DNA ANALSYT CERTIFICATION EXAM | ALL PRACTICE
Q&A 2026/2027 | A+ GRADED | COMPREHENSIVE
EXAM GUIDE 2026&2027
1. Which principle is most important when a forensic DNA analyst receives a biological
evidence package for examination?
A. Begin extraction immediately to minimize processing time
B. Verify the evidence packaging, seals, identifiers, and chain-of-custody documentation
C. Remove all packaging and place the evidence directly into the laboratory refrigerator
D. Transfer the evidence to another analyst without documentation
Answer: B
The analyst must first verify the integrity, identification, and documentation associated with
the evidence. This establishes traceability and helps preserve the chain of custody before
analytical work begins.
2. Which molecule carries the primary hereditary information analyzed in forensic DNA
testing?
A. RNA
B. ATP
C. DNA
D. Protein
Answer: C
DNA stores hereditary genetic information and contains the variable regions used for forensic
identification.
3. A DNA analyst observes that an evidence sample produces a very low quantity of
amplifiable DNA. Which issue should be considered first when interpreting the result?
A. The sample may contain insufficient template DNA
B. The suspect must be excluded
C. The electrophoresis instrument is necessarily defective
D. The sample must contain only mitochondrial DNA
Answer: A
Low-template samples can produce weak or incomplete amplification because insufficient
DNA was available for the analytical process.
,4. Which biological material is generally most appropriate for obtaining a nuclear DNA
profile from a routine forensic sample?
A. Mature red blood cells
B. Sweat alone
C. Saliva-free urine
D. Nucleated epithelial cells
Answer: D
Nucleated epithelial cells contain nuclear DNA and can be recovered from materials such as
saliva or skin-cell deposits. Mature human red blood cells do not contain nuclei.
5. During DNA extraction, the primary purpose of cell lysis is to:
A. Separate alleles by size
B. Break open cells and release their contents
C. Amplify target DNA sequences
D. Detect fluorescently labeled fragments
Answer: B
Cell lysis disrupts cellular structures so that DNA can be released and subsequently purified.
6. Which technique is specifically designed to amplify selected DNA regions exponentially?
A. PCR
B. Electrophoresis
C. Centrifugation
D. Spectrophotometry
Answer: A
Polymerase chain reaction, or PCR, amplifies targeted DNA sequences through repeated
cycles of denaturation, annealing, and extension.
7. Why is a negative amplification control included in a forensic DNA batch?
A. To provide a known DNA profile
B. To determine the victim's genotype
C. To monitor for contamination introduced during amplification
D. To increase the quantity of sample DNA
Answer: C
,A negative amplification control contains no intended DNA template and helps identify
contamination introduced during PCR setup or amplification.
8. A positive control fails to produce the expected DNA profile while case samples also fail.
What is the most appropriate response?
A. Report all case samples as exclusions
B. Ignore the control because the case samples are more important
C. Repeat only the electrophoresis
D. Investigate the analytical failure before reporting case results
Answer: D
A failed positive control indicates that the analytical system may not have performed as
expected. The failure must be investigated before reliable case conclusions are issued.
9. STR analysis primarily examines:
A. Repetitive DNA regions characterized by variation in repeat number
B. Entire chromosomes using microscopy
C. RNA transcription levels
D. Protein concentrations
Answer: A
Short tandem repeats are DNA regions containing repeated sequence motifs whose repeat
numbers vary among individuals, making them useful for forensic identification.
10. Why are STR loci useful for forensic identification?
A. They are identical in every individual
B. Their allelic variation allows individuals to be statistically differentiated
C. They occur only in mitochondrial DNA
D. They cannot be affected by biological variation
Answer: B
Variation in STR alleles among individuals allows a DNA profile to be compared statistically
with reference populations.
11. In a standard STR profile, an individual who is heterozygous at a locus will generally
display:
A. No alleles
B. One allele only
, C. Two different alleles
D. Four alleles
Answer: C
A diploid individual normally carries two copies of each autosomal chromosome, so a
heterozygous locus contains two different alleles.
12. An individual who has the same allele inherited from both parents at an autosomal STR
locus is described as:
A. Homozygous
B. Heteroplasmic
C. Haploid
D. Recombinant
Answer: A
A homozygous genotype contains two copies of the same allele at a locus.
13. Which step of PCR separates double-stranded DNA into single strands?
A. Annealing
B. Extension
C. Detection
D. Denaturation
Answer: D
During denaturation, heat disrupts hydrogen bonding between DNA strands, producing
single-stranded templates for subsequent primer binding.
14. What is the primary function of primers during PCR?
A. Destroy contaminating DNA
B. Define the regions to be amplified
C. Separate DNA fragments by size
D. Measure DNA concentration
Answer: B
Primers bind to complementary sequences flanking the target region and provide starting
points for DNA polymerase.
15. A forensic laboratory obtains a DNA profile from an evidence sample and compares it
with a reference sample. What should be evaluated before reporting an inclusion?
Q&A 2026/2027 | A+ GRADED | COMPREHENSIVE
EXAM GUIDE 2026&2027
1. Which principle is most important when a forensic DNA analyst receives a biological
evidence package for examination?
A. Begin extraction immediately to minimize processing time
B. Verify the evidence packaging, seals, identifiers, and chain-of-custody documentation
C. Remove all packaging and place the evidence directly into the laboratory refrigerator
D. Transfer the evidence to another analyst without documentation
Answer: B
The analyst must first verify the integrity, identification, and documentation associated with
the evidence. This establishes traceability and helps preserve the chain of custody before
analytical work begins.
2. Which molecule carries the primary hereditary information analyzed in forensic DNA
testing?
A. RNA
B. ATP
C. DNA
D. Protein
Answer: C
DNA stores hereditary genetic information and contains the variable regions used for forensic
identification.
3. A DNA analyst observes that an evidence sample produces a very low quantity of
amplifiable DNA. Which issue should be considered first when interpreting the result?
A. The sample may contain insufficient template DNA
B. The suspect must be excluded
C. The electrophoresis instrument is necessarily defective
D. The sample must contain only mitochondrial DNA
Answer: A
Low-template samples can produce weak or incomplete amplification because insufficient
DNA was available for the analytical process.
,4. Which biological material is generally most appropriate for obtaining a nuclear DNA
profile from a routine forensic sample?
A. Mature red blood cells
B. Sweat alone
C. Saliva-free urine
D. Nucleated epithelial cells
Answer: D
Nucleated epithelial cells contain nuclear DNA and can be recovered from materials such as
saliva or skin-cell deposits. Mature human red blood cells do not contain nuclei.
5. During DNA extraction, the primary purpose of cell lysis is to:
A. Separate alleles by size
B. Break open cells and release their contents
C. Amplify target DNA sequences
D. Detect fluorescently labeled fragments
Answer: B
Cell lysis disrupts cellular structures so that DNA can be released and subsequently purified.
6. Which technique is specifically designed to amplify selected DNA regions exponentially?
A. PCR
B. Electrophoresis
C. Centrifugation
D. Spectrophotometry
Answer: A
Polymerase chain reaction, or PCR, amplifies targeted DNA sequences through repeated
cycles of denaturation, annealing, and extension.
7. Why is a negative amplification control included in a forensic DNA batch?
A. To provide a known DNA profile
B. To determine the victim's genotype
C. To monitor for contamination introduced during amplification
D. To increase the quantity of sample DNA
Answer: C
,A negative amplification control contains no intended DNA template and helps identify
contamination introduced during PCR setup or amplification.
8. A positive control fails to produce the expected DNA profile while case samples also fail.
What is the most appropriate response?
A. Report all case samples as exclusions
B. Ignore the control because the case samples are more important
C. Repeat only the electrophoresis
D. Investigate the analytical failure before reporting case results
Answer: D
A failed positive control indicates that the analytical system may not have performed as
expected. The failure must be investigated before reliable case conclusions are issued.
9. STR analysis primarily examines:
A. Repetitive DNA regions characterized by variation in repeat number
B. Entire chromosomes using microscopy
C. RNA transcription levels
D. Protein concentrations
Answer: A
Short tandem repeats are DNA regions containing repeated sequence motifs whose repeat
numbers vary among individuals, making them useful for forensic identification.
10. Why are STR loci useful for forensic identification?
A. They are identical in every individual
B. Their allelic variation allows individuals to be statistically differentiated
C. They occur only in mitochondrial DNA
D. They cannot be affected by biological variation
Answer: B
Variation in STR alleles among individuals allows a DNA profile to be compared statistically
with reference populations.
11. In a standard STR profile, an individual who is heterozygous at a locus will generally
display:
A. No alleles
B. One allele only
, C. Two different alleles
D. Four alleles
Answer: C
A diploid individual normally carries two copies of each autosomal chromosome, so a
heterozygous locus contains two different alleles.
12. An individual who has the same allele inherited from both parents at an autosomal STR
locus is described as:
A. Homozygous
B. Heteroplasmic
C. Haploid
D. Recombinant
Answer: A
A homozygous genotype contains two copies of the same allele at a locus.
13. Which step of PCR separates double-stranded DNA into single strands?
A. Annealing
B. Extension
C. Detection
D. Denaturation
Answer: D
During denaturation, heat disrupts hydrogen bonding between DNA strands, producing
single-stranded templates for subsequent primer binding.
14. What is the primary function of primers during PCR?
A. Destroy contaminating DNA
B. Define the regions to be amplified
C. Separate DNA fragments by size
D. Measure DNA concentration
Answer: B
Primers bind to complementary sequences flanking the target region and provide starting
points for DNA polymerase.
15. A forensic laboratory obtains a DNA profile from an evidence sample and compares it
with a reference sample. What should be evaluated before reporting an inclusion?
