Question 1

Which of the graphs above best represents the relationship between the intensity of directional selection and the genetic variation present within a population?

Accepted Answer

A)    
B)   
C)    
D)   
E)

Question 2

Dark-eyed junco birds have white outer tail feathers that the males display during aggressive interactions and also during courtship displays.Males with more white in their tail are more likely to win aggressive interactions with other males,and females prefer to mate with males with more white in their tails.In the case of juncos,aggression (fighting) by males is a type of ________ selection;thus,we would expect that variation in reproductive success to be higher in ________ and this species should exhibit ________ sexual dimorphism.

Accepted Answer

A)  intrasexual;males;greater
B)  intersexual;males;less
C)  intrasexual;males;less
D)  intersexual;females;greater
E)  intrasexual;females;greater

Question 3

Genetic drift occurs in a population.Which of the following statements might be true?

Accepted Answer

A)  Genetic drift increased the population's fitness.
B)  Genetic drift decreased the population's fitness.
C)  The population was relatively small.
D)  Two of the above statements might be true.
E)  Any of the above statements might be true.

Question 4

Researchers (Helle et al.,2004) analyzed rates of twin births in the Sami population of Northern Scandinavia during the eighteenth and nineteenth centuries.They found that (1) a baby born from a singleton pregnancy was more likely to survive to adulthood than a baby born from a twin pregnancy,and (2) the average number of offspring raised to adulthood was higher for women who had twins than for those who never had twins.These data suggest that in this population,human twinning rate was

Accepted Answer

A)  under direction selection.
B)  under stabilizing selection.
C)  under disruptive selection.
D)  under sexual selection.
E)  undergoing genetic drift.

Question 5

For a biologist studying a small fish population in the lab,which Hardy-Weinberg condition is easiest to meet?

Accepted Answer

A)  no selection
B)  no genetic drift
C)  no gene flow
D)  no mutation
E)  random mating

Question 6

In 1986,a nuclear power accident in Chernobyl,USSR (now the Ukraine) ,led to high radiation levels for miles surrounding the plant.The high levels of radiation caused elevated mutation rates in the surviving organisms,and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since.Based on your understanding of evolutionary mechanisms,which of the following most likely occurred in the rodent populations following the accident?

Accepted Answer

A)  Mutation by itself led to major changes in rodent physiology over time.
B)  Mutation led to increased genetic variation.
C)  Mutation caused genetic drift and decreased fitness.
D)  Mutation caused the fixation of new alleles.

Question 7

Humans have domesticated a number of plants and animals.In the domestication process,a few individuals of a species are "captured" to have a starting population and then these are bred for many generations.This is an example of a ________ and you would therefore predict that domesticated organisms would show ________.

Accepted Answer

A)  founder effect;a lot of genetic variation
B)  bottleneck effect;little genetic variation
C)  bottleneck effect;many useful adaptations for surviving floods
D)  gene flow;speciation
E)  founder effect;little genetic variation E

Question 8

Mutation is the only evolutionary mechanism that

Accepted Answer

A)  does little to change allele frequencies on its own.
B)  always causes decreased fitness.
C)  is more important in eukaryotes than in prokaryotes.
D)  is not mentioned by the Hardy-Weinberg model.
E)  has no effect on genetic variation.

Question 9

Based on the information given above,which of the following types of selection was most likely initially involved in the evolution of white outer tail feathers in juncos?

Accepted Answer

A)  directional selection
B)  stabilizing selection
C)  disruptive selection
D)  sexual selection

Question 10

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years.If 9 in 10,000 newborn babies have the disease,what are the expected frequencies of the dominant (A₁) and recessive (A₂) alleles according to the Hardy-Weinberg model?

Accepted Answer

A)  f(A₁) = 0.9997,f(A₂) = 0.0003
B)  f(A₁) = 0.9800,f(A₂) = 0.0200
C)  f(A₁) = 0.9700,f(A₂) = 0.0300
D)  f(A₁) = 0.9604,f(A₂) = 0.0392
E)  f(A₁) = 0.9600,f(A₂) = 0.0400

Question 11

Which of the following best describes the effect of the migration of individuals into a population?

Accepted Answer

A)  Migration of individuals into a population generally increases the genetic variability within the recipient population.
B)  Migration of individuals into a population generally causes no change in the genetic variability within the recipient population because it is a case of artificial selection.
C)  Migration of individuals into a population generally causes the recipient population to diverge so much that it becomes a new species.
D)  Migration of individuals into a population generally decreases the genetic variability within the recipient population.
E)  Migration of individuals into a population generally increases the genetic variability within the donor population.

Question 12

Which sex typically has more extreme sex-selected characteristics: males or females? Why? Give an example.

Accepted Answer

Males;fund...

Question 13

Why doesn't inbreeding depression,by itself,cause evolution?

Accepted Answer

A)  It decreases the population's average fitness.
B)  It limits gene flow.
C)  It does not change the population's allele frequencies.
D)  It increases homozygosity.
E)  It violates the Hardy-Weinberg assumptions.

Question 14

A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness.She hypothesizes that the population is experiencing

Accepted Answer

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

Question 15

Currently the only predators of Galápagos marine iguanas are Galápagos hawks.Iguana body size is not correlated with risk of hawk predation,although small iguanas can sprint faster than large iguanas.If predators (e.g.,cats) that preferably catch and eat slower iguanas are introduced to the island,iguana body size is likely to ________ in the absence of other factors;the iguanas would then be under ________ selection.

Accepted Answer

A)  increase;directional
B)  increase;disruptive
C)  decrease;directional
D)  decrease;stabilizing
E)  stay the same;stabilizing

Question 16

Which of the following is true?

Accepted Answer

A)  Hardy-Weinberg can be used to examine only 1 gene at a time.
B)  Hardy-Weinberg considers an organism's entire genotype (all genes) .
C)  Hardy-Weinberg can be used to examine more than 1 gene at a time. A

Question 17

Which of the following is FALSE with respect to natural selection and genetic drift?

Accepted Answer

A)  Both natural selection and genetic drift result in allele frequency changes.
B)  Both natural selection and genetic drift involve differences in fitness.
C)  Both natural selection and genetic drift require genetically inherited traits.

Question 18

Consider the following two scenarios: 1) A flash-flood sweeps through an area and random lemmings are killed,resulting in a change in lemming phenotype in subsequent generations;2) A flash-flood sweeps through an area and some lemmings are able to survive because they are able to hold their breath longer than other lemmings,resulting in a change in lemming phenotype in subsequent generations.What are the primary differences between the two scenarios?

Accepted Answer

A)  Scenario 1 represents genetic drift because changes in the population were not adaptive,while Scenario 2 represents natural selection because some individuals were better adapted than other individuals.
B)  Scenario 1 represents natural selection because changes in the population were adaptive,while Scenario 2 represents genetic drift because changes in the population were due to higher fitness of some individuals.
C)  Both scenarios represent genetic drift because the flash-flood is a random event.
D)  Both scenarios represent natural selection because some individuals survived in each scenario.

Question 19

Which of the following describes what we should expect when a population is in Hardy-Weinberg genetic equilibrium?

Accepted Answer

A)  a sexually reproducing population that is increasing in size
B)  an asexually reproducing population that is increasing in size
C)  a sexually reproducing population that is not evolving
D)  an asexually reproducing population that is not evolving
E)  a sexually reproducing population that is evolving.

Question 20

Given the information above,what is the frequency of the A₂ allele in this population?

Accepted Answer

A)  0) 75
B)  0) 8
C)  0) 85
D)  0) 875
E)  0) 9

Exam 25: Evolutionary Processes

Which of the graphs above best represents the relationship between the intensity of directional selection and the genetic variation present within a population?

Correct Answer
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Correct Answer
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Genetic drift occurs in a population.Which of the following statements might be true?

Correct Answer
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Correct Answer
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For a biologist studying a small fish population in the lab,which Hardy-Weinberg condition is easiest to meet?

Correct Answer
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Correct Answer
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Correct Answer
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E

Mutation is the only evolutionary mechanism that

Correct Answer
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Based on the information given above,which of the following types of selection was most likely initially involved in the evolution of white outer tail feathers in juncos?

Correct Answer
verified

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years.If 9 in 10,000 newborn babies have the disease,what are the expected frequencies of the dominant (A₁) and recessive (A₂) alleles according to the Hardy-Weinberg model?

Correct Answer
verified

Which of the following best describes the effect of the migration of individuals into a population?

Correct Answer
verified

Which sex typically has more extreme sex-selected characteristics: males or females? Why? Give an example.

Correct Answer
verified
Males;fund...
View Answer

Why doesn't inbreeding depression,by itself,cause evolution?

Correct Answer
verified

A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness.She hypothesizes that the population is experiencing

Correct Answer
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C

Correct Answer
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Which of the following is true?

Correct Answer
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A

Which of the following is FALSE with respect to natural selection and genetic drift?

Correct Answer
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Correct Answer
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Which of the following describes what we should expect when a population is in Hardy-Weinberg genetic equilibrium?

Correct Answer
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Given the information above,what is the frequency of the A₂ allele in this population?

Correct Answer
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Exam 25: Evolutionary Processes

Which of the graphs above best represents the relationship between the intensity of directional selection and the genetic variation present within a population?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Genetic drift occurs in a population.Which of the following statements might be true?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

For a biologist studying a small fish population in the lab,which Hardy-Weinberg condition is easiest to meet?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedE

Mutation is the only evolutionary mechanism that

Correct AnswerverifiedShow Answer

Based on the information given above,which of the following types of selection was most likely initially involved in the evolution of white outer tail feathers in juncos?

Correct AnswerverifiedShow Answer

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years.If 9 in 10,000 newborn babies have the disease,what are the expected frequencies of the dominant (A₁) and recessive (A₂) alleles according to the Hardy-Weinberg model?

Correct AnswerverifiedShow Answer

Which of the following best describes the effect of the migration of individuals into a population?

Correct AnswerverifiedShow Answer

Which sex typically has more extreme sex-selected characteristics: males or females? Why? Give an example.

Correct AnswerverifiedMales;fund...View AnswerShow Answer

Why doesn't inbreeding depression,by itself,cause evolution?

Correct AnswerverifiedShow Answer

A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness.She hypothesizes that the population is experiencing

Correct AnswerverifiedC

Correct AnswerverifiedShow Answer

Which of the following is true?

Correct AnswerverifiedA

Which of the following is FALSE with respect to natural selection and genetic drift?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following describes what we should expect when a population is in Hardy-Weinberg genetic equilibrium?

Correct AnswerverifiedShow Answer

Given the information above,what is the frequency of the A₂ allele in this population?

Correct AnswerverifiedShow Answer

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E

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Males;fund...
View Answer

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C

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A

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