Complete Exam Guide Subject-wise practice platform
0 XP
Genetics

Mutations Practice Questions

39 free Mutations practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.

Practice in Quiz Mode

Question 1 of 39 Medium

Which type of mutation involves a change in a single nucleotide pair?

  1. A Chromosomal mutation
  2. B Frameshift mutation
  3. C Point mutation
  4. D Genome mutation

Correct answer: Point mutation

Point mutations affect a single nucleotide pair in the DNA. They are the smallest scale of genetic mutations.

Question 2 of 39 Medium

A substitution mutation that does not alter the amino acid sequence is called:

  1. A Missense mutation
  2. B Nonsense mutation
  3. C Silent mutation
  4. D Frameshift mutation

Correct answer: Silent mutation

Silent mutations change a codon without changing the amino acid due to redundancy in the genetic code. Protein function usually remains unaffected.

Question 3 of 39 Medium

Which mutation results in the formation of a premature stop codon?

  1. A Silent mutation
  2. B Missense mutation
  3. C Nonsense mutation
  4. D Insertion mutation

Correct answer: Nonsense mutation

Nonsense mutations convert an amino acid codon into a stop codon. This leads to truncated and usually nonfunctional proteins.

Question 4 of 39 Medium

Frameshift mutations are typically caused by:

  1. A Base substitutions occurring during replication
  2. B Insertion or deletion of nucleotides
  3. C Chromosome duplication
  4. D Polyploidy

Correct answer: Insertion or deletion of nucleotides

Frameshift mutations occur when nucleotides are inserted or deleted in numbers not divisible by three. This shifts the reading frame of the gene.

Question 5 of 39 Medium

Which of the following is a chromosomal structural mutation?

  1. A Point mutation
  2. B Deletion
  3. C Missense mutation
  4. D Silent mutation

Correct answer: Deletion

Deletion involves the loss of a segment of a chromosome. It is classified as a chromosomal structural mutation.

Question 6 of 39 Medium

Which agent is considered a physical mutagen?

  1. A Ethyl methanesulfonate
  2. B Ultraviolet radiation
  3. C Nitrous acid
  4. D Acridine dyes

Correct answer: Ultraviolet radiation

Ultraviolet radiation is a physical mutagen that induces DNA damage such as thymine dimers. It interferes with DNA replication.

Question 7 of 39 Medium

Chemical mutagens such as base analogs cause mutations by:

  1. A Breaking chromosomes into fragmented pieces
  2. B Replacing normal bases during replication
  3. C Inhibiting transcription
  4. D Preventing DNA repair

Correct answer: Replacing normal bases during replication

Base analogs resemble normal DNA bases and can be incorporated during replication. This leads to incorrect base pairing and mutations.

Question 8 of 39 Medium

Which mutation alters a codon so that it codes for a different amino acid?

  1. A Silent synonymous mutation
  2. B Nonsense mutation
  3. C Missense mutation
  4. D Deletion mutation

Correct answer: Missense mutation

Missense mutations change one amino acid in the protein sequence. This may alter protein structure or function.

Question 9 of 39 Medium

A mutation that affects somatic cells will:

  1. A Be inherited by offspring
  2. B Affect only the individual
  3. C Always be lethal
  4. D Cause chromosomal abnormalities in gametes

Correct answer: Affect only the individual

Somatic mutations occur in body cells and are not passed to offspring. Their effects are limited to the individual.

Question 10 of 39 Medium

Which of the following is an example of a genome mutation?

  1. A Deletion
  2. B Inversion
  3. C Polyploidy
  4. D Point mutation

Correct answer: Polyploidy

Genome mutations involve changes in the number of chromosome sets. Polyploidy results in more than two complete sets of chromosomes.

Question 11 of 39 Medium

Ionizing radiation causes mutations primarily by:

  1. A Base substitution
  2. B Formation of thymine dimers
  3. C Breakage of DNA strands
  4. D Insertion of nucleotides

Correct answer: Breakage of DNA strands

Ionizing radiation produces free radicals that break DNA strands. These breaks can result in severe chromosomal mutations.

Question 12 of 39 Medium

Which chromosomal mutation involves reversal of a chromosome segment?

  1. A Deletion
  2. B Duplication
  3. C Inversion
  4. D Translocation

Correct answer: Inversion

Inversion occurs when a chromosome segment breaks and reinserts in the opposite orientation. This alters gene order.

Question 13 of 39 Medium

Which mutation is most likely to have a severe effect on protein function?

  1. A Silent mutation
  2. B Conservative missense mutation
  3. C Frameshift mutation
  4. D Neutral substitution

Correct answer: Frameshift mutation

Frameshift mutations alter the entire downstream amino acid sequence. This often produces nonfunctional proteins.

Question 14 of 39 Medium

Mutations that occur naturally without external agents are called:

  1. A Chemically induced mutations
  2. B Artificial mutations
  3. C Spontaneous mutations
  4. D Lethal mutations

Correct answer: Spontaneous mutations

Spontaneous mutations arise from errors during DNA replication or repair. They occur without exposure to mutagens.

Question 15 of 39 Medium

Which enzyme system primarily helps correct replication errors to reduce mutations?

  1. A RNA-dependent polymerase enzymes
  2. B DNA ligase
  3. C DNA proofreading enzymes
  4. D Reverse transcriptase

Correct answer: DNA proofreading enzymes

DNA polymerases have proofreading activity that corrects mismatched bases. This greatly reduces mutation rates.

Question 16 of 39 Medium

Which consequence of mutation provides raw material for evolution?

  1. A Genetic variation
  2. B Genetic uniformity
  3. C Reduced adaptability
  4. D Species extinction

Correct answer: Genetic variation

Mutations introduce new genetic variations into populations. These variations are essential for natural selection and evolution.

Question 17 of 39 Medium

Which type of mutation is most often associated with genetic disorders?

  1. A Silent mutations
  2. B Neutral mutations
  3. C Harmful mutations
  4. D Synonymous mutations

Correct answer: Harmful mutations

Harmful mutations disrupt normal gene or protein function. Many genetic disorders result from such mutations.

Question 18 of 39 Medium

Which of the following can cause insertion or deletion mutations?

  1. A Base analogs
  2. B Acridine dyes
  3. C Ultraviolet rays
  4. D X-rays

Correct answer: Acridine dyes

Acridine dyes intercalate between DNA bases, leading to insertions or deletions during replication. This often causes frameshift mutations.

Question 19 of 39 Medium

Why are most mutations considered neutral or harmful rather than beneficial?

  1. A They invariably change the encoded protein structure
  2. B They disrupt existing functional systems
  3. C They prevent natural selection
  4. D They increase survival rates

Correct answer: They disrupt existing functional systems

Most mutations alter well-adapted genetic systems. Beneficial mutations are rare compared to neutral or harmful ones.

Question 20 of 39 Medium

What type of mutation occurs when a single purine is replaced by another purine, or a pyrimidine by another pyrimidine?

  1. A Transition
  2. B Transversion
  3. C Inversion
  4. D Translocation

Correct answer: Transition

A transition is a point mutation that replaces a nitrogenous base with another of the same chemical class. For example, Adenine being replaced by Guanine is a transition.

Question 21 of 39 Medium

Which of the following describes a 'missense' mutation?

  1. A A mutation that results in the same amino acid
  2. B A mutation that changes a codon to a stop codon
  3. C A mutation that results in a different amino acid
  4. D A mutation that occurs in a non-coding intronic region

Correct answer: A mutation that results in a different amino acid

In a missense mutation, the altered codon corresponds to a different amino acid than the original. This may or may not significantly alter the function of the resulting protein.

Question 22 of 39 Medium

An insertion of two nucleotides into the coding region of a gene usually results in:

  1. A A silent mutation
  2. B A frameshift mutation
  3. C A transition mutation
  4. D A neutral substitution

Correct answer: A frameshift mutation

Because the genetic code is read in triplets, inserting any number of nucleotides not divisible by three shifts the reading frame. This changes every subsequent codon and usually results in a non-functional protein.

Question 23 of 39 Medium

Which chromosomal aberration involves the movement of a segment of DNA from one chromosome to a non-homologous chromosome?

  1. A Inversion
  2. B Recombination
  3. C Translocation
  4. D Deletion

Correct answer: Translocation

Translocation occurs when a chromosomal segment breaks off and attaches to a different, non-homologous chromosome. This can be reciprocal or non-reciprocal.

Question 24 of 39 Medium

Ultra-violet (UV) radiation primarily causes mutations by inducing the formation of:

  1. A Double-strand breaks
  2. B Pyrimidine dimers
  3. C Free radicals
  4. D Base analogs

Correct answer: Pyrimidine dimers

UV light promotes the formation of covalent bonds between adjacent pyrimidine bases (usually thymines). These dimers distort the DNA backbone and interfere with replication and transcription.

Question 25 of 39 Medium

What is the consequence of a 'nonsense' mutation in a protein-coding gene?

  1. A The protein is longer than usual
  2. B The protein remains unchanged
  3. C The protein is truncated early
  4. D The protein becomes a branched chain

Correct answer: The protein is truncated early

A nonsense mutation changes a sense codon into a premature stop codon (UAA, UAG, or UGA). This results in a truncated polypeptide that is often unstable and non-functional.

Question 26 of 39 Medium

Which of these is a chemical mutagen that acts as a 'base analog'?

  1. A Nitrous acid
  2. B Ethidium bromide
  3. C 5-Bromouracil
  4. D Ethyl methanesulfonate (EMS)

Correct answer: 5-Bromouracil

5-Bromouracil is chemically similar to thymine. During DNA replication, it can be incorporated into DNA instead of thymine, leading to base-pairing errors during the next round of replication.

Question 27 of 39 Medium

Mutations that occur in the gametes and can be passed on to offspring are known as:

  1. A Somatic mutations
  2. B Germline mutations
  3. C Induced mutations
  4. D Spontaneous mutations

Correct answer: Germline mutations

Germline mutations occur in the cells that produce eggs or sperm. Unlike somatic mutations, they are heritable and are present in every cell of the resulting offspring.

Question 28 of 39 Medium

A mutation that restores the original phenotype by occurring at a different site than the original mutation is called a:

  1. A Back mutation
  2. B Suppressor mutation
  3. C Forward mutation
  4. D Silent point mutation

Correct answer: Suppressor mutation

A suppressor mutation is a second mutation that alleviates or 'suppresses' the phenotypic effects of a primary mutation. It occurs at a different locus than the original mutation.

Question 29 of 39 Medium

In a 'transversion' mutation, which of the following could occur?

  1. A Cytosine is replaced by Thymine
  2. B Guanine is replaced by Adenine
  3. C Adenine is replaced by Cytosine
  4. D Thymine is replaced by Uracil

Correct answer: Adenine is replaced by Cytosine

A transversion involves the replacement of a purine (A, G) by a pyrimidine (C, T) or vice versa. Adenine (purine) being replaced by Cytosine (pyrimidine) is a transversion.

Question 30 of 39 Medium

What happens during a chromosomal 'inversion'?

  1. A A segment of the chromosome is lost
  2. B A segment is reversed in orientation
  3. C A segment is copied twice
  4. D A segment moves to the end of the chromosome

Correct answer: A segment is reversed in orientation

Inversion occurs when a chromosome breaks in two places and the intervening segment is reinserted in the reverse orientation. This may change the gene order but usually doesn't change the total DNA content.

Question 31 of 39 Medium

Which of the following is an example of an 'aneuploidy' mutation?

  1. A Trisomy 21 (Down Syndrome)
  2. B Triploidy (3n)
  3. C Point mutation in hemoglobin
  4. D Reciprocal translocation

Correct answer: Trisomy 21 (Down Syndrome)

Aneuploidy refers to a condition where the chromosome number is not an exact multiple of the haploid set (e.g., 2n+1 or 2n-1). Down Syndrome is caused by having three copies of chromosome 21.

Question 32 of 39 Medium

Which type of mutation is most likely to be 'neutral' regarding the survival of an organism?

  1. A Frameshift mutation
  2. B Nonsense mutation
  3. C Silent mutation
  4. D Large deletion

Correct answer: Silent mutation

Silent mutations change the DNA sequence but not the amino acid sequence of the protein due to the degeneracy of the genetic code. Therefore, the protein's function is typically unaffected.

Question 33 of 39 Medium

The fluctuating migration of 'transposable elements' (jumping genes) can cause mutations by:

  1. A Directly altering the pH of the nucleus
  2. B Inserting into functional genes
  3. C Removing the nuclear envelope
  4. D Changing the cell's ATP concentration

Correct answer: Inserting into functional genes

Transposable elements are DNA sequences that can move around the genome. If they land inside a coding region or a regulatory sequence, they can disrupt gene function or expression levels.

Question 34 of 39 Medium

Which mechanism of DNA repair is specifically designed to correct incorrectly paired bases that escaped proofreading during replication?

  1. A Photoreactivation
  2. B Non-homologous end joining
  3. C Base excision repair
  4. D Mismatch repair (MMR)

Correct answer: Mismatch repair (MMR)

Mismatch repair systems scan newly synthesized DNA to identify and replace incorrectly paired nucleotides. They distinguish the new strand from the template strand to ensure the error is corrected.

Question 35 of 39 Medium

Which of the following describes a 'polyploidy' event?

  1. A The loss of a single chromosome
  2. B The addition of an extra chromosome to a pair
  3. C The swapping of parts between homologous chromosomes
  4. D Having more than two complete chromosome sets

Correct answer: Having more than two complete chromosome sets

Polyploidy is a genome-level mutation where an organism has three or more complete sets of chromosomes (e.g., 3n, 4n). This is common in plants but often lethal in higher animals.

Question 36 of 39 Medium

Tautomeric shifts in nitrogenous bases can lead to mutations because they:

  1. A Cause the DNA to melt
  2. B Destroy the phosphodiester bonds
  3. C Prevent the binding of DNA polymerase
  4. D Result in unusual base-pairing

Correct answer: Result in unusual base-pairing

Tautomers are structural isomers of bases that exist in equilibrium. If a base shifts to its rare form during replication, it can form hydrogen bonds with a non-complementary partner, leading to a substitution mutation.

Question 37 of 39 Medium

In 'anticipation,' a genetic phenomenon where symptoms become more severe in successive generations, the underlying mutation is usually:

  1. A A point mutation
  2. B A large chromosomal deletion
  3. C An unbalanced reciprocal translocation
  4. D An expansion of trinucleotide repeats

Correct answer: An expansion of trinucleotide repeats

Disorders like Huntington's disease or Fragile X syndrome involve repeats (like CAG) that tend to increase in number during gamete formation. More repeats often correlate with earlier onset and increased severity.

Question 38 of 39 Medium

A 'null' mutation is one that results in:

  1. A Complete loss of gene function
  2. B Partial loss of gene function
  3. C Gain of a new, toxic function
  4. D Increased expression of the gene

Correct answer: Complete loss of gene function

A null mutation (or amorphic mutation) completely eliminates the function of a gene. This can happen through large deletions or nonsense mutations occurring very early in the coding sequence.

Question 39 of 39 Medium

Intercalating agents, such as proflavine or acridine orange, typically cause which type of mutation?

  1. A Transversions
  2. B Transitions
  3. C Aneuploidy
  4. D Frameshifts

Correct answer: Frameshifts

Intercalating agents are flat molecules that slide between the stacked nitrogenous bases of the DNA double helix. This distortion causes DNA polymerase to add or skip bases during replication, resulting in insertions or deletions (frameshifts).

0 / 39 answered