,BIOD 102 Module 5 | Q&A | 2026/2027 | Essential Biology | Portage
Learning
1. The primary mechanism by which populations of organisms change over
time in response to their environment is called:
A) Genetic drift
B) Natural selection
C) Gene flow
D) Mutation
Correct Answer: Natural selection
Rationale: Natural selection is the process by which individuals with traits
that are better suited to their environment are more likely to survive and
reproduce, passing those advantageous traits to future generations. Genetic
drift is random, gene flow involves migration, and mutation is the source of
new alleles.
2. Genetic drift is best defined as:
A) The movement of alleles between populations
B) The differential survival and reproduction of individuals based on their
traits
C) A random change in allele frequencies, especially significant in small
populations
D) The introduction of new alleles through mutation
Correct Answer: A random change in allele frequencies, especially significant
in small populations
Rationale: Genetic drift refers to random fluctuations in allele frequencies
due to chance events, which are particularly pronounced in small
,populations. This can lead to the loss of genetic diversity and is distinct from
natural selection.
3. The movement of alleles from one population to another is called:
A) Genetic drift
B) Natural selection
C) Gene flow
D) Speciation
Correct Answer: Gene flow
Rationale: Gene flow is the transfer of genetic material between populations
through migration or interbreeding. It can introduce new alleles and reduce
genetic differences between populations.
4. Which of the following is required for natural selection to occur?
A) Genetic variation within a population
B) A stable, unchanging environment
C) All individuals having identical traits
D) The absence of mutations
Correct Answer: Genetic variation within a population
Rationale: Natural selection acts on heritable variation within a population.
Without variation, there are no traits for selection to act upon. Mutations
provide the raw material for this variation.
5. An adaptation is best described as:
, A) A trait that an organism acquires during its lifetime
B) A heritable trait that increases an organism's fitness in its environment
C) A random change in allele frequencies
D) The movement of individuals between populations
Correct Answer: A heritable trait that increases an organism's fitness in its
environment
Rationale: Adaptations are traits that enhance an organism's ability to
survive and reproduce in a particular environment. They arise through
natural selection and are heritable.
6. The biological species concept defines a species as:
A) A group of organisms that look alike
B) A group of organisms that share a common ancestor
C) A group of populations that can interbreed and produce viable, fertile
offspring
D) A group of organisms that occupy the same niche
Correct Answer: A group of populations that can interbreed and produce
viable, fertile offspring
Rationale: The biological species concept defines a species based on
reproductive compatibility. Organisms that can interbreed and produce
viable, fertile offspring are considered members of the same species.
7. Which of the following is an example of a prezygotic isolating mechanism?
A) Hybrid sterility
B) Temporal isolation
Learning
1. The primary mechanism by which populations of organisms change over
time in response to their environment is called:
A) Genetic drift
B) Natural selection
C) Gene flow
D) Mutation
Correct Answer: Natural selection
Rationale: Natural selection is the process by which individuals with traits
that are better suited to their environment are more likely to survive and
reproduce, passing those advantageous traits to future generations. Genetic
drift is random, gene flow involves migration, and mutation is the source of
new alleles.
2. Genetic drift is best defined as:
A) The movement of alleles between populations
B) The differential survival and reproduction of individuals based on their
traits
C) A random change in allele frequencies, especially significant in small
populations
D) The introduction of new alleles through mutation
Correct Answer: A random change in allele frequencies, especially significant
in small populations
Rationale: Genetic drift refers to random fluctuations in allele frequencies
due to chance events, which are particularly pronounced in small
,populations. This can lead to the loss of genetic diversity and is distinct from
natural selection.
3. The movement of alleles from one population to another is called:
A) Genetic drift
B) Natural selection
C) Gene flow
D) Speciation
Correct Answer: Gene flow
Rationale: Gene flow is the transfer of genetic material between populations
through migration or interbreeding. It can introduce new alleles and reduce
genetic differences between populations.
4. Which of the following is required for natural selection to occur?
A) Genetic variation within a population
B) A stable, unchanging environment
C) All individuals having identical traits
D) The absence of mutations
Correct Answer: Genetic variation within a population
Rationale: Natural selection acts on heritable variation within a population.
Without variation, there are no traits for selection to act upon. Mutations
provide the raw material for this variation.
5. An adaptation is best described as:
, A) A trait that an organism acquires during its lifetime
B) A heritable trait that increases an organism's fitness in its environment
C) A random change in allele frequencies
D) The movement of individuals between populations
Correct Answer: A heritable trait that increases an organism's fitness in its
environment
Rationale: Adaptations are traits that enhance an organism's ability to
survive and reproduce in a particular environment. They arise through
natural selection and are heritable.
6. The biological species concept defines a species as:
A) A group of organisms that look alike
B) A group of organisms that share a common ancestor
C) A group of populations that can interbreed and produce viable, fertile
offspring
D) A group of organisms that occupy the same niche
Correct Answer: A group of populations that can interbreed and produce
viable, fertile offspring
Rationale: The biological species concept defines a species based on
reproductive compatibility. Organisms that can interbreed and produce
viable, fertile offspring are considered members of the same species.
7. Which of the following is an example of a prezygotic isolating mechanism?
A) Hybrid sterility
B) Temporal isolation
