AMT Molecular Diagnostics Technologist
(MDT) Certification Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download
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Q1. Which of the following nitrogenous bases is a purine found in BOTH
DNA and RNA?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
Correct ,,,,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
Correct ,,,,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
Correct ,,,,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) Chromatin
D) Histone
Correct ,,,,answer,,,: B) RNA
Rationale: RNA is typically single-stranded, whereas DNA exists as a double
helix. This structural difference allows RNA to fold into complex shapes and
perform diverse cellular functions.
Q5. What is the complementary base pair for adenine in DNA?
A) Cytosine
B) Guanine
C) Thymine
D) Uracil
Correct ,,,,answer,,,: C) Thymine
Rationale: In DNA, adenine pairs with thymine via two hydrogen bonds. In RNA,
adenine pairs with uracil.
Q6. Which base pairs with cytosine in DNA?
A) Adenine
B) Thymine
, C) Guanine
D) Uracil
Correct ,,,,answer,,,: C) Guanine
Rationale: Cytosine pairs with guanine via three hydrogen bonds in both DNA and
RNA.
Q7. What is the primary function of DNA in cells?
A) Protein synthesis
B) Energy production
C) Genetic information storage
D) Cell membrane structure
Correct ,,,,answer,,,: C) Genetic information storage
Rationale: DNA stores genetic information in its nucleotide sequence, which is
transcribed into RNA and then translated into proteins.
Q8. Which process describes the conversion of DNA to RNA?
A) Translation
B) Replication
C) Transcription
D) Transformation
Correct ,,,,answer,,,: C) Transcription
(MDT) Certification Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download
Q1. Which of the following nitrogenous bases is a purine found in BOTH
DNA and RNA?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
Correct ,,,,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
Correct ,,,,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
Correct ,,,,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) Chromatin
D) Histone
Correct ,,,,answer,,,: B) RNA
Rationale: RNA is typically single-stranded, whereas DNA exists as a double
helix. This structural difference allows RNA to fold into complex shapes and
perform diverse cellular functions.
Q5. What is the complementary base pair for adenine in DNA?
A) Cytosine
B) Guanine
C) Thymine
D) Uracil
Correct ,,,,answer,,,: C) Thymine
Rationale: In DNA, adenine pairs with thymine via two hydrogen bonds. In RNA,
adenine pairs with uracil.
Q6. Which base pairs with cytosine in DNA?
A) Adenine
B) Thymine
, C) Guanine
D) Uracil
Correct ,,,,answer,,,: C) Guanine
Rationale: Cytosine pairs with guanine via three hydrogen bonds in both DNA and
RNA.
Q7. What is the primary function of DNA in cells?
A) Protein synthesis
B) Energy production
C) Genetic information storage
D) Cell membrane structure
Correct ,,,,answer,,,: C) Genetic information storage
Rationale: DNA stores genetic information in its nucleotide sequence, which is
transcribed into RNA and then translated into proteins.
Q8. Which process describes the conversion of DNA to RNA?
A) Translation
B) Replication
C) Transcription
D) Transformation
Correct ,,,,answer,,,: C) Transcription
