AMT Molecular Diagnostics Technologist
(MDT) Certification Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download
Pdf
SECTION I: MOLECULAR BIOLOGY FUNDAMENTALS
Q1. Which of the following nitrogenous bases is a purine found in BOTH
DNA and RNA?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
,,,answer,,,: C) Guanine
Rationale: Guanine and adenine are purines characterized by a double-ring
structure and are present in both DNA and RNA. Cytosine is a pyrimidine found in
both, while thymine is unique to DNA and uracil is unique to RNA.
Q2. In a DNA molecule, the phosphodiester bond links which two
components?
A) Two nitrogenous bases across the double helix
B) The 5' phosphate group of one nucleotide to the 3' hydroxyl group of another
,C) The sugar molecule to the nitrogenous base
D) The amino acid sequence to the mRNA codon
,,,answer,,,: B) The 5' phosphate group of one nucleotide to the 3' hydroxyl group
of another
Rationale: The backbone of DNA is formed by phosphodiester bonds that link the
3' carbon atom of one sugar molecule to the 5' carbon atom of another, facilitating
the polymerization of nucleotides.
Q3. During DNA replication, which enzyme is responsible for unwinding the
double helix at the replication fork?
A) Helicase
B) Primase
C) Ligase
D) Topoisomerase
,,,answer,,,: A) Helicase
Rationale: Helicase unwinds the double-stranded DNA by breaking the hydrogen
bonds between base pairs, creating the replication fork where DNA synthesis can
occur.
Q4. Which nucleic acid is typically single-stranded?
A) DNA
B) RNA
C) Both DNA and RNA
D) Neither DNA nor RNA
,,,answer,,,: B) RNA
Rationale: RNA is typically single-stranded, though it can form secondary
structures through intramolecular base pairing. DNA is typically double-stranded.
Q5. Which process describes the conversion of DNA to RNA?
A) Translation
,B) Replication
C) Transcription
D) Transformation
,,,answer,,,: C) Transcription
Rationale: Transcription is the process of synthesizing RNA from a DNA
template, catalyzed by RNA polymerase.
Q6. Which process converts RNA to protein?
A) Transcription
B) Translation
C) Replication
D) Hybridization
,,,answer,,,: B) Translation
Rationale: Translation uses messenger RNA (mRNA) as a template to synthesize
proteins at ribosomes.
Q7. What is the central dogma of molecular biology?
A) RNA → DNA → Protein
B) DNA → Protein → RNA
C) DNA → RNA → Protein
D) Protein → RNA → DNA
,,,answer,,,: C) DNA → RNA → Protein
Rationale: The central dogma describes the flow of genetic information from
DNA to RNA via transcription, and from RNA to protein via translation.
Q8. What is a mutation?
A) Normal DNA replication process
B) Change in DNA sequence
C) Protein synthesis event
D) RNA transcription error correction
, ,,,answer,,,: B) Change in DNA sequence
Rationale: Mutations are alterations in the nucleotide sequence of DNA that can
occur spontaneously or be induced by mutagens.
Q9. A "nonsense" mutation results in which of the following?
A) Replacement of one amino acid with another
B) Premature termination of the polypeptide chain
C) A shift in the reading frame of the gene
D) No change in the amino acid sequence
,,,answer,,,: B) Premature termination of the polypeptide chain
Rationale: A nonsense mutation changes a codon that specifies an amino acid into
a stop codon (UAG, UAA, or UGA), leading to a truncated, usually nonfunctional
protein.
Q10. Which type of mutation involves a single base change that alters one
amino acid?
A) Frameshift mutation
B) Missense mutation
C) Silent mutation
D) Nonsense mutation
,,,answer,,,: B) Missense mutation
Rationale: A missense mutation results from a single nucleotide substitution that
changes one amino acid to another, which may affect protein function depending
on the location and nature of the change.
Q11. Which mutation shifts the reading frame of the genetic code?
A) Silent mutation
B) Missense mutation
C) Frameshift mutation
D) Nonsense mutation
(MDT) Certification Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download
SECTION I: MOLECULAR BIOLOGY FUNDAMENTALS
Q1. Which of the following nitrogenous bases is a purine found in BOTH
DNA and RNA?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
,,,answer,,,: C) Guanine
Rationale: Guanine and adenine are purines characterized by a double-ring
structure and are present in both DNA and RNA. Cytosine is a pyrimidine found in
both, while thymine is unique to DNA and uracil is unique to RNA.
Q2. In a DNA molecule, the phosphodiester bond links which two
components?
A) Two nitrogenous bases across the double helix
B) The 5' phosphate group of one nucleotide to the 3' hydroxyl group of another
,C) The sugar molecule to the nitrogenous base
D) The amino acid sequence to the mRNA codon
,,,answer,,,: B) The 5' phosphate group of one nucleotide to the 3' hydroxyl group
of another
Rationale: The backbone of DNA is formed by phosphodiester bonds that link the
3' carbon atom of one sugar molecule to the 5' carbon atom of another, facilitating
the polymerization of nucleotides.
Q3. During DNA replication, which enzyme is responsible for unwinding the
double helix at the replication fork?
A) Helicase
B) Primase
C) Ligase
D) Topoisomerase
,,,answer,,,: A) Helicase
Rationale: Helicase unwinds the double-stranded DNA by breaking the hydrogen
bonds between base pairs, creating the replication fork where DNA synthesis can
occur.
Q4. Which nucleic acid is typically single-stranded?
A) DNA
B) RNA
C) Both DNA and RNA
D) Neither DNA nor RNA
,,,answer,,,: B) RNA
Rationale: RNA is typically single-stranded, though it can form secondary
structures through intramolecular base pairing. DNA is typically double-stranded.
Q5. Which process describes the conversion of DNA to RNA?
A) Translation
,B) Replication
C) Transcription
D) Transformation
,,,answer,,,: C) Transcription
Rationale: Transcription is the process of synthesizing RNA from a DNA
template, catalyzed by RNA polymerase.
Q6. Which process converts RNA to protein?
A) Transcription
B) Translation
C) Replication
D) Hybridization
,,,answer,,,: B) Translation
Rationale: Translation uses messenger RNA (mRNA) as a template to synthesize
proteins at ribosomes.
Q7. What is the central dogma of molecular biology?
A) RNA → DNA → Protein
B) DNA → Protein → RNA
C) DNA → RNA → Protein
D) Protein → RNA → DNA
,,,answer,,,: C) DNA → RNA → Protein
Rationale: The central dogma describes the flow of genetic information from
DNA to RNA via transcription, and from RNA to protein via translation.
Q8. What is a mutation?
A) Normal DNA replication process
B) Change in DNA sequence
C) Protein synthesis event
D) RNA transcription error correction
, ,,,answer,,,: B) Change in DNA sequence
Rationale: Mutations are alterations in the nucleotide sequence of DNA that can
occur spontaneously or be induced by mutagens.
Q9. A "nonsense" mutation results in which of the following?
A) Replacement of one amino acid with another
B) Premature termination of the polypeptide chain
C) A shift in the reading frame of the gene
D) No change in the amino acid sequence
,,,answer,,,: B) Premature termination of the polypeptide chain
Rationale: A nonsense mutation changes a codon that specifies an amino acid into
a stop codon (UAG, UAA, or UGA), leading to a truncated, usually nonfunctional
protein.
Q10. Which type of mutation involves a single base change that alters one
amino acid?
A) Frameshift mutation
B) Missense mutation
C) Silent mutation
D) Nonsense mutation
,,,answer,,,: B) Missense mutation
Rationale: A missense mutation results from a single nucleotide substitution that
changes one amino acid to another, which may affect protein function depending
on the location and nature of the change.
Q11. Which mutation shifts the reading frame of the genetic code?
A) Silent mutation
B) Missense mutation
C) Frameshift mutation
D) Nonsense mutation
