Question 1

Which of the following statements about disruptive selection is false?

Accepted Answer

A)  It involves multi-gene inheritance.
B)  It results in polymorphism.
C)  It results in a bimodal distribution of phenotypes within a population.
D)  It increases heterozygosity within the population.
E)  It selects against individuals with intermediate phenotypes.F) A) and B)
G) All of the above

Question 2

One extreme of an array of phenotypes is favored.

Accepted Answer

A)  directional selection
B)  stabilizing selection
C)  disruptive selection
D)  guppies with pike cichlids and killifish
E)  guppies with killifishF) B) and C)
G) A) and E)

Question 3

In disruptive selection,over time

Accepted Answer

A)  a population goes extinct.
B)  the most extreme outliers of a population are eliminated (e.g. ,the largest beaks and smallest beaks are eliminated) .
C)  the population is strongly selected for in one direction (e.g. ,larger beak size) .
D)  the population is strongly selected for in two directions (e.g. ,larger beak size and smaller beak size) .
E)  a population increases its variation (E.g. ,a wide selection of all beak sizes) .F) A) and B)
G) A) and C)

Question 4

Darwin proposed that natural selection occurs in an environment by

Accepted Answer

A)  favoring heritable features that make the organism better suited to survive and reproduce.
B)  producing a constant number of offspring while in that environment.
C)  surviving for a fixed amount of time.
D)  resisting the environment and keeping the environment from changing.
E)  favoring those individuals with the most favorable acquired characteristics.F) B) and D)
G) A) and D)

Question 5

The text discusses sickle-cell anemia,which is a classic example of

Accepted Answer

A)  founder effect.
B)  genetic bottleneck.
C)  point mutation.
D)  heterozygote advantage.
E)  heterozygosity.F) B) and E)
G) A) and E)

Question 6

About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century.As a result,one would expect

Accepted Answer

A)  low rates of mutation.
B)  many polymorphic alleles.
C)  little variation in physiology and behavior.
D)  Hardy-Weinberg equilibrium.
E)  random mating.F) B) and C)
G) C) and D)

Question 7

The phenomenon in which rare alleles become more common in new populations is called

Accepted Answer

A)  founder effect.
B)  gene flow.
C)  genetic drift.
D)  assortative mating.
E)  mutation.F) B) and C)
G) A) and E)

Question 8

In small populations,frequencies of certain alleles may change by chance alone.Such random change in the frequency of alleles is called

Accepted Answer

A)  mutation.
B)  migration.
C)  genetic drift.
D)  nonrandom mating.
E)  selection.F) A) and E)
G) D) and E)

Question 9

Small,drab,early reproduction is favored.

Accepted Answer

A)  directional selection
B)  stabilizing selection
C)  disruptive selection
D)  guppies with pike cichlids and killifish
E)  guppies with killifishF) B) and C)
G) None of the above

Question 10

Natural selection as a mechanism of evolution that acts on variants within populations and ultimately leads to the evolution of different species was proposed by

Accepted Answer

A)  Mendel.
B)  Lyell.
C)  Malthus.
D)  Darwin.
E)  Founder.F) A) and C)
G) B) and E)

Question 11

Coloration in the peppered moth (Biston betularia) is determined by a single gene with two alleles showing complete dominance.Dark moths are homozygous dominant or heterozygous for the gene,light moths are homozygous recessive.In a sample of 100 moths,you determine that 64 of the moths are dark.According to the Hardy-Weinberg rule,the expected frequency of the dominant allele is ____.

Accepted Answer

A)  0.4
B)  0.36
C)  0.6
D)  0.64
E)  cannot be determinedF) A) and C)
G) B) and D)

Question 12

The recessive phenotype of a trait occurs in 20% of a population.There are no selection pressures affecting this trait.What would be the expected frequency of the heterozygote genotype after six generations of continued non-selection?

Accepted Answer

A)  0.2
B)  0.306
C)  0.447
D)  0.494
E)  0.553F) A) and E)
G) A) and B)

Question 13

Migration and hybridization between individuals of adjacent populations causes gene _______.

Accepted Answer

A)  blending
B)  flow
C)  mutation
D)  dominanceE) None of the above
F) All of the above

Question 14

A gene is represented in the gene pool of a population of 10,000 individuals by a dominant (W) and recessive allele (w) .If the initial frequency of W in the pool is 0.7,how many generations of complete selection against it would be required to eliminate all W alleles from the population? Assume that there is no mutation and the population meets all other Hardy-Weinberg conditions.

Accepted Answer

A)  1
B)  2
C)  5
D)  20
E)  can never be eliminatedF) A) and B)
G) A) and C)

Question 15

The midrange of an array of phenotypes is favored.

Accepted Answer

A)  directional selection
B)  stabilizing selection
C)  disruptive selection
D)  guppies with pike cichlids and killifish
E)  guppies with killifishF) A) and C)
G) C) and E)

Question 16

Cheetahs have been through a genetic bottleneck;evidence for this is that

Accepted Answer

A)  little natural selection occurs in this species.
B)  the body is long,thin,and graceful.
C)  there is very little genetic variability.
D)  these cats are members of an endangered species.
E)  they originally came from small areas of Africa.F) B) and E)
G) A) and B)

Question 17

Which one of the following is not an agent of natural evolutionary change?

Accepted Answer

A)  mutation
B)  migration
C)  genetic drift
D)  non-random mating
E)  artificial selectionF) B) and D)
G) C) and D)

Question 18

The total of all the alleles of all the genes in a population can be thought of as

Accepted Answer

A)  an allele mixture.
B)  a gene pool.
C)  a genetic melting pot.
D)  a genome.
E)  variant genes.F) A) and B)
G) C) and E)

Question 19

The Hardy-Weinberg equilibrium conditions for populations of organisms result in

Accepted Answer

A)  polymorphic alleles.
B)  assortive mating.
C)  natural selection.
D)  maintenance of recessive alleles in the gene pool.
E)  no evolutionary changes.F) A) and B)
G) All of the above

Question 20

The key point in Darwin's proposal is that the ___________ imposes the conditions that determine the results of selection and thus the direction of selection.

Accepted Answer

A)  parent
B)  gene
C)  individual
D)  environmentE) All of the above
F) A) and C)

Exam 20: Genes Within Populations

Which of the following statements about disruptive selection is false?

Correct Answer
verified

Darwin proposed that natural selection occurs in an environment by

Correct Answer
verified

The Hardy-Weinberg equilibrium conditions for populations of organisms result in

Correct Answer
verified

Small,drab,early reproduction is favored.

Correct Answer
verified

About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century.As a result,one would expect

Correct Answer
verified

Natural selection as a mechanism of evolution that acts on variants within populations and ultimately leads to the evolution of different species was proposed by

Correct Answer
verified

The phenomenon in which rare alleles become more common in new populations is called

Correct Answer
verified

The total of all the alleles of all the genes in a population can be thought of as

Correct Answer
verified

Cheetahs have been through a genetic bottleneck;evidence for this is that

Correct Answer
verified

In small populations,frequencies of certain alleles may change by chance alone.Such random change in the frequency of alleles is called

Correct Answer
verified

One extreme of an array of phenotypes is favored.

Correct Answer
verified

In disruptive selection,over time

Correct Answer
verified

Correct Answer
verified

The text discusses sickle-cell anemia,which is a classic example of

Correct Answer
verified

The midrange of an array of phenotypes is favored.

Correct Answer
verified

Which one of the following is not an agent of natural evolutionary change?

Correct Answer
verified

Migration and hybridization between individuals of adjacent populations causes gene _______.

Correct Answer
verified

Correct Answer
verified

The recessive phenotype of a trait occurs in 20% of a population.There are no selection pressures affecting this trait.What would be the expected frequency of the heterozygote genotype after six generations of continued non-selection?

Correct Answer
verified

The key point in Darwin's proposal is that the ___________ imposes the conditions that determine the results of selection and thus the direction of selection.

Correct Answer
verified

Exam 20: Genes Within Populations

Which of the following statements about disruptive selection is false?

Correct AnswerverifiedShow Answer

Darwin proposed that natural selection occurs in an environment by

Correct AnswerverifiedShow Answer

The Hardy-Weinberg equilibrium conditions for populations of organisms result in

Correct AnswerverifiedShow Answer

Small,drab,early reproduction is favored.

Correct AnswerverifiedShow Answer

About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century.As a result,one would expect

Correct AnswerverifiedShow Answer

Natural selection as a mechanism of evolution that acts on variants within populations and ultimately leads to the evolution of different species was proposed by

Correct AnswerverifiedShow Answer

The phenomenon in which rare alleles become more common in new populations is called

Correct AnswerverifiedShow Answer

The total of all the alleles of all the genes in a population can be thought of as

Correct AnswerverifiedShow Answer

Cheetahs have been through a genetic bottleneck;evidence for this is that

Correct AnswerverifiedShow Answer

In small populations,frequencies of certain alleles may change by chance alone.Such random change in the frequency of alleles is called

Correct AnswerverifiedShow Answer

One extreme of an array of phenotypes is favored.

Correct AnswerverifiedShow Answer

In disruptive selection,over time

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The text discusses sickle-cell anemia,which is a classic example of

Correct AnswerverifiedShow Answer

The midrange of an array of phenotypes is favored.

Correct AnswerverifiedShow Answer

Which one of the following is not an agent of natural evolutionary change?

Correct AnswerverifiedShow Answer

Migration and hybridization between individuals of adjacent populations causes gene _______.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The recessive phenotype of a trait occurs in 20% of a population.There are no selection pressures affecting this trait.What would be the expected frequency of the heterozygote genotype after six generations of continued non-selection?

Correct AnswerverifiedShow Answer

The key point in Darwin's proposal is that the ___________ imposes the conditions that determine the results of selection and thus the direction of selection.

Correct AnswerverifiedShow Answer

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