1) 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

2) 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

3) With what other idea of his time was Cuvier's theory of catastrophism most in conflict?
A) gradualism
B) the fixity of species
C) island biogeography
D) uniformitarianism
E) the scala naturae

Answer: D

4) 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

5) 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

6) 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 yes

Answer: C

7) 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

8) 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

9) 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

10) 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

11) 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

12) 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

13) 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 squirrels of subsequent generations should show greater levels of genetic variation than previous generations, because squirrels that would not have survived in the past will now survive.
D) Three of the statements above are correct.
E) Two of the statements above are correct.

Answer: E

14) 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

15) 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

16) 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

17) 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

18) 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

19) 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

20) 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

21) 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

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 in size.
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: B

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

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled AD.

38) 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

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled AD.

39) 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

40) 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. SEE IMAGE
B. SEE IMAGE
C. SEE IMAGE
D. SEE IMAGE
E. SEE IMAGE

Answer: D

The following questions refer to the evolutionary tree in Figure 22.2.

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.

41) 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

The following questions refer to the evolutionary tree in Figure 22.2.

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.

42) 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

The following questions refer to the evolutionary tree in Figure 22.2.

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.

43) 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

The following questions refer to the evolutionary tree in Figure 22.2.

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.

44) 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

The following questions refer to the evolutionary tree in Figure 22.2.

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.

45) 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

The following questions refer to the evolutionary tree in Figure 22.2.

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.

46) 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

The following questions refer to the evolutionary tree in Figure 22.2.

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.

47) Evolutionary trees such as this are properly understood by scientists to be
A) theories.
B) hypotheses.
C) guesses.
D) dogmas.
E) facts.

Answer: B

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).

48) 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

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).

49) 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

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).

50) A 14th species that descended from the original ancestral finch, the Cocos Island finch, is endemic to its namesake island, located 550 km off Costa Rica. The Cocos Island finch is genetically much more similar to the tree finches than is the vegetarian finch, yet it is classified in its own genus Pinarolaxias. Moreover, the Cocos Island finch and the vegetarian finch are the two finch species that are most genetically different from the ancestral Galápagos finch. Thus, if classification is to reflect evolutionary relationships, the vegetarian finch should
A) remain in the genus Camarhynchus.
B) be switched from Camarhynchus to Certhidea.
C) be switched from Camarhynchus to Pinarolaxias.
D) be switched from Camarhynchus to Geospiza.
E) be placed in its own genus.

Answer: E

51) 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

52) 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 can be found 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

53) 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 drug-resistant 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

54) 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

55) 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

1) During an individual organism's lifetime, which of these is most likely to help the organism respond properly to changes in its environment?
A) microevolution
B) change in allele or gene frequency
C) change in gene expression
D) change in average heterozygosity

Answer: C

2) If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be
A) 23%.
B) 46%.
C) 54%.
D) There is not enough information to say.

Answer: C

3) Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed?
A) average heterozygosity
B) nucleotide variability
C) geographic variability
D) average number of loc

Answer: A

4) Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?
A) Each bird evolved a deeper, stronger beak as the drought persisted.
B) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.
C) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.
D) The frequency of the strong-beak alleles increased in each bird as the drought persisted.

Answer: B

5) Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence?
A) mutation
B) nonrandom mating
C) genetic drift
D) natural selection
E) gene flow

Answer: C

6) In modern terminology, diversity is understood to be a result of genetic variation. Which of the following is a recognized source of variation for evolution?
A) mistakes in translation of structural genes
B) mistakes in protein folding
C) rampant changes to the dictionary of the genetic code
D) binary fission
E) recombination by crossing over in meiosis

Answer: E

7) A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of
A) a cline.
B) a bottleneck.
C) relative fitness.
D) genetic drift.
E) geographic variation.

Answer: A

8) The higher the proportion of loci that are "fixed" in a population, the lower is that population's
A) nucleotide variability only.
B) genetic polyploidy only.
C) average heterozygosity only.
D) nucleotide variability, average heterozygosity, and genetic polyploidy.
E) nucleotide variability and average heterozygosity only

Answer: E

9) Which statement about variation is true?
A) All phenotypic variation is the result of genotypic variation.
B) All genetic variation produces phenotypic variation.
C) All nucleotide variability results in neutral variation.
D) All new alleles are the result of nucleotide variability.
E) All geographic variation results from the existence of clines.

Answer: D

10) Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide:
1. insertion mutation deep within an intron
2. substitution mutation at the third position of an exonic codon
3. substitution mutation at the second position of an exonic codon
4. deletion mutation within the first exon of the gene

A) 1, 2, 3, 4
B) 4, 3, 2, 1
C) 2, 1, 4, 3
D) 3, 1, 4, 2
E) 2, 3, 1, 4

Answer: B

11) Most invertebrates have a cluster of ten similar Hox genes, all located on the same chromosome. Most vertebrates have four such clusters of Hox genes, located on four nonhomologous chromosomes. The process that could have potentially contributed to the cluster's presence on more than one chromosome was ________.

A) binary fission
B) translation
C) gene duplication
D) nondisjunction
E) transcription

Answer: D

12) Which of the following is a true statement concerning genetic variation?
A) It is created by the direct action of natural selection.
B) It arises in response to changes in the environment.
C) It must be present in a population before natural selection can act upon the population.
D) It tends to be reduced by the processes involved when diploid organisms produce gametes.
E) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity

Answer: C

13) How many of these statements regarding populations are true?
1. Mature males and females of a population can interbreed with each other.
2. Populations are sometimes geographically isolated from other populations.
3. Biological species are made up of populations.
4. Members of a population tend to be genetically more similar to each other than to members of other populations.
5. Populations have genomes, but not gene pools.

A) Only one of these statements is true.
B) Two of these statements are true.
C) Three of these statements are true.
D) Four of these statements are true.
E) All five of these statements are true

Answer: D

14) Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus
A) the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change.
B) natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency.
C) this means that, at this locus, two alleles are present in equal proportions.
D) the population itself is not evolving, but individuals within the population may be evolving.

Answer: A

15) In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because
A) the population is diploid.
B) heterozygotes can come about in two ways.
C) the population is doubling in number.
D) heterozygotes have two alleles.

Answer: B

16) In the formula for determining a population’s genotype frequencies, the pq in the term 2pq is necessary because
A) the population is diploid.
B) heterozygotes can come about in two ways.
C) the population is doubling in number.
D) heterozygotes have two alleles

Answer: D

17) Hardy-Weinberg equilibrium must occur in populations wherein
A) an allele remains fixed.
B) no genetic variation exists.
C) natural selection is not operating.
D) All three of the responses above are correct.
E) Only two of the responses above are correct.

Answer: E

18) In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the percentage of the population that is homozygous for this allele?
A) 0.09
B) 0.49
C) 0.9
D) 9.0
E) 49.0

Answer: D

19) In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the percentage of the population that is heterozygous for this allele?
A) 0.2
B) 2.0
C) 4.0
D) 16.0
E) 32.0

Answer: E

20) In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?
A) 0.20
B) 0.32
C) 0.42
D) 0.81
E) Genotype frequency cannot be determined from the information provided.

Answer: D

21) You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population?
A) 0.07
B) 0.08
C) 0.09
D) 0.70
E) Allele frequency cannot be determined from this information.

Answer: E

22) In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
A) 0.36
B) 0.64
C) 0.75
D) 0.80

Answer: D

23) Evolution
A) must happen, due to organisms’ innate desire to survive.
B) must happen whenever a population is not well-adapted to its environment.
C) can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met.
D) requires the operation of natural selection.
E) requires that populations become better suited to their environments

Answer: C

24) Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing
A) nonrandom mating.
B) geographic isolation.
C) genetic drift.
D) gene flow.

Answer: D

25) Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined, thereby producing a genetically distinctive virus, which can subsequently cause widespread disease.

The production of new types of flu virus in the manner described above is most similar to the phenomenon of
A) bottleneck effect.
B) founder effect.
C) natural selection.
D) gene flow.
E) sexual selection.

Answer: D

26) If the original finches that had been blown over to the Galápagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galápagos, this would have been an example of
A) genetic drift.
B) bottleneck effect.
C) founder effect.
D) all three of these.
E) both the first and third of these.

Answer: E

27) What is true of natural selection?
A) Natural selection is a random process.
B) Natural selection creates beneficial mutations.
C) The only way to eliminate harmful mutations is through natural selection.
D) Mutations occur at random; natural selection can preserve and distribute beneficial mutations.
E) Mutations occur when directed by the good of the species; natural selection edits out harmful mutations and causes populations to adapt to the beneficial mutations.

Answer: D

28) The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from
A) frequency-dependent selection.
B) evolutionary imbalance.
C) heterozygote advantage.
D) neutral variation.
E) genetic variation being preserved by diploidy.

Answer: A

29) The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur?
A) Methylated DNA should become fixed in the gene pools of bacterial species.
B) Nonmethylated DNA should become fixed in the gene pools of bacteriophages.
C) Methylated DNA should become fixed in the gene pools of bacteriophages.
D) Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time.
E) Both the first and second responses are correct.

Answer: D

30) Arrange the following from most general (i.e., most inclusive) to most specific (i.e., least inclusive):
1. natural selection
2. microevolution
3. intrasexual selection
4. evolution
5. sexual selection

A) 4, 1, 2, 3, 5
B) 4, 2, 1, 3, 5
C) 4, 2, 1, 5, 3
D) 1, 4, 2, 5, 3
E) 1, 2, 4, 5, 3

Answer: C

31) Sexual dimorphism is most often a result of
A) pansexual selection.
B) stabilizing selection.
C) intrasexual selection.
D) intersexual selection.
E) artificial selection.

Answer: D

32) In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. These colors come from carotenoid pigments that are found in the birds' diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male's feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food-gathering efforts (all other factors being equal). During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation?
A) Alleles that promote more efficient acquisition of carotenoid-containing foods by males should increase over the course of generations.
B) Alleles that promote more effective deposition of carotenoid pigments in the feathers of males should increase over the course of generations.
C) There should be directional selection for bright red feathers in males.
D) Three of the statements are correct.
E) Two of the statements are correct.

Answer: D

33) During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following terms are appropriately applied to this situation?
A) sexual selection
B) mate choice
C) intersexual selection
D) Three of the responses are correct.
E) Two of the responses are correct.

Answer: D

34) Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then
A) sexual dimorphism was developing over time in these species.
B) intrasexual selection seems to have occurred.
C) stabilizing selection was occurring in these species concerning larynx size.
D) selection was acting more directly upon genotype than upon phenotype.

Answer: A

35) Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from
A) pansexual selection.
B) directional selection.
C) disruptive selection.
D) stabilizing selection.
E) asexual selection

Answer: C

36) Which of the following statements best summarizes evolution as it is viewed today?
A) It represents the result of selection for acquired characteristics.
B) It is synonymous with the process of gene flow.
C) It is the descent of humans from the present-day great apes.
D) It is the differential survival and reproduction of the most-fit phenotypes.

Answer: D

37) Which of the following is most likely to produce an African butterfly species in the wild whose members have one of two strikingly different color patterns?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

Answer: D

38) Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

Answer: C

39) The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infant's diet lacks the amino acid phenylalanine. What maintains the presence of this harmful allele in a population's gene pool?
A) heterozygote advantage
B) stabilizing selection
C) diploidy
D) balancing selection

Answer: C

40) Heterozygote advantage should be most closely linked to which of the following?
A) sexual selection
B) stabilizing selection
C) random selection
D) directional selection
E) disruptive selection

Answer: B

41) In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?
A) disruptive selection
B) directional selection
C) stabilizing selection
D) No selection would operate because the population is in Hardy-Weinberg equilibrium

Answer: B

42) When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of
A) sexual selection.
B) disruptive selection.
C) balancing selection.
D) stabilizing selection.
E) frequency-dependent selection

Answer: E

43) The same gene that causes various coat patterns in wild and domesticated cats also causes the cross-eyed condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is supported by these observations?
A) Evolution is progressive and tends toward a more perfect population.
B) Phenotype is often the result of compromise.
C) Natural selection reduces the frequency of maladaptive genes in populations over the course of time.
D) Polygenic inheritance is generally maladaptive, and should become less common in future generations.
E) In all environments, coat pattern is a more important survival factor than is eye-muscle tone.

Answer: B

44) A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because
A) natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time.
B) in many cases, phenotype is not merely determined by genotype, but by the environment as well.
C) though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design.
D) natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

Answer: D

45) There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception?
A) Advantageous alleles do not arise on demand.
B) A population's evolution is limited by historical constraints.
C) Adaptations are often compromises.
D) Evolution can be influenced by environmental change.

Answer: A

46) Blue light is that portion of the visible spectrum that penetrates the deepest into bodies of water. Ultraviolet (UV) light, though, can penetrate even deeper. A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light, and another allele for a photopigment that is sensitive to blue light. Which of the following graphs best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best? (SEE IMAGE)

A) A
B) B
C) C
D) D

Answer: B

47) Anopheles mosquitoes, which carry the malaria parasite, cannot live above elevations of 5,900 feet. In addition, oxygen availability decreases with higher altitude. Consider a hypothetical human population that is adapted to life on the slopes of Mt. Kilimanjaro in Tanzania, a country in equatorial Africa. Mt. Kilimanjaro's base is about 2,600 feet above sea level and its peak is 19,341 feet above sea level. If the incidence of the sickle-cell allele in the population is plotted against altitude (feet above sea level), which of the following distributions is most likely, assuming little migration of people up or down the mountain?

A. SEE IMAGE
B. SEE IMAGE
C. SEE IMAGE
D. SEE IMAGE

Answer: B

48) If global warming permits mosquitoes to live at higher altitudes than they currently do, then in which direction should the entire plot in the correct distribution below be shifted?

A) to the right
B) to the left
C) upward
D) downward

Answer: A

In a very large population, a quantitative trait has the following distribution pattern:

49) What is true of the trait whose frequency distribution in a large population appears in the previous figure? It has probably undergone
A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) normal selection.

Answer: B

50) If the curve in the previous figure shifts to the left or to the right, there is no gene flow, and the population size consequently increases over successive generations. Which of the following is (are) probably occurring?

1. immigration or emigration
2. directional selection
3. adaptation
4. genetic drift
5. disruptive selection

A) 1 only
B) 4 only
C) 2 and 3
D) 4 and 5
E) 1, 2, and 3

Answer: C

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

51) Which of the following represents the treatment option most likely to avoid the production of drug-resistant HIV (assuming no drug interactions or side effects)?
A) using a series of NAs, one at a time, and changed about once a week
B) using a single PI, but slowly increasing the dosage over the course of a week
C) using high doses of NA and a PI at the same time for a period not to exceed one day
D) using moderate doses of NA and two different PIs at the same time for several months

Answer: D

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

52) Within the body of an HIV-infected individual who is being treated with a single NA, and whose HIV particles are currently vulnerable to this NA, which of these situations can increase the virus' relative fitness?
1. mutations resulting in RTs with decreased rates of nucleotide mismatch
2. mutations resulting in RTs with increased rates of nucleotide mismatch
3. mutations resulting in RTs that have proofreading capability
A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 2 and 3

Answer: B

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

53) HIV has nine genes in its RNA genome. Every HIV particle contains two RNA molecules, and each molecule contains all nine genes. If, for some reason, the two RNA molecules within a single HIV particle do not have identical sequences, then which of these terms can be applied due to the existence of the nonidentical regions?
A) homozygous
B) gene variability
C) nucleotide variability
D) average heterozygosity
E) All but one of the responses are correct.

Answer: E

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

54) Every HIV particle contains two RNA molecules. If two genes from one RNA molecule become detached and then, as a unit, get attached to one end of the other RNA molecule within a single HIV particle, which of these is true?
A) There are now fewer genes within the viral particle.
B) There are now more genes within the viral particle.
C) A point substitution mutation has occurred in the retroviral genome.
D) The retroviral equivalent of crossing over has occurred, no doubt resulting in a heightened positive effect.
E) One of the RNA molecules has experienced gene duplication as the result of translocation.

Answer: E

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

55) In a hypothetical population's gene pool, an autosomal gene, which had previously been fixed, undergoes a mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations?
A) The proportions of both types of homozygote should decrease.
B) The proportion of the population that is heterozygous at this locus should remain constant.
C) The population's average heterozygosity should decrease.
D) The two homozygotes should decrease at different rates.

Answer: A

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

56) What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?
A) The population is undergoing genetic drift.
B) The two phenotypes are about equally adaptive under laboratory conditions.
C) The genotype AA is lethal.
D) There has been a high rate of mutation of allele A to allele a.
E) There has been sexual selection favoring allele a.

Answer: B

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

57) What is the estimated frequency of allele A in the gene pool?
A) 0.25
B) 0.50
C) 0.75

Answer: B

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

58) What proportion of the population is probably heterozygous (Aa) for this trait?
A) 0.05
B) 0.25
C) 0.50
D) 0.75

Answer: C

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown.

59) In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?
A) population A
B) population B
C) population C
D) They are all the same.
E) It is impossible to tell from the information given.

Answer: B

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown.

60) Which population is most likely to be subject to the bottleneck effect?
A) population A
B) population B
C) population C
D) They are all equally likely.
E) It is impossible to tell from the information given.

Answer: A

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.

61) What should be the proportion of heterozygous individuals in populations that live here?
A) 0.04
B) 0.16
C) 0.20
D) 0.32
E) 0.80

Answer: D

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.

62) If the sickle-cell allele is recessive, what proportion of the population should be susceptible to sickle-cell anemia under typical conditions?
A) 0.04
B) 0.16
C) 0.20
D) 0.32
E) 0.80

Answer: A

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.

63) In the United States, the parasite that causes malaria is not present, but African-Americans whose ancestors were from equatorial Africa are present. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa?
A) stabilizing selection; disruptive selection
B) disruptive selection; stabilizing selection
C) disruptive selection; directional selection
D) directional selection; disruptive selection
E) directional selection; stabilizing selection

Answer: E

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.

64) With respect to the sickle-cell allele, what should be true of the β hemoglobin locus in U.S. populations of African-Americans whose ancestors were from equatorial Africa?
1. The average heterozygosity at this locus should be decreasing over time.
2. There is an increasing heterozygote advantage at this locus.
3. Diploidy is helping to preserve the sickle-cell allele at this locus.
4. Frequency-dependent selection is helping to preserve the sickle-cell allele at this locus.

A) 1 only
B) 1 and 3
C) 2 and 3
D) 1, 2, and 3
E) 1, 2, and 4

Answer: B

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.

65) Considering the overall human population of the U.S. mainland at the time when the slave trade brought large numbers of people from equatorial Africa, what was primarily acting to change the frequency of the sickle-cell allele in the overall U.S. population?
A) natural selection
B) gene flow
C) genetic drift
D) founder effect
E) Two of the responses are correct.

Answer: B

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.

66) The sickle-cell allele is pleiotropic (i.e., it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria. Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." Such individuals remain less susceptible to malaria. Thus, pleiotropic genes/alleles such as this can help explain why
A) new advantageous alleles do not arise on demand.
B) evolution is limited by historical constraints.
C) adaptations are often compromises.
D) chance events can affect the evolutionary history of populations.

Answer: C

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.

67) Which of these is closest to the allele frequency in the founding population?
A) 0.1 a, 0.9 A
B) 0.2 a, 0.8 A
C) 0.5 a, 0.5 A
D) 0.8 a, 0.2 A
E) 0.4 a, 0.6 A

Answer: A

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.

68) If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about how many people will have attached earlobes when the planet's population reaches 10,000?
A) 100
B) 400
C) 800
D) 1,000
E) 10,000

Answer: A

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.

69) If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of
A) diploidy.
B) gene flow.
C) genetic drift.
D) disruptive selection.
E) stabilizing selection.

Answer: C

70) You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to
A) cross your flies with flies from another lab.
B) reduce the number of flies that you transfer at each generation.
C) transfer only the largest flies.
D) change the temperature at which you rear the flies.
E) shock the flies with a brief treatment of heat or cold to make them more hardy.

Answer: A

71) The volcano is currently dormant, but in a hypothetical future scenario, satellite cones at the base of Mt. Kilimanjaro spew sulfurous gases and lava, destroying all life located between the base and 6,000 feet above sea level. As a result of this catastrophe, how should the frequency of the sickle-cell allele change in the remnant human population that survives above 6,000 feet, and which phenomenon accounts for this change in allele frequency?
A) decreases; disruptive selection
B) increases; genetic drift
C) decreases; gene flow
D) increases; nonrandom mating
E) decreases; bottleneck effect

Answer: E

72) Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?
A) The new virus will maintain its Tamiflu-resistance gene, just in case of future exposure to Tamiflu.
B) The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment.
C) If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.
D) If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will become dormant until Tamiflu is present.

Answer: C

73) Natural selection changes allele frequencies because some ________ survive and reproduce more successfully than others.
A) alleles
B) loci
C) gene pools
D) species
E) individuals

Answer: E

74) No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is
A) new mutations that occurred in the preceding generation.
B) genetic drift due to the small size of the population.
C) the reshuffling of alleles in sexual reproduction.
D) geographic variation within the population.
E) environmental effects.

Answer: C

75) Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating
A) the bottleneck effect.
B) disruptive selection.
C) frequency-dependent selection.
D) neutral variation.
E) stabilizing selection.

Answer: E

76) If the nucleotide variability of a locus equals 0%, what is the gene variability and number of alleles at that locus?
A) gene variability = 0%; number of alleles = 0
B) gene variability = 0%; number of alleles = 1
C) gene variability = 0%; number of alleles = 2
D) gene variability > 0%; number of alleles = 2
E) Without more information, gene variability and number of alleles cannot be determined.

Answer: B

77) There are 40 individuals in population 1, all with genotype A1A1, and there are 25 individuals in population 2, all with genotype A2A2. Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation is most likely an example of
A) genetic drift.
B) gene flow.
C) disruptive selection.
D) discrete variation.
E) directional selection.

Answer: A

78) A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2?
A) 0.7
B) 0.49
C) 0.21
D) 0.42
E) 0.09

Answer: D

1) What is true of macroevolution?
A) It is the same as microevolution, but includes the origin of new species.
B) It is evolution above the species level.
C) It is defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye.
D) It is defined as a change in allele or gene frequency over the course of many generations.
E) It is the conceptual link between irritability and adaptation.

Answer: B

2) What is true of the flightless cormorants of the Galápagos Islands?
A) They are descendants of the same common ancestor that gave rise to the unique finches of these islands.
B) They are close relatives of flightless cormorants from the Americas.
C) If they are still able to breed successfully with flying cormorants, it would probably be with North American cormorants, rather than with South American cormorants.
D) Flightless cormorants on one island have restricted gene flow with those on other islands, which could someday lead to a macroevolutionary event.
E) Their DNA has low levels of sequence homology with the DNA of flying American cormorants.

Answer: D

3) Which of the following statements about species, as defined by the biological species concept, is (are) correct?
I. Biological species are defined by reproductive isolation.
II. Biological species are the model used for grouping extinct forms of life.
III. The biological species is the largest unit of population in which successful interbreeding is possible.
A) I and II
B) I and III
C) II and III
D) I, II, and III

Answer: B

4) Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?
A) phylogenetic
B) ecological
C) biological
D) morphological

Answer: C

5) There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept is most applicable in this example?
A) phylogenetic
B) ecological
C) morphological
D) biological

Answer: D

6) You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?
A) biological
B) phylogenetic
C) ecological
D) morphological

Answer: D

7) Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?
A) reduced hybrid fertility
B) hybrid breakdown
C) mechanical isolation
D) habitat isolation
E) gametic isolation

Answer: D

8) Rank the following from most general to most specific:

1. gametic isolation
2. reproductive isolating mechanism
3. pollen-stigma incompatibility
4. prezygotic isolating mechanism

A) 2, 3, 1, 4
B) 2, 4, 1, 3
C) 4, 1, 2, 3
D) 4, 2, 1, 3
E) 2, 1, 4, 3

Answer: B

9) Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate?
A) the postzygotic barrier called hybrid inviability
B) the postzygotic barrier called hybrid breakdown
C) the prezygotic barrier called hybrid sterility
D) gametic isolation

Answer: A

10) Theoretically, the production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) should
A) result in the extinction of one of the two parental species.
B) cause convergent evolution.
C) strengthen postzygotic barriers between horses and donkeys.
D) weaken the intrinsic reproductive barriers between horses and donkeys.
E) eventually result in the formation of a single species from the two parental species.

Answer: C

11) When male horses (stallions) and female donkeys (jennets) mate, they produce a sterile hybrid called a hinny. Hinnies occur much less frequently than do mules, but are just as healthy and robust as mules. Logically, which of the following best accounts for the relative rarity of hinnies, and what kind of prezygotic isolating mechanism is at work here?
A) Most hinnies die during fetal development; reduced hybrid viability.
B) Most hinnies die soon after being born; hybrid breakdown.
C) Most hinnies are reproductively sterile; reduced hybrid fertility.
D) Stallions and jennets are choosier about their mating partners than are mares and jacks; behavioral isolation.
E) Stallions and jennets are choosier about their mating partners than are mares and jacks; gametic isolation.

Answer: D

12) Dogs (Canis lupus familiaris) and gray wolves (Canis lupus) can interbreed to produce viable, fertile offspring. These species shared a common ancestor recently (in geologic time) and have a high degree of genetic similarity, although their anatomies vary widely. Judging from this evidence, which two species concepts are most likely to place dogs and wolves together into a single species?
A) ecological and morphological
B) ecological and phylogenetic
C) morphological and phylogenetic
D) biological and morphological
E) biological and phylogenetic

Answer: E

13) Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms are applicable?

1. sympatric species
2. prezygotic isolation
3. postzygotic isolation
4. allopatric species
5. habitat isolation
6. reduced hybrid fertility

A) 1 and 2
B) 2 and 4
C) 1, 3, and 6
D) 2, 4, and 5
E) 1, 2, 5, and 6

Answer: A

14) Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms is applicable?
A) behavioral isolation
B) mechanical isolation
C) hybrid breakdown
D) reduced hybrid viability

Answer: B

15) What does the biological species concept use as the primary criterion for determining species boundaries?
A) geographic isolation
B) niche differences
C) gene flow
D) morphological similarity
E) molecular (DNA, RNA, protein) similarity

Answer: C

16) In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In rangelands of the western United States, pronghorns and cattle often associate with one another. If some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood, then over time which of these should occur, if the host mammal can be considered as the fleas' habitat?

1. reproductive isolation
2. sympatric speciation
3. habitat isolation
4. prezygotic barriers

A) 1 only
B) 2 and 3
C) 1, 2, and 3
D) 2, 3, and 4
E) 1 through 4

Answer: E

17) Two closely related populations of mice have been separated for many generations by a river. Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a zone of overlap. Which of the following is not a possible outcome when they meet?
A) They interbreed freely and produce fertile hybrid offspring.
B) They no longer attempt to interbreed.
C) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations.
D) They remain separate in the extremes of their ranges but develop a persistent hybrid zone in the area of overlap.
E) They interbreed in the region of overlap, but produce sterile offspring.

Answer: C

18) The difference between geographic isolation and habitat differentiation is the
A) relative locations of two populations as speciation occurs.
B) speed (tempo) at which two populations undergo speciation.
C) amount of genetic variation that occurs among two gene pools as speciation occurs.
D) identity of the phylogenetic kingdom or domain in which these phenomena occur.
E) the ploidy of the two populations as speciation occurs.

Answer: A

19) Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?

1. allopatric speciation
2. sympatric speciation
3. sexual selection
4. polyploidy

A) 1 and 3
B) 1 and 4
C) 2 and 3
D) 2 and 4

Answer: D

20) Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it?
A) allopatric speciation; ecological isolation
B) sympatric speciation; habitat differentiation
C) allopatric speciation; behavioral isolation
D) sympatric speciation; sexual selection
E) sympatric speciation; allopolyploidy

Answer: B

21) The origin of a new plant species by hybridization, coupled with accidents during nuclear division, is an example of
A) allopatric speciation.
B) sympatric speciation.
C) autopolyploidy.
D) habitat selection

Answer: B

22) The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and
A) their chromosomes are no longer homologous enough to permit meiosis.
B) a constant number of viable, fertile hybrids is produced over the course of generations.
C) the hybrid zone is inhospitable to hybrid survival.
D) an increasing number of viable, fertile hybrids is produced over the course of generations.
E) a decreasing number of viable, fertile hybrids is produced over the course of generations

Answer: D

23) A hybrid zone is properly defined as
A) an area where two closely related species' ranges overlap.
B) an area where mating occurs between members of two closely related species, producing viable offspring.
C) a zone that features a gradual change in species composition where two neighboring ecosystems border each other.
D) a zone that includes the intermediate portion of a cline.
E) an area where members of two closely related species intermingle, but experience no gene flow.

Answer: B

24) Which of these should decline in hybrid zones where reinforcement is occurring?
A) gene flow between distinct gene pools
B) speciation
C) the genetic distinctness of two gene pools
D) mutation rate
E) hybrid sterility

Answer: A

25) The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is
A) sexual selection.
B) habitat differentiation.
C) polyploidy.
D) pollution.
E) introduction of a new predator.

Answer: A

26) The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is
A) reinforcement.
B) fusion.
C) stability.
D) geographic isolation.
E) polyploidy.

Answer: B

27) A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is true of those alleles that are unique to the parental species?
A) Such alleles should be absent.
B) Their allele frequency should be nearly the same as the allele frequencies in toad populations distant from the hybrid zone.
C) The alleles' heterozygosity should be higher among the hybrid toads there.
D) Their allele frequency on one edge of the hybrid zone should roughly equal their frequency on the opposite edge of the hybrid zone.

Answer: C

28) According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that
A) the species is now extinct.
B) speciation occurred instantaneously.
C) speciation occurred in one generation.
D) speciation occurred rapidly in geologic time.
E) the species will consequently have a relatively short existence, compared with other species.

Answer: D

29) According to the concept of punctuated equilibrium,
A) natural selection is unimportant as a mechanism of evolution.
B) given enough time, most existing species will branch gradually into new species.
C) a new species accumulates most of its unique features as it comes into existence.
D) evolution of new species features long periods during which changes are occurring, interspersed with short periods of equilibrium, or stasis.
E) transitional fossils, intermediate between newer species and their parent species, should be abundant.

Answer: C

30) Speciation
A) occurs at such a slow pace that no one has ever observed the emergence of new species.
B) occurs only by the accumulation of genetic change over vast expanses of time.
C) must begin with the geographic isolation of a small, frontier population.
D) and microevolution are synonymous.
E) can involve changes to a single gene.

Answer: E

31) Which of the following statements about speciation is correct?
A) The goal of natural selection is speciation.
B) When reunited, two allopatric populations will interbreed freely if speciation has occurred.
C) Natural selection chooses the reproductive barriers for populations.
D) Prezygotic reproductive barriers usually evolve before postzygotic barriers.
E) Speciation is a basis for understanding macroevolution.

Answer: E

32) In order for speciation to occur, what must be true?
A) The number of chromosomes in the gene pool must change.
B) Changes to centromere location or chromosome size must occur within the gene pool.
C) Large numbers of genes that affect a single phenotypic trait must change.
D) Large numbers of genes that affect numerous phenotypic traits must change.
E) At least one gene, affecting at least one phenotypic trait, must change.

Answer: E

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.

33) Which species is most closely related to species W?
A) V is most closely related to species W.
B) X is most closely related to species W.
C) Y and Z are equally closely related to W.
D) It is not possible to say from this tree.

Answer: A

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.

34) Which species is least expected to have a good record of transitional fossils; in other words, which species' fossils, if present at all, are expected only in relatively superficial (i.e., shallow) strata?
A) V
B) W
C) X
D) Y
E) Z

Answer: A

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.

35) Which of these five species originated earliest and appeared suddenly in the fossil record?
A) V
B) W
C) X
D) Y
E) Z

Answer: B

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.

36) Which conclusion can be drawn from this evolutionary tree?
A) Gradualistic speciation and speciation involving punctuated equilibrium are mutually exclusive concepts; only one of them can occur.
B) Eldredge and Gould would deny that the lineages labeled X, Y, and Z could represent true species.
C) Assuming that the tip of each line represents a species, there are five extant (i.e., not extinct) species resulting from the earliest common ancestor.
D) A single clade (i.e., a group of species that share a common ancestor) can exhibit both gradualism and punctuated equilibrium.
E) V and W shared a common ancestor more recently than any of the other species.

Answer: D

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.

37) Which of these five species is the extant (i.e., not extinct) species that is most closely related to species X, and why is this so?
A) V; shared a common ancestor with X most recently
B) W; shared a common ancestor with X most recently
C) Y; arose in the same fashion (i.e., at the same tempo) as X
D) Z; shared a common ancestor with X most recently, and arose in the same fashion as X
E) This tree does not provide enough information to answer this question

Answer: A

n a hypothetical situation, the National Park Service, which administers Grand Canyon National Park in Arizona, builds a footbridge over the Colorado River at the bottom of the canyon. The footbridge permits interspersal of two closely related antelope squirrels. Previously, one type of squirrel had been restricted to the terrain south of the river, and the other type had been restricted to terrain on the north side of the river. Immediately before and ten years after the bridge's completion, researchers collected ten antelope squirrels from both sides of the river, took blood samples, and collected frequencies of alleles unique to the two types of antelope squirrels (see the following graphs).

38) The data in the previous graphs indicate that
A) a hybrid zone was established after the completion of the bridge.
B) no interspersal of the two types of squirrel occurred after the completion of the bridge.
C) gene flow occurred from one type of squirrel into the gene pool of the other type of squirrel.
D) two-way migration of squirrels occurred across the bridge, but without hybridization.
E) some northern squirrels migrated south, but no southern squirrels migrated north across the bridge.

Answer: D

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

39) Which of the following reduces gene flow between the gene pools of the two species on Sao Tomé, despite the existence of hybrids?
A) hybrid breakdown
B) hybrid inviability
C) hybrid sterility
D) temporal isolation
E) a geographic barrier

Answer: C

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

40) The observation that island D. yakuba are more closely related to mainland D. yakuba than island D. yakuba are to D. santomea is best explained by proposing that D. santomea
A) descended from a now-extinct, non-African fruit fly.
B) arrived on the island before D. yakuba.
C) descended from a single colony of D. yakuba, which had been introduced from elsewhere, with no subsequent colonization events.
D) descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.

Answer: D

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

41) If a speciation event occurred on Sao Tomé, producing D. santomea from a parent colony of D. yakuba, then which terms apply?

I.macroevolution
IIallopatric speciation
III.sympatric speciation

A) I only
B) II only
C) I and II
D) I and III

Answer: D

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago

43) Which of these evolutionary trees represents the situation described in the previous paragraph (Note: Yakuba (I) represents the island population, and yakuba (M) represents the mainland population)?

A. SEE IMAGE
B. SEE IMAGE
C. SEE IMAGE
D. SEE IMAGE

Answer: A

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago

44) If the low number of hybrid flies in the hybrid zone, relative to the number of D. santomea flies there, is due to the fact that hybrids are poorly adapted to conditions in the hybrid zone, and if fewer hybrid flies are produced with the passage of time, these conditions will most likely lead to
A) fusion.
B) reinforcement.
C) stability.
D) further speciation events.

Answer: B

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

45) Which two of the following have operated to increase divergence between mosquitofish populations on Andros?

1. improved gene flow
2. bottleneck effect
3. sexual selection
4. founder effect
5. natural selection

A) 1 and 3
B) 2 and 3
C) 2 and 4
D) 3 and 4
E) 3 and 5

Answer: E

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

46) Which type of reproductive isolation operates to keep the mosquitofish isolated, even when fish from different ponds are reunited in the same body of water?
A) behavioral isolation
B) habitat isolation
C) temporal isolation
D) mechanical isolation
E) gametic isolation

Answer: A

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

48) If one builds a canal linking a predator-rich pond to a predator-poor pond, then what type(s) of selection should subsequently be most expected among the mosquitofish in the original predator-rich pond, and what type(s) should be most expected among the mosquitofish in the formerly predator-poor pond?
A) stabilizing selection; directional selection
B) stabilizing selection; stabilizing selection
C) less-intense directional selection; more-intense directional selection
D) less-intense disruptive selection; more-intense disruptive selection

Answer: C

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

49) The predatory fish rely on visual cues and speed to capture mosquitofish. Mosquitofish rely on speed and visual cues to avoid the predatory fish. Which adaptation(s) might help the predators survive in ponds that are home to faster mosquitofish?

1. directional selection for increased speed
2. stabilizing selection for speed that matches that of the mosquitofish
3. change in hunting behavior that replaces reliance on visual cues with reliance on tactile cues, which can be used to hunt at night
4. change in hunting behavior that eliminates speed in favor of better camouflage, which permits an ambush strategy

A) 1 only
B) 2 only
C) either 1 or 3
D) either 2 or 3
E) 1, 3, or 4

Answer: E

n the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

50) Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?
A) They have been geographically isolated from each other for a longer time.
B) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp.
C) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.
D) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.

Answer: A

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.

51) In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?
A) A3
B) A5
C) B4
D) either A3 or A5
E) any species from any one of the side A habitats

Answer: C

n the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.

52) Which of these habitats is likely to harbor the youngest species?
A) A5
B) B4
C) A3
D) B2
E) A1

Answer: E

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.

53) Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?
A) A1 and A5
B) A1 and B5
C) B5 and B1
D) A5 and B5
E) Both A1/A5 and B1/B5 should have the greatest, but equal amounts of, genetic divergence.

Answer: D

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.

54) Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?
A) the relative shortness of time they have been separated
B) the depth of the ocean
C) the number of actual depth habitats between the surface and the sea floor
D) the elevation of the isthmus above sea level
E) the depth of the canal

Answer: A

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.

55) The Panama Canal was completed in 1914, and its depth is about 50 feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?
A) A5 and B5
B) A3 and B3
C) A1 and B1
D) either A1 and A2, or B1 and B2
E) A1—A3 and B1—B3 have equal likelihoods of harboring snapping shrimp species that can hybridize.

Answer: C

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.

56) There are currently two, large, permanent bridges that span the Panama Canal. The bridges are about 8 miles apart. If snapping shrimp avoid swimming at night and avoid swimming under shadows, then what do these bridges represent for the snapping shrimp?
A) sources of refuge
B) geographic barriers
C) sources of a hybrid zone between the two bridges
D) sources for increased gene flow

Answer: B

57) The largest unit within which gene flow can readily occur is a
A) population.
B) species.
C) genus.
D) hybrid.
E) phylum

Answer: B

58) Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent?
A) habitat isolation
B) temporal isolation
C) behavioral isolation
D) gametic isolation
E) postzygotic barriers

Answer: C

59) According to the punctuated equilibria model,
A) natural selection is unimportant as a mechanism of evolution.
B) given enough time, most existing species will branch gradually into new species.
C) most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.
D) most evolution occurs in sympatric populations.
E) speciation is usually due to a single mutation.

Answer: C

60) Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?
A) The two forms interbreed often in nature, and their offspring have good survival and reproduction.
B) The two forms live in similar habitats.
C) The two forms have many genes in common.
D) The two forms have similar food requirements.
E) The two forms are very similar in coloration.

Answer: A

61) Which of the following factors would not contribute to allopatric speciation?
A) A population becomes geographically isolated from the parent population.
B) The separated population is small, and genetic drift occurs.
C) The isolated population is exposed to different selection pressures than the ancestral population.
D) Different mutations begin to distinguish the gene pools of the separated populations.
E) Gene flow between the two populations is extensive.

Answer: E

62) Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be
A) 12.
B) 14.
C) 16.
D) 28.
E) 56.

Answer: D

63) Suppose that a group of male pied flycatchers migrated from a region where there were no collared flycatchers to a region where both species were present. Assuming events like this are very rare, which of the following scenarios is least likely?
A) The frequency of hybrid offspring would increase.
B) Migrant pied males would produce fewer offspring than would resident pied males.
C) Pied females would rarely mate with collared males.
D) Migrant males would mate with collared females more often than with pied females.
E) The frequency of hybrid offspring would decrease

Answer: E

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) 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) Two of the responses are correct.

Answer: D

6) Which individual would make the worst systematist? One who is uncomfortable with the
A) Linnaean system of classification.
B) notion of hypothetical phylogenies.
C) PhyloCode method of classification.
D) notion of permanent polytomies

Answer: B

7) 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

8) 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

9) 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

10) Which of the following pairs 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

11) 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

12) 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

13) Which mutation should least require realignment of homologous regions of a gene that is common to several related species?
A) three-base insertion
B) one-base substitution
C) four-base insertion
D) one-base deletion
E) three-base deletion

Answer: B

14) 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

15) 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

16) 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

17) 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

18) 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

19) A researcher wants to determine the genetic relatedness of several breeds of dog (Canis lupus familiaris). The researcher should compare homologous sequences of this type of biochemical________which can be described as ________.

A) fatty acids; highly conserved
B) lipids; poorly conserved
C) proteins; highly conserved
D) amino acids; highly conserved
E) nucleic acids, poorly conserved

Answer: E

20) Concerning growth in genome size over evolutionary time, which of these is least associated with the others?
A) orthologous genes
B) gene duplications
C) paralogous genes
D) gene families

Answer: A

21) Nucleic acid sequences that undergo few changes over the course of evolutionary time are said to be conserved. Conserved sequences of nucleic acids
A) are found in the most crucial portions of proteins.
B) include all mitochondrial DNA.
C) are abundant in ribosomes.
D) are proportionately more common in eukaryotic introns than in eukaryotic exons.
E) comprise a larger proportion of pre-mRNA (immature mRNA)
than of mature mRNA.

Answer: C

22) Species that are not closely related and that do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their
A) plasmids.
B) mitochondrial genomes.
C) homologous genes that are poorly conserved.
D) homologous genes that are highly conserved.

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) 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

25) The lakes of northern Minnesota are home to many similar species of damselflies of the genus Enallagma that have apparently undergone speciation from ancestral stock since the last glacial retreat about 10,000 years ago. Sequencing which of the following would probably be most useful in sorting out evolutionary relationships among these closely related species?
A) nuclear DNA
B) mitochondrial DNA
C) small nuclear RNA
D) ribosomal RNA
E) amino acids in proteins

Answer: B

26) Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of sequence homology?
A) Dogs and wolves have very similar morphologies.
B) Dogs and wolves belong to the same order.
C) Dogs and wolves are both members of the order Carnivora.
D) Dogs and wolves shared a common ancestor very recently.

Answer: D

27) The reason that paralogous genes can diverge from each other within the same gene pool, whereas orthologous genes diverge only after gene pools are isolated from each other, is that
A) having multiple copies of genes is essential for the occurrence of sympatric speciation in the wild.
B) paralogous genes can occur only in diploid species; thus, they are absent from most prokaryotes.
C) polyploidy is a necessary precondition for the occurrence of sympatric speciation in the wild.
D) having an extra copy of a gene permits modifications to the copy without loss of the original gene product.

Answer: D

28) Paralogous genes that have lost the function of coding for any functional gene product are known as "pseudogenes." Which of these is a valid prediction regarding the fate of pseudogenes over evolutionary time?
A) They will be preserved by natural selection.
B) They will be highly conserved.
C) They will ultimately regain their original function.
D) They will be transformed into orthologous genes.
E) They will have relatively high mutation rates.

Answer: E

29) 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

30) 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

31) 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

32) 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

33) 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

34) What important criterion was used in the late 1960s to distinguish between the three multicellular eukaryotic kingdoms of the five-kingdom classification system?
A) the number of cells present in individual organisms
B) the geological stratum in which fossils first appear
C) the nutritional modes they employ
D) the biogeographic province where each first appears
E) the features of their embryos

Answer: C

35) Members of which kingdom have cell walls and are all heterotrophic?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer: B

36) Which kingdom has been replaced with two domains?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer: E

37) Which eukaryotic kingdom is polyphyletic, and therefore unacceptable, based on cladistics?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer: D

38) Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient proteobacterium and an ancient cyanobacterium?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer: A

39) 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

40) 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 26.1?
A) A
B) B
C) C
D) D
E) E

Answer: A

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 26.2).

Figure 26.2 contrasts the "Within the artiodactyls" origin of the whale lineage with the "Without the artiodactyls" origin of the whale lineage

48) What can be properly inferred from Figure 26.2?
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

50) Which of the following items does not necessarily exist in a simple linear relationship with the number of gene-duplication events when placed as the label on the vertical axis of the following graph?

A) number of genes
B) number of DNA base pairs
C) genome size
D) mass (in picograms) of DNA
E) phenotypic complexity

Answer: E

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.

62) 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.
C) The rest of the reptiles should be reclassified as a subclass within the class Aves.
D) Science is consensual. Taxonomy is a science. Variant classification schemes involving the birds should be tolerated until consensus is reached.

Answer: D

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.

63) Traditional zoologists have long agreed that birds evolved from dinosaurs. What keeps such zoologists from agreeing that birds, like dinosaurs, should be considered reptiles?
A) There is not yet enough evidence to be sure.
B) Stubbornness, insofar as they are unwilling to change their thinking when new data warrants it.
C) They deny the validity of genetic molecular data.
D) They differ in what they consider to be important traits for assigning organisms to the class Reptilia.

Answer: D

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.

64) For a proponent of PhyloCode classification, what is true of the reptile clade if birds are not included in it?
A) It becomes paraphyletic and, thus, an invalid reflection of evolutionary history.
B) It becomes a subclass, instead of a class.
C) It becomes a superclass, whereas the birds remain a class.
D) PhyloCode does not concern itself with what is, or is not, a clade

Answer: A

69) 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 valid taxon.
B) a monophyletic clade.
C) an ingroup, with species U as the outgroup.
D) a paraphyletic group.
E) a polyphyletic group.

Answer: D

70) In a comparison of birds and mammals, 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

72) Based on this tree, 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.

Answer: D

73) 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

1) All protists are
A) unicellular.
B) eukaryotic.
C) symbionts.
D) monophyletic.
E) mixotrophic.

Answer: B

2) Biologists have long been aware that the defunct kingdom Protista is polyphyletic. Which of these statements is most consistent with this conclusion?
A) Many species within this kingdom were once classified as monerans.
B) Animals, plants, and fungi arose from different protist ancestors.
C) The eukaryotic condition has evolved more than once among the protists.
D) Chloroplasts among various protists are similar to those found in prokaryotes.
E) Some protists, all animals, and all fungi share a protist common ancestor, but these protists, animals, and fungi are currently assigned to three different kingdoms.

Answer: C

3) According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate?
A) from infoldings of the plasma membrane, coupled with mutations of genes for proteins in energy-transfer reactions
B) from engulfed, originally free-living proteobacteria
C) by secondary endosymbiosis
D) from the nuclear envelope folding outward and forming mitochondrial membranes
E) when a protoeukaryote engaged in a symbiotic relationship with a protocell

Answer: B

4) Which process could have allowed the nucleomorphs of chlorarachniophytes to be reduced, without the net loss of any genetic information?
A) conjugation
B) horizontal gene transfer
C) binary fission
D) phagocytosis
E) meiosis

Answer: B

5) An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?
A) It relies on photosystems that float freely in its cytosol.
B) It must have gained extra mitochondria when it lost its plastids.
C) It engulfs organic material by phagocytosis or by absorption.
D) It has an endospore.
E) It is protected by a case made of silica.

Answer: C

6) Which of the following was derived from an ancestral cyanobacterium?
A) chloroplast
B) mitochondrion
C) hydrogenosome
D) mitosome
E) Two of the responses above are correct.

Answer: A

7) Which two genera have members that can evade the human immune system by frequently changing their surface proteins?

1. Plasmodium
2. Trichomonas
3. Paramecium
4. Trypanosoma
5. Entamoeba

A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 4 and 5

Answer: B

8) Which of the following pairs of protists and their characteristics is mismatched?
A) apicomplexans–internal parasites
B) golden algae–planktonic producers
C) euglenozoans–unicellular flagellates
D) ciliates–red tide organisms
E) entamoebas–ingestive heterotrophs

Answer: D

9) Which of the following statements about dinoflagellates is true?
A) They possess two flagella.
B) All known varieties are autotrophic.
C) Their walls are usually composed of silica plates.
D) Many types lack mitochondria.
E) Their dead cells accumulate on the seafloor, and are mined to serve as a filtering material.

Answer: A

11) Which of the following is characteristic of ciliates?
A) They use pseudopods as locomotory structures or as feeding structures.
B) They are relatively specialized cells.
C) They can exchange genetic material with other ciliates by the process of mitosis.
D) Most live as solitary autotrophs in fresh water.
E) They are often multinucleate

Answer: E

12) Which process results in genetic recombination, but is separate from the process by which the population size of Paramecium increases?
A) budding
B) meiotic division
C) mitotic division
D) conjugation
E) binary fission

Answer: D

17) Which of the following is a characteristic of the water molds (oomycetes)?
A) the presence of filamentous feeding structures
B) zoospores that are spread by breezes
C) the same nutritional mode as possessed by cyanobacteria
D) a morphological similarity to fungi that is the result of common ancestry
E) a feeding Plasmodium

Answer: A

20) The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?
A) cyanobacteria → green algae → land plants
B) cyanobacteria → green algae → fungi → land plants
C) red algae → brown algae → green algae → land plants
D) cyanobacteria → red algae → green algae → land plants

Answer: A

21) The chloroplasts of all of the following are thought to be derived from ancestral red algae, except those of
A) golden algae.
B) diatoms.
C) dinoflagellates.
D) green algae.
E) brown algae.

Answer: D

23) Green algae differ from land plants in that many green algae
A) are heterotrophs.
B) are unicellular.
C) have plastids.
D) have alternation of generations.
E) have cell walls containing cellulose

Answer: B

27) Which of the following statements concerning protists is true?
A) All protists have mitochondria, though in some species they are much reduced and known by different names.
B) The primary organism that transmits malaria to humans by its bite is the tsetse fly.
C) All apicomplexans are autotrophic.
D) All slime molds have an amoeboid stage that may be followed by a stage during which spores are produced.
E) Euglenozoans that are mixotrophic lack functional chloroplasts.

Answer: A

73) Biologists suspect that endosymbiosis gave rise to mitochondria before plastids partly because
A) the products of photosynthesis could not be metabolized without mitochondrial enzymes.
B) all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.
C) mitochondrial DNA is less similar to prokaryotic DNA than is plastid DNA.
D) without mitochondrial CO₂ production, photosynthesis could not occur.
E) mitochondrial proteins are synthesized on cytosolic ribosomes, whereas plastids utilize their own ribosomes.

Answer: B

75) Which protists are in the same eukaryotic supergroup as land plants?
A) green algae
B) dinoflagellates
C) red algae
D) brown algae
E) both green algae and red algae

Answer: E

76) In life cycles with an alternation of generations, multicellular haploid forms alternate with
A) unicellular haploid forms.
B) unicellular diploid forms.
C) multicellular haploid forms.
D) multicellular diploid forms.
E) multicellular polyploid forms.

Answer: D

1) Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that only animals derive their nutrition by
A) preying on animals.
B) ingesting it.
C) consuming living, rather than dead, prey.
D) using enzymes to digest their food.

Answer: B

2) The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following most directly favors the evolution of the latter, more radical, kind of metamorphosis?
A) natural selection of sexually immature forms of insects
B) changes in the homeobox genes governing early development
C) the evolution of meiosis
D) the development of an oxidizing atmosphere on Earth
E) the origin of a brain

Answer: B

3) Which of the following is (are) unique to animals?
A) cells that have mitochondria
B) the structural carbohydrate, chitin
C) nervous conduction and muscular movement
D) heterotrophy
E) Two of these responses are correct

Answer: C

4) What do animals as diverse as corals and monkeys have in common?
A) body cavity between body wall and digestive system
B) number of embryonic tissue layers
C) type of body symmetry
D) presence of Hox genes
E) degree of cephalization

Answer: D

5) The Hox genes came to regulate each of the following in what sequence, from earliest to most recent?

1. identity and position of paired appendages in protostome embryos
2. anterior-posterior orientation of segments in protostome embryos
3. positioning of tentacles in cnidarians
4. anterior-posterior orientation in vertebrate embryos

A) 4 → 1 → 3 → 2
B) 4 → 2 → 3 → 1
C) 4 → 2 → 1 → 3
D) 3 → 2 → 1 → 4
E) 3 → 4 → 1 → 2

Answer: D

12) Fossil evidence indicates that the following events occurred in what sequence, from earliest to most recent?

1. Protostomes invade terrestrial environments.
2. Cambrian explosion occurs.
3. Deuterostomes invade terrestrial environments.
4. Vertebrates become top predators in the seas.

A) 2 → 4 → 3 → 1
B) 2 → 1 → 4 → 3
C) 2 → 4 → 1 → 3
D) 2 → 3 → 1 → 4
E) 2 → 1 → 3 → 4

Answer: C

13) What is the probable sequence in which the following clades of animals originated, from earliest to most recent?

1. tetrapods
2. vertebrates
3. deuterostomes
4. amniotes
5. bilaterians

A) 5 → 3 → 2 → 4 → 1
B) 5 → 3 → 2 → 1 → 4
C) 5 → 3 → 4 → 2 → 1
D) 3 → 5 → 4 → 2 → 1
E) 3 → 5 → 2 → 1 → 4

Answer: B

14) Arthropods invaded land about 100 million years before vertebrates did so. This most clearly implies that
A) arthropods evolved before vertebrates did.
B) extant terrestrial arthropods are better adapted to terrestrial life than are extant terrestrial vertebrates.
C) ancestral arthropods must have been poorly adapted to aquatic life, and thus experienced a selective pressure to invade land.
D) vertebrates evolved from arthropods.
E) arthropods have had more time to coevolve with land plants than have vertebrates.

Answer: E

15) An adult animal that possesses bilateral symmetry is most certainly also
A) triploblastic.
B) a deuterostome.
C) eucoelomate.
D) highly cephalized.

Answer: A

18) At which developmental stage should one be able to first distinguish a diploblastic embryo from a triploblastic embryo?
A) fertilization
B) cleavage
C) gastrulation
D) coelom formation
E) metamorphosis

Answer: C

19) At which developmental stage should one be able to first distinguish a protostome embryo from a deuterostome embryo?
A) fertilization
B) cleavage
C) gastrulation
D) coelom formation
E) metamorphosis

Answer: B

20) What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates
A) have a body cavity, whereas pseudocoelomates have a solid body.
B) contain tissues derived from mesoderm, whereas pseudocoelomates have no such tissue.
C) have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.
D) have a complete digestive system with mouth and anus, whereas pseudocoelomates have a digestive tract with only one opening.
E) have a gut that lacks suspension within the body cavity, whereas pseudocoelomates have mesenteries that hold the digestive system in place.

Answer: C

21) You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?
A) It is triploblastic.
B) It has bilateral symmetry.
C) It possesses sensory structures at its anterior end.
D) Muscular activity of its digestive system distorts the body wall.

Answer: D

22) The blastopore is a structure that first becomes evident during
A) fertilization.
B) gastrulation.
C) the eight-cell stage of the embryo.
D) coelom formation.
E) cleavage.

Answer: B

23) The blastopore denotes the presence of an endoderm-lined cavity in the developing embryo, a cavity that is known as the
A) archenteron.
B) blastula.
C) coelom.
D) germ layer.
E) blastocoel.

Answer: A

25) Which of the following characteristics generally applies to protostome development?
A) radial cleavage
B) determinate cleavage
C) diploblastic embryo
D) blastopore becomes the anus
E) archenteron absent

Answer: B

26) Protostome characteristics generally include which of the following?
A) a mouth that develops secondarily, and far away from the blastopore
B) radial body symmetry
C) radial cleavage
D) determinate cleavage
E) absence of a body cavity

Answer: D

30) Phylogenetic trees are best described as
A) true and inerrant statements about evolutionary relationships.
B) hypothetical portrayals of evolutionary relationships.
C) the most accurate representations possible of genetic relationships among taxa.
D) theories of evolution.
E) the closest things to absolute certainty that modern systematics can produce.

Answer: B

35) What is true of the clade Ecdysozoa?
A) It includes all animals that molt at some time during their lives.
B) It includes all animals that undergo metamorphosis at some time during their lives.
C) It includes all animals that have body cavities known as pseudocoeloms.
D) It includes all animals with genetic similarities that are shared with no other animals.
E) It includes all animals in the former clade Protostomia that truly do have protostome development.

Answer: D

36) Which distinction is given more emphasis by the morphological phylogeny than by the molecular phylogeny?
A) metazoan and eumetazoan
B) radial and bilateral
C) true coelom and pseudocoelom
D) protostome and deuterostome
E) molting and lack of molting

Answer: D

38) Which of these, if true, would support the claim that the ancestral cnidarians had bilateral symmetry?

1. Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.
2. Cnidarians have fewer Hox genes than bilaterians.
3. All extant cnidarians, including Nematostella, are diploblastic.
4. β-catenin turns out to be essential for gastrulation in all animals in which it occurs.
5. All cnidarians are acoelomate.

A) 1 only
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 4 and 5

Answer: B

The previous figure shows a chart of the animal kingdom set up as a modified phylogenetic tree. Use the diagram to answer the following question.

41) Which two groups are most clearly represented in the Ediacaran fauna?
A) I and II
B) I and III
C) II and IV
D) II and V
E) IV and V

Answer: B

44) According to the phylogenies depicted in the previous pair of figures, if one were to create a taxon called Radiata that included all animal species whose members have true radial symmetry, then such a taxon would be
A) paraphyletic.
B) polyphyletic.
C) monophyletic.
D) a clade.
E) More than one of these responses are correct.

Answer: A

45) What is true of the deuterostomes in the molecular phylogeny (B) that is not true in the traditional phylogeny (A)?
A) Deuterostomia is a clade.
B) To maintain Deuterostomia as a clade, some phyla had to be removed from it.
C) Deuterostomia now includes the Acoela.
D) It is actually a grade, rather than a clade.
E) It diverged from the rest of the Bilateria earlier than did the Acoela

Answer: B

46) In the traditional phylogeny (A), the phylum Platyhelminthes is depicted as a sister taxon to the rest of the protostome phyla, and as having diverged earlier from the lineage that led to the rest of the protostomes. In the molecular phylogeny (B), Platyhelminthes is depicted as a lophotrochozoan phylum. What probably led to this change?
A) Platyhelminthes ceased to be recognized as true protostomes.
B) The removal of the acoel flatworms (Acoela) from the Platyhelminthes allowed the remaining flatworms to be clearly tied to the Lophotrochozoa.
C) All Platyhelminthes must have a well-developed lophophore as their feeding apparatus.
D) Platyhelminthes' close genetic ties to the arthropods became clear as their Hox gene sequences were studied.

Answer: B

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, though the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. The next three questions refer to the phylogenetic trees that follow.

47) Which phylogeny has been created by emphasizing genomic features of placozoans?

Answer: C

A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45 degrees and to lie in the grooves between larger, underlying cells (i.e., spiral cleavage).

57) This embryo may potentially develop into a(n)
A) turtle.
B) earthworm.
C) sea star.
D) fish.
E) sea urchin.

Answer: B

70) Among the characteristics unique to animals is
A) gastrulation.
B) multicellularity.
C) sexual reproduction.
D) flagellated sperm.
E) heterotrophic nutrition.

Answer: A

Answer: A

71) The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of
A) a body cavity.
B) a complete digestive tract.
C) a circulatory system.
D) true tissues.
E) mesoderm.

Answer: D

72) Acoelomates are characterized by
A) the absence of a brain.
B) the absence of mesoderm.
C) deuterostome development.
D) a coelom that is not completely lined with mesoderm.
E) a solid body without a cavity surrounding internal organs.

Answer: E

74) Which of the following is a point of conflict between the phylogenetic analyses presented in these two figures?
A) the monophyly of the animal kingdom
B) the relationship of taxa of segmented animals to taxa of nonsegmented animals
C) that sponges are basal animals
D) that chordates are deuterostomes
E) the monophyly of the bilaterians

Answer: B

1) A sponge's structural materials (spicules, spongin) are manufactured by the
A) pore cells.
B) epidermal cells.
C) choanocytes.
D) amoebocytes.

Answer: D

2) How many of the following can be observed in the mesohyl of various undisturbed sponges at one time or another?

1. amoebocytes
2. spicules
3. spongin
4. zygotes
5. choanocytes

A) one of these
B) two of these
C) three of these
D) four of these
E) five of these

Answer: D

4) In terms of food capture, which sponge cell is most similar to the cnidocyte of a cnidarian?
A) amoebocyte
B) choanocyte
C) epidermal cell
D) pore cell

Answer: B

44) Which of the following animal groups is entirely aquatic?
A) Mollusca
B) Crustacea
C) Echinodermata
D) Nematoda
E) Platyhelminthes

Answer: C

15) Planarians lack dedicated respiratory and circulatory systems because
A) none of their cells are far removed from the gastrovascular cavity or from the external environment.
B) they lack mesoderm as embryos and, therefore, lack the adult tissues derived from mesoderm.
C) their flame bulbs can carry out respiratory and circulatory functions.
D) their body cavity, a pseudocoelom, carries out these functions.

Answer: A

49) Which structure do sea slugs use to feed on their prey?
A) nematocysts
B) a sharp beak
C) an incurrent siphon
D) a radula
E) a mantle cavity

Answer: D

47) Which of the following factors, when used to label the horizontal axis of the previous graph, would account most directly for the shape of the plot?
A) spongin concentration (gm/unit volume)
B) rate of cribrostatin synthesis (molecules/unit time)
C) number of pores per sponge
D) number of spicules per sponge
E) number of choanocytes per sponge

Answer: E

4) In terms of food capture, which sponge cell is most similar to the cnidocyte of a cnidarian?
A) amoebocyte
B) choanocyte
C) epidermal cell
D) pore cell

Answer: B

10) Corals are most closely related to which group?
A) jellies
B) freshwater hydras
C) sea anemones
D) sponges
E) barnacles

Answer: C

11) Which characteristic(s) is (are) shared by both cnidarians and flatworms?
A) dorsoventrally flattened bodies
B) true muscle
C) radial symmetry
D) a digestive system with a single opening
E) two of these

Answer: D

21) Which mollusc clade includes members that undergo embryonic torsion?
A) chitons
B) bivalves
C) gastropods
D) cephalopods

Answer: C

22) A terrestrial mollusc without a shell belongs to which clade?
A) chitons
B) bivalves
C) gastropods
D) cephalopods

Answer: C

23) A radula is present in members of which clade(s)?
A) chitons
B) bivalves
C) gastropods
D) cephalopods
E) both chitons and gastropods

Answer: E

24) Which of the following is found only among annelids?
A) a hydrostatic skeleton
B) segmentation
C) a clitellum
D) a closed circulatory system
E) a cuticle made of chitin

Answer: C

27) How many of the following can be used to distinguish a nematode worm from an annelid worm?

1. type of body cavity
2. number of muscle layers in the body wall
3. presence of segmentation
4. number of embryonic tissue layers
5. shape of worm in cross-sectional view

A) one of these
B) two of these
C) three of these
D) four of these
E) five of these

Answer: C

2) Which of the following statements would be least acceptable to most zoologists?
A) The extant lancelets are contemporaries, not ancestors, of vertebrates.
B) The first fossils resembling lancelets appeared in the fossil record around 530 million years ago.
C) Recent work in molecular systematics supports the hypothesis that lancelets are the most recent common ancestor of all vertebrates.
D) The extant lancelets are the immediate ancestors of the fishes.
E) Lancelets display the same method of swimming as do fishes.

Answer: D

9) The earliest known mineralized structures in vertebrates are associated with which function?
A) reproduction
B) feeding
C) locomotion
D) defense
E) respiration

Answer: B

104) Vertebrates and tunicates share
A) jaws adapted for feeding.
B) a high degree of cephalization.
C) the formation of structures from the neural crest.
D) an endoskeleton that includes a skull.
E) a notochord and a dorsal, hollow nerve cord.

Answer: E

20) Arrange these taxonomic terms from most inclusive (most general) to least inclusive (most specific).

1. lobe-fins
2. amphibians
3. gnathostomes
4. osteichthyans
5. tetrapods

A) 4, 3, 1, 5, 2
B) 4, 3, 2, 5, 1
C) 4, 2, 3, 5, 1
D) 3, 4, 1, 5, 2
E) 3, 4, 5, 1, 2

Answer: D

35) Which of the following represents the strongest evidence that two of the three middle ear bones of mammals are homologous to certain reptilian jawbones?
A) They are similar in size to the reptilian jawbones.
B) They are similar in shape to the reptilian jawbones.
C) The mammalian jaw has fewer bones than does the reptilian jaw.
D) These bones can be observed to move from the developing jaw to the developing middle ear in mammalian embryos.
E) Mammals can hear better than reptiles.

Answer: D

Match the extant vertebrate groups with the descriptions.

38) Their scales most closely resemble teeth in both structure and origin.
A) amphibians
B) nonbird reptiles
C) chondrichthyans
D) mammals
E) osteichthyans

Answer: C

Fishes that have swim bladders can regulate their density and, thus, their buoyancy. There are two types of swim bladder: physostomus and physoclistus. The ancestral version is the physostomus version, in which the swim bladder is connected to the esophagus via a short tube (Figure 34.1). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching." The physoclistus version is more derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder.

61) Rank the following fish, from most to least, in terms of the amount of energy it must use to maintain its position (depth) in the water column over the long term.

1. physoclistus fish
2. physostomus fish
3. chondrichthyan fish

A) 1, 2, 3
B) 2, 3, 1
C) 2, 1, 3
D) 3, 1, 2
E) 3, 2, 1

Answer: E

104) Vertebrates and tunicates share
A) jaws adapted for feeding.
B) a high degree of cephalization.
C) the formation of structures from the neural crest.
D) an endoskeleton that includes a skull.
E) a notochord and a dorsal, hollow nerve cord.

Answer: E

3) Certain nutrients are considered "essential" in the diets of some animals because
A) only those animals use those nutrients.
B) the nutrients are subunits of important polymers.
C) these animals are not able to synthesize these nutrients.
D) the nutrients are necessary coenzymes.
E) only certain foods contain them

Answer: C

16) The large surface area in the gut directly facilitates
A) secretion.
B) absorption.
C) elimination.
D) filtration
E) temperature regulation.

Answer: B

17) An advantage of a complete digestive system over a gastrovascular cavity is that the complete system
A) excludes the need for extracellular digestion.
B) allows specialized functions in specialized regions.
C) allows digestive enzymes to be more specific.
D) allows extensive branching.
E) facilitates intracellular digestion.

Answer: B

46) An enlarged cecum is typical of
A) rabbits, horses, and herbivorous bears.
B) carnivorous animals.
C) tubeworms that digest via symbionts.
D) humans and other primates.
E) tapeworms and other intestinal parasites.

Answer: A

54) Examine the digestive system structures in the figure above. The highest rate of nutrient absorption occurs at location(s)
A) 3 only.
B) 4 only.
C) 1 and 4.
D) 3 and 4.
E) 1, 3, and 4.

Answer: B

55) Examine the digestive system structures in the figure above. Most of the digestion of fats occurs in section(s)
A) 3 only.
B) 4 only.
C) 1 and 4.
D) 3 and 4.
E) 1, 3, and 4.

Answer: B

59) Which of the following animals is incorrectly paired with its feeding mechanism?
A) lionsubstrate feeder
B) baleen whalesuspension feeder
C) aphidfluid feeder
D) clamsuspension feeder
E) snakebulk feeder

Answer: A

60) The mammalian trachea and esophagus both connect to the
A) large intestine.
B) stomach.
C) pharynx.
D) rectum.
E) epiglottis.

Answer: C

61) Which of the following organs is incorrectly paired with its function?
A) stomachprotein digestion
B) oral cavitystarch digestion
C) large intestinebile production
D) small intestinenutrient absorption
E) pancreasenzyme production

Answer: C

62) Which of the following is not a major activity of the stomach?
A) mechanical digestion
B) HCl secretion
C) mucus secretion
D) nutrient absorption
E) enzyme secretion

Answer: D

5) Circulatory systems in molluscs
A) are open in all species of molluscs.
B) are closed in all species of molluscs.
C) are open in species of large-sized molluscs and are closed in species of small-sized molluscs.
D) are open in species of small-sized molluscs and are closed in species of large-sized molluscs.
E) are open or closed without regard to body size.

Answer: D

6) The circulatory system of bony fishes, rays, and sharks is similar to
A) that of birds, with a four-chambered heart.
B) the portal systems of mammals, where two capillary beds occur sequentially, without passage of blood through a pumping chamber.
C) that of reptiles, with one pumping chamber driving blood flow to a gas-exchange organ, and a different pumping chamber driving blood to the rest of the circulation.
D) that of sponges, where gas exchange in all cells occurs directly with the external environment.
E) that of humans, where there are four pumping chambers to drive blood flow.

Answer: B

56) Countercurrent exchange in the fish gill helps to maximize
A) endocytosis.
B) blood pressure.
C) diffusion.
D) active transport.
E) osmosis.

Answer: C

19) Because the foods eaten by animals are often composed largely of macromolecules, this requires the animals to have mechanisms for
A) elimination.
B) dehydration synthesis.
C) enzymatic hydrolysis.
D) regurgitation.
E) demineralization

Answer: C

8) Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have
A) an open circulatory system.
B) a closed circulatory system.
C) a gastrovascular cavity.
D) branched tracheae.
E) hemolymph

Answer: B

10) The only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart are the
A) amphibians.
B) birds.
C) fishes.
D) mammals.
E) reptiles.

Answer: C

17) Which of the following is the correct sequence of blood flow in reptiles and mammals?
A) left ventricle → aorta → lungs → systemic circulation
B) right ventricle → pulmonary vein → pulmocutaneous circulation
C) pulmonary vein → left atrium → left ventricle → pulmonary circuit
D) vena cava → right atrium → right ventricle → pulmonary circuit
E) right atrium → pulmonary artery → left atrium → ventricle

Answer: D

23) The set of blood vessels with the slowest velocity of blood flow is
A) the arteries.
B) the arterioles.
C) the metarterioles.
D) the capillaries.
E) the veins.

Answer: D

29) The blood pressure is lowest in the
A) aorta.
B) arteries.
C) arterioles.
D) capillaries.
E) venae cavae.

Answer: E

2) Organisms categorized as osmoconformers are most likely
A) found in freshwater lakes and streams.
B) marine.
C) amphibious.
D) found in arid terrestrial environments.
E) found in terrestrial environments with adequate moisture.

Answer: B

3) The body fluids of an osmoconformer would be ________ with its ________ environment.
A) hyperosmotic; freshwater
B) isotonic; freshwater
C) hyperosmotic; saltwater
D) isoosmotic; saltwater
E) hypoosmotic; saltwater

Answer: D

12) Urea is produced in the
A) liver from NH₃ and CO₂.
B) liver from glycogen.
C) kidneys from glucose.
D) kidneys from glycerol and fatty acids.
E) bladder from uric acid and H₂O.

Answer: A

15) Ammonia is likely to be the primary nitrogenous waste in living conditions that include
A) lots of fresh water flowing across the gills of a fish.
B) lots of seawater, such as a bird living in a marine environment.
C) lots of seawater, such as a marine mammal (e.g., a polar bear).
D) a terrestrial environment, such as that supporting crickets.
E) a moist system of burrows, such as those of naked mole rats.

Answer: A

17) The nitrogenous waste that requires the most energy to produce is
A) ammonia.
B) ammonium.
C) urea.
D) uric acid.

Answer: D

21) The primary nitrogenous waste excreted by birds is
A) ammonia.
B) nitrate.
C) nitrite.
D) urea.
E) uric acid.

Answer: E

24) Birds secrete uric acid as their nitrogenous waste because uric acid
A) is readily soluble in water.
B) is metabolically less expensive to synthesize than other excretory products.
C) requires little water for nitrogenous waste disposal, thus reducing body mass.
D) excretion allows birds to live in desert environments.

Answer: C

48) Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more
A) juxtamedullary nephrons.
B) Bowman's capsules.
C) ureters.
D) podocytes.
E) urinary bladders.

Answers: A

29) The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of
A) protonephridia.
B) metanephridia.
C) Malpighian tubules.
D) nephrons.
E) ananephredia.

Answer: A