PORTAGE LEARNING | BIOLOGICAL SCIENCES EXAMINATION SERIES
BIOD 102 Biology II - Module 6 Exam
Portage Learning | 2026/2027 Updated Edition | Answer Key with Detailed Rationales
COURSE MODULE FOCUS AREAS TOTAL QUESTIONS
BIOD 102 Evolution, Population Genetics, Speciation, Phylogeny,
Module 6 75 (Sections 1-6)
Biology II History of Life, Applications
Instructions: This examination contains 75 multiple-choice questions organized into six sections. Select the single
best answer for each question. For every item, the correct option is marked [CORRECT] and is followed by a
detailed rationale that explains the evolutionary mechanisms, evidence interpretation, or population-genetics
principles involved and identifies why each distractor is incorrect. Cognitive-level distribution: 30 percent recall,
50 percent application, 20 percent analysis.
SECTION 1
Principles of Evolution and Natural Selection
Darwinian Theory, Evidence for Evolution, and Mechanisms of Change | Questions 1-12
Q1: A population of beetles contains individuals ranging from light green to dark brown. Birds
preferentially eat the more conspicuous green beetles when they rest on dark tree bark, and
body color is a heritable trait. Over many generations, the population becomes predominantly
dark brown. Which principle of Darwin's theory of natural selection does this scenario
primarily demonstrate?
A. Organisms acquire beneficial traits during their lifetimes and pass those traits to their
offspring
B. Mutations arise in direct response to what the population needs for survival
C. Individuals with heritable traits that enhance survival and reproduction leave
more offspring [CORRECT]
D. All members of a population evolve simultaneously toward an ideal form
Correct Answer: C
Rationale: Natural selection acts on pre-existing heritable variation, producing differential
reproductive success: beetles carrying the dark-brown alleles survive bird predation and contribute
more offspring, so the allele frequencies shift across generations. Options A and B describe
Lamarckism and directed mutation, both discredited because traits are not acquired in response to need
during a lifetime. Option D wrongly implies that individuals evolve; populations evolve, and the
process is not goal-directed toward perfection.
Portage Learning | BIOD 102 Biology II 1
,BIOD 102 Biology II - Module 6 Exam | Portage Learning | 2026/2027
Q2: A student states: "Giraffes stretched their necks to reach high leaves during their lifetimes,
and their offspring were therefore born with longer necks." Which concept does this statement
incorrectly apply?
A. Uniformitarianism
B. Descent with modification
C. Catastrophism
D. Inheritance of acquired characteristics [CORRECT]
Correct Answer: D
Rationale: The statement is Lamarck's inheritance of acquired characteristics, the mistaken idea that
traits developed during an organism's lifetime are transmitted to its offspring. Modern genetics refutes
this: only changes present in germline DNA are heritable, so a stretched neck is a somatic change that
cannot reach the next generation. Option A names Lyell's geological principle of gradual uniform
processes, Option B, descent with modification, is Darwin's accurate summary of evolution, and
Option C is Cuvier's idea of sudden catastrophic extinctions.
Q3: Darwin's reading of Thomas Malthus's essay on human population growth contributed
directly to which insight in his theory of evolution by natural selection?
A. Earth must be millions of years old for gradual geological change to occur
B. More offspring are produced than resources can support, creating a struggle for
existence [CORRECT]
C. Island species typically resemble those of the nearest mainland
D. Species remain unchanged between fossil layers separated by catastrophe boundaries
Correct Answer: B
Rationale: Malthus argued that human populations grow faster than their food supplies, producing
inevitable competition; Darwin applied this logic to all organisms, recognizing that overproduction of
offspring with limited resources ensures that only some individuals survive to reproduce. This struggle
for existence is the engine that makes differential survival and selection possible. Option A came from
Lyell and Hutton, Option C reflects Darwin's biogeographic observations from the voyage of the
Beagle, and Option D is Cuvier's catastrophism, not Malthus's argument.
Portage Learning | BIOD 102 Biology II 2
,BIOD 102 Biology II - Module 6 Exam | Portage Learning | 2026/2027
Q4: In the Darwinian sense, which individual in a beetle population would be considered the
MOST biologically fit?
A. The largest and strongest beetle in the colony
B. The beetle with the most elaborate and striking coloration
C. The beetle that survives to the oldest age without reproducing
D. The beetle that leaves the greatest number of viable, fertile offspring
[CORRECT]
Correct Answer: D
Rationale: Evolutionary fitness is measured strictly by relative reproductive success, meaning the
contribution of viable, fertile offspring to the next generation's gene pool. Strength (Option A) and
showy traits (Option B) increase fitness only insofar as they improve reproduction, and survival without
reproduction (Option C) contributes zero genes to the next generation. Natural selection maximizes
gene transmission across generations, not longevity, size, or appearance for their own sakes.
Q5: The forelimbs of humans, whales, bats, and cats share the same arrangement of bones
(humerus, radius, ulna, and digits) yet perform very different functions such as grasping,
swimming, flying, and walking. These structures are best described as:
A. Analogous, resulting from convergent evolution under similar selective pressures
B. Vestigial, having lost virtually all of their original function
C. Homologous, reflecting inheritance of the same underlying construction from a
common ancestor [CORRECT]
D. Molecularly identical, reflecting unchanged DNA sequences across the four species
Correct Answer: C
Rationale: Homologous structures share the same underlying anatomical construction because they
were inherited from a common ancestor, even though natural selection has modified them for different
functions such as swimming, flying, or grasping. Option A describes structures similar in function but
different in construction, like bird and insect wings. Option B describes reduced remnants such as the
whale pelvis, and Option D is false because homology concerns structural and developmental
similarity, not identical DNA sequences.
Portage Learning | BIOD 102 Biology II 3
, BIOD 102 Biology II - Module 6 Exam | Portage Learning | 2026/2027
Q6: A bird's wing and a butterfly's wing both enable powered flight, but the bird wing is
supported by modified forelimb bones whereas the butterfly wing is a veined membrane
lacking any bones. Which conclusion about these structures is correct?
A. They are homologous, proving that birds and butterflies share a recent common
ancestor
B. They are vestigial remnants inherited from a single winged ancestral arthropod
C. They are analogous, having evolved independently through convergent evolution
[CORRECT]
D. They demonstrate that all flying animals inherited flight from one original flying
ancestor
Correct Answer: C
Rationale: The two wings serve the same function but have fundamentally different structures and
embryological origins, so they are analogous structures produced by convergent evolution, in which
similar selective pressures independently shaped unrelated lineages. This is exactly why wings cannot
be used as evidence of close common ancestry between birds and butterflies. Options A and D
incorrectly treat functional similarity as proof of shared descent, and Option B is wrong because
neither structure is a reduced, nonfunctional remnant.
Q7: Why are the human appendix, the pelvic bones of pythons and whales, and human wisdom
teeth considered evidence for evolution?
A. They are vestigial structures, reduced remnants of structures that were
functional in ancestral species [CORRECT]
B. They are homologous structures that are identical in every vertebrate species
C. They are analogous structures that evolved new digestive functions independently
D. They prove that humans evolved directly from modern snakes and whales
Correct Answer: A
Rationale: Vestigial structures are reduced or nonfunctional versions of features that served important
roles in ancestral organisms: the appendix is a remnant of a larger cellulose-digesting cecum, and pelvic
remnants trace to legged ancestors. Such leftover anatomy makes sense only as inheritance with
modification from ancestors in which the structures functioned. Option B is false because the
structures are not identical across vertebrates, Option C mislabels them as newly functional analogies,
and Option D commits the common error of linear descent from modern species rather than shared
ancestry.
Portage Learning | BIOD 102 Biology II 4
BIOD 102 Biology II - Module 6 Exam
Portage Learning | 2026/2027 Updated Edition | Answer Key with Detailed Rationales
COURSE MODULE FOCUS AREAS TOTAL QUESTIONS
BIOD 102 Evolution, Population Genetics, Speciation, Phylogeny,
Module 6 75 (Sections 1-6)
Biology II History of Life, Applications
Instructions: This examination contains 75 multiple-choice questions organized into six sections. Select the single
best answer for each question. For every item, the correct option is marked [CORRECT] and is followed by a
detailed rationale that explains the evolutionary mechanisms, evidence interpretation, or population-genetics
principles involved and identifies why each distractor is incorrect. Cognitive-level distribution: 30 percent recall,
50 percent application, 20 percent analysis.
SECTION 1
Principles of Evolution and Natural Selection
Darwinian Theory, Evidence for Evolution, and Mechanisms of Change | Questions 1-12
Q1: A population of beetles contains individuals ranging from light green to dark brown. Birds
preferentially eat the more conspicuous green beetles when they rest on dark tree bark, and
body color is a heritable trait. Over many generations, the population becomes predominantly
dark brown. Which principle of Darwin's theory of natural selection does this scenario
primarily demonstrate?
A. Organisms acquire beneficial traits during their lifetimes and pass those traits to their
offspring
B. Mutations arise in direct response to what the population needs for survival
C. Individuals with heritable traits that enhance survival and reproduction leave
more offspring [CORRECT]
D. All members of a population evolve simultaneously toward an ideal form
Correct Answer: C
Rationale: Natural selection acts on pre-existing heritable variation, producing differential
reproductive success: beetles carrying the dark-brown alleles survive bird predation and contribute
more offspring, so the allele frequencies shift across generations. Options A and B describe
Lamarckism and directed mutation, both discredited because traits are not acquired in response to need
during a lifetime. Option D wrongly implies that individuals evolve; populations evolve, and the
process is not goal-directed toward perfection.
Portage Learning | BIOD 102 Biology II 1
,BIOD 102 Biology II - Module 6 Exam | Portage Learning | 2026/2027
Q2: A student states: "Giraffes stretched their necks to reach high leaves during their lifetimes,
and their offspring were therefore born with longer necks." Which concept does this statement
incorrectly apply?
A. Uniformitarianism
B. Descent with modification
C. Catastrophism
D. Inheritance of acquired characteristics [CORRECT]
Correct Answer: D
Rationale: The statement is Lamarck's inheritance of acquired characteristics, the mistaken idea that
traits developed during an organism's lifetime are transmitted to its offspring. Modern genetics refutes
this: only changes present in germline DNA are heritable, so a stretched neck is a somatic change that
cannot reach the next generation. Option A names Lyell's geological principle of gradual uniform
processes, Option B, descent with modification, is Darwin's accurate summary of evolution, and
Option C is Cuvier's idea of sudden catastrophic extinctions.
Q3: Darwin's reading of Thomas Malthus's essay on human population growth contributed
directly to which insight in his theory of evolution by natural selection?
A. Earth must be millions of years old for gradual geological change to occur
B. More offspring are produced than resources can support, creating a struggle for
existence [CORRECT]
C. Island species typically resemble those of the nearest mainland
D. Species remain unchanged between fossil layers separated by catastrophe boundaries
Correct Answer: B
Rationale: Malthus argued that human populations grow faster than their food supplies, producing
inevitable competition; Darwin applied this logic to all organisms, recognizing that overproduction of
offspring with limited resources ensures that only some individuals survive to reproduce. This struggle
for existence is the engine that makes differential survival and selection possible. Option A came from
Lyell and Hutton, Option C reflects Darwin's biogeographic observations from the voyage of the
Beagle, and Option D is Cuvier's catastrophism, not Malthus's argument.
Portage Learning | BIOD 102 Biology II 2
,BIOD 102 Biology II - Module 6 Exam | Portage Learning | 2026/2027
Q4: In the Darwinian sense, which individual in a beetle population would be considered the
MOST biologically fit?
A. The largest and strongest beetle in the colony
B. The beetle with the most elaborate and striking coloration
C. The beetle that survives to the oldest age without reproducing
D. The beetle that leaves the greatest number of viable, fertile offspring
[CORRECT]
Correct Answer: D
Rationale: Evolutionary fitness is measured strictly by relative reproductive success, meaning the
contribution of viable, fertile offspring to the next generation's gene pool. Strength (Option A) and
showy traits (Option B) increase fitness only insofar as they improve reproduction, and survival without
reproduction (Option C) contributes zero genes to the next generation. Natural selection maximizes
gene transmission across generations, not longevity, size, or appearance for their own sakes.
Q5: The forelimbs of humans, whales, bats, and cats share the same arrangement of bones
(humerus, radius, ulna, and digits) yet perform very different functions such as grasping,
swimming, flying, and walking. These structures are best described as:
A. Analogous, resulting from convergent evolution under similar selective pressures
B. Vestigial, having lost virtually all of their original function
C. Homologous, reflecting inheritance of the same underlying construction from a
common ancestor [CORRECT]
D. Molecularly identical, reflecting unchanged DNA sequences across the four species
Correct Answer: C
Rationale: Homologous structures share the same underlying anatomical construction because they
were inherited from a common ancestor, even though natural selection has modified them for different
functions such as swimming, flying, or grasping. Option A describes structures similar in function but
different in construction, like bird and insect wings. Option B describes reduced remnants such as the
whale pelvis, and Option D is false because homology concerns structural and developmental
similarity, not identical DNA sequences.
Portage Learning | BIOD 102 Biology II 3
, BIOD 102 Biology II - Module 6 Exam | Portage Learning | 2026/2027
Q6: A bird's wing and a butterfly's wing both enable powered flight, but the bird wing is
supported by modified forelimb bones whereas the butterfly wing is a veined membrane
lacking any bones. Which conclusion about these structures is correct?
A. They are homologous, proving that birds and butterflies share a recent common
ancestor
B. They are vestigial remnants inherited from a single winged ancestral arthropod
C. They are analogous, having evolved independently through convergent evolution
[CORRECT]
D. They demonstrate that all flying animals inherited flight from one original flying
ancestor
Correct Answer: C
Rationale: The two wings serve the same function but have fundamentally different structures and
embryological origins, so they are analogous structures produced by convergent evolution, in which
similar selective pressures independently shaped unrelated lineages. This is exactly why wings cannot
be used as evidence of close common ancestry between birds and butterflies. Options A and D
incorrectly treat functional similarity as proof of shared descent, and Option B is wrong because
neither structure is a reduced, nonfunctional remnant.
Q7: Why are the human appendix, the pelvic bones of pythons and whales, and human wisdom
teeth considered evidence for evolution?
A. They are vestigial structures, reduced remnants of structures that were
functional in ancestral species [CORRECT]
B. They are homologous structures that are identical in every vertebrate species
C. They are analogous structures that evolved new digestive functions independently
D. They prove that humans evolved directly from modern snakes and whales
Correct Answer: A
Rationale: Vestigial structures are reduced or nonfunctional versions of features that served important
roles in ancestral organisms: the appendix is a remnant of a larger cellulose-digesting cecum, and pelvic
remnants trace to legged ancestors. Such leftover anatomy makes sense only as inheritance with
modification from ancestors in which the structures functioned. Option B is false because the
structures are not identical across vertebrates, Option C mislabels them as newly functional analogies,
and Option D commits the common error of linear descent from modern species rather than shared
ancestry.
Portage Learning | BIOD 102 Biology II 4
