PCB4674 Exam 2: Evolution Comprehensive Quiz 2026 – FSU
1. In the context of the Neutral Theory of Molecular Evolution, what does a
dN/dS ratio greater than 1 indicate?
A. Purifying selection is acting on the sequence.
B. The sequence is evolving under neutral drift.
C. The gene is likely a non-functional pseudogene.
D. Positive directional selection is favoring amino acid changes.
Answer: D
Rationale: A dN/dS ratio > 1 means non-synonymous substitutions are occurring faster
than synonymous ones, suggesting positive selection for new functional traits.
2. Which process is most likely to reduce genetic divergence between two
populations?
A. Gene flow
B. Genetic drift
C. Mutation
D. Directional selection
Answer: A
Rationale: Gene flow involves the transfer of alleles between populations, which tends to
homogenize them and decrease genetic differences.
,3. According to Hamilton’s Rule (rb > c), altruism is favored when:
A. The cost to the actor is higher than the benefit to the recipient.
B. The benefit to the recipient, weighted by relatedness, exceeds the cost.
C. The degree of relatedness is zero.
D. The actor and recipient are members of different species.
Answer: B
Rationale: Hamilton’s Rule states that kin selection favors altruistic behavior when the
benefit to the relative (b) multiplied by the relatedness (r) is greater than the cost (c) to the
performer.
4. What is the primary cause of Muller’s Ratchet in asexual populations?
A. The irreversible accumulation of deleterious mutations.
B. Rapid beneficial mutations.
C. Frequent genetic recombination.
D. High levels of horizontal gene transfer.
Answer: A
Rationale: Muller’s Ratchet describes the process by which the genomes of an asexual
population accumulate deleterious mutations irreversibly due to the lack of recombination.
5. In a phylogeny, a group consisting of a common ancestor and some, but not
all, of its descendants is called:
A. Monophyletic
B. Polyphyletic
C. Paraphyletic
D. An outgroup
Answer: C
Rationale: Paraphyletic groups include the common ancestor but exclude one or more
descendant groups (e.g., ‘reptiles’ excluding birds).
, 6. Which of the following is an example of a post-zygotic isolating mechanism?
A. Temporal isolation in flowering times.
B. Behavioral isolation in mating calls.
C. Mechanical isolation of genitalia.
D. Hybrid sterility.
Answer: D
Rationale: Hybrid sterility (like a mule) occurs after fertilization and zygote formation,
making it a post-zygotic barrier.
7. The ‘Red Queen Hypothesis’ suggests that organisms must constantly evolve
to:
A. Reach a state of perfect adaptation.
B. Survive against ever-evolving pathogens and competitors.
C. Increase their body size over geological time.
D. Transition from sexual to asexual reproduction.
Answer: B
Rationale: The Red Queen Hypothesis posits that species must constantly adapt and
proliferate to survive while pitted against ever-evolving opposing species.
8. What does the term ‘Synapomorphy’ refer to in cladistics?
A. An ancestral trait shared by all members of a clade.
B. A character state unique to a single terminal taxon.
C. A shared derived character state.
D. Convergent evolution of similar traits.
Answer: C
Rationale: A synapomorphy is a trait that is shared by two or more taxa and their most
recent common ancestor, whose own ancestor did not possess the trait.
1. In the context of the Neutral Theory of Molecular Evolution, what does a
dN/dS ratio greater than 1 indicate?
A. Purifying selection is acting on the sequence.
B. The sequence is evolving under neutral drift.
C. The gene is likely a non-functional pseudogene.
D. Positive directional selection is favoring amino acid changes.
Answer: D
Rationale: A dN/dS ratio > 1 means non-synonymous substitutions are occurring faster
than synonymous ones, suggesting positive selection for new functional traits.
2. Which process is most likely to reduce genetic divergence between two
populations?
A. Gene flow
B. Genetic drift
C. Mutation
D. Directional selection
Answer: A
Rationale: Gene flow involves the transfer of alleles between populations, which tends to
homogenize them and decrease genetic differences.
,3. According to Hamilton’s Rule (rb > c), altruism is favored when:
A. The cost to the actor is higher than the benefit to the recipient.
B. The benefit to the recipient, weighted by relatedness, exceeds the cost.
C. The degree of relatedness is zero.
D. The actor and recipient are members of different species.
Answer: B
Rationale: Hamilton’s Rule states that kin selection favors altruistic behavior when the
benefit to the relative (b) multiplied by the relatedness (r) is greater than the cost (c) to the
performer.
4. What is the primary cause of Muller’s Ratchet in asexual populations?
A. The irreversible accumulation of deleterious mutations.
B. Rapid beneficial mutations.
C. Frequent genetic recombination.
D. High levels of horizontal gene transfer.
Answer: A
Rationale: Muller’s Ratchet describes the process by which the genomes of an asexual
population accumulate deleterious mutations irreversibly due to the lack of recombination.
5. In a phylogeny, a group consisting of a common ancestor and some, but not
all, of its descendants is called:
A. Monophyletic
B. Polyphyletic
C. Paraphyletic
D. An outgroup
Answer: C
Rationale: Paraphyletic groups include the common ancestor but exclude one or more
descendant groups (e.g., ‘reptiles’ excluding birds).
, 6. Which of the following is an example of a post-zygotic isolating mechanism?
A. Temporal isolation in flowering times.
B. Behavioral isolation in mating calls.
C. Mechanical isolation of genitalia.
D. Hybrid sterility.
Answer: D
Rationale: Hybrid sterility (like a mule) occurs after fertilization and zygote formation,
making it a post-zygotic barrier.
7. The ‘Red Queen Hypothesis’ suggests that organisms must constantly evolve
to:
A. Reach a state of perfect adaptation.
B. Survive against ever-evolving pathogens and competitors.
C. Increase their body size over geological time.
D. Transition from sexual to asexual reproduction.
Answer: B
Rationale: The Red Queen Hypothesis posits that species must constantly adapt and
proliferate to survive while pitted against ever-evolving opposing species.
8. What does the term ‘Synapomorphy’ refer to in cladistics?
A. An ancestral trait shared by all members of a clade.
B. A character state unique to a single terminal taxon.
C. A shared derived character state.
D. Convergent evolution of similar traits.
Answer: C
Rationale: A synapomorphy is a trait that is shared by two or more taxa and their most
recent common ancestor, whose own ancestor did not possess the trait.
