PCB4674 Exam 1: Evolution 2026 – FSU
1. What is the primary definition of biological fitness in an evolutionary context?
A. The relative contribution of an individual to the gene pool of the next generation
B. The ability of an organism to survive for many years
C. The physical strength and speed of an organism
D. The complexity of an organism’s social structure
Answer: A
Rationale: Fitness is defined by reproductive success; it is the ability of an individual to
pass its genes to the next generation relative to others in the population.
2. Which of the following is an example of a vestigial structure?
A. The wing of a bat used for flight
B. The human tailbone (coccyx)
C. The streamline body of a shark
D. The long neck of a giraffe
Answer: B
Rationale: Vestigial structures are remnants of features that served a function in an
organism’s ancestors but no longer serve a significant purpose.
,3. In a population in Hardy-Weinberg equilibrium, if the frequency of the
recessive allele (q) is 0.3, what is the frequency of the homozygous dominant
genotype?
A. 0.09
B. 0.70
C. 0.42
D. 0.49
Answer: D
Rationale: If q = 0.3, then p = 1 - 0.3 = 0.7. The frequency of the homozygous dominant
genotype (p^2) is 0.7 * 0.7 = 0.49.
4. Which evolutionary force is most likely to lead to a decrease in genetic
variation within a small, isolated population?
A. Genetic drift
B. Gene flow
C. Mutation
D. Random mating
Answer: A
Rationale: Genetic drift describes random fluctuations in allele frequencies, which can lead
to the loss of alleles and reduced genetic variation, especially in small populations.
5. Which of the following was a key contribution of Thomas Malthus to Darwin’s
theory of evolution?
A. The realization that populations produce more offspring than can survive
B. The idea that acquired characteristics are inherited
C. The concept of deep time and geological change
D. The discovery of the laws of inheritance
Answer: A
, Rationale: Malthus’s essay on population growth suggested that resources are limited and
populations grow faster than food supplies, leading to a struggle for existence.
6. What is the term for the process where unrelated species evolve similar traits
due to similar environmental pressures?
A. Parallel evolution
B. Divergent evolution
C. Coevolution
D. Convergent evolution
Answer: D
Rationale: Convergent evolution occurs when different lineages evolve similar analogous
traits independently, such as the wings of insects and birds.
7. Which type of selection favors individuals at both extremes of a phenotypic
range over those with intermediate phenotypes?
A. Disruptive selection
B. Directional selection
C. Stabilizing selection
D. Sexual selection
Answer: A
Rationale: Disruptive selection (or diversifying selection) favors the extremes, which can
potentially lead to speciation.
8. Which of the following describes a ‘synapomorphy’?
A. A trait shared by a group but not their common ancestor
B. A primitive trait shared by all members of a clade
C. A unique trait found only in a single species
D. A shared derived character that defines a monophyletic group
Answer: D
1. What is the primary definition of biological fitness in an evolutionary context?
A. The relative contribution of an individual to the gene pool of the next generation
B. The ability of an organism to survive for many years
C. The physical strength and speed of an organism
D. The complexity of an organism’s social structure
Answer: A
Rationale: Fitness is defined by reproductive success; it is the ability of an individual to
pass its genes to the next generation relative to others in the population.
2. Which of the following is an example of a vestigial structure?
A. The wing of a bat used for flight
B. The human tailbone (coccyx)
C. The streamline body of a shark
D. The long neck of a giraffe
Answer: B
Rationale: Vestigial structures are remnants of features that served a function in an
organism’s ancestors but no longer serve a significant purpose.
,3. In a population in Hardy-Weinberg equilibrium, if the frequency of the
recessive allele (q) is 0.3, what is the frequency of the homozygous dominant
genotype?
A. 0.09
B. 0.70
C. 0.42
D. 0.49
Answer: D
Rationale: If q = 0.3, then p = 1 - 0.3 = 0.7. The frequency of the homozygous dominant
genotype (p^2) is 0.7 * 0.7 = 0.49.
4. Which evolutionary force is most likely to lead to a decrease in genetic
variation within a small, isolated population?
A. Genetic drift
B. Gene flow
C. Mutation
D. Random mating
Answer: A
Rationale: Genetic drift describes random fluctuations in allele frequencies, which can lead
to the loss of alleles and reduced genetic variation, especially in small populations.
5. Which of the following was a key contribution of Thomas Malthus to Darwin’s
theory of evolution?
A. The realization that populations produce more offspring than can survive
B. The idea that acquired characteristics are inherited
C. The concept of deep time and geological change
D. The discovery of the laws of inheritance
Answer: A
, Rationale: Malthus’s essay on population growth suggested that resources are limited and
populations grow faster than food supplies, leading to a struggle for existence.
6. What is the term for the process where unrelated species evolve similar traits
due to similar environmental pressures?
A. Parallel evolution
B. Divergent evolution
C. Coevolution
D. Convergent evolution
Answer: D
Rationale: Convergent evolution occurs when different lineages evolve similar analogous
traits independently, such as the wings of insects and birds.
7. Which type of selection favors individuals at both extremes of a phenotypic
range over those with intermediate phenotypes?
A. Disruptive selection
B. Directional selection
C. Stabilizing selection
D. Sexual selection
Answer: A
Rationale: Disruptive selection (or diversifying selection) favors the extremes, which can
potentially lead to speciation.
8. Which of the following describes a ‘synapomorphy’?
A. A trait shared by a group but not their common ancestor
B. A primitive trait shared by all members of a clade
C. A unique trait found only in a single species
D. A shared derived character that defines a monophyletic group
Answer: D
