archaean lineage C) the eukaryotic lineage D) the trunk of the tree E) the part corresponding to the first living cell on Earth Answer: D Figure 20.4 Humans, chimpanzees, gorillas, and orangutans are members of a clade called the great apes, which shared a common ancestor about 18 million years ago. Gibbons and siamangs comprise a clade called the lesser apes. Tree-branch lengths indicate elapsed time. 13) The great apes comprise the family Hominidae, whereas the lesser apes comprise the family Hylobatidae. If the extant organisms on the far right side of Figure 20.4 comprise the next-most exclusive (i.e., specific) taxon, then they comprise different A) subspecies. B) species. C) genuses. D) genera. E) orders. Answer: D 14) Together, the lesser apes and great apes shared a common ancestor most recently with other members of their A) order. B) class. C) subclass. D) subfamily. E) family. Answer: A 15) Assuming chimps and gorillas are humans' closest relatives, removing humans from the great ape clade and placing them in a different clade has the effect of making the phylogenetic tree of the great apes A) polyphyletic. B) paraphyletic. C) monophyletic. D) conform with Linnaeus's view of great ape phylogeny. Answer: B 16) From Figure 20.4, which other event occurred closest in time to the divergence of gorillas from the lineage that led to humans and chimps? A) the divergence of chimps and humans B) the divergence of Dryopithecus and Ouranopithecus C) the divergence of gibbons and siamangs D) could be either the divergence of chimps and humans OR of Dryopithecus and Ouranopithecus E) could be either the divergence of chimps and humans OR of gibbons and siamangs Answer: E The next questions refer to Table 20.1, which compares the % sequence homology of four different parts (two introns and two exons) of a gene that is found in five different eukaryotic species. Each part is numbered to indicate its distance from the promoter (e.g., Intron I is the one closest to the promoter). The data reported for species A were obtained by comparing DNA from one member of species A to the DNA of another member of species A. Table 20.1 17) Based on the tabular data, and assuming that time advances vertically, which cladogram (a type of phylogenetic tree) is the most likely depiction of the evolutionary relationships among these five species? A) B) C) D) Answer: D 18) Which of the following is the best explanation for the high degree of sequence homology observed in Exon I among these five species? A) It is the most-upstream exon of this gene. B) Due to alternative gene splicing, this exon is often treated as an intron. C) It codes for a polypeptide domain that has a crucial function. D) These five species must actually constitute a single species. E) This exon is rich in G-C base pairs; thus, it is more stable. Answer: C 19) Regarding these sequence homology data, the principle of maximum parsimony would be applicable in A) distinguishing introns from exons. B) determining degree of sequence homology. C) selecting appropriate genes for comparison among species. D) inferring evolutionary relatedness from the number of sequence differences. Answer: D 20) Which of these four gene parts should allow the construction of the most accurate phylogenetic tree, assuming that this is the only part of the gene that has acted as a reliable molecular clock? A) Intron I B) Exon I C) Intron VI D) Exon V Answer: C 20.3 Scenario Question Traditionally, zoologists have placed birds in their own class, Aves. More recently, molecular evidence has shown that birds are more closely related to reptiles than their anatomy reveals. Genetically, birds are more closely related to crocodiles than crocodiles are to turtles. Thus, bird anatomy has become highly modified as they have adapted to flight, without their genes having undergone nearly as much change. 1) Taxonomically, what should be done with the birds? A) The traditional stance is correct. Such dramatic morphological change as undergone by birds merits that the birds be placed in their own order, separate from the reptiles. B) The birds should be reclassified, and their new taxon should be the subclass Aves. Genetic similarity trumps morphological dissimilarity in cases where morphological traits are uninformative. C) The rest of the reptiles should be reclassified as a subclass within the class Aves. D) The classification scheme should remain the same because of historical precedence. Answer: B 20.4 End-of-Chapter Questions 1) In a comparison of birds and mammals, the condition of having four limbs is A) a shared ancestral character. B) a shared derived character. C) a character useful for distinguishing birds from mammals. D) an example of analogy rather than homology. E) a character useful for sorting bird species. Answer: A 2) To apply parsimony to constructing a phylogenetic tree, A) choose the tree that assumes all evolutionary changes are equally probable. B) choose the tree in which the branch points are based on as many shared derived characters as possible. C) base phylogenetic trees only on the fossil record, as this provides the simplest explanation for evolution. D) choose the tree that represents the fewest evolutionary changes in either DNA sequences or morphology. E) choose the tree with the fewest branch points. Answer: D 3) In figure shown below, which similarly inclusive taxon descended from the same common ancestor as Canidae? A) Felidae B) Mustelidae C) Carnivora D) Canis E) Lutra Answer: B 4) Three living species X, Y, and Z share a common ancestor T, as do extinct species U and V. A grouping that consists of species T, X, Y, and Z (but not U or V) makes up A) a monophyletic taxon. B) a clade. C) an ingroup, with species U as the outgroup. D) a paraphyletic group. E) a polyphyletic group. Answer: D 5) Based on the tree below, which statement is not correct? A) The salamander lineage is a basal taxon. B) Salamanders are a sister group to the group containing lizards, goats, and humans. C) Salamanders are as closely related to goats as to humans. D) Lizards are more closely related to salamanders than to humans. E) The group highlighted by shading is paraphyletic. Answer: D 6) If you were using cladistics to build a phylogenetic tree of cats, which of the following would be the best outgroup? A) lion B) domestic cat C) wolf D) leopard E) tiger Answer: C 7) The relative lengths of the frog and mouse branches in the phylogenetic tree in the figure given below indicate that A) frogs evolved before mice. B) mice evolved before frogs. C) the genes of frogs and mice have only coincidental homoplasies. D) the homolog has evolved more slowly in mice. E) the homolog has evolved more rapidly in mice. Answer: D Test Bank for Campbell Biology in Focus Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson, Jane B. Reece 9780321813664, 9780321962751, 9780134710679

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