AP Biology Practice Quiz: Mutations
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 16 questions to check your progress.
Question 1 of 16
All Questions (16)
A) An alteration in a DNA sequence.
B) A change that is always detrimental to an organism.
C) An error that occurs exclusively during meiosis.
D) A change in an organism's phenotype.
Correct Answer: A
The text explicitly states, 'Mutations are alterations in a DNA sequence.' The other options are either incorrect characterizations (mutations can be neutral or beneficial) or describe potential causes or effects, not the definition itself.
A) The process of natural selection.
B) Phenotypes that enhance survival.
C) Random mutations.
D) Changes in chromosome number during mitosis.
Correct Answer: C
The text states, 'Random mutations... are a primary source of genetic variation.' Natural selection acts on this variation but does not create it. Phenotypes are the expression of the genotype, and while changes in chromosome number are a type of mutation, 'random mutations' is the broader, primary source mentioned.
A) By causing nondisjunction during mitosis, which alters the environment.
B) By altering the DNA sequence, which can change the protein produced.
C) By directly responding to environmental pressures to ensure survival.
D) By preventing DNA replication or repair from occurring.
Correct Answer: B
The content explains that 'Mutations are alterations in a DNA sequence that can change the protein produced and the resulting phenotype.' This directly links the change in genotype (DNA sequence) to the potential change in phenotype through protein production.
A) Only beneficial or detrimental.
B) Only neutral.
C) Beneficial, neutral, or detrimental.
D) Always resulting in a visible change in phenotype.
Correct Answer: C
The text clearly states that mutations 'can be beneficial, neutral, or detrimental.' This indicates that they can have a range of effects on an organism's fitness and phenotype.
A) A change in a single protein's amino acid sequence.
B) An error in the DNA repair mechanism.
C) A change in the number of chromosomes.
D) A random mutation caused by an external factor.
Correct Answer: C
The content specifies that 'Errors in mitosis or meiosis, such as nondisjunction, can result in changes in chromosome number and phenotype.' This distinguishes it from mutations that alter a single DNA sequence.
A) Natural selection causes random mutations to occur.
B) Mutations provide the variation upon which natural selection can act.
C) All mutations are selected against by natural selection.
D) Natural selection and mutations are independent processes with no interaction.
Correct Answer: B
The text explains that 'alterations in DNA sequences contribute to variation that can be subject to natural selection' and that 'Genetic changes that enhance survival can be selected for.' This shows that mutations create variation, and natural selection acts on that variation.
A) The process of natural selection.
B) Changes in an organism's phenotype.
C) Errors in DNA replication or repair.
D) Changes in chromosome number.
Correct Answer: C
The text states, 'Random mutations can be caused by errors in DNA replication or repair, or by external factors.' The other options describe consequences or related concepts, not direct causes of random mutations.
A) When it is a neutral mutation.
B) When it results from nondisjunction.
C) When it enhances survival.
D) When it is caused by an external factor.
Correct Answer: C
According to the text, 'Genetic changes that enhance survival can be selected for by environmental pressures.' This highlights the core principle of natural selection acting on beneficial traits.
A) Beneficial
B) Detrimental
C) Neutral
D) A result of nondisjunction
Correct Answer: C
Since the mutation did not change the protein, it would not alter the phenotype in a way that affects survival. Therefore, it would be considered neutral. The text states mutations can be 'beneficial, neutral, or detrimental,' and a no-change outcome fits the definition of neutral.
A) They ensure that all phenotypes are identical, which increases survival.
B) They are caused by natural selection to create new traits on demand.
C) They introduce new genotypes, which may result in new phenotypes.
D) They only occur during meiosis, ensuring offspring are different from parents.
Correct Answer: C
The text links alterations in DNA (genotype) to changes in proteins and phenotypes. This creation of new genotypes/phenotypes is the basis of the variation that 'can be subject to natural selection.' The other options misrepresent the cause or effect of mutations.
A) DNA repair.
B) DNA replication.
C) Mitosis or meiosis.
D) Protein synthesis.
Correct Answer: C
The content directly states, 'Errors in mitosis or meiosis, such as nondisjunction, can result in changes in chromosome number and phenotype.' This links the chromosomal abnormality to cell division processes.
A) Mutations are always harmful errors in DNA replication that natural selection removes from a population.
B) Mutations are deliberate changes in DNA that organisms make to adapt to new environments.
C) Mutations are random changes in DNA that create genetic diversity, which can then be acted upon by natural selection.
D) Mutations are exclusively large-scale changes in chromosome number that lead to new species.
Correct Answer: C
This statement correctly combines several key points from the text: mutations are random alterations in DNA (points 4, 5), they are a primary source of genetic variation (point 5), and this variation is subject to natural selection (points 3, 7).
A) A replication error alters a DNA sequence, while nondisjunction changes chromosome number.
B) A replication error is always neutral, while nondisjunction is always detrimental.
C) A replication error is caused by external factors, while nondisjunction is an error in DNA repair.
D) A replication error affects phenotype, while nondisjunction affects genotype.
Correct Answer: A
The text describes mutations as 'alterations in a DNA sequence' and mentions they can be caused by 'errors in DNA replication.' It separately describes nondisjunction as an error in mitosis/meiosis that results in 'changes in chromosome number.' This highlights the difference in scale and mechanism between the two types of alterations.
A) The population has a very high rate of beneficial mutations.
B) Natural selection is not occurring in this population's environment.
C) The primary source of genetic variation, random mutation, is occurring at a very low rate.
D) All mutations in the population are caused by errors in mitosis.
Correct Answer: C
The text establishes that random mutations are the 'primary source of genetic variation' and that changes in genotype can lead to changes in phenotype. If there is little phenotypic variation, it is logical to infer that the source of that variation (mutation) may be infrequent.
A) An error made by an enzyme during DNA replication.
B) A failure of chromosomes to separate during meiosis.
C) Exposure to radiation that damages a DNA molecule.
D) A genetic change that enhances survival.
Correct Answer: C
An error during replication or meiosis is an internal cellular process. A genetic change that enhances survival is a description of a mutation's effect, not its cause. Exposure to an environmental agent like radiation is an external factor that can cause a mutation.
A) Change in phenotype → Natural selection → Alteration in DNA sequence
B) Alteration in DNA sequence → Change in protein/phenotype → Natural selection
C) Natural selection → Alteration in DNA sequence → Change in phenotype
D) Change in protein → Alteration in DNA sequence → Natural selection
Correct Answer: B
The text explains that an alteration in a DNA sequence (mutation) can change the protein produced, resulting in a new phenotype. This new phenotype is then subject to natural selection based on environmental pressures. This matches the sequence in option B.