Question 1

When selection acts to eliminate one extreme from an array of phenotypes it is called

Accepted Answer

A)  natural selection.
B)  stabilizing selection.
C)  disruptive selection.
D)  directional selection.
E)  artificial selection.F) D) and E)
G) All of the above

Question 2

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 dominant allele after six generations of continued non-selection?

Accepted Answer

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

Question 3

For a gene with two alternative alleles,a (frequency p) and a (frequency q) ,the term in the algebraic form of the Hardy-Weinberg equilibrium for the heterozygote genotype frequency is

Accepted Answer

A)  p2.
B)  q2.
C)  2pq.
D)  (p+q) 2.
E)  2Aa.F) A) and E)
G) C) and D)

Question 4

Selection cannot alter a trait with little or no genetic variation and will not eliminate _________ alleles.

Accepted Answer

A)  dominant
B)  recessive
C)  detrimental
D)  neutralE) C) and D)
F) B) and D)

Question 5

The Hardy-Weinberg equations only hold true,that is,a population is only in equilibrium

Accepted Answer

A)  when immigration in and out of the area are held constant.
B)  when changes only take place over long periods of time.
C)  when it includes episodes of extinction.
D)  when the population is designed to survive in new habitats.
E)  when all of the Hardy-Weinberg assumptions are met.F) A) and E)
G) B) and E) E

Question 6

Genotypes are said to be in ___________ equilibrium if there is random mating and no other forces tend to alter the proportions of alleles from one generation to the next.

Accepted Answer

A)  steady state
B)  homeostatic
C)  Hardy-Weinberg
D)  MedelianE) A) and C)
F) B) and D)

Question 7

Sometimes a restriction in genetic variability is imposed on populations by natural catastrophes such as flooding,earthquake,etc.The surviving individuals reflect only a small,random genetic sample of the population affected.This process is termed

Accepted Answer

A)  mutation.
B)  migration.
C)  genetic drift.
D)  assortative mating.
E)  bottleneck effect.F) B) and E)
G) C) and D)

Question 8

Although it was a rare trait in the mainland population,one of the original female mice is homozygous for very large ears.This will lead to a population with a higher incidence of big ears than the mainland population because of

Accepted Answer

A)  bottleneck effect.
B)  founder effect.
C)  mutation.
D)  genetic drift.
E)  selection pressurE.F) A) and B)
G) B) and D)

Question 9

The several hundred species of picture-winged fruit flies of the Hawaiian Islands are genetically very similar,yet they all differ markedly from their ancestral population in Asia.This is probably an example of

Accepted Answer

A)  sexual selection.
B)  directional selection.
C)  disruptive selection.
D)  founder effect.
E)  gene flow.F) None of the above
G) A) and C)

Question 10

In a large population of randomly reproducing rabbits,a recessive allele r comprises 80% of the alleles for a gene,while a dominant allele R comprises the remaining 20%.What percentage of the rabbits would you expect to have the recessive phenotype?

Accepted Answer

A)  4%
B)  32%
C)  64%
D)  80%
E)  noneF) A) and B)
G) None of the above C

Question 11

"The inheritance of acquired characteristics" proposal was put forward by

Accepted Answer

A)  Darwin.
B)  Lamarck.
C)  Wallace.
D)  Founder.
E)  Hardy-Weinberg.F) A) and D)
G) B) and C)

Question 12

The fitness of an individual may depend on all of the following factors except

Accepted Answer

A)  life span of the individual.
B)  climate change.
C)  offspring produced per mating.
D)  frequency of individual's phenotype in population.
E)  presence of many pleiotropic genes.F) A) and E)
G) B) and E)

Question 13

Which of the following would be expected to produce the largest evolutionary change in a given period of time in a population of birds?

Accepted Answer

A)  mutation
B)  natural selection
C)  migration
D)  random mating
E)  Hardy-Weinberg equilibriumF) A) and B)
G) C) and D) C

Question 14

Large,colorful,later 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) A) and D)
G) C) and E)

Question 15

The frequency of a particular allele within a population can be changed,over time,by

Accepted Answer

A)  genetic outflow.
B)  large population size.
C)  selection.
D)  inheritance of acquired characteristics.
E)  random mating.F) C) and D)
G) D) and E)

Question 16

In some populations the drive is to mate with individuals that are phenotypically different at a variety of loci.This leads to large numbers of heterozygotes and is called

Accepted Answer

A)  neutral theory.
B)  disassortative mating.
C)  shifting balance theory.
D)  bottleneck effect.
E)  founder effect.F) B) and D)
G) A) and E)

Question 17

In some instances environmental change causes a situation where one phenotype is favored for a period of time,and then a different phenotype is favored.This oscillating selection causes

Accepted Answer

A)  the maintenance of genetic variation in the population.
B)  elimination of rarer genotypes because of uneven selection.
C)  an increase in point mutations.
D)  high population increase to maintain phenotypic variation.
E)  extinction of the population.F) B) and E)
G) A) and E)

Question 18

In order for natural selection to occur within a population,certain conditions must be met.One such condition is

Accepted Answer

A)  phenotypic differences resulting from environmental conditions.
B)  frequent mutations that are inherited.
C)  low rates of immigration.
D)  phenotypic variations that are genetic.
E)  heterozygosity must be very low.F) B) and E)
G) A) and B)

Question 19

Which of the following statements about the laboratory and field studies on evolution of protective coloration in the guppy (as described in the textbook) is false?

Accepted Answer

A)  Pike cichlids are only found below waterfalls.
B)  Guppies transferred to pools above waterfalls remained drab if killifish were present there.
C)  Guppy predation was greater in pools below waterfalls than above waterfalls.
D)  Killifish can be found both above and below waterfalls.
E)  Substantial evolutionary changes in guppy populations can occur in as few as several years.F) A) and E)
G) C) and D)

Question 20

The genetic contribution of an individual to succeeding generations,compared with that of other individuals in the population,is known as

Accepted Answer

A)  variation.
B)  microevolution.
C)  macroevolution.
D)  fitness.
E)  adaptive makeup.F) B) and D)
G) A) and B)

Exam 20: Genes Within Populations

When selection acts to eliminate one extreme from an array of phenotypes it is called

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 dominant allele after six generations of continued non-selection?

Correct AnswerverifiedShow Answer

For a gene with two alternative alleles,a (frequency p) and a (frequency q) ,the term in the algebraic form of the Hardy-Weinberg equilibrium for the heterozygote genotype frequency is

Correct AnswerverifiedShow Answer

Selection cannot alter a trait with little or no genetic variation and will not eliminate _________ alleles.

Correct AnswerverifiedShow Answer

The Hardy-Weinberg equations only hold true,that is,a population is only in equilibrium

Correct AnswerverifiedE

Genotypes are said to be in ___________ equilibrium if there is random mating and no other forces tend to alter the proportions of alleles from one generation to the next.

Correct AnswerverifiedShow Answer

Sometimes a restriction in genetic variability is imposed on populations by natural catastrophes such as flooding,earthquake,etc.The surviving individuals reflect only a small,random genetic sample of the population affected.This process is termed

Correct AnswerverifiedShow Answer

Although it was a rare trait in the mainland population,one of the original female mice is homozygous for very large ears.This will lead to a population with a higher incidence of big ears than the mainland population because of

Correct AnswerverifiedShow Answer

The several hundred species of picture-winged fruit flies of the Hawaiian Islands are genetically very similar,yet they all differ markedly from their ancestral population in Asia.This is probably an example of

Correct AnswerverifiedShow Answer

In a large population of randomly reproducing rabbits,a recessive allele r comprises 80% of the alleles for a gene,while a dominant allele R comprises the remaining 20%.What percentage of the rabbits would you expect to have the recessive phenotype?

Correct AnswerverifiedC

"The inheritance of acquired characteristics" proposal was put forward by

Correct AnswerverifiedShow Answer

The fitness of an individual may depend on all of the following factors except

Correct AnswerverifiedShow Answer

Which of the following would be expected to produce the largest evolutionary change in a given period of time in a population of birds?

Correct AnswerverifiedC

Large,colorful,later reproduction is favored.

Correct AnswerverifiedShow Answer

The frequency of a particular allele within a population can be changed,over time,by

Correct AnswerverifiedShow Answer

In some populations the drive is to mate with individuals that are phenotypically different at a variety of loci.This leads to large numbers of heterozygotes and is called

Correct AnswerverifiedShow Answer

In some instances environmental change causes a situation where one phenotype is favored for a period of time,and then a different phenotype is favored.This oscillating selection causes

Correct AnswerverifiedShow Answer

In order for natural selection to occur within a population,certain conditions must be met.One such condition is

Correct AnswerverifiedShow Answer

Which of the following statements about the laboratory and field studies on evolution of protective coloration in the guppy (as described in the textbook) is false?

Correct AnswerverifiedShow Answer

The genetic contribution of an individual to succeeding generations,compared with that of other individuals in the population,is known as

Correct AnswerverifiedShow Answer

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