BIOL180 Practice Exam 6 Evolution
and Natural Selection Questions And
Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
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1. Which statement best describes biological evolution?
A. The development of an individual organism during its lifetime
B. The tendency of organisms to become more complex over time
C. A change in the genetic composition of a population across
generations
D. The ability of an organism to respond behaviorally to its environment
Answer: C. A change in the genetic composition of a population across
generations
Rationale: Evolution occurs when the frequencies of heritable genetic
variants in a population change from one generation to the next.
Individual organisms do not evolve genetically during their lifetimes;
rather, populations evolve over generations. Evolution also does not
necessarily result in greater complexity because natural selection can
favor simpler, more efficient, or otherwise specialized characteristics.
2. What is the primary mechanism of natural selection?
A. Differential survival and reproduction of individuals with
heritable traits
B. Random production of identical offspring
,C. Acquisition of traits through repeated use
D. Directed mutation in response to environmental need
Answer: A. Differential survival and reproduction of individuals with
heritable traits
Rationale: Natural selection occurs when individuals possessing
heritable characteristics that improve survival or reproductive success
contribute more offspring to subsequent generations. Over time, the
advantageous traits become more common. Natural selection does not
intentionally direct mutations or guarantee that organisms become
better in every environment.
3. Which scientist is most closely associated with the theory of
natural selection?
A. Gregor Mendel
B. Louis Pasteur
C. James Watson
D. Charles Darwin
Answer: D. Charles Darwin
Rationale: Charles Darwin developed the theory of evolution by
natural selection and published his major evidence in On the Origin of
Species in 1859. Alfred Russel Wallace independently developed a
similar mechanism and communicated his ideas with Darwin. Mendel
contributed foundational work on heredity, while Watson was involved
in discovering the structure of DNA.
4. What observation is essential to the process of natural selection?
A. All individuals in a population are genetically identical.
B. Individuals within a population vary in their traits.
,C. Organisms intentionally modify their genes.
D. Every individual has the same reproductive success.
Answer: B. Individuals within a population vary in their traits.
Rationale: Variation among individuals provides the raw material on
which natural selection can act. For natural selection to produce
evolutionary change, at least some of the variation must be heritable
and associated with differences in reproductive success. If every
individual were genetically identical for a trait, selection could not
change the frequency of that trait.
5. Which statement about fitness in evolutionary biology is most
accurate?
A. Fitness means physical strength.
B. Fitness measures how long an organism lives.
C. Fitness refers to an organism's intelligence.
D. Fitness refers to relative reproductive success.
Answer: D. Fitness refers to relative reproductive success.
Rationale: Evolutionary fitness is measured by an individual's
contribution of viable, fertile offspring to future generations relative to
others in the population. A physically strong organism may have low
evolutionary fitness if it produces few offspring. Likewise, an organism
that survives for a long time may have little evolutionary impact if it
does not reproduce successfully.
6. Which condition is required for natural selection to cause
evolutionary change?
A. All mutations must be beneficial.
B. Individuals must consciously choose advantageous traits.
C. Variation in a trait must be heritable and associated with
, differences in reproductive success.
D. Every environmental change must cause mutation.
Answer: C. Variation in a trait must be heritable and associated with
differences in reproductive success.
Rationale: Natural selection changes populations when individuals
differ in heritable traits and those differences influence survival or
reproduction. If a trait is not heritable, selection on that trait will not
reliably cause its frequency to increase in subsequent generations.
Mutations can be neutral, harmful, or beneficial and are not produced
because an organism needs them.
7. What is the ultimate source of new genetic variation?
A. Mutation
B. Natural selection
C. Genetic drift
D. Migration alone
Answer: A. Mutation
Rationale: Mutations are changes in DNA sequence and provide new
genetic variants. Recombination, independent assortment, and
crossing over rearrange existing genetic variation, while gene flow can
introduce variants from other populations. Natural selection and
genetic drift change the frequencies of existing variants but do not
create new alleles.
8. Which process involves the movement of alleles between
populations?
A. Genetic drift
B. Gene flow
and Natural Selection Questions And
Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which statement best describes biological evolution?
A. The development of an individual organism during its lifetime
B. The tendency of organisms to become more complex over time
C. A change in the genetic composition of a population across
generations
D. The ability of an organism to respond behaviorally to its environment
Answer: C. A change in the genetic composition of a population across
generations
Rationale: Evolution occurs when the frequencies of heritable genetic
variants in a population change from one generation to the next.
Individual organisms do not evolve genetically during their lifetimes;
rather, populations evolve over generations. Evolution also does not
necessarily result in greater complexity because natural selection can
favor simpler, more efficient, or otherwise specialized characteristics.
2. What is the primary mechanism of natural selection?
A. Differential survival and reproduction of individuals with
heritable traits
B. Random production of identical offspring
,C. Acquisition of traits through repeated use
D. Directed mutation in response to environmental need
Answer: A. Differential survival and reproduction of individuals with
heritable traits
Rationale: Natural selection occurs when individuals possessing
heritable characteristics that improve survival or reproductive success
contribute more offspring to subsequent generations. Over time, the
advantageous traits become more common. Natural selection does not
intentionally direct mutations or guarantee that organisms become
better in every environment.
3. Which scientist is most closely associated with the theory of
natural selection?
A. Gregor Mendel
B. Louis Pasteur
C. James Watson
D. Charles Darwin
Answer: D. Charles Darwin
Rationale: Charles Darwin developed the theory of evolution by
natural selection and published his major evidence in On the Origin of
Species in 1859. Alfred Russel Wallace independently developed a
similar mechanism and communicated his ideas with Darwin. Mendel
contributed foundational work on heredity, while Watson was involved
in discovering the structure of DNA.
4. What observation is essential to the process of natural selection?
A. All individuals in a population are genetically identical.
B. Individuals within a population vary in their traits.
,C. Organisms intentionally modify their genes.
D. Every individual has the same reproductive success.
Answer: B. Individuals within a population vary in their traits.
Rationale: Variation among individuals provides the raw material on
which natural selection can act. For natural selection to produce
evolutionary change, at least some of the variation must be heritable
and associated with differences in reproductive success. If every
individual were genetically identical for a trait, selection could not
change the frequency of that trait.
5. Which statement about fitness in evolutionary biology is most
accurate?
A. Fitness means physical strength.
B. Fitness measures how long an organism lives.
C. Fitness refers to an organism's intelligence.
D. Fitness refers to relative reproductive success.
Answer: D. Fitness refers to relative reproductive success.
Rationale: Evolutionary fitness is measured by an individual's
contribution of viable, fertile offspring to future generations relative to
others in the population. A physically strong organism may have low
evolutionary fitness if it produces few offspring. Likewise, an organism
that survives for a long time may have little evolutionary impact if it
does not reproduce successfully.
6. Which condition is required for natural selection to cause
evolutionary change?
A. All mutations must be beneficial.
B. Individuals must consciously choose advantageous traits.
C. Variation in a trait must be heritable and associated with
, differences in reproductive success.
D. Every environmental change must cause mutation.
Answer: C. Variation in a trait must be heritable and associated with
differences in reproductive success.
Rationale: Natural selection changes populations when individuals
differ in heritable traits and those differences influence survival or
reproduction. If a trait is not heritable, selection on that trait will not
reliably cause its frequency to increase in subsequent generations.
Mutations can be neutral, harmful, or beneficial and are not produced
because an organism needs them.
7. What is the ultimate source of new genetic variation?
A. Mutation
B. Natural selection
C. Genetic drift
D. Migration alone
Answer: A. Mutation
Rationale: Mutations are changes in DNA sequence and provide new
genetic variants. Recombination, independent assortment, and
crossing over rearrange existing genetic variation, while gene flow can
introduce variants from other populations. Natural selection and
genetic drift change the frequencies of existing variants but do not
create new alleles.
8. Which process involves the movement of alleles between
populations?
A. Genetic drift
B. Gene flow
