Mastering Biology 24/25

Feathers either play a role, or may have played a role, in _____.

_____ is rapid speciation under conditions in which there is little competition.

Mass extinctions create conditions that promote _____.

The appearance of an evolutionary novelty promotes _____.

The different finch species found on the Galápagos Islands probably arose as a result of _____.

Speciation, or the formation of new species, is

Which of the following would a biologist describe as microevolution?

Under the biological species concept, a species is a group of organisms that

The biological species concept is

Which of the following has been shown to cause speciation most rapidly? A. differential resource exploitation B. autopolyploidy C. sexual selection D. hybridization E. punctuated equilibrium

A certain species of salamander was split into two populations by a wide, dry valley, and the populations began to diverge from each other. After a period of time, some members of the two populations began to interbreed in a hybrid zone at the southern end of the valley. Only weak reproductive barriers existed by this time, so the two populations could freely interbreed and re-establish gene flow. This outcome in a hybrid zone is known as _____. A. speciation B. punctuated equilibrium C. fusion D. stability E reinforcement

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. the species will consequently have a relatively short existence, compared with other species. D. speciation occurred in one generation. E. speciation occurred rapidly in geologic time.

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

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

The question refers to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change. 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? V W X Y Z

According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods. A. punctuated equilibrium B. adaptive radiation C. gradualist D. geographic isolation E. nondisjunction

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

Select the correct statement describing sympatric speciation. A. Sympatric speciation can occur in a single generation. B. Sympatric speciation is always initiated by geographic isolation of two populations. C. Sympatric speciation has never been observed in nature.

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

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. introduction of a new predator. B. pollution. C. sexual selection. D. habitat differentiation. E. polyploidy.

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

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

The question refers to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change. Which species is most closely related to species W? A. X is most closely related to species W. B. Y and Z are equally closely related to W. C. V is most closely related to species W. D. It is not possible to say from this tree.

Adaptive radiations on archipelagos (island chains) represent some of the best-understood speciation events. Why is an ancestral species more likely to give rise to multiple descendent species on an archipelago than on an equal-sized area of mainland? A. Populations on nearby islands are more likely to be genetically isolated than populations that are equally close to one another on the mainland. B. By chance, different species will colonize different islands in a chain. C. Favorable mutations are more likely to arise on an archipelago as populations try to adapt to conditions on their specific island.

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

What hypothesis did the researchers test in this study? a. Dusky salamanders are undergoing sympatric speciation. b. Reproductive isolation increases with geographic distance between dusky salamander populations. c. Dusky salamanders are in the process of speciation.

Identify the independent variable in this study. a. the presence of sperm in cloacas of female dusky salamanders b. the reproductive isolation values for pairs of dusky salamander populations c. the geographic distance between dusky salamander populations d. the mountain ranges that dusky salamander populations live in

Identify the dependent variable in this study. a. the geographic distance between dusky salamander populations b. the presence of sperm in cloacas of female dusky salamanders c. the reproductive isolation values for pairs of dusky salamander populations d. the courtship behaviors of dusky salamander populations

Why did the researchers set up four possible matings for each pair of populations: female A + male A; female B + male B; female A + male B; female B + male A? a. to assess whether or not populations A and B are separate species b. to assess whether males or females determine mating success c. to identify the behavioral or morphological features that contribute to reproductive isolation d. to compare the proportion of successful matings within populations to the proportion of successful matings between populations

Why did the researchers set up 30 trials for each type of mating? a. to provide replication b. to provide a control group c. to control variables d. to avoid experimenter bias

Calculate the value of the reproductive isolation index if all of the matings within a population were successful but none of the matings between populations were successful. a. 0 b. 1.0 c. 1.5 d. 2.0

How do reproductive isolation values change with geographic distance among pairs of dusky salamander populations? a. Reproductive isolation values increase with geographic distance. b. Reproductive isolation values decrease with geographic distance. c. Reproductive isolation values do not change with geographic distance.

What does the scatter plot suggest about the process of allopatric speciation? a. Geographically isolated populations represent separate species. b. Reproductive isolation of populations leads to geographic isolation. c. Reproductive isolation is more likely to occur as populations become separated by greater distances. d. Geographically isolated populations are also reproductively isolated.

Which hypothesis suggests a possible cause of the relationship shown in the scatter plot? a. Geographically separated populations of dusky salamanders gradually diverge, and the divergence increases with geographic distance. b. The founder effect results in divergence between geographically separated populations of dusky salamanders. c. Small populations of dusky salamanders gradually diverge due to genetic drift. d. Sympatric populations of dusky salamanders gradually diverge because they exploit different food sources.

Miller and Urey's experiments that attempted to recreate conditions on early Earth were significant because _____.

Earth probably formed _____ years ago, and the first life evolved as early as _____ years ago.

Which of the following statements about adaptive radiation is correct?

Which organisms are not examples of an adaptive radiation?

True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species.

Which Anolis lizard ecomorph has long legs?

Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true?

What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean?

True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection.

What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites? A.They were delivered in the form of polypeptides. B. There were more kinds of amino acids on the chondrites than are found in living organisms today. C. Their abundance would have been dramatically reduced upon passage through early Earth's oxidizing atmosphere. D. They had the same proportion of L and D isomers as Earth does today.

Recent evidence indicates that the first major diversification of multicellular eukaryotes may have coincided in time with the A. origin of multicellular organisms. B. melting that ended the "snowball Earth" period. C. massive eruptions of deep-sea vents. D. origin of prokaryotes. E. switch to an oxidizing atmosphere.

The existence of the phenomenon of exaptation is most closely associated with which of the following observations that natural selection cannot fashion perfect organisms? A. Natural selection and sexual selection can work at cross-purposes to each other. B./ Evolution is limited by historical constraints. C.Chance events affect the evolutionary history of populations in environments that can change unpredictably. D. Adaptations are often compromises.

Which of the following is a defining characteristic that all protobionts had in common? A. the ability to replicate RNA B. a surrounding membrane or membrane-like structure C. the ability to synthesize enzymes D. RNA genes

If natural selection in a particular environment favored genetic systems that permitted the production of daughter "cells" that were genetically dissimilar from the mother "cells," then one should expect selection for which of the following? I. polynucleotide polymerase with low mismatch error rates II. polynucleotide polymerases without proofreading capability III. batteries of efficient polynucleotide repair enzymes IV. polynucleotide polymerases with proofreading capability V. polynucleotide polymerases with high mismatch error rates A. I only B. I and IV C. I, III, and IV D. II and V E. II, III and V

The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of A. earlier genetic systems than those based on DNA. B. the abiotic synthesis of organic monomers. C. the endosymbiotic origin of mitochondria and chloroplasts. D. a snowball Earth. E. the delivery of organic matter to Earth by meteors and comets

The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere? A. the persistence of some animal groups in anaerobic habitats B. the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen C. the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules D. the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria E. the evolution of multicellular eukaryotic colonies from communities of prokaryotes

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it? A. How did RNA sequences come to carry the code for amino acid sequences? B. How could polymers involving lipids and/or proteins form membranes in aqueous environments? C. How can RNA molecules act as templates for the synthesis of complementary RNA molecules? D. How can RNA molecules catalyze reactions? E. How can amino acids, simple sugars, and nucleotides be synthesized abiotically?

Why do some scientists believe that RNA, rather than DNA, was the first genetic material? A. RNA can replicate more accurately than DNA. B. All the proto-cells on early Earth contained RNA. C. RNA could have evolved into DNA. D. RNA has both information storage and catalytic properties. E. RNA contains uracil in place of thymine

Which of the following is the correct sequence of events in the origin of life? I. formation of protobionts II. synthesis of organic monomers III. synthesis of organic polymers IV. formation of DNA-based genetic systems A. II, III, I, IV B. I, II, III, IV C. II, III, IV, I D.I, III, II, IV

Which event is nearest in time to the end of the period known as snowball Earth? A. evolution of mitochondria B. Cambrian explosion C. oxygenation of Earth's seas and atmosphere D. evolution of true multicellularity E. Permian extinction

If two continents converge and are united, then the collision should cause A. a net loss of intertidal zone and coastal habitat. B. an overall decrease in the surface area located in the continental interior. C. the extinction of any species adapted to intertidal and coastal habitats. D. the maintenance of the previously existing ocean currents and wind patterns. E. a decrease in climatic extremes in the interior of the new supercontinent.

The figure shows eyes found among living molluscs, ranging from a patch of pigmented cells in a limpet to a complex, image-forming eye in a squid. Is it possible that a structure as complex as an image-forming eye evolved by natural selection? A. Yes, if the photoreceptor cells and simple eyes that preceded it were useful to the animals in which they arose. B. Yes. Because an image-forming eye is so useful, natural selection would favor less useful intermediate structures. C. No. An image-forming eye needs all of its components to function, so a partial eye would not have been useful.

A paleontologist finds a new tyrannosaur in a site she is excavating, and wishes to date the fossil. What is the most likely method she will use? A. She will measure the amount of the radioisotope uranium-238 in the stratum where she found the tyrannosaur. B. She will infer the age of the fossil by dating layers of volcanic rock above and below the stratum containing the fossil. C. She will determine the fossil's age by measuring the ratio of carbon-14 to carbon-12 in the fossil.

Which of the following statements provides the strongest evidence that prokaryotes evolved before eukaryotes? A. The oldest fossilized cells resemble prokaryotes. B. The meteorites that have struck Earth contain fossils only of prokaryotes. C Laboratory experiments have produced liposomes abiotically. D. Liposomes closely resemble prokaryotic cells. E. Prokaryotic cells lack nuclei.

Refer to the following information to answer the question below. Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous period. The dicynodonts had two large tusks, extending down from their upper jaws. The tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record in sedimentary rocks, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Anatomically, what was true of Lystrosaurus? A. It was a tetrapod. B. It had skin without scales, typical of modern amphibians. C. It would have had no temporal fenestra in its skull. D. Its jaw would have been hinged the same way as the jaws of the early reptiles were hinged.

One explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, modern insect wings could best be described as A. adaptations. B. examples of natural selection's predictive ability. C. mutations. D. isolating mechanisms. E. exaptations.

The following question refers to the description and figure below. The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above, on average Earth's magnetic field has undergone reversal once every A. 100,000 years. B. 1,000,000 years. C. 25,000 years. D. 10,000 years. E. 250,000 years.

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that A. evolution generally progresses toward some predetermined goal. B. in particular environments, similar adaptations can be beneficial in more than one species. C. a larger volume-to-surface area ratio is beneficial to all mammals. D. evolution always tends toward increased complexity or increased size. E. an unseen guiding force is at work.

Refer to the following information to answer the question below. Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous period. The dicynodonts had two large tusks, extending down from their upper jaws. The tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record in sedimentary rocks, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Which of the following is the most likely explanation for the modern-day distribution of dicynodont fossils? A. The dicynodonts could survive for periods of months aboard "rafts" of vegetation, few of which made their way to the northern hemisphere. B. The dicynodonts were distributed more abundantly throughout Gondwanaland than throughout any other land mass. C. There had been two previous supercontinents that existed at different times long before the Permian period. D. The dicynodonts were evenly distributed throughout all of Pangaea. E/ The dicynodonts were amphibious and able to swim long distances.

The snowball Earth hypothesis provides a possible explanation for the A. origin of oxygen-releasing photosynthesis. B. oxygenation of Earth's seas and atmosphere. C. existence of prokaryotes around hydrothermal vents on the ocean floor. D. diversification of animals during the late Proterozoic era. E. colonization of land by plants and fungi.

Which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells? A. the observation that some eukaryotic cells lack mitochondria B. the size disparity between most prokaryotic cells and most eukaryotic cells C. the existence of structural and molecular differences between the plasma membranes of prokaryotes and the internal membranes of mitochondria and chloroplasts D. the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts

The following question refers to the description and figure below. The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. If a particular marine organism is fossilized in the sediments immediately overlying the igneous rock at the arrow labeled "II," at which other location, labeled AE, would a search be most likely to find more fossils of this organism? A. B only B. C only C. D only D. B and C E. C and D

Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers. If some of these feather-bearing dinosaurs incubated clutches of eggs in carefully constructed nests, this might be evidence supporting the claim that A. all fossils with feathers are actually some kind of bird. B. the earliest reptiles could fly, and the feathers of flightless dinosaurs were vestigial flight surfaces. C. the feathers were plucked from the bodies of other adults to provide nest-building materials. D. their feathers originally served as insulation, and only later became flight surfaces. E. dinosaurs were as fully endothermal (warm-blooded) as modern birds and mammals.

The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____. A. used water as an electron source for photosynthesis B. had chloroplasts C. were oxygen respiring D. were chemoautotrophic E. used hydrogen sulfide as an energy source

Which measurement(s) would help determine absolute dates by radiometric means? A. the accumulation of the daughter isotope B. the loss of daughter isotopes C. the loss of parent isotopes D. Three of the responses above are correct. E. Two of the responses above are correct.

The first terrestrial organisms probably were considered which of the following? 1. burrowers 2. photosynthetic 3. multicellular 4. prokaryotes 5. eukaryotes 6. plants and their associated fungi A. 2, 3, 5, and 6 B. 2 and 4 C. 2, 3, and 6 D. 1, 3, and 5 E. 3 and 5

What is true of the Cambrian explosion? A. Recent evidence supports the contention that the Cambrian explosion may have occurred over a longer period of time than was once thought. B. The Cambrian explosion is evidence for the instantaneous creation of life on Earth. C. The Cambrian explosion marks the appearance of filter-feeding animals in the fossil record. D. There are no fossils in geological strata that are older than the Cambrian explosion. E. Only the fossils of microorganisms are found in geological strata older than the Cambrian explosion.

Refer to the following information to answer the question below. Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous period. The dicynodonts had two large tusks, extending down from their upper jaws. The tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record in sedimentary rocks, these pig-sized organisms were the most common mammal-like reptiles of the Permian. How many of Lystrosaurus' features below can help explain why these organisms fossilized so abundantly? I. the presence of hard parts, such as tusks II. its arid environment III. its persistence across at least two geological eras IV. its abundance V. its mixture of reptilian and mammalian features A. I B. I and IV C. I, II, III D. I, II, III, IV E. All the statements are correct

According to the theory of sea-floor spreading, oceanic islands, such as the Hawaiian Islands depicted in the figure, form as oceanic crustal plates move over a stationary "hot spot" in the mantle. Currently, the big island of Hawaii is thought to be over a hot spot, which is why it is the only one of the seven islands that has active volcanoes. What should be true of the island of Hawaii? 1. Scientists in search of ongoing speciation events are more likely to find them here than on the other six islands. 2. Its species should be more closely related to those of nearer islands than to those of farther islands. 3. It should have a rich fossil record of terrestrial organisms. 4. There is a good chance of finding endemic species on this island. 5. On average, it should have fewer species per unit surface area than the other six islands. A. 1, 2, and 5 B. 1, 2, and 3 C. 2, 3, 4, and 5 D. 1, 2, 4, and 5 E. 1, 2, 3, and 4

The following question refers to the description and figure below. The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. Which section of sea-floor crust should have the thickest layer of overlying sediment, assuming a continuous rate of sediment deposition? A B C D E

Approximately how far back in time does the fossil record extend? A. 3.5 million years B. 5.0 billion years C. 5.0 million years D. 3.5 billion years

Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia? A. India is in the process of separating from the rest of Asia. B. India was a separate continent until 45 million years ago. C. Life in India was wiped out by ancient volcanic eruptions. D. The climates of the two regions are similar. E.The species became separated by convergent evolution.