CSI Forensic Analysis Techniques 2 — Questions and Answers
Question 1: What technique uses antibodies to detect specific proteins or antigens in tissue samples?
- Immunohistochemistry (Correct answer)
- Gas chromatography
- Polymerase chain reaction
- Spectrophotometry
Correct answer: Immunohistochemistry
Immunohistochemistry (IHC) uses labeled antibodies to detect and localize specific proteins within tissue sections.
Question 2: In forensic toxicology, what does 'postmortem redistribution' refer to?
- Drug concentration changes in tissues after death (Correct answer)
- Transfer of toxins between victims
- Redistribution of blood to dependent body areas
- Movement of poisons through soil to remains
Correct answer: Drug concentration changes in tissues after death
Postmortem redistribution describes how drug concentrations in tissues can change significantly after death, complicating toxicological interpretation.
Question 3: Which microscopy technique is most useful for examining the surface topography of bullet striations?
- Scanning electron microscopy (SEM) (Correct answer)
- Transmission electron microscopy (TEM)
- Polarized light microscopy
- Phase contrast microscopy
Correct answer: Scanning electron microscopy (SEM)
SEM provides high-resolution three-dimensional surface imaging ideal for examining fine details on bullets and tool marks.
Question 4: What is the purpose of using a 'blank' sample in forensic chemical analysis?
- To detect contamination and establish baseline readings (Correct answer)
- To calibrate the instrument to maximum sensitivity
- To test the solvent system only
- To verify the chain of custody
Correct answer: To detect contamination and establish baseline readings
A blank contains all reagents except the analyte, helping identify contamination and establish background signal levels.
Question 5: Which technique separates compounds based on their migration through a gel under an electric field?
- Electrophoresis (Correct answer)
- Chromatography
- Centrifugation
- Distillation
Correct answer: Electrophoresis
Electrophoresis separates molecules, including DNA fragments and proteins, by size and charge as they move through a gel matrix.
Question 6: A forensic analyst finds soot particles inside a victim's airway. What does this finding indicate?
- The victim was alive during the fire (Correct answer)
- The fire was accelerant-based
- The victim died before the fire started
- The fire originated from within the building
Correct answer: The victim was alive during the fire
Soot in the airways indicates the victim was breathing smoke, proving they were alive when the fire occurred.
Question 7: What is 'Locard's Exchange Principle' as applied to trace evidence analysis?
- Every contact leaves a trace between two surfaces (Correct answer)
- Evidence must be exchanged between labs for verification
- Trace evidence degrades at a predictable rate
- Chain of custody must be maintained for all exchanges
Correct answer: Every contact leaves a trace between two surfaces
Locard's Exchange Principle states that whenever two objects contact each other, material is transferred bidirectionally between them.
CSI Forensic Analysis Techniques 2
What technique uses antibodies to detect specific proteins or antigens in tissue samples?