Question 1

Which of the following is a true statement concerning genetic variation?

Accepted Answer

A) It is created by the direct action of natural selection. 
B) It arises in response to changes in the environment. 
C) It must be present in a population before natural selection can act upon the population. 
D) It tends to be reduced by the processes involved when diploid organisms produce gametes. 
E) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity. 
A) It is created by the direct action of natural selection. 
B) It arises in response to changes in the environment. 
C) It must be present in a population before natural selection can act upon the population. 
D) It tends to be reduced by the processes involved when diploid organisms produce gametes. 
E) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity.

Question 2

The following questions refer to the following paragraph.
HIV's genome of RNA includes the code for reverse transcriptase (RT),an enzyme that acts early in infection to synthesize a DNA genome from an RNA template.The HIV genome also codes for protease (PR),an enzyme that acts later in infection by cutting long viral polyproteins into smaller,functional proteins.Both RT and PR represent potential targets for antiretroviral drugs.Drugs called nucleoside analogues (NA)act against RT,whereas drugs called protease inhibitors (PI)act against PR.
-Which of the following represents the treatment option most likely to avoid the production of drug-resistant HIV (assuming no drug interactions or side effects)?

Accepted Answer

A) using a series of NAs, one at a time, and changed about once a week 
B) using a single PI, but slowly increasing the dosage over the course of a week 
C) using high doses of NA and a PI at the same time for a period not to exceed one day 
D) using moderate doses of NA and two different PIs at the same time for several months 
A) using a series of NAs, one at a time, and changed about once a week 
B) using a single PI, but slowly increasing the dosage over the course of a week 
C) using high doses of NA and a PI at the same time for a period not to exceed one day 
D) using moderate doses of NA and two different PIs at the same time for several months

Question 3

Use this information to answer the following questions.
You are studying three populations of birds.Population A has ten birds,of which one is brown (a recessive trait)and nine are red.Population B has 100 birds,of which ten are brown.Population C has 30 birds,and three of them are brown.
-Which population is most likely to be subject to genetic drift?

Accepted Answer

A) population A 
B) population B 
C) population C 
D) It would depend on the severity of a natural disaster. 
E) The population with the higher number of dispersing individuals. 
A) population A 
B) population B 
C) population C 
D) It would depend on the severity of a natural disaster. 
E) The population with the higher number of dispersing individuals.

Question 4

In Kluane National Park,red squirrels have been recorded giving birth 18 days earlier than a decade ago.Offspring born earlier become larger and more likely to survive.What mode of selection best describes these current research findings?

Accepted Answer

A) stabilizing selection 
B) directional selection 
C) disruptive selection 
D) transitional selection 
E) Selection will vary depending on temperature and amount of snow in spring. 
A) stabilizing selection 
B) directional selection 
C) disruptive selection 
D) transitional selection 
E) Selection will vary depending on temperature and amount of snow in spring.

Question 5

Mutation is the only evolutionary mechanism that

Accepted Answer

A) introduces new alleles into the population. 
B) is more important in eukaryotes than in prokaryotes. 
C) occurs frequently in all populations. 
D) has no effect on genetic variation/evolution. 
E) A and C 
A) introduces new alleles into the population. 
B) is more important in eukaryotes than in prokaryotes. 
C) occurs frequently in all populations. 
D) has no effect on genetic variation/evolution. 
E) A and C

Question 6

Use this information to answer the following questions.
You are studying three populations of birds.Population A has ten birds,of which one is brown (a recessive trait)and nine are red.Population B has 100 birds,of which ten are brown.Population C has 30 birds,and three of them are brown.
-In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?

Accepted Answer

A) population A 
B) population B 
C) population C 
D) They are all the same. 
E) It is impossible to tell from the information given. 
A) population A 
B) population B 
C) population C 
D) They are all the same. 
E) It is impossible to tell from the information given.

Question 7

Phenotypic characters,such as height in humans and coat color in horses are

Accepted Answer

A) influenced by multiple genes. 
B) determined by a single gene locus. 
C) a result of different chromosomes producing distinct phenotypes. 
D) due to the presence of different alleles, which express the dominant color. 
E) due to the blending of several genes. 
A) influenced by multiple genes. 
B) determined by a single gene locus. 
C) a result of different chromosomes producing distinct phenotypes. 
D) due to the presence of different alleles, which express the dominant color. 
E) due to the blending of several genes.

Question 8

Use this information below to answer the following questions.
A large population of laboratory animals has been allowed to breed randomly for a number of generations.After several generations,25% of the animals display a recessive trait (aa),the same percentage as at the beginning of the breeding program.The rest of the animals show the dominant phenotype,with heterozygotes indistinguishable from the homozygous dominants.
-What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa)has not changed over time?

Accepted Answer

A) The population is undergoing genetic drift. 
B) The two phenotypes are about equally adaptive under laboratory conditions. 
C) The genotype AA is lethal. 
D) There has been a high rate of mutation of allele A to allele a. 
E) There has been sexual selection favouring allele a. 
A) The population is undergoing genetic drift. 
B) The two phenotypes are about equally adaptive under laboratory conditions. 
C) The genotype AA is lethal. 
D) There has been a high rate of mutation of allele A to allele a. 
E) There has been sexual selection favouring allele a.

Question 9

If the nucleotide variability of a locus equals 0%,what is the gene variability and number of alleles at that locus?

Accepted Answer

A) gene variability = 0%; number of alleles = 0 
B) gene variability = 0%; number of alleles = 1 
C) gene variability = 0%; number of alleles = 2 
D) gene variability > 0%; number of alleles = 2 
E) Without more information, gene variability and number of alleles cannot be determined. 
A) gene variability = 0%; number of alleles = 0 
B) gene variability = 0%; number of alleles = 1 
C) gene variability = 0%; number of alleles = 2 
D) gene variability > 0%; number of alleles = 2 
E) Without more information, gene variability and number of alleles cannot be determined.

Question 10

No two people are genetically identical,except for identical twins.The main source of genetic variation among human individuals is

Accepted Answer

A) new mutations that occurred in the preceding generation. 
B) genetic drift due to the small size of the population. 
C) the reshuffling of alleles in sexual reproduction. 
D) geographic variation within the population. 
E) environmental effects. 
A) new mutations that occurred in the preceding generation. 
B) genetic drift due to the small size of the population. 
C) the reshuffling of alleles in sexual reproduction. 
D) geographic variation within the population. 
E) environmental effects.

Question 11

In a Hardy-Weinberg population with two alleles,A and a,that are in equilibrium,the frequency of the allele a is 0.3.What is the percentage of the population that is homozygous for this allele?

Accepted Answer

A) 0)09 
B) 0)49 
C) 0)9 
D) 9)0 
E) 49.0 
A) 0)09 
B) 0)49 
C) 0)9 
D) 9)0 
E) 49.0

Question 12

Natural selection changes allele frequencies because some ________ survive and reproduce more successfully than others.

Accepted Answer

A) alleles 
B) loci 
C) gene pools 
D) species 
E) individuals 
A) alleles 
B) loci 
C) gene pools 
D) species 
E) individuals

Question 13

Adult male humans generally have deeper voices than do adult female humans,which is the direct result of higher levels of testosterone causing growth of the larynx.If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males,then

Accepted Answer

A) sexual dimorphism was developing over time in these species. 
B) intrasexual selection seems to have occurred. 
C) stabilizing selection was occurring in these species concerning larynx size. 
D) selection was acting more directly upon genotype than upon phenotype. 
A) sexual dimorphism was developing over time in these species. 
B) intrasexual selection seems to have occurred. 
C) stabilizing selection was occurring in these species concerning larynx size. 
D) selection was acting more directly upon genotype than upon phenotype.

Question 14

Adult male humans generally have deeper voices than do adult female humans,which is the direct result of higher levels of testosterone causing growth of the larynx.If one excludes the involvement of gender in the situation,then the pattern that is apparent in the fossil record is most similar to one that should be expected from

Accepted Answer

A) pansexual selection. 
B) directional selection. 
C) disruptive selection. 
D) stabilizing selection. 
E) asexual selection. 
A) pansexual selection. 
B) directional selection. 
C) disruptive selection. 
D) stabilizing selection. 
E) asexual selection.

Question 15

If,on average,46% of the loci in a species' gene pool are heterozygous,then the average homozygosity of the species should be

Accepted Answer

A) 23%. 
B) 46%. 
C) 54%. 
D) There is not enough information to say. 
A) 23%. 
B) 46%. 
C) 54%. 
D) There is not enough information to say.

Question 16

Sexual dimorphism is most often a result of

Accepted Answer

A) pansexual selection. 
B) stabilizing selection. 
C) intrasexual selection. 
D) intersexual selection. 
E) artificial selection. 
A) pansexual selection. 
B) stabilizing selection. 
C) intrasexual selection. 
D) intersexual selection. 
E) artificial selection.

Question 17

Rank the following one-base-point mutations (from most likely to least likely)with respect to their likelihood of affecting the structure of the corresponding polypeptide:
1)insertion mutation deep within an intron
2)substitution mutation at the third position of an exonic codon
3)substitution mutation at the second position of an exonic codon
4)deletion mutation within the first exon of the gene

Accepted Answer

A) 1, 2, 3, 4 
B) 4, 3, 2, 1 
C) 2, 1, 4, 3 
D) 3, 1, 4, 2 
E) 2, 3, 1, 4 
A) 1, 2, 3, 4 
B) 4, 3, 2, 1 
C) 2, 1, 4, 3 
D) 3, 1, 4, 2 
E) 2, 3, 1, 4

Question 18

Which of the following statements is a misconception about evolution of populations?

Accepted Answer

A) Natural selection acts on individuals. 
B) Without genetic variation, evolution would not be possible. 
C) Microevolution is a change in the genetic structure of a population over time. 
D) For a population to evolve, individual members of the population must also evolve. 
E) Most heritable variation involves quantitative characters. 
A) Natural selection acts on individuals. 
B) Without genetic variation, evolution would not be possible. 
C) Microevolution is a change in the genetic structure of a population over time. 
D) For a population to evolve, individual members of the population must also evolve. 
E) Most heritable variation involves quantitative characters.

Question 19

The following questions refer to the following paragraph.
HIV's genome of RNA includes the code for reverse transcriptase (RT),an enzyme that acts early in infection to synthesize a DNA genome from an RNA template.The HIV genome also codes for protease (PR),an enzyme that acts later in infection by cutting long viral polyproteins into smaller,functional proteins.Both RT and PR represent potential targets for antiretroviral drugs.Drugs called nucleoside analogues (NA)act against RT,whereas drugs called protease inhibitors (PI)act against PR.
-Every HIV particle contains two RNA molecules.If two genes from one RNA molecule become detached and then,as a unit,get attached to one end of the other RNA molecule within a single HIV particle,which of these is true?

Accepted Answer

A) There are now fewer genes within the viral particle. 
B) There are now more genes within the viral particle. 
C) A point substitution mutation has occurred in the retroviral genome. 
D) The retroviral equivalent of crossing over has occurred, no doubt resulting in a heightened positive effect. 
E) One of the RNA molecules has experienced gene duplication as the result of translocation. 
A) There are now fewer genes within the viral particle. 
B) There are now more genes within the viral particle. 
C) A point substitution mutation has occurred in the retroviral genome. 
D) The retroviral equivalent of crossing over has occurred, no doubt resulting in a heightened positive effect. 
E) One of the RNA molecules has experienced gene duplication as the result of translocation.

Question 20

Heterozygote advantage should be most closely linked to which of the following?

Accepted Answer

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

Exam 23: The Evolution of Populations

Which of the following is a true statement concerning genetic variation?

In Kluane National Park,red squirrels have been recorded giving birth 18 days earlier than a decade ago.Offspring born earlier become larger and more likely to survive.What mode of selection best describes these current research findings?

Mutation is the only evolutionary mechanism that

Phenotypic characters,such as height in humans and coat color in horses are

If the nucleotide variability of a locus equals 0%,what is the gene variability and number of alleles at that locus?

No two people are genetically identical,except for identical twins.The main source of genetic variation among human individuals is

In a Hardy-Weinberg population with two alleles,A and a,that are in equilibrium,the frequency of the allele a is 0.3.What is the percentage of the population that is homozygous for this allele?

Natural selection changes allele frequencies because some ________ survive and reproduce more successfully than others.

If,on average,46% of the loci in a species' gene pool are heterozygous,then the average homozygosity of the species should be

Sexual dimorphism is most often a result of

Which of the following statements is a misconception about evolution of populations?

Heterozygote advantage should be most closely linked to which of the following?

Introduction: Evolution and Themes of Biology

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure,Growth,and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons,Synapses,and Signalling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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