Question 1

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing

Accepted Answer

A) non-random mating. 
B) geographic isolation. 
C) genetic drift. 
D) mutations. 
E) gene flow. 
A) non-random mating. 
B) geographic isolation. 
C) genetic drift. 
D) mutations. 
E) gene flow. E

Question 2

Which of these is the smallest unit upon which natural selection directly acts?

Accepted Answer

A) a species' gene frequency 
B) a population's gene frequency 
C) an individual's genome 
D) an individual's genotype 
E) an individual's phenotype 
A) a species' gene frequency 
B) a population's gene frequency 
C) an individual's genome 
D) an individual's genotype 
E) an individual's phenotype E

Question 3

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) 92% 
E) There is not enough information to say. 
A) 23% 
B) 46% 
C) 54% 
D) 92% 
E) There is not enough information to say. C

Question 4

Use the following information to answer the questions below.
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 estimated frequency of allele A in the gene pool?

Accepted Answer

A) 0.05 
B) 0.25 
C) 0.50 
D) 0.75 
E) 1.00 
A) 0.05 
B) 0.25 
C) 0.50 
D) 0.75 
E) 1.00

Question 5

Adult male humans generally have deeper voices than do adult female humans, as the direct result of higher levels of testosterone causing growth of the larynx.
-If one excludes the involvement of gender in the situation described in the paragraph above, 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 6

A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2?

Accepted Answer

A) 0.7 
B) 0.49 
C) 0.21 
D) 0.42 
E) 0.09 
A) 0.7 
B) 0.49 
C) 0.21 
D) 0.42 
E) 0.09

Question 7

The outcome of the conflict between bacteria and bacteriophage at any point in time results from

Accepted Answer

A) frequency-dependent selection. 
B) evolutionary imbalance. 
C) heterozygote advantage. 
D) neutral variation. 
E) genetic variation being preserved by diploidy. 
A) frequency-dependent selection. 
B) evolutionary imbalance. 
C) heterozygote advantage. 
D) neutral variation. 
E) genetic variation being preserved by diploidy.

Question 8

Use the following information to answer the questions below.
HIV's genome of RNA includes code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of 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 analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.
-HIV has 9 genes in its RNA genome. Every HIV particle contains two RNA molecules, each molecule containing all 9 genes. If, for some reason, the two RNA molecules within a single HIV particle do not have identical sequences, then which of these terms can be applied due to the existence of the non-identical regions?

Accepted Answer

A) homozygous 
B) gene variability 
C) nucleotide variability 
D) average heterozygosity 
E) all except A 
A) homozygous 
B) gene variability 
C) nucleotide variability 
D) average heterozygosity 
E) all except A

Question 9

The following questions refer to this information:
In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.
-If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about how many people will have attached earlobes when the planet's population reaches 10,000?

Accepted Answer

A) 100 
B) 400 
C) 800 
D) 1,000 
E) 10,000 
A) 100 
B) 400 
C) 800 
D) 1,000 
E) 10,000

Question 10

Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence?

Accepted Answer

A) Mutation 
B) Non-random mating 
C) Genetic drift 
D) Natural selection 
E) Gene flow 
A) Mutation 
B) Non-random mating 
C) Genetic drift 
D) Natural selection 
E) Gene flow

Question 11

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Consequently, which statement about mules is True?

Accepted Answer

A) They have a relative evolutionary fitness of zero. 
B) Their offspring have less genetic variation than the parents. 
C) Mutations cannot occur in their genomes. 
D) If crossing-over happens in mules, then it must be limited to prophase of mitosis. 
E) When two mules interbreed, genetic recombination cannot occur by meiotic crossing over, but only by the act of fertilization. 
A) They have a relative evolutionary fitness of zero. 
B) Their offspring have less genetic variation than the parents. 
C) Mutations cannot occur in their genomes. 
D) If crossing-over happens in mules, then it must be limited to prophase of mitosis. 
E) When two mules interbreed, genetic recombination cannot occur by meiotic crossing over, but only by the act of fertilization.

Question 12

In modern terminology, diversity is understood to be a result of genetic variation. Sources of variation for evolution include all of the following except

Accepted Answer

A) mistakes in translation of structural genes. 
B) mistakes in DNA replication. 
C) translocations and mistakes in meiosis. 
D) recombination at fertilization. 
E) recombination by crossing over in meiosis. 
A) mistakes in translation of structural genes. 
B) mistakes in DNA replication. 
C) translocations and mistakes in meiosis. 
D) recombination at fertilization. 
E) recombination by crossing over in meiosis.

Question 13

Use the following information to answer the questions below.
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.
-In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the percentage of the population that is heterozygous for this allele?

Accepted Answer

A) 90 
B) 81 
C) 49 
D) 18 
E) 10 
A) 90 
B) 81 
C) 49 
D) 18 
E) 10

Question 14

The following questions refer to this information:
In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.
-If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of

Accepted Answer

A) diploidy. 
B) gene flow. 
C) genetic drift. 
D) disruptive selection. 
E) stabilizing selection. 
A) diploidy. 
B) gene flow. 
C) genetic drift. 
D) disruptive selection. 
E) stabilizing selection.

Question 15

Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed?

Accepted Answer

A) Average heterozygosity 
B) Nucleotide variability 
C) Geographic variability 
D) Average number of loci 
A) Average heterozygosity 
B) Nucleotide variability 
C) Geographic variability 
D) Average number of loci

Question 16

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is True?

Accepted Answer

A) Each bird evolved a deeper, stronger beak as the drought persisted. 
B) Each bird developed a deeper, stronger beak as the drought persisted. 
C) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted. 
D) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation. 
E) The frequency of the strong-beak alleles increased in each bird as the drought persisted. 
A) Each bird evolved a deeper, stronger beak as the drought persisted. 
B) Each bird developed a deeper, stronger beak as the drought persisted. 
C) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted. 
D) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation. 
E) The frequency of the strong-beak alleles increased in each bird as the drought persisted.

Question 17

Use the following information to answer the questions below.
HIV's genome of RNA includes code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of 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 analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.
-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 18

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to

Accepted Answer

A) cross your flies with flies from another lab. 
B) reduce the number of flies that you transfer at each generation. 
C) transfer only the largest flies. 
D) change the temperature at which you rear the flies. 
E) shock the flies with a brief treatment of heat or cold to make them more hardy. 
A) cross your flies with flies from another lab. 
B) reduce the number of flies that you transfer at each generation. 
C) transfer only the largest flies. 
D) change the temperature at which you rear the flies. 
E) shock the flies with a brief treatment of heat or cold to make them more hardy.

Question 19

Use the following information to answer the questions below.
HIV's genome of RNA includes code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of 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 analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.
-Which 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 larger 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 larger average heterozygosity.

Question 20

The average birth weight for human babies is about 3 kg. Which of the following terms best describes this?

Accepted Answer

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

Exam 23: The Evolution of Populations

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing

Which of these is the smallest unit upon which natural selection directly acts?

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

A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2?

The outcome of the conflict between bacteria and bacteriophage at any point in time results from

Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence?

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Consequently, which statement about mules is True?

In modern terminology, diversity is understood to be a result of genetic variation. Sources of variation for evolution include all of the following except

Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed?

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is True?

The average birth weight for human babies is about 3 kg. Which of the following terms best describes this?

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and the Fitness of the Environment

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: Harvesting Chemical Energy

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

Control of Gene Expression

Viruses

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 Introduction to Animal Diversity

Invertebrates

Vertebrates

Plant Structure, Growth, and Development

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 Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems

Conservation Biology and Restoration Ecology

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