Multiple Choice (Value 30) Identify the choice that best completes
the statement or answers the question.
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1.
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All the genes of all members of a particular population make up the
population’s
a. | relative frequency. | c. | genotype. | b. | phenotype. | d. | gene pool. |
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2.
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If an allele makes up one fourth of a population’s alleles for a given
trait, its relative frequency is
a. | 100 percent. | c. | 25 percent. | b. | 75 percent. | d. | 4 percent. |
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3.
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Interbreeding among members of a population results in
a. | different types of alleles in the gene pool. | b. | changes in the
relative frequencies of alleles in the gene pool. | c. | no changes in the relative frequencies of
alleles in the gene pool. | d. | an absence of genetic variation in the
population. |
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4.
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In a population, the sum of the relative frequencies of all alleles for a
particular trait is
a. | equal to 100 percent. | b. | equal to the number of alleles for the
trait. | c. | constantly changing. | d. | dependent on the number of
alleles. |
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5.
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A change in a sequence of DNA is called a
a. | recombination. | c. | single-gene trait. | b. | polygenic trait. | d. | mutation. |
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6.
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The two main sources of genetic variation are
a. | genotypes and phenotypes. | b. | gene shuffling and
mutations. | c. | single-gene traits and polygenic traits. | d. | directional
selection and disruptive selection. |
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7.
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In organisms that reproduce sexually, inheritable variation is due mostly
to
a. | mutations during gamete formation. | b. | polygenic traits. | c. | gene shuffling
during gamete formation. | d. | the effects of
radiation. |
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8.
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In a particular population, sexual reproduction can produce
a. | mutations. | c. | new allele frequencies. | b. | many different
phenotypes. | d. | meiosis. |
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9.
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The gene shuffling that occurs as part of sexual reproduction
a. | changes the gene pool’s allele frequencies. | b. | does not change the
gene pool’s allele frequencies. | c. | keeps the phenotypes
consistent. | d. | is caused by radiation or chemicals. |
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10.
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A single-gene trait that has two alleles and that shows a simple
dominant-recessive pattern will result in
a. | one phenotype. | c. | four phenotypes. | b. | two phenotypes. | d. | millions of
phenotypes. |
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11.
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An example of a single-gene trait is
a. | widow’s peak in humans. | c. | height in
humans. | b. | weight of human infants at birth. | d. | beak size in the Galápagos
finches. |
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12.
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The number of phenotypes produced for a given trait depends upon
a. | the number of genes that control the trait. | b. | which form of the
trait is dominant. | c. | the relative frequencies of the various
alleles. | d. | the relationship of allele frequencies to Mendelian
ratios. |
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13.
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The phenotypes for a typical polygenic trait can often be expressed as
a. | a bar graph. | c. | Mendelian ratios. | b. | a bell-shaped curve. | d. | allele
frequencies. |
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14.
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A polygenic trait can have
a. | many possible genotypes, but few possible phenotypes. | b. | many possible
genotypes, producing many possible phenotypes. | c. | fewer phenotypes than most single-gene
traits. | d. | fewer genotypes than most single-gene traits. |
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15.
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Natural selection acts directly on
a. | alleles. | c. | individual organisms. | b. | genes. | d. | mutations. |
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16.
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Which of the following is NOT a way in which natural selection affects the
distribution of phenotypes?
a. | directional selection | c. | disruptive selection | b. | stabilizing selection | d. | chance events |
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17.
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When individuals at only one end of a bell curve of phenotype frequencies have
high fitness, the result is
a. | directional selection. | c. | disruptive selection. | b. | stabilizing
selection. | d. | genetic
drift. |
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18.
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When individuals with an average form of a trait have the highest fitness, the
result is
a. | not predictable. | c. | directional selection. | b. | disruptive
selection. | d. | stabilizing
selection. |
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19.
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If a mutation introduces a new skin color in a lizard population, which factor
might determine whether the frequency of the new allele will increase?
a. | how many other alleles are present | b. | whether the mutation makes some lizards more
fit for their environment than other lizards | c. | how many phenotypes the population
has | d. | whether the mutation was caused by nature or by human
intervention |
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20.
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Genetic drift tends to occur in populations that
a. | are very large. | c. | are formed from new species. | b. | are
small. | d. | have unchanging
allele frequencies. |
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21.
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The type of genetic drift that follows the colonization of a new habitat by a
small group of individuals is called
a. | the Hardy-Weinberg principle. | c. | directional
selection. | b. | the founder effect. | d. | stabilizing selection. |
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22.
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One similarity between natural selection and genetic drift is that both
events
a. | are based completely on chance. | b. | begin with one or more
mutations. | c. | involve a change in a population’s allele frequencies. | d. | take place only in
very small groups. |
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23.
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One of the conditions required to maintain genetic equilibrium is
a. | natural selection. | b. | mutations. | c. | nonrandom
mating. | d. | no movement into or out of the population. |
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24.
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The genetic equilibrium of a population can be disturbed by each of the
following EXCEPT
a. | nonrandom mating. | b. | movement into and out of the
population. | c. | a large population size. | d. | mutations. |
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25.
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The allele frequencies of a population are more likely to remain unchanged
if
a. | the population size is reduced. | b. | frequent movement into and out of the
population occurs. | c. | all mating is random. | d. | the mutation rate
increases. |
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26.
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According to the Hardy-Weinberg principle, genetic equilibrium would be more
likely in a population of mice if
a. | the population size rapidly decreases. | b. | mutation rates within the population
rise. | c. | no natural selection takes place. | d. | there is frequent movement into and out of the
population. |
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27.
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Which factor would most likely disrupt genetic equilibrium in a large
population?
a. | the production of large numbers of offspring | b. | mating that is not
random | c. | the absence of movement into and out of the population | d. | the absence of
mutations |
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28.
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The separation of populations by barriers such as rivers, mountains, or bodies
of water is called
a. | temporal isolation. | c. | behavioral isolation. | b. | geographic
isolation. | d. | genetic
equilibrium. |
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29.
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A factor that is necessary for the formation of a new species is
a. | reproduction at different times. | c. | different mating
behaviors. | b. | geographic barriers. | d. | reproductive isolation. |
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30.
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What situation might develop in a population having some plants whose flowers
open at midday and other plants whose flowers open late in the day?
a. | behavioral isolation | c. | temporal isolation | b. | geographic isolation | d. | genetic drift |
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31.
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Although they often live in the same habitat, the American toad breeds earlier
in the spring than the Fowler’s toad does. What can be inferred from this information?
a. | The two species do not interbreed because of geographic
isolation. | b. | The two species do not interbreed because of temporal isolation. | c. | The two species
interbreed throughout the spring season. | d. | The American toad will cause the extinction of
the Fowler’s toad. |
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32.
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Which is the first step that occurred in the speciation of the Galápagos
finches?
a. | establishing genetic equilibrium | c. | ecological
competition | b. | behavioral isolation | d. | arrival of the founding population |
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33.
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The Galápagos finch species are an excellent example of
a. | speciation. | c. | stabilizing selection. | b. | genetic
equilibrium. | d. | selection on
single-gene traits. |
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34.
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In Rosemary and Peter Grant’s study of the Galápagos finches, what
process was encouraged by ecological competition during the dry season?
a. | stabilizing selection | c. | directional selection | b. | reproductive
isolation | d. | genetic
drift |
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35.
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Which statement about evolution in the Galápagos finches is true?
a. | Natural selection on beak size and shape is driven by available
food. | b. | Stabilizing selection has favored an intermediate beak type for all of the
finches. | c. | Mate choice likely plays no role in the finches’ evolution. | d. | None of the finch
species is reproductively isolated. |
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Modified True/False (Value 15) Indicate whether the statement is true or false. If false,
change the identified word or phrase to make the statement true.
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36.
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Because all members of a population can interbreed, biologists often
study their genes as a single group. _________________________
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37.
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In a gene pool, as the relative frequency of one allele for a trait increases,
the relative frequencies of other alleles for that trait decrease.
_________________________
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38.
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Most inheritable differences are due to gene shuffling that occurs during the
production of gametes. _________________________
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39.
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Mutations do not always affect an organism’s phenotype—its
physical, behavioral, and biochemical characteristics. _________________________
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40.
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A polygenic trait is controlled by one gene.
_________________________
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41.
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On a graph, the distribution of phenotypes for a single-gene trait tends
to form a bell-shaped curve. _________________________
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42.
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Natural selection on single-gene traits can lead to changes in allele
frequencies. _________________________
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43.
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In a population of snakes with a range of body lengths, if the longest
individuals have the highest fitness, disruptive selection is likely to occur.
_________________________
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44.
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In small populations, an allele can become more or less common simply by
chance. _________________________
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45.
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Genetic drift may occur when a small group of individuals colonize a new
habitat. _________________________
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46.
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When mutations introduce new alleles into a population, genetic variation
is disrupted. _________________________
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47.
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In a population of birds, if females prefer males with long tails, the
population violates the condition of directional selection described by the Hardy-Weinberg
principle. _________________________
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48.
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In the type of reproductive isolation called behavioral isolation, two
populations are separated by barriers such as rivers or mountains. _________________________
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49.
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Two populations that have overlapping ranges can remain reproductively isolated
through behavioral isolation or temporal isolation from each other.
_________________________
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50.
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The first step of the speciation of the Galápagos finches likely was
the arrival of founders from South America. _________________________
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