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AMT Molecular Diagnostics Technologist (MDT)
Certification Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION:
This comprehensive set of multiple-choice questions is designed for the AMT Molecular
Diagnostics Technologist (MDT) Certification Exam. The questions systematically cover all
major domains of molecular diagnostics, including nucleic acid extraction and amplification
(PCR, RT-PCR, qPCR, dPCR), sequencing technologies (Sanger, NGS, pyrosequencing),
genotyping, mutation detection, laboratory quality control, pre-analytical variables, and
clinical applications in infectious diseases, oncology, and genetics. Each question includes a
correct answer and a concise expert rationale, providing an effective study tool for
candidates seeking to validate their technical knowledge and problem-solving skills in a
clinical molecular biology laboratory setting.
QUESTION 1
Which of the following describes the role of DNA polymerase in the Sanger sequencing
reaction?
A) Ligating Okazaki fragments
B) Adding deoxynucleotides and dideoxynucleotides randomly
C) Extending the primer by adding deoxynucleotides until a dideoxynucleotide is
incorporated
D) Unwinding the DNA double helix
CORRECT ANSWER: C
EXPERT RATIONALE: DNA polymerase adds nucleotides to the 3' end of the primer;
incorporation of a dideoxynucleotide (ddNTP) terminates extension because it lacks a 3'-
OH group.
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QUESTION 2
A patient sample yields an abnormal melting curve in a real-time PCR HRM assay. This
most likely indicates:
A) Primer-dimer formation
B) A sequence variation in the amplicon
C) Complete absence of target DNA
D) Contamination with RNase
CORRECT ANSWER: B
EXPERT RATIONALE: High-resolution melting analysis detects sequence variants (e.g.,
SNPs, mutations) by altered melting temperatures due to base mismatches.
QUESTION 3
What is the purpose of a no-template control (NTC) in a PCR run?
A) To verify extraction efficiency
B) To detect contamination in reagents
C) To normalize fluorescence between wells
D) To assess reverse transcription efficiency
CORRECT ANSWER: B
EXPERT RATIONALE: NTC contains all reaction components except template DNA;
amplification indicates reagent or environmental contamination.
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QUESTION 4
In a reverse transcription PCR (RT-PCR) for RNA quantification, omission of the reverse
transcriptase enzyme would result in:
A) No amplification if the target is RNA
B) Double the amount of product
C) Non-specific bands only
D) Increased fluorescent signal
CORRECT ANSWER: A
EXPERT RATIONALE: Without reverse transcriptase, RNA cannot be converted to cDNA,
so subsequent PCR amplification of an RNA target fails.
QUESTION 5
Which of the following is a characteristic of next-generation sequencing (NGS)
compared to Sanger sequencing?
A) Lower throughput
B) Longer read lengths
C) Massively parallel sequencing of millions of fragments
D) Requires radioactive labeling
CORRECT ANSWER: C
EXPERT RATIONALE: NGS platforms simultaneously sequence millions of DNA
fragments, enabling high-throughput analysis, unlike Sanger's single-reaction approach.
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QUESTION 6
The term "Ct value" in real-time PCR refers to:
A) Cycle at which fluorescence first exceeds background threshold
B) Concentration of target at end of reaction
C) Melting temperature of the product
D) Number of cycles completed
CORRECT ANSWER: A
EXPERT RATIONALE: Ct (threshold cycle) is the cycle number where reporter
fluorescence rises above baseline, correlating with initial target quantity.
QUESTION 7
Which specimen type is most appropriate for detecting respiratory viruses by multiplex
PCR?
A) Whole blood EDTA tube
B) Nasopharyngeal swab in viral transport medium
C) Serum separator tube
D) Urine cup
CORRECT ANSWER: B
EXPERT RATIONALE: Respiratory viruses infect epithelial cells of the upper respiratory
tract; nasopharyngeal swabs provide highest viral yield.
AMT Molecular Diagnostics Technologist (MDT)
Certification Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION:
This comprehensive set of multiple-choice questions is designed for the AMT Molecular
Diagnostics Technologist (MDT) Certification Exam. The questions systematically cover all
major domains of molecular diagnostics, including nucleic acid extraction and amplification
(PCR, RT-PCR, qPCR, dPCR), sequencing technologies (Sanger, NGS, pyrosequencing),
genotyping, mutation detection, laboratory quality control, pre-analytical variables, and
clinical applications in infectious diseases, oncology, and genetics. Each question includes a
correct answer and a concise expert rationale, providing an effective study tool for
candidates seeking to validate their technical knowledge and problem-solving skills in a
clinical molecular biology laboratory setting.
QUESTION 1
Which of the following describes the role of DNA polymerase in the Sanger sequencing
reaction?
A) Ligating Okazaki fragments
B) Adding deoxynucleotides and dideoxynucleotides randomly
C) Extending the primer by adding deoxynucleotides until a dideoxynucleotide is
incorporated
D) Unwinding the DNA double helix
CORRECT ANSWER: C
EXPERT RATIONALE: DNA polymerase adds nucleotides to the 3' end of the primer;
incorporation of a dideoxynucleotide (ddNTP) terminates extension because it lacks a 3'-
OH group.
,2|Page
QUESTION 2
A patient sample yields an abnormal melting curve in a real-time PCR HRM assay. This
most likely indicates:
A) Primer-dimer formation
B) A sequence variation in the amplicon
C) Complete absence of target DNA
D) Contamination with RNase
CORRECT ANSWER: B
EXPERT RATIONALE: High-resolution melting analysis detects sequence variants (e.g.,
SNPs, mutations) by altered melting temperatures due to base mismatches.
QUESTION 3
What is the purpose of a no-template control (NTC) in a PCR run?
A) To verify extraction efficiency
B) To detect contamination in reagents
C) To normalize fluorescence between wells
D) To assess reverse transcription efficiency
CORRECT ANSWER: B
EXPERT RATIONALE: NTC contains all reaction components except template DNA;
amplification indicates reagent or environmental contamination.
,3|Page
QUESTION 4
In a reverse transcription PCR (RT-PCR) for RNA quantification, omission of the reverse
transcriptase enzyme would result in:
A) No amplification if the target is RNA
B) Double the amount of product
C) Non-specific bands only
D) Increased fluorescent signal
CORRECT ANSWER: A
EXPERT RATIONALE: Without reverse transcriptase, RNA cannot be converted to cDNA,
so subsequent PCR amplification of an RNA target fails.
QUESTION 5
Which of the following is a characteristic of next-generation sequencing (NGS)
compared to Sanger sequencing?
A) Lower throughput
B) Longer read lengths
C) Massively parallel sequencing of millions of fragments
D) Requires radioactive labeling
CORRECT ANSWER: C
EXPERT RATIONALE: NGS platforms simultaneously sequence millions of DNA
fragments, enabling high-throughput analysis, unlike Sanger's single-reaction approach.
, 4|Page
QUESTION 6
The term "Ct value" in real-time PCR refers to:
A) Cycle at which fluorescence first exceeds background threshold
B) Concentration of target at end of reaction
C) Melting temperature of the product
D) Number of cycles completed
CORRECT ANSWER: A
EXPERT RATIONALE: Ct (threshold cycle) is the cycle number where reporter
fluorescence rises above baseline, correlating with initial target quantity.
QUESTION 7
Which specimen type is most appropriate for detecting respiratory viruses by multiplex
PCR?
A) Whole blood EDTA tube
B) Nasopharyngeal swab in viral transport medium
C) Serum separator tube
D) Urine cup
CORRECT ANSWER: B
EXPERT RATIONALE: Respiratory viruses infect epithelial cells of the upper respiratory
tract; nasopharyngeal swabs provide highest viral yield.
