BSFS Bachelor of Science in Forensic Science 3 — Questions and Answers
Question 1: Which technique is used to separate DNA fragments by size during forensic DNA analysis?
- Mass spectrometry
- Agarose gel electrophoresis (Correct answer)
- Thin-layer chromatography
- Infrared spectroscopy
Correct answer: Agarose gel electrophoresis
Agarose gel electrophoresis uses an electric field to separate DNA fragments by size, with smaller fragments migrating farther through the gel.
Question 2: In bloodstain pattern analysis, what does a 'satellite stain' indicate?
- Blood from a secondary victim
- A small droplet that broke away from a larger impact stain (Correct answer)
- Blood that traveled by wind
- A stain left by a weapon
Correct answer: A small droplet that broke away from a larger impact stain
Satellite stains are small secondary droplets that break off from a parent drop upon impact and land near the main stain.
Question 3: What is the primary purpose of CODIS in the United States?
- To track criminal court records nationwide
- To store and search DNA profiles from crime scenes and offenders (Correct answer)
- To catalog fingerprints from all citizens
- To maintain ballistics records for firearms
Correct answer: To store and search DNA profiles from crime scenes and offenders
CODIS (Combined DNA Index System) is the FBI's national DNA database that allows forensic labs to compare DNA profiles from crime scenes with known offender profiles.
Question 4: Which type of evidence is considered 'class evidence' rather than 'individual evidence'?
- A single fingerprint with 12 matching minutiae
- A DNA profile matching a specific person
- Fibers that match the manufacturer's lot but not a specific garment (Correct answer)
- A bite mark matched to a suspect's dental mold
Correct answer: Fibers that match the manufacturer's lot but not a specific garment
Class evidence can only narrow the source to a group or category, not to a single unique source; fibers matching a manufacturer's lot are class evidence.
Question 5: What is rigor mortis and when does it typically begin?
- Skin discoloration; begins within minutes of death
- Muscle stiffening due to ATP depletion; begins 2-6 hours after death (Correct answer)
- Decomposition odor; begins 12-24 hours after death
- Skin slippage; begins 3-5 days after death
Correct answer: Muscle stiffening due to ATP depletion; begins 2-6 hours after death
Rigor mortis is the temporary stiffening of muscles after death caused by ATP depletion; it typically begins 2-6 hours postmortem and resolves within 24-48 hours.
Question 6: Which instrument provides both molecular weight and structural information about an unknown compound in forensic drug analysis?
- UV-Vis spectrophotometer
- Gas chromatograph-mass spectrometer (GC-MS) (Correct answer)
- Atomic absorption spectrometer
- Polarimeter
Correct answer: Gas chromatograph-mass spectrometer (GC-MS)
GC-MS combines separation by gas chromatography with mass spectrometric identification, providing molecular weight and fragmentation patterns that confirm compound identity.
Question 7: What does 'chain of custody' documentation primarily ensure in a forensic investigation?
- That evidence was collected by a certified examiner
- That evidence integrity and accountability can be traced from collection to court (Correct answer)
- That witnesses are sequestered during a trial
- That crime scene photos are properly labeled
Correct answer: That evidence integrity and accountability can be traced from collection to court
Chain of custody is a chronological record documenting who collected, handled, transferred, and analyzed evidence, ensuring its integrity and admissibility in court.
BSFS Bachelor of Science in Forensic Science 3
Which technique is used to separate DNA fragments by size during forensic DNA analysis?