Chapter 15
Teacher Guide and Answers
Diagnostic Test
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Page 38
1. The correct answer is C. Based on student
responses, use the list below to address
preconceptions.
• Student thinks Darwin developed the theory of
evolution aboard the HMS Beagle. Direct
student to the developing the theory of evolution
by natural selection discussion in Section 1.
• Student thinks people living during Darwin’s
time accepted the theory of evolution. Direct
student to the developing the theory of evolution
by natural selection discussion in Section 1.
• Student thinks Darwin observed evolutionary
changes. Explain to student that most evolutionary changes normally occur over long periods of
time and are not observable.
• Student confuses evolution with natural
selection. Explain to student that evolution is
the theory that species change over time, but
natural selection is the proposed process by
which species change.
• Student is confused by the idea of natural selection. Direct student to the developing the theory
of evolution by natural selection discussion in
Section 1.
2. The correct answer is D. Based on student
responses, use the list below to address
preconceptions.
• Student is unaware of vestigial structures.
Direct student to the comparative anatomy
discussion in Section 2.
• Student thinks the fossil record demonstrates
clear evidence of evolutionary changes for most
organisms. Direct student to the fossil record
discussion in Section 2.
• Student thinks breeding domesticated varieties of organisms demonstrates evolutionary
change. Explain that domesticated varieties of
organisms, such as dog breeds, are not separate
species that demonstrate a change in a species
over time.
• Student thinks vertebrate embryos do not
share common features. Direct student to the
comparative embryology discussion in Section 2.
Unit 4
3. The six species share a recent common ancestor—they possibly belonged to the same species
in the past. Because of a physical or behavioral
isolating mechanism they evolved into the six
species present today. These species are not able
to interbreed. Based on student responses, use
the list below to address preconceptions.
• Student does not understand that the six species of chickadees share a common ancestor.
Direct student to the speciation discussion in
Section 3.
• Student thinks members of different species
can interbreed. Direct student to the speciation
discussion in Section 3.
• Student thinks two species always evolve due to
a physical barrier that isolates two populations.
Direct student to the speciation discussion in
Section 3.
• Student does not understand how natural
selection causes speciation. Direct student to
the speciation discussion in Section 3.
Launch Lab
Page 39 • How does selection work?
Analysis
1. Answers will vary. Square 1 is less likely to be
chosen in the group with eight red squares.
2. It is less likely Square 1 from the group with
eight red squares will be eaten because there are
more red squares in that group that the predator
can choose from.
MiniLab
Page 40 • Investigate Mimicry
Analysis
1. The monarch butterfly is dark orange with black
veins and a row of white spots on the edge of its
wings. The viceroy has the same color pattern
except for a black horizontal stripe across the
bottom of its wings.
2. Answers may vary, but the bright colors serve as
warnings to signal the toxicity to predators.
CHAPTER 15 TEACHER GUIDE AND ANSWERS 151
Chapter 15
Teacher Guide and Answers
BioLab
Page 41 • Can scientists model natural selection?
Real-World Biology: Lab
Page 43 • Modeling Natural Selection
Planning the Activity
Use this activity to reinforce student understanding
of natural selection. It can also be used to reinforce
basic principles of genetics, gene frequency, and
predator-prey relationships.
Purpose
Students develop a model to observe how natural
selection can affect a population of organisms when
the environment changes.
Career Applications
Wildlife managers perform many duties associated
with conserving species of fish and wildlife. They
conduct population counts, reintroduce endangered species, and evaluate the impact of state and
federal programs. They might use aerial or ground
152 CHAPTER 15 TEACHER GUIDE AND ANSWERS
Materials Tips
Materials page of newspaper want ads, sheet of
brown butcher paper of the same size, envelope with
50 butcher-paper circles and 50 newspaper want-ad
circles cut out with a paper punch, stopwatch or clock
• A paper punch should be used to make the
butcher-paper circles and newspaper want-ad
circles.
• Place circles in envelopes or small film containers
until needed. Have students replace the circles in
the containers after the activity so you can reuse
them.
• When you punch out the newspaper circles, be
sure there is print on both sides of each circle.
• If a stopwatch is not available, a clock with a second hand can be used.
Teaching Strategies
• Have students read the procedure first, then ask
them “Which lizards do you think will be easier to
see on the black-and-white background?” “Which
lizards do you think will be easier to see on the
brown background?”
Unit 4
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Analyze and Conclude
1. To calculate the percentage, students should
divide the number of forceps/pliers that survived
by the total number of forceps/pliers in the community. Answers will vary based on class data.
2. To determine the number of offspring produced
in the community, students should calculate the
number of offspring produced by the forceps/
pliers in each group, and then add the group
members.
3. To calculate the ratio, students should write (the
number of offspring forceps): (the number of
offspring pliers). Answers will vary based on
class data.
4. Answers will vary based on class data. If the
survival percentage is low, the population will
not persist. If relatively few offspring are produced, the population will likely decline over
generations.
5. The population that produces the most offspring
will be most likely to grow over time. Body
structure variations that make it easier to obtain
food are likely to be passed to offspring by surviving individuals.
photography to track animals or monitor the migration of animals. Wildlife managers enforce laws and
regulations that are designed to maintain wildlife
populations at optimum levels. Additionally, wildlife managers are public relations specialists and
educators.
A career in wildlife management requires a strong
interest in wildlife and the outdoors. Excellent physical and mental health is needed. Wildlife managers
should like and understand people as well as wildlife
because most jobs involve working with the public.
A wildlife manager should have the ability to assume
responsibility and work on his or her own.
To be a wildlife manager, a person must have a
college degree in biology or natural resources management. Studies must include courses in wildlife
subjects, zoology, and botany or related plant sciences. Preparing for a career in wildlife management can begin in high school by taking courses in
biology, chemistry, physics, math, and computers.
Activities such as camping, hiking, hunting and
fishing, bird watching, and wildlife photography will
help to understand wildlife.
Chapter 15
Teacher Guide and Answers
• Monitor students to be sure that the circles are
randomly scattered on the background and not
piled up.
• Turn the classroom lights down to make picking
up the “lizards” more difficult. Tell students that
the owl predator in this activity hunts for prey just
before sunrise or just after sunset.
• You might have to review with students how to
calculate the percentage of survivors and the percentage of lizards that died.
• Below Level: If students are having trouble with
question 4, review the basics of Mendelian genetics
and population genetics.
• Above Level: Have students test their predictions
from question 5. Have them take the surviving
lizards from step 5, place them on newspaper, and
repeat step 3.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Answers to Student Worksheet
Analyze and Conclude
1. The percentage of speckled lizards that survived
probably decreased when the environment
changed because they would be more easily seen
and picked up by the owl against the brown
background.
2. The percentage of brown lizards that survived
probably increased when the environment
changed because they would be harder for
the owl to see and pick up against the brown
background.
3. If an organism has characteristics that enable it
to blend in with its environment, its chances of
survival will increase, and it will be more likely
to reproduce than organisms that do not have
such characteristics.
4. When BB and bb lizards mate, Bb lizards will be
produced. When Bb lizards mate, some brown
bb lizards will be produced. Because Bb lizards
are likely to survive and reproduce, brown bb
lizards are not likely to disappear completely
from the population.
5. The fitness of speckled lizards would increase in
the black-and-white rock environment; therefore,
more would survive and reproduce. The number
of speckled lizards in the population would
gradually increase. Brown lizards would decrease
in number because they would be less fit.
Unit 4
6. Changing the predator would introduce another
variable into the experiment. For example, partners might have different eyesight or be able to
pick up the circles at different speeds.
Careers in Biology
Wildlife managers help conserve species of fish and
wildlife. They conduct population counts, reintroduce endangered species, and evaluate the impact of
state and federal programs.
Enrichment
Page 45 • Darwin’s Finches
Student articles will vary but should be clearly
written and accurate. All questions posed should
be thoroughly researched, and answers should be
supported by the research. All sources should be
accurately cited. Drawings or photographs of the
finches would be useful in student articles.
Concept Mapping
Page 46 • Patterns of Evolution
1. adaptive radiation
2. convergent evolution
3. more similar to unrelated species
4. change in response to each other
5. many similar but distinct species
6. unrelated species with similar characteristics
7. species with symbiotic relationships
8. Galápagos finches
Study Guide
Page 47 • Section 1
1. true
2. false
3. true
4. false
5. false
6. A
7. B
8. D
9. C
CHAPTER 15 TEACHER GUIDE AND ANSWERS 153
Chapter 15
Teacher Guide and Answers
Page 48 • Section 2
1. C
2. E
3. D
4. B
5. A
6. Homologous Structure
7. Vestigial Structure
8. Comparative Biochemistry
9. Analogous Structure
10. Vestigial Structure
11. true
12. biogeography
13. true
14. adaptations
15. harmful
16. true
17. true
18. true
Page 50 • Section 3
Guía de estudio
Página 51 • Sección 1
1. verdadero
2. falso
3. verdadero
4. falso
154 CHAPTER 15 TEACHER GUIDE AND ANSWERS
Página 52 • Sección 2
1. C
2. E
3. D
4. B
5. A
6. Estructura homóloga
7. Estructura vestigial
8. Bioquímica comparativa
9. Estructura análoga
10. Estructura vestigial
11. verdadero
12. biogeografía
13. verdadero
14. adaptaciones
15. dañina
16. verdadero
17. verdadero
18. verdadero
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
1. Genetic drift
2. Disruptive selection
3. stabilizing selection
4. founder effect
5. sympatric speciation
6. Directional selection
7. allopatric speciation
8. Sexual selection
9. adaptive radiation
10. gradualism
11. the darker moth (moth B)
12. industrial melanism
5. falso
6. A
7. B
8. D
9. C
Página 54 • Sección 3
1. deriva genética
2. selección disruptiva
3. selección estabilizadora
4. efecto fundador
5. especiación simpátrica
6. selección direccional
7. especiación alopátrica
8. selección sexual
9. radiación adaptiva
10. gradualismo
11. la mariposa más oscura (mariposa B)
12. melanismo industrial
Unit 4
Chapter 15
Teacher Guide and Answers
Section Quick Check
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Page 55 • Section 1
1. (1) Individuals in a population show differences, or variations, even among individuals of
the same species. (2) Variations are inherited.
(3) Animals have more young than can survive
on the available resources. (4) Variations that
increase reproductive success will be common in
the next generation.
2. Alfred Russel Wallace’s theory was almost identical to Darwin’s theory.
3. All of today’s species are descended from one or
a few ancestral species, and natural selection is
the process by which ancestral species become
modified into new species.
4. Artificial and natural selection both result in
species changing over time. In artificial selection, humans breed a species to increase the
frequency of a trait. In natural selection, species
change over time according to variations that
increase the reproductive success.
5. Wheat would be tested for fiber content, and
only those with a high level would be planted and
crossbred. The offspring of successive generations
would also be tested and crossed. Eventually, the
level of fiber in the offspring will increase.
Page 56 • Section 2
1. An adaptation is a trait that makes individuals
better able to survive or reproduce than individuals without those traits.
2. If a structure such as a wing does not increase
the reproductive success of the organism, it
might become a vestigial structure through
evolution. This can happen when a population
contains individuals that expend less energy on
the development of such a structure and more
energy on other activities. These individuals will
probably be more successful in reproduction. As
a result, these individuals will survive in greater
numbers and pass on their traits to their offspring. Eventually, individuals that have smaller
versions of the structure, and thus use the least
energy on developing the structure, will become
most prevalent in a population.
Unit 4
3. Homologous structures are inherited from a
common ancestor, and analogous structures
are not.
4. The color pattern of the California kingsnake
is mimicry, not camouflage. It makes the snake
resemble a harmful species but does not help the
snake blend in with its surroundings.
5. Squirrels and rabbits will have more similar
DNA because squirrels are more like rabbits
than like antelope. DNA is more similar in more
closely related species.
Page 57 • Section 3
1. Genetic bottlenecks reduce the total alleles in a
gene pool, and the population that results can be
unusually genetically similar.
2. relatively sudden speciation followed by long
periods of stability
3. Scientists determine that evolution will not occur
in a population unless the allelic frequencies are
acted on by outside forces that cause change.
4. There are 60 + 60 + 30 = 150 O alleles and
30 + 10 + 10 = 50 o alleles. The total number of
alleles is 150 + 50 = 200 alleles. The O allele frequency is 150/200, or 0.75. The o allele frequency
is 50/200, or 0.25.
5. Sexual selection does not always result in selection of traits that are best for survival in a particular environment, so it will not always lead to
better survival of a species.
Chapter Test A
Page 58 • Part A: Multiple Choice
1. C
2. D
3. C
Page 58 • Part B: Matching
Matching Set 1
1. homologous structure
2. vestigial structure
3. analogous structure
4. vestigial structure
CHAPTER 15 TEACHER GUIDE AND ANSWERS 155
Chapter 15
Teacher Guide and Answers
Matching Set 2
5. D
6. A
7. B
Page 59 • Part C: Interpreting Graphs
1. The graph illustrates directional selection. The
graph shows a shift in snail numbers away from
one extreme, which is light coloration.
2. The graph illustrates disruptive selection. The
graph shows a shift in number toward the
extremes of a trait and away from the mean.
Page 59 • Part D: Short Answer
Page 60 • Part E: Concept Application
1. Darwin would have explained the many different verities of guppies as an example of artificial
selection. He would have noticed that the breeders of guppies were breeding fish for certain
characteristics. This is known as selective breeding today. Through artificial selection, breeders
have chosen guppies with different traits such as
varying colors and tail shapes. Although guppies
show a wide variety of traits, all guppies are still
considered one species.
2. The adaptation of the syrphid fly is an example
of mimicry. Mimicry is an adaptation of body
features so that one species resembles another
156 CHAPTER 15 TEACHER GUIDE AND ANSWERS
Chapter Test B
Page 61 • Part A: Multiple Choice
1. C
2. D
3. B
4. A
Page 61 • Part B: Matching and Completion
Matching
1. homologous structure
2. vestigial structure
3. analogous structure
4. vestigial structure
Completion
5. artificial selection
6. adaptation
7. fitness
8. sexual selection
Page 62 • Part C: Interpreting Graphs
1. The graph illustrates directional selection. The
dark-colored snails can camouflage better with
their natural surroundings and avoid predation
more frequently than the light-colored snails.
2. The graph illustrates disruptive selection. The
population probably has two primary habitats.
The squirrels with light-colored fur populate
a light-colored habitat, and the squirrels with
dark-colored fur populate a dark-colored habitat. A squirrel with a color of fur between light
and dark matches neither habitat and presents
an easier target for predators.
Page 62 • Part D: Short Answer
1. The peppered moth produces more offspring
than can survive on the available resources, and
these offspring show a variation in colors. Some
moths are light colored and others are dark.
These color traits are passed down from parent moths to their offspring. During the initial
Unit 4
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
1. Animals produce more young than can survive
on the available resources. Offspring of the same
species show variation of traits. These traits are
passed on from parents to offspring. Finally,
variations that increase reproductive success will
be more common in future generations.
2. Evolution is the change in a species over time.
3. The bull fur seal, a mammal, and the emperor
penguin, a bird, are different animals, but
both are adapted to an aquatic environment.
Convergent evolution is when organisms that
live in different places and are often unrelated
resemble each other in shape, size, and behavior.
The bull fur seal and the emperor penguin are
such an example. They are different animals
from different places, but have similar structures
and shapes.
species. The fly is harmless, but because its
markings resemble the stinging yellow jacket, it
is less vulnerable to predation.
Chapter 15
Teacher Guide and Answers
industrialization of England, air pollution darkened the trunks of trees making the darker colored moths better camouflaged from predators.
More dark-colored moths survived to reproduce,
and this reproductive success led to the dark-colored moths becoming more common.
2. The shared traits among vertebrate embryos,
such as a tail, provide evidence of the shared
ancestry of vertebrates. Physical traits that are
not always apparent or present in the adults
of different species can be observed in their
embryos. This is why scientists often compare
embryos to search for evolutionary relationships.
3. This is an example of convergent evolution.
The bull fur seal, a mammal, and the emperor
penguin, a bird, are different animals, but both
of these animals are adapted to an aquatic environment. These organisms evolved in different places and are not closely related, but they
evolved similar structures and behaviors in
response to their environments.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Page 63 • Part E: Concept Application
1. The syrphid fly is about the same size as the
yellow jacket, and it has black and yellow stripes.
The fly is harmless and cannot sting, but
because it mimics the stinging yellow jacket, it is
less desirable to predators.
2. The conditions include: random mating, no
emigration or immigration, no mutations, and
no natural selection. The violation is that the
population is small, not large.
Chapter Test C
Page 64 • Part A: Multiple Choice
1. A
2. B
3. D
4. D
5. A
Page 64 • Part B: Completion
1. artificial selection
2. evolution
3. comparative embryology
4. constraint
Unit 4
5. bottleneck
6. gradualism
Page 65 • Part C: Interpreting Graphs
1. The graph illustrates directional selection. The
dark snails probably have the advantage of better
camouflage against predators, but if the snails’
environment becomes lighter in color, the snails
with a light coloration will have the advantage.
A lighter colored environment will cause an
increase in the survival rate of light-colored individuals, and the graph will shift back toward the
light color extreme.
2. The population probably has two primary habitats. The squirrels with light color fur populate a
light-colored habitat, and the squirrels with dark
color fur populate a dark-colored habitat. This
is disruptive selection—when two populations
are created with extreme traits. If one of the
habitats changes colors or becomes uninhabitable for squirrels, the coloration of the squirrel
fur will shift toward directional selection. This
means that the coloration of the squirrels would
begin to tend toward the color of the unaffected
environment.
Page 65 • Part D: Short Answer
1. Both are morphological adaptations. Mimicry
is an adaptation in which one species resembles
another species, and camouflage is an adaptation
in which a species resembles its surroundings.
The adaptation can be combined if a species
mimics the camouflage of another species.
2. Homologous structures are anatomically similar
structures inherited from a common ancestor.
An example would be bird wings evolved from
reptile forearms. Vestigial structures, such as the
human appendix, are features with a reduced
function in the organism. Analogous structures
have the same function, but they do not have a
common ancestry. Eagle wings and bee wings
would be an example.
3. Homozygous dominant: 0.525; heterozygous
dominant: 0.397, homozygous recessive: 0.075.
Note: Numbers are rounded to the thousandth
place.
CHAPTER 15 TEACHER GUIDE AND ANSWERS 157
Chapter 15
Teacher Guide and Answers
Page 66 • Part E: Concept Application
158 CHAPTER 15 TEACHER GUIDE AND ANSWERS
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
1. Polar bears produce more offspring than can
survive on the available resources and these offspring show a variation in fur colors. Some of
the bear cubs are born with thicker fur that is
lighter in color. These fur color and thickness
traits are passed down from parent bears to
their offspring. The snow-covered environment
favored the lighter colored bears because they
were better camouflaged to hunt prey. Bears
with thicker fur also had a survival advantage in
the cold northern temperature than thin-furred
bears. More light-colored, thick-furred bears
survived to reproduce, and this reproductive
success led to white bears with thick fur becoming more common. The isolation of polar bears
from brown bears eventually led to the evolution
of two distinct species.
2. Eye color in humans is a trait, but it is presently
not considered an adaptation because it does not
contribute to the survival and reproductive success of an individual. Measurements of the fitness of people with different eye colors would be
statistically equal.
3. They exhibit sympatric speciation because the
two species evolved without being separated by
any natural barriers. Presumably, the ancestor
species and new species lived side by side during
the speciation process.
Unit 4