AMT MOLECULAR DIAGNOSTICS
TECHNOLOGIST (MDT) CERTIFICATION
Exam Test Questions And Correct
Answers (Verified Answers) Plus
Rationales 2025/2026 Q&A | Instant
Download Pdf
1. A sample for PCR testing shows low DNA yield after extraction. What is the
MOST likely pre-analytical cause?
A. Excess primer concentration
B. Improper specimen storage or degradation
C. Excess PCR cycles
D. Incorrect thermal cycling
Answer: B. Improper specimen storage or degradation
Rationale: DNA integrity is highly dependent on proper collection, transport, and
storage conditions.
2. During qPCR, amplification curves appear in negative controls. What is the
MOST likely explanation?
A. High template concentration
B. Contamination of reagents or workflow
C. Primer efficiency improvement
D. Correct assay performance
,Answer: B. Contamination of reagents or workflow
Rationale: Amplification in controls indicates contamination and invalidates
results.
3. A technician observes a flat amplification curve in a positive control. What is
the FIRST action?
A. Report as negative result
B. Repeat assay and check reagent integrity
C. Increase annealing temperature
D. Dilute sample further
Answer: B. Repeat assay and check reagent integrity
Rationale: Failure in controls requires assay validation before reporting results.
4. Which molecule is primarily amplified in RT-PCR assays?
A. Protein
B. RNA converted to cDNA
C. Lipid
D. Carbohydrate
Answer: B. RNA converted to cDNA
Rationale: RT-PCR targets RNA by reverse transcription into complementary DNA.
5. A sample shows inhibition in PCR reaction. What is MOST likely cause?
A. Excess magnesium
B. Presence of heme or other inhibitors
C. High annealing temperature
D. Excess primers
Answer: B. Presence of heme or other inhibitors
Rationale: Blood components and chemicals can inhibit polymerase activity.
,6. What is the PRIMARY purpose of a housekeeping gene in qPCR?
A. Increase mutation rate
B. Normalize gene expression levels
C. Increase fluorescence
D. Replace controls
Answer: B. Normalize gene expression levels
Rationale: Housekeeping genes serve as internal controls for quantification.
7. A melting curve shows multiple peaks in a SYBR Green assay. What does this
indicate?
A. High specificity
B. Non-specific amplification or primer-dimers
C. Perfect amplification
D. No DNA present
Answer: B. Non-specific amplification or primer-dimers
Rationale: Multiple peaks indicate unintended PCR products.
8. A lab reports inconsistent Ct values across replicates. What is MOST likely
issue?
A. Proper pipetting technique
B. Poor assay precision or pipetting error
C. Excess template quality
D. Correct calibration
Answer: B. Poor assay precision or pipetting error
Rationale: Variability indicates technical inconsistency.
9. Which technique is MOST appropriate for detecting known point mutations?
A. Western blot
B. Allele-specific PCR
, C. ELISA
D. Gram stain
Answer: B. Allele-specific PCR
Rationale: AS-PCR targets specific nucleotide changes.
10. A specimen arrives without proper labeling but is already processed. What
should the technologist do FIRST?
A. Proceed with testing
B. Reject or quarantine specimen per lab policy
C. Guess patient identity
D. Dilute sample
Answer: B. Reject or quarantine specimen per lab policy
Rationale: Identification integrity is critical for patient safety.
11. Which phase of PCR involves strand separation?
A. Annealing
B. Extension
C. Denaturation
D. Elongation
Answer: C. Denaturation
Rationale: Heat separates DNA strands.
12. A contamination event is suspected in a molecular lab. What is the MOST
appropriate immediate action?
A. Continue testing
B. Stop workflow and investigate source
C. Change report format
D. Increase PCR cycles
TECHNOLOGIST (MDT) CERTIFICATION
Exam Test Questions And Correct
Answers (Verified Answers) Plus
Rationales 2025/2026 Q&A | Instant
Download Pdf
1. A sample for PCR testing shows low DNA yield after extraction. What is the
MOST likely pre-analytical cause?
A. Excess primer concentration
B. Improper specimen storage or degradation
C. Excess PCR cycles
D. Incorrect thermal cycling
Answer: B. Improper specimen storage or degradation
Rationale: DNA integrity is highly dependent on proper collection, transport, and
storage conditions.
2. During qPCR, amplification curves appear in negative controls. What is the
MOST likely explanation?
A. High template concentration
B. Contamination of reagents or workflow
C. Primer efficiency improvement
D. Correct assay performance
,Answer: B. Contamination of reagents or workflow
Rationale: Amplification in controls indicates contamination and invalidates
results.
3. A technician observes a flat amplification curve in a positive control. What is
the FIRST action?
A. Report as negative result
B. Repeat assay and check reagent integrity
C. Increase annealing temperature
D. Dilute sample further
Answer: B. Repeat assay and check reagent integrity
Rationale: Failure in controls requires assay validation before reporting results.
4. Which molecule is primarily amplified in RT-PCR assays?
A. Protein
B. RNA converted to cDNA
C. Lipid
D. Carbohydrate
Answer: B. RNA converted to cDNA
Rationale: RT-PCR targets RNA by reverse transcription into complementary DNA.
5. A sample shows inhibition in PCR reaction. What is MOST likely cause?
A. Excess magnesium
B. Presence of heme or other inhibitors
C. High annealing temperature
D. Excess primers
Answer: B. Presence of heme or other inhibitors
Rationale: Blood components and chemicals can inhibit polymerase activity.
,6. What is the PRIMARY purpose of a housekeeping gene in qPCR?
A. Increase mutation rate
B. Normalize gene expression levels
C. Increase fluorescence
D. Replace controls
Answer: B. Normalize gene expression levels
Rationale: Housekeeping genes serve as internal controls for quantification.
7. A melting curve shows multiple peaks in a SYBR Green assay. What does this
indicate?
A. High specificity
B. Non-specific amplification or primer-dimers
C. Perfect amplification
D. No DNA present
Answer: B. Non-specific amplification or primer-dimers
Rationale: Multiple peaks indicate unintended PCR products.
8. A lab reports inconsistent Ct values across replicates. What is MOST likely
issue?
A. Proper pipetting technique
B. Poor assay precision or pipetting error
C. Excess template quality
D. Correct calibration
Answer: B. Poor assay precision or pipetting error
Rationale: Variability indicates technical inconsistency.
9. Which technique is MOST appropriate for detecting known point mutations?
A. Western blot
B. Allele-specific PCR
, C. ELISA
D. Gram stain
Answer: B. Allele-specific PCR
Rationale: AS-PCR targets specific nucleotide changes.
10. A specimen arrives without proper labeling but is already processed. What
should the technologist do FIRST?
A. Proceed with testing
B. Reject or quarantine specimen per lab policy
C. Guess patient identity
D. Dilute sample
Answer: B. Reject or quarantine specimen per lab policy
Rationale: Identification integrity is critical for patient safety.
11. Which phase of PCR involves strand separation?
A. Annealing
B. Extension
C. Denaturation
D. Elongation
Answer: C. Denaturation
Rationale: Heat separates DNA strands.
12. A contamination event is suspected in a molecular lab. What is the MOST
appropriate immediate action?
A. Continue testing
B. Stop workflow and investigate source
C. Change report format
D. Increase PCR cycles
