AP Bio Evolution

c

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative of A) the influence of environment on development. B) paedomorphosis. C) a change in a developmental gene or its regulation that altered the spatial organization of body parts. D) heterochrony. E) gene duplication.

A

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.

C

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.

D

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.

C

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.

C

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.

B

All animals with eyes or eyespots that have been studied so far share a gene in common. When mutated, the gene Pax-6 causes lack of eyes in fruit flies, tiny eyes in mice, and missing irises (and other eye parts) in humans. The sequence of Pax-6 in humans and mice is identical. There are so few sequence differences with fruit fly Pax-6 that the human/mouse version can cause eye formation in eyeless fruit flies, even though vertebrates and invertebrates last shared a common ancestor more than 500 million years ago. 68) Pax-6 usually causes the production of a type of light-receptor pigment. In vertebrate eyes, though, a different gene (the rh gene family) is responsible for the light-receptor pigments of the retina. The rh gene, like Pax-6, is ancient. In the marine ragworm, for example, the rh gene causes production of c-opsin, which helps regulate the worm's biological clock. Which of these most likely accounts for vertebrate vision? A) The Pax-6 gene mutated to become the rh gene among early mammals. B) During vertebrate evolution, the rh gene for biological clock opsin was co-opted as a gene for visual receptor pigments. C) In animals more ancient than ragworms, the rh gene(s) coded for visual receptor pigments; in lineages more recent than ragworms, rh has flip-flopped several times between producing biological clock opsins and visual receptor pigments. D) Pax-6 was lost from the mammalian genome, and replaced by the rh gene much later.

C

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

d

An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to A) generate intense lightning storms. B) change the atmosphere from oxidizing to reducing. C) make it easier to maintain reduced molecules. D) cause iron in ocean water and terrestrial rocks to rust (oxidize). E) prevent the formation of an ozone layer.

c

An organism has a relatively large number of Hox genes in its genome. Which of the following is true of this organism? A) These genes are fundamental, and are expressed in all cells of the organism. B) The organism must have multiple paired appendages along the length of its body. C) The organism has the genetic potential to have a relatively complex anatomy. D) Most of its Hox genes owe their existence to gene fusion events. E) Its Hox genes cooperate to bring about sexual maturity at the proper stage of development

C

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

D

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.

B

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.

D

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.

C

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.

c

Fossilized stromatolites A) all date from 2.7 billion years ago. B) formed around deep-sea vents. C) resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays. D) provide evidence that plants moved onto land in the company of fungi around 500 million years ago. E) contain the first undisputed fossils of eukaryotes and date from 2.1 billion years ago.

E

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.

B

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

d

How many of the following statements concerning the loss of hind limbs during whale evolution are true? 1. It is well documented by a series of transitional fossils. 2. It explains why modern whales have vestigial pelvic girdles. 3. It involved changes in the sequence or expression of Hox genes. 4. It is an example of macroevolution. 5. It, and the loss of limbs by snakes, are an example of similar adaptations to a similar environment. A) Only one statement is true. B) Two statements are true. C) Three statements are true. D) Four statements are true. E) All five statements are true.

E

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.

A

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.

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

e

If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (for example, lava, volcanic ash) nearby, then it should be A) easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been "reset" by the heat of the igneous rocks. B) easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil. C) easy to determine, as long as there is enough metamorphic rock nearby. D) difficult to determine the absolute age of the fossil, because the "marker fossils" common to igneous rock will be absent. E) difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.

c

If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then one should be surprised to observe evidence of which of the following within such microfossils? I. double-stranded DNA II. a nuclear envelope III. a nucleoid IV. a nucleolus V. ribosomes A) II only B) III only C) II and IV D) II, III, and IV E) all five of these

b

If one organ is an exaptation of another organ, then what must be true of these two organs? A) They are both vestigial organs. B) They are both homologous organs. C) They are undergoing convergent evolution. D) They are found together in the same hybrid species. E) They have the same function

b

If one organ is an exaptation of another organ, then what must be true of these two organs? A) They are both vestigial organs. B) They are both homologous organs. C) They are undergoing convergent evolution. D) They are found together in the same hybrid species. E) They have the same function.

B

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.

E

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

B

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.

C

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

E

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

B

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.

C

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.

D

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.

C

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

C

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.

C

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.

E

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

c

On the basis of their morphologies, how might Linnaeus have classified the Hawaiian silverswords? A) He would have placed them all in the same species. B) He would have classified them the same way that modern botanists do. C) He would have placed them in more species than modern botanists do. D) He would have used evolutionary relatedness as the primary criterion for their classification.

c

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 can amino acids, simple sugars, and nucleotides be synthesized abiotically? B) How can RNA molecules catalyze reactions? C) How did RNA sequences come to carry the code for amino acid sequences? D) How could polymers involving lipids and/or proteins form membranes in aqueous environments? E) How can RNA molecules act as templates for the synthesis of complementary RNA molecules?

D

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

E

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.

E

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.

a

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

B

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

a

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 evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules B) the persistence of some animal groups in anaerobic habitats C) the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen D) the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria E) the evolution of multicellular eukaryotic colonies from communities of prokaryotes

D

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.

C

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

A

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.

C

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.

C

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.

B

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.

b

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) a snowball Earth. B) earlier genetic systems than those based on DNA. C) the abiotic synthesis of organic monomers. D) the delivery of organic matter to Earth by meteors and comets. E) the endosymbiotic origin of mitochondria and chloroplasts.

A

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

D

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.

C

What is true of the fossil record of mammalian origins? A) It is a good example of punctuated equilibrium. B) It shows that mammals and birds evolved from the same kind of dinosaur. C) It includes transitional forms with progressively specialized teeth. D) It indicates that mammals and dinosaurs did not overlap in geologic time. E) It includes a series that shows the gradual change of scales into fur.

B

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.

A

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.

e

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

D

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.

A

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.

e

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

C

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.

D

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

D

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.

B

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.

C

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.

b

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

D

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.

A

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.

c

he first genes on Earth were probably A) DNA produced by reverse transcriptase from abiotically produced RNA. B) DNA molecules whose information was transcribed to RNA and later translated in polypeptides. C) auto-catalytic RNA molecules. D) oligopeptides located within protobionts.