BIO 102: PRINCIPLES OF BIOLOGY QUESTIONS AND ANSWERS
WITH RATIONALES/GRADED A+/2026 UPDATE/100% CORRECT
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Section A: Evolution, Biodiversity, and Ecology (Questions 1-25)
1. Which of the following is the best definition of evolution?
A. Changes in an individual organism during its lifetime
B. A change in allele frequencies in a population over generations
C. The development of new species in a single generation
D. The survival of the strongest individuals
Answer: B
Rationale: Evolution is defined as a change in allele frequencies in a population over time.
Individuals do not evolve (A). Speciation takes many generations (C). Survival of the fittest (D) is
a mechanism, not the definition.
2. Which of the following is required for natural selection to occur?
A. All individuals in a population are identical
B. Traits are acquired during an organisms lifetime and passed to offspring
C. Heritable variation exists within a population
D. The population is very small
Answer: C
Rationale: Natural selection requires heritable variation, differential survival and reproduction,
and overproduction of offspring. Identical individuals (A) provide no variation. Acquired traits (B)
are not inherited. Small populations (D) are more affected by genetic drift, not selection.
3. Which type of evidence for evolution examines the forelimbs of humans, cats, whales, and
bats, which share similar bone structures but different functions?
A. Molecular homology
, B. Analogous structures
C. Homologous structures
D. Vestigial structures
Answer: C
Rationale: Homologous structures are similar in origin and anatomy but serve different
functions, indicating common ancestry. Analogous structures (B) have similar functions but
different origins. Molecular homology (A) compares DNA or proteins. Vestigial structures (D) are
reduced remnants with no function.
4. Which scientist is credited with proposing the theory of evolution by natural selection
alongside Charles Darwin?
A. Gregor Mendel
B. Jean-Baptiste Lamarck
C. Alfred Russel Wallace
D. Thomas Malthus
Answer: C
Rationale: Alfred Russel Wallace independently conceived the theory of natural selection and
co-presented with Darwin in 1858. Mendel (A) founded genetics. Lamarck (B) proposed
inheritance of acquired characteristics. Malthus (D) influenced Darwin with population studies.
5. A population of beetles has two color variants: green and brown. Birds eat more brown
beetles than green beetles on vegetation. Over time, the green beetle population increases. This
is an example of:
A. Directional selection
B. Stabilizing selection
C. Disruptive selection
D. Sexual selection
Answer: A
Rationale: Directional selection favors one extreme phenotype (green) over the other (brown),
shifting the population mean. Stabilizing selection (B) favors intermediate traits. Disruptive
selection (C) favors both extremes. Sexual selection (D) involves mating advantage.
WITH RATIONALES/GRADED A+/2026 UPDATE/100% CORRECT
/INSTANT DOWNLOAD
Section A: Evolution, Biodiversity, and Ecology (Questions 1-25)
1. Which of the following is the best definition of evolution?
A. Changes in an individual organism during its lifetime
B. A change in allele frequencies in a population over generations
C. The development of new species in a single generation
D. The survival of the strongest individuals
Answer: B
Rationale: Evolution is defined as a change in allele frequencies in a population over time.
Individuals do not evolve (A). Speciation takes many generations (C). Survival of the fittest (D) is
a mechanism, not the definition.
2. Which of the following is required for natural selection to occur?
A. All individuals in a population are identical
B. Traits are acquired during an organisms lifetime and passed to offspring
C. Heritable variation exists within a population
D. The population is very small
Answer: C
Rationale: Natural selection requires heritable variation, differential survival and reproduction,
and overproduction of offspring. Identical individuals (A) provide no variation. Acquired traits (B)
are not inherited. Small populations (D) are more affected by genetic drift, not selection.
3. Which type of evidence for evolution examines the forelimbs of humans, cats, whales, and
bats, which share similar bone structures but different functions?
A. Molecular homology
, B. Analogous structures
C. Homologous structures
D. Vestigial structures
Answer: C
Rationale: Homologous structures are similar in origin and anatomy but serve different
functions, indicating common ancestry. Analogous structures (B) have similar functions but
different origins. Molecular homology (A) compares DNA or proteins. Vestigial structures (D) are
reduced remnants with no function.
4. Which scientist is credited with proposing the theory of evolution by natural selection
alongside Charles Darwin?
A. Gregor Mendel
B. Jean-Baptiste Lamarck
C. Alfred Russel Wallace
D. Thomas Malthus
Answer: C
Rationale: Alfred Russel Wallace independently conceived the theory of natural selection and
co-presented with Darwin in 1858. Mendel (A) founded genetics. Lamarck (B) proposed
inheritance of acquired characteristics. Malthus (D) influenced Darwin with population studies.
5. A population of beetles has two color variants: green and brown. Birds eat more brown
beetles than green beetles on vegetation. Over time, the green beetle population increases. This
is an example of:
A. Directional selection
B. Stabilizing selection
C. Disruptive selection
D. Sexual selection
Answer: A
Rationale: Directional selection favors one extreme phenotype (green) over the other (brown),
shifting the population mean. Stabilizing selection (B) favors intermediate traits. Disruptive
selection (C) favors both extremes. Sexual selection (D) involves mating advantage.
