PCB4674 Exam 1: Evolution (Comprehensive Review) 2026 – FSU
1. Which of the following best defines biological evolution?
A. Change in the properties of groups of organisms over the course of generations.
B. The survival of the physically strongest individuals in a population.
C. The process by which an individual adapts to its environment during its lifetime.
D. A linear progression from simple to complex organisms.
Answer: A
Rationale: Evolution is defined as the change in allele frequencies or inherited traits
within a population across generations, not changes within a single individual.
2. In a phylogenetic tree, what does a ‘node’ represent?
A. The extinction of a lineage.
B. The most recent common ancestor of the descendant lineages.
C. The accumulation of mutations in a single species.
D. A specific phenotypic trait shared by all members.
Answer: B
Rationale: Nodes represent branching points where an ancestral lineage splits into two or
more descendant lineages, marking their common ancestor.
3. Which mechanism of evolution is entirely stochastic (random) in its effect on
allele frequencies?
A. Natural Selection
B. Genetic Drift
C. Sexual Selection
D. Gene Flow
Answer: B
,Rationale: Genetic drift refers to random fluctuations in allele frequencies due to chance
events, especially prevalent in small populations.
4. The concept of ‘Uniformitarianism,’ which influenced Darwin, was proposed
by whom?
A. Jean-Baptiste Lamarck
B. Alfred Russel Wallace
C. Thomas Malthus
D. Charles Lyell
Answer: D
Rationale: Lyell argued that the same geological processes occurring today have been
happening throughout Earth’s history at the same rate.
5. What is a synapomorphy?
A. A primitive character state shared by all taxa.
B. A derived character state shared by two or more groups and their common ancestor.
C. A trait that evolved independently in two different lineages.
D. A trait that is unique to a single terminal taxon.
Answer: B
Rationale: Synapomorphies are shared derived characters used to define monophyletic
groups in cladistics.
6. Under the Hardy-Weinberg equilibrium, if the frequency of allele ‘p’ is 0.7,
what is the frequency of the heterozygotes?
A. 0.49
B. 0.09
C. 0.21
D. 0.42
Answer: D
, Rationale: Using 2pq: p=0.7, q=0.3. 2 * 0.7 * 0.3 = 0.42.
7. Which type of selection favors individuals at both extremes of a trait’s
distribution?
A. Stabilizing selection
B. Directional selection
C. Disruptive selection
D. Purifying selection
Answer: C
Rationale: Disruptive selection increases variation by favoring extreme phenotypes over
intermediate ones.
8. The ‘Modern Synthesis’ effectively unified which two fields?
A. Geology and Astronomy
B. Microbiology and Chemistry
C. Ecology and Behavioral Science
D. Darwinian Selection and Mendelian Genetics
Answer: D
Rationale: The Modern Synthesis bridged the gap between natural selection and the
particulate inheritance of genes.
9. Which of the following is an example of homology?
A. The wings of a butterfly and the wings of a bat.
B. The streamlined body shape of a shark and a dolphin.
C. The eyes of an octopus and the eyes of a human.
D. The forelimbs of a human and the flippers of a whale.
Answer: D
Rationale: Homology refers to traits inherited from a common ancestor, like the
pentadactyl limb structure in mammals.
1. Which of the following best defines biological evolution?
A. Change in the properties of groups of organisms over the course of generations.
B. The survival of the physically strongest individuals in a population.
C. The process by which an individual adapts to its environment during its lifetime.
D. A linear progression from simple to complex organisms.
Answer: A
Rationale: Evolution is defined as the change in allele frequencies or inherited traits
within a population across generations, not changes within a single individual.
2. In a phylogenetic tree, what does a ‘node’ represent?
A. The extinction of a lineage.
B. The most recent common ancestor of the descendant lineages.
C. The accumulation of mutations in a single species.
D. A specific phenotypic trait shared by all members.
Answer: B
Rationale: Nodes represent branching points where an ancestral lineage splits into two or
more descendant lineages, marking their common ancestor.
3. Which mechanism of evolution is entirely stochastic (random) in its effect on
allele frequencies?
A. Natural Selection
B. Genetic Drift
C. Sexual Selection
D. Gene Flow
Answer: B
,Rationale: Genetic drift refers to random fluctuations in allele frequencies due to chance
events, especially prevalent in small populations.
4. The concept of ‘Uniformitarianism,’ which influenced Darwin, was proposed
by whom?
A. Jean-Baptiste Lamarck
B. Alfred Russel Wallace
C. Thomas Malthus
D. Charles Lyell
Answer: D
Rationale: Lyell argued that the same geological processes occurring today have been
happening throughout Earth’s history at the same rate.
5. What is a synapomorphy?
A. A primitive character state shared by all taxa.
B. A derived character state shared by two or more groups and their common ancestor.
C. A trait that evolved independently in two different lineages.
D. A trait that is unique to a single terminal taxon.
Answer: B
Rationale: Synapomorphies are shared derived characters used to define monophyletic
groups in cladistics.
6. Under the Hardy-Weinberg equilibrium, if the frequency of allele ‘p’ is 0.7,
what is the frequency of the heterozygotes?
A. 0.49
B. 0.09
C. 0.21
D. 0.42
Answer: D
, Rationale: Using 2pq: p=0.7, q=0.3. 2 * 0.7 * 0.3 = 0.42.
7. Which type of selection favors individuals at both extremes of a trait’s
distribution?
A. Stabilizing selection
B. Directional selection
C. Disruptive selection
D. Purifying selection
Answer: C
Rationale: Disruptive selection increases variation by favoring extreme phenotypes over
intermediate ones.
8. The ‘Modern Synthesis’ effectively unified which two fields?
A. Geology and Astronomy
B. Microbiology and Chemistry
C. Ecology and Behavioral Science
D. Darwinian Selection and Mendelian Genetics
Answer: D
Rationale: The Modern Synthesis bridged the gap between natural selection and the
particulate inheritance of genes.
9. Which of the following is an example of homology?
A. The wings of a butterfly and the wings of a bat.
B. The streamlined body shape of a shark and a dolphin.
C. The eyes of an octopus and the eyes of a human.
D. The forelimbs of a human and the flippers of a whale.
Answer: D
Rationale: Homology refers to traits inherited from a common ancestor, like the
pentadactyl limb structure in mammals.
