Question 1

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 2

How many of these statements regarding populations are true?
1)Mature males and females of a population can interbreed with each other.
2)Populations are sometimes geographically isolated from other populations.
3)Biological species are made up of populations.
4)Members of a population tend to be genetically more similar to each other than to members of other populations.
5)Populations have genomes, but not gene pools.

Accepted Answer

A)  Only one of these statements is true. 
B)  Two of these statements are true. 
C)  Three of these statements are true. 
D)  Four of these statements are true. 
E)  All five of these statements are true. 
A)  Only one of these statements is true. 
B)  Two of these statements are true. 
C)  Three of these statements are true. 
D)  Four of these statements are true. 
E)  All five of these statements are true.

Question 3

Use the following information to answer the following questions.
In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.
-What should be the proportion of heterozygous individuals in populations that live here?

Accepted Answer

A)  0.04 
B)  0.16 
C)  0.20 
D)  0.32 
E)  0.80 
A)  0.04 
B)  0.16 
C)  0.20 
D)  0.32 
E)  0.80

Question 4

Blue light is that portion of the visible spectrum that penetrates the deepest into bodies of water. Ultraviolet (UV)light, though, can penetrate even deeper. A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light, and another allele for a photopigment that is sensitive to blue light. Which of the following graphs best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
A)  A 
B)  B 
C)  C 
D)  D

Question 5

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined, thereby producing a genetically distinctive virus, which can subsequently cause widespread disease.
The production of new types of flu virus in the manner described above is most similar to the phenomenon of

Accepted Answer

A)  bottleneck effect. 
B)  founder effect. 
C)  natural selection. 
D)  gene flow. 
E)  sexual selection. 
A)  bottleneck effect. 
B)  founder effect. 
C)  natural selection. 
D)  gene flow. 
E)  sexual selection.

Question 6

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 7

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 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 nine genes in its RNA genome. Every HIV particle contains two RNA molecules, and each molecule contains all nine 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 nonidentical regions?

Accepted Answer

A)  homozygous 
B)  gene variability 
C)  nucleotide variability 
D)  average heterozygosity 
E)  All but one of the responses are correct. 
A)  homozygous 
B)  gene variability 
C)  nucleotide variability 
D)  average heterozygosity 
E)  All but one of the responses are correct.

Question 8

Use this information 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 estimated frequency of allele A in the gene pool?

Accepted Answer

A)  0.25 
B)  0.50 
C)  0.75 
A)  0.25 
B)  0.50 
C)  0.75

Question 9

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

Accepted Answer

A)  nonrandom mating. 
B)  geographic isolation. 
C)  genetic drift. 
D)  gene flow. 
A)  nonrandom mating. 
B)  geographic isolation. 
C)  genetic drift. 
D)  gene flow.

Question 10

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 11

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

Accepted Answer

A)  0.36 
B)  0.64 
C)  0.75 
D)  0.80 
A)  0.36 
B)  0.64 
C)  0.75 
D)  0.80

Question 12

If the original finches that had been blown over to the Galápagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galápagos, this would have been an example of

Accepted Answer

A)  genetic drift. 
B)  bottleneck effect. 
C)  founder effect. 
D)  all three of these. 
E)  both the first and third of these. 
A)  genetic drift. 
B)  bottleneck effect. 
C)  founder effect. 
D)  all three of these. 
E)  both the first and third of these.

Question 13

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating

Accepted Answer

A)  the bottleneck effect. 
B)  disruptive selection. 
C)  frequency-dependent selection. 
D)  neutral variation. 
E)  stabilizing selection. 
A)  the bottleneck effect. 
B)  disruptive selection. 
C)  frequency-dependent selection. 
D)  neutral variation. 
E)  stabilizing selection.

Question 14

In a very large population, a quantitative trait has the following distribution pattern:
  
-What is true of the trait whose frequency distribution in a large population appears in the previous figure? It has probably undergone

Accepted Answer

A)  directional selection. 
B)  stabilizing selection. 
C)  disruptive selection. 
D)  normal selection. 
A)  directional selection. 
B)  stabilizing selection. 
C)  disruptive selection. 
D)  normal selection.

Question 15

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 16

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 17

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of

Accepted Answer

A)  a cline. 
B)  a bottleneck. 
C)  relative fitness. 
D)  genetic drift. 
E)  geographic variation. 
A)  a cline. 
B)  a bottleneck. 
C)  relative fitness. 
D)  genetic drift. 
E)  geographic variation.

Question 18

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.

Exam 23: The Evolution of Populations

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

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

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

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

If the original finches that had been blown over to the Galápagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galápagos, this would have been an example of

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating

In a very large population, a quantitative trait has the following distribution pattern: -What is true of the trait whose frequency distribution in a large population appears in the previous figure? It has probably undergone

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?

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

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of

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

Introduction: Themes in the Study of Life

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

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 Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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