American Board Of Criminalistics
Molecular Biology Certification
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of DNA extraction in forensic molecular
biology?
A. Amplify DNA
B. Separate DNA from proteins and cellular debris
C. Sequence DNA
D. Visualize chromosomes
Answer: B
Rationale: DNA extraction is the initial step in forensic analysis that
isolates DNA from other cellular components such as proteins, lipids, and
inhibitors. This purification is essential to ensure downstream processes
like PCR are accurate and uncontaminated.
2. Which enzyme is most commonly used in PCR amplification?
A. Ligase
B. Helicase
C. Taq polymerase
D. Restriction enzyme
Answer: C
, Rationale: Taq polymerase is a heat-stable DNA polymerase derived from
Thermus aquaticus. It withstands high denaturation temperatures in PCR
cycles, making it essential for DNA amplification.
3. What is the role of STRs in forensic DNA analysis?
A. Protein coding
B. RNA transcription
C. Genetic fingerprinting
D. Lipid identification
Answer: C
Rationale: Short Tandem Repeats (STRs) are highly polymorphic regions
used to create unique DNA profiles for individuals, making them ideal for
forensic identification.
4. During PCR, what occurs in the denaturation step?
A. Primers bind DNA
B. DNA strands separate
C. DNA is synthesized
D. Proteins are formed
Answer: B
Rationale: Denaturation involves heating DNA to separate the double-
stranded helix into single strands, allowing primers to bind in the next
step.
5. Which forensic technique separates DNA fragments by size?
A. Spectroscopy
B. Gel electrophoresis
C. Chromatography
D. ELISA
Answer: B
, Rationale: Gel electrophoresis uses an electric field to separate DNA
fragments based on size, with smaller fragments migrating faster through
the gel matrix.
6. What is a major source of contamination in forensic DNA analysis?
A. UV light
B. Airborne dust
C. Gloves and laboratory equipment
D. Centrifugation
Answer: C
Rationale: Contamination often arises from improper handling, including
reused gloves or inadequately sterilized tools, leading to foreign DNA
introduction.
7. Which DNA region is inherited maternally?
A. STRs
B. Y chromosome
C. Mitochondrial DNA
D. Autosomal DNA
Answer: C
Rationale: Mitochondrial DNA is passed exclusively from mother to
offspring, making it useful in degraded samples and maternal lineage
tracing.
8. What is the purpose of the annealing step in PCR?
A. DNA replication
B. Primer binding
C. DNA denaturation
D. Protein synthesis
Answer: B
, Rationale: During annealing, primers attach to complementary sequences
on single-stranded DNA, initiating amplification.
9. What is allele dropout in forensic DNA analysis?
A. Excess DNA amplification
B. Failure to detect an allele
C. Mutation during sequencing
D. PCR contamination
Answer: B
Rationale: Allele dropout occurs when one allele in a heterozygous sample
fails to amplify, often due to low DNA quantity or degradation.
10.What is the function of positive controls in PCR?
A. Detect contamination
B. Confirm amplification works
C. Measure DNA size
D. Prevent mutation
Answer: B
Rationale: Positive controls contain known DNA and ensure that PCR
reagents and conditions are functioning properly.
11.What does a DNA electropherogram display?
A. Protein bands
B. STR allele peaks
C. RNA sequences
D. Chromosome structure
Answer: B
Rationale: Electropherograms show fluorescent peaks representing STR
allele sizes used in DNA profiling.
Molecular Biology Certification
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of DNA extraction in forensic molecular
biology?
A. Amplify DNA
B. Separate DNA from proteins and cellular debris
C. Sequence DNA
D. Visualize chromosomes
Answer: B
Rationale: DNA extraction is the initial step in forensic analysis that
isolates DNA from other cellular components such as proteins, lipids, and
inhibitors. This purification is essential to ensure downstream processes
like PCR are accurate and uncontaminated.
2. Which enzyme is most commonly used in PCR amplification?
A. Ligase
B. Helicase
C. Taq polymerase
D. Restriction enzyme
Answer: C
, Rationale: Taq polymerase is a heat-stable DNA polymerase derived from
Thermus aquaticus. It withstands high denaturation temperatures in PCR
cycles, making it essential for DNA amplification.
3. What is the role of STRs in forensic DNA analysis?
A. Protein coding
B. RNA transcription
C. Genetic fingerprinting
D. Lipid identification
Answer: C
Rationale: Short Tandem Repeats (STRs) are highly polymorphic regions
used to create unique DNA profiles for individuals, making them ideal for
forensic identification.
4. During PCR, what occurs in the denaturation step?
A. Primers bind DNA
B. DNA strands separate
C. DNA is synthesized
D. Proteins are formed
Answer: B
Rationale: Denaturation involves heating DNA to separate the double-
stranded helix into single strands, allowing primers to bind in the next
step.
5. Which forensic technique separates DNA fragments by size?
A. Spectroscopy
B. Gel electrophoresis
C. Chromatography
D. ELISA
Answer: B
, Rationale: Gel electrophoresis uses an electric field to separate DNA
fragments based on size, with smaller fragments migrating faster through
the gel matrix.
6. What is a major source of contamination in forensic DNA analysis?
A. UV light
B. Airborne dust
C. Gloves and laboratory equipment
D. Centrifugation
Answer: C
Rationale: Contamination often arises from improper handling, including
reused gloves or inadequately sterilized tools, leading to foreign DNA
introduction.
7. Which DNA region is inherited maternally?
A. STRs
B. Y chromosome
C. Mitochondrial DNA
D. Autosomal DNA
Answer: C
Rationale: Mitochondrial DNA is passed exclusively from mother to
offspring, making it useful in degraded samples and maternal lineage
tracing.
8. What is the purpose of the annealing step in PCR?
A. DNA replication
B. Primer binding
C. DNA denaturation
D. Protein synthesis
Answer: B
, Rationale: During annealing, primers attach to complementary sequences
on single-stranded DNA, initiating amplification.
9. What is allele dropout in forensic DNA analysis?
A. Excess DNA amplification
B. Failure to detect an allele
C. Mutation during sequencing
D. PCR contamination
Answer: B
Rationale: Allele dropout occurs when one allele in a heterozygous sample
fails to amplify, often due to low DNA quantity or degradation.
10.What is the function of positive controls in PCR?
A. Detect contamination
B. Confirm amplification works
C. Measure DNA size
D. Prevent mutation
Answer: B
Rationale: Positive controls contain known DNA and ensure that PCR
reagents and conditions are functioning properly.
11.What does a DNA electropherogram display?
A. Protein bands
B. STR allele peaks
C. RNA sequences
D. Chromosome structure
Answer: B
Rationale: Electropherograms show fluorescent peaks representing STR
allele sizes used in DNA profiling.
