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Descent with Modification: A Darwinian View of Life

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes),
was Cuvierʹs attempt to explain the existence of
A) evolution.
B) the fossil record.
C) uniformitarianism.
D) the origin of new species.
E) natural selection.

b

Which of the events described below agrees with the idea of catastrophism?
A) The gradual uplift of the Himalayas by the collision of the Australian crustal plate with the Eurasian
crustal plate
B) The formation of the Grand Canyon by the Colorado River over millions of years
C) The gradual deposition of sediments many kilometers thick on the floors of seas and oceans
D) The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial
body with Earth
E) The development of the Galapagos Islands from underwater seamounts over millions of years

d

What was the prevailing notion 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.

a

During a study session about evolution, one of your fellow students remarks, ʺThe giraffe stretched its neck
while reaching for higher leaves; its offspring inherited longer necks as a result.ʺ Which statement is most likely
to be helpful in correcting this studentʹs misconception?
A) Characteristics acquired during an organismʹs 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) Overproduction of offspring leads to a struggle for survival.

a

Which group is composed entirely of individuals who maintained that species are fixed (i.e., unchanging)?
A) Aristotle, Cuvier, and Lamarck
B) Linnaeus, Cuvier, and Lamarck
C) Lyell, Linnaeus, and Lamarck
D) Aristotle, Linnaeus, and Cuvier
E) Hutton, Lyell, and Darwin

d

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. Lysenkoʹs attempts in this
regard were most in agreement with the ideas of
A) Cuvier.
B) Hutton.
C) Lamarck.
D) Darwin.
E) Plato.

c

Which stratum should contain the greatest proportion of extinct organisms?

d

If ʺxʺ 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?

c

Who would have proposed that the boundaries between each stratum mark the occurrence of different
localized floods?
A) Lyell
B) Cuvier
C) Hutton
D) Darwin
E) Lamarck

b

Which pair would have been likely to agree that strata such as those depicted here were deposited gradually
over long periods of time by subtle mechanisms that are still at work?
A) Cuvier and Aristotle
B) Cuvier and Lamarck
C) Lyell and Linnaeus
D) Aristotle and Hutton
E) Hutton and Lyell

e

Darwinʹs mechanism of natural selection required long time spans in order to modify species. From whom did
Darwin get the concept of Earthʹs ancient age?
A) Georges Cuvier
B) Charles Lyell
C) Alfred Wallace
D) Thomas Malthus
E) John Henslow

b

As a young biologist, Charles Darwin had expected the living plants of temperate South America would
resemble those of temperate Europe, but he was surprised to find that they more closely resembled the plants
of tropical South America. The biological explanation for this observation is most properly associated with the
field of
A) meteorology.
B) embryology.
C) vertebrate anatomy.
D) bioengineering.
E) biogeography.

e

Which of these naturalists synthesized a concept of natural selection independently of Darwin?
A) Charles Lyell
B) Gregor Mendel
C) Alfred Wallace
D) John Henslow
E) Thomas Malthus

c

Charles Darwin was the first person to propose
A) that evolution occurs.
B) a mechanism for how evolution occurs.
C) that the Earth is older than a few thousand years.
D) a mechanism for evolution that was supported by evidence.
E) a way to use artificial selection as a means of domesticating plants and animals.

d

In Darwinʹs thinking, the more closely related two different organisms are, the
A) more similar their habitats are.
B) less similar their DNA sequences are.
C) more recently they shared a common ancestor.
D) less likely they are to have the same genes in common.
E) more similar they are in size.

c

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.

a

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

e

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?
A) All species are fixed in the form in which they are created.
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.

b

Which statement about natural selection is most correct?
A) Adaptations beneficial in one habitat should generally be beneficial in all other habitats as well.
B) Different species that occupy the same habitat will adapt to that habitat by undergoing the same genetic
changes.
C) Adaptations beneficial at one time should generally be beneficial during all other times as well.
D) Well-adapted individuals leave more offspring, and thus contribute more to the next generationʹs gene
pool, than do poorly adapted individuals.
E) Natural selection is the sole means by which populations can evolve.

d

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

a

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 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 number of predators may have decreased.
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) A and B only
E) A, B, and C

e

To observe natural selectionʹs effects on a population, which of these must be true?
A) One must observe more than one generation of the population.
B) The population must contain genetic variation.
C) Members of the population must increase or decrease the use of some portion of their anatomy.
D) A and C only
E) A and B only

e

If the HMS Beagle had completely bypassed the Galapagos Islands, Darwin would have had a much poorer
understanding of the
A) relative stability of a well-adapted populationʹs numbers over many generations.
B) ability of populations to undergo modification as they adapt to a particular environment.
C) tendency of organisms to produce the exact number of offspring that the environment can support.
D) unlimited resources that support population growth in most natural environments.
E) lack of genetic variation among all members of a population.

b

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large,
hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should
one expect to result from natural selection?
A) Small birds gaining larger beaks by exercising their mouth parts.
B) Small birds mutating their beak genes with the result that later-generation offspring have larger beaks.
C) Small birds anticipating the long drought and eating more to gain weight and, consequently, growing
larger beaks.
D) More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent
generations have a higher percentage of birds with large beaks.
E) Larger birds eating less so smaller birds can survive

d

Which of the following statements is an inference of natural selection?
A) Subsequent generations of a population should have greater proportions of individuals that possess traits
better suited for success in unchanging environments.
B) An individual organism undergoes evolution over the course of its lifetime.
C) Habitats do not generally have unlimited resources.
D) Natural populations tend to reproduce to their full biological potential.
E) Some of the variation that exists among individuals in a population is genetic.

a

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) B and C only
E) A, B, and C

a

Which of Darwinʹs ideas had the strongest connection to Darwin having read Malthusʹs 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 ʺtree thinkingʺ
E) That the ancestors of the Galapagos finches had come from the South American mainland

c

How many separate species, both extant and extinct, are depicted in this tree?
A) 2
B) 3
C) 4
D) 5
E) 6

e

According to this tree, what percent of the species seem to be extant (i.e., not extinct)?
A) 25%
B) 33%
C) 50%
D) 66%
E) 75%

d

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) X
D) Y
E) Z

c

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

b

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

e

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

b

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

b

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (i.e., they
locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids,
which of the following should least likely 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

c

Which statement best describes the evolution of pesticide resistance in a population of insects?
A) Individual members of the population slowly adapt to the presence of the chemical by striving to meet
the new challenge.
B) All insects exposed to the insecticide begin to use a formerly silent gene to make a new enzyme that
breaks down the insecticide molecules.
C) Insects observe the behavior of other insects that survive pesticide application, and adjust their own
behaviors to copy those of the survivors.
D) Offspring of insects that are genetically resistant to the pesticide become more abundant as the
susceptible insects die off.

d

DDT was once considered a ʺsilver bulletʺ 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.

d

Some members of a photosynthetic plant species are genetically resistant to an herbicide, while other members
of the same species are not resistant to the herbicide. Which combination of events should cause the most
effective replacement of the non-herbicide-resistant strain of plants by the resistant strain?
1. The presence of the herbicide in the environment
2. The absence of the herbicide from the environment
3. The maintenance of the proper conditions for one generation
4. The maintenance of the proper conditions for many generations
A) 1 and 3
B) 1 and 4
C) 2 and 3
D) 2 and 4

b

If 3TC resistance is costly for HIV, then which plot (I—IV) best represents the response of a strain of
3TC-resistant HIV over time, if 3TC administration begins at the time indicated by the arrow?
A) I
B) II
C) III
D) IV

c

Of the following anatomical structures, which is homologous to the wing of a bird?
A) Dorsal fin of a shark
B) Hindlimb of a kangaroo
C) Wing of a butterfly
D) Tail fin of a flying fish
E) Flipper of a cetacean

e

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.

b

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
B) By the principle of convergent evolution
C) By proposing that humans, bats, and dolphins share a common ancestor
D) A and C only
E) A, B, and C

d

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.

c

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.

b

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 (i.e., 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.

e

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.

c

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.
E) Both species reproduce sexually.

b

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) A and C only
E) B and C only

e

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.

a

Monkeys of South and Central America have prehensile tails, meaning that their tails can be used to grasp
objects. The tails of African and Asian monkeys are not prehensile. Which discipline is most likely to provide
an evolutionary explanation for how this difference in tails came about?
A) Aerodynamics
B) Biogeography
C) Physiology
D) Biochemistry
E) Botany

b

The theory of evolution is most accurately described as
A) an educated guess about how species originate.
B) one possible explanation, among several scientific alternatives, about how species have come into
existence.
C) an opinion that some scientists hold about how living things change over time.
D) an overarching explanation, supported by much evidence, for how populations change over time.
E) an idea about how acquired characteristics are passed on to subsequent generations.

d

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 suited.
E) Only a fraction of the offspring produced by an individual may survive.

b

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.

c

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 birdsʹ 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.

d

Within a few weeks of treatment with the drug 3TC, a patientʹs HIV population consists entirely of
3TC-resistant viruses. How can this result best be explained?
A) HIV can change its surface proteins and resist vaccines.
B) The patient must have become reinfected with 3TC-resistant viruses.
C) HIV began making drug-resistant versions of reverse transcriptase in response to the drug.
D) A few drug-resistant viruses were present at the start of treatment, and natural selection increased their
frequency.
E) The drug caused the HIV RNA to change.

d

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.

a

Which of the following pairs of structures is least likely to represent homology?
A) The wings of a bat and the arms of a human
B) The hemoglobin of a baboon and that of a gorilla
C) The mitochondria of a plant and those of an animal
D) The wings of a bird and those of an insect
E) The brain of a cat and that of a dog

d

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