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Natural selection causes genetic changes in populations.

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The elaborate courtship displays common among animals are the result of


A) random mating.
B) sexual selection.
C) disruptive selection.
D) spontaneous mutations.
E) stabilizing selection.

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Individuals who have one dominant allele and one recessive allele for a trait are referred to as __________ .

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According to the Hardy-Weinberg principle, if 75% of the alleles in the gene pool are A1 and 25% are A2, what is the proportion of individuals with genotype A1A2 in this population?


A) 0.375
B) 0.5625
C) 0.0625
D) 0.025
E) 0.1875

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The use of antibiotics caused the mutation that produced methicillin-resistant Staphylococcus aureus (MRSA).

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Which of the following can be measured to estimate an organismʹs evolutionary fitness?


A) The number of eggs it produces over its lifetime
B) The number of gametes it produces over its lifetime
C) The number of offspring it produces over its lifetime
D) The number of offspring it produces over its lifetime that survive to breed
E) The size of its offspring

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Suppose a population of mostly sand-colored crabs migrates from a sand beach to a pebble beach and evolves a darker, speckled coloration that closely resembles the pebble beach. This is an example of


A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

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Despite causing a life-threatening disease, the sickle-cell allele in some areas of Africa has remained in high frequency in those populations because it protects against malaria. In the United States, malaria was eradicated shortly before World War II by eliminating the mosquito that spreads the disease. What is likely to happen to the frequency of the sickle-cell allele in African Americans living in the United States?


A) The frequency of the sickle-cell allele will decrease.
B) The frequency of the sickle-cell allele will not change.
C) The sickle-cell allele will disappear from the African American population.
D) The frequency of the sickle-cell allele will increase.
E) The normal allele will disappear from the African American population.

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Natural selection selects for or against certain


A) populations.
B) gene pools.
C) alleles.
D) phenotypes.
E) genotypes.

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Evolution by genetic drift is most obvious in


A) small populations.
B) invertebrate species.
C) large populations.
D) aquatic organisms.
E) migratory species.

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The interaction of genes and environment produces a specific


A) gene pool.
B) population.
C) allele.
D) phenotype.
E) genotype.

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The allele frequency of a population is the


A) number of all alleles in that population.
B) sum of all genes in that population.
C) relative proportion of a given allele in that population.
D) number of different types of alleles in that population.

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In a very small population of birds, assume 5 out of 20 alleles are the type that codes for blue feathers. What is the allele frequency of the ʺblue feather alleleʺ in this population?


A) 0.25
B) 0.50
C) 0.20
D) 0.40
E) 5

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When a species lives in a constant environment for a long time, the ʺaverage typeʺ of individual may have the best chance of surviving and producing the most offspring. What type of selection is occurring?


A) Sexual
B) Stabilizing
C) Artificial
D) Disruptive
E) Directional

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Natural selection causes genetic changes in an individual.

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Evolution by natural selection is


A) constantly occurring at the same rate in all organisms.
B) a rare event that has never been observed by scientists.
C) a process that has occurred only in the past.
D) currently occurring but only in scientific laboratories.
E) a process that occurs as a result of differences in fitness.

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The Pennsylvania Amish have a very high frequency of an unusual allele that results in short arms and legs and extra fingers. This high frequency is thought to be the result of


A) the founder effect.
B) the addition of new members to an already established population.
C) nonrandom mutations.
D) coevolution.
E) a population bottleneck.

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A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, q2 represents the


A) proportion of homozygous dominant individuals.
B) decrease in heterozygous individuals.
C) proportion of homozygous recessive individuals.
D) increase in homozygous individuals.
E) proportion of heterozygous individuals.

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Shrews have been documented to travel across frozen lakes and establish populations on previously uninhabited islands. The low level of genetic diversity in the new populations is the result of


A) a population bottleneck.
B) assortative mating.
C) genetic drift.
D) coevolution.
E) the founder effect.

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Imagine that a mutation for red eye color becomes very common in a population of flies because female flies in this population prefer to mate with red -eyed males. This is an example of


A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

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