Forensic Biology MCQs — Part 1 (Q1–Q25)

Q1. The gold-standard DNA markers used in human identification are:

A. SNPs
B. STRs (Short Tandem Repeats) ✅
C. RAPDs
D. Minisatellites

A: SNPs are useful for ancestry/phenotyping but have lower power per locus for identity than STR panels.
B: STRs are highly polymorphic microsatellites used in routine forensic profiling (e.g., CODIS).
C: RAPDs are not forensically validated due to poor reproducibility.
D: Minisatellites (VNTRs) were early methods; less common now due to large DNA requirement.

Q2. Which inheritance pattern makes mitochondrial DNA useful in degraded remains?

A. Autosomal dominant
B. Maternal inheritance ✅
C. X-linked recessive
D. Paternal inheritance

A: Autosomal modes do not describe mtDNA.
B: mtDNA is maternally inherited, allowing comparison to maternal relatives and persists when nuclear DNA is degraded.
C: X-linked concerns nuclear genes.
D: Paternal mtDNA is typically not transmitted.

Q3. Y-STR analysis is particularly helpful in:

A. Identifying female contributors in mixtures
B. Male-specific profiling in sexual assault mixtures ✅
C. Determining maternal lineage
D. Age estimation

A: Y-STRs ignore female DNA; not for female contributors.
B: Targets Y-chromosome to isolate male signal in mixed samples.
C: Maternal lineage is mtDNA.
D: STRs do not estimate age.

Q4. The primary purpose of a chain of custody form is to:

A. Increase DNA yield
B. Document possession and transfers of evidence ✅
C. Improve PCR amplification
D. Determine time since death

A/C/D: Scientific steps; chain of custody is legal documentation.
B: Ensures integrity/admissibility by recording who handled evidence and when.

Q5. Which is a common presumptive test for blood?

A. Teichmann crystal test
B. Kastle–Meyer (phenolphthalein) test ✅
C. Microscopic sperm search
D. p30 (PSA) immunoassay

A: Teichmann is a confirmatory microcrystal test.
B: Kastle–Meyer detects hemoglobin peroxidase activity—screening only.
C: Sperm search pertains to semen, not blood.
D: p30 detects prostate antigen (semen).

Q6. A blue chemiluminescence used to detect latent bloodstains is:

A. Leuco-malachite green
B. Luminol ✅
C. Diatom test
D. Ninhydrin

A: LM green is a color test for blood, not chemiluminescent.
B: Luminol emits blue light upon reaction with heme’s peroxidase-like activity.
C: Diatom test relates to drowning.
D: Ninhydrin visualizes amino acids in fingerprints.

Q7. The random match probability (RMP) in STR profiling is primarily calculated using:

A. Bayes’ theorem on prior guilt
B. Allele frequencies and Hardy–Weinberg equilibrium ✅
C. Ct values from qPCR
D. Isotopic ratios of hair

A: Priors on guilt are not part of lab stats.
B: RMP uses population allele frequencies assuming H–W equilibrium (with substructure adjustments).
C/D: Not related to STR identity statistics.

Q8. A common PCR inhibitor in soil that can stop amplification is:

A. Sodium chloride
B. Humic acid ✅
C. EDTA
D. Calcium carbonate

A: Typical levels don’t fully inhibit PCR.
B: Humic substances bind polymerases/DNA → inhibition.
C: EDTA chelates Mg²⁺; in excess may inhibit but soil concern is humic acids.
D: CaCO₃ is less problematic for PCR than humic acids.

Q9. For touch DNA collection from a smooth surface, the best approach is:

A. Submerge item in water
B. Moistened sterile swab with gentle rubbing ✅
C. Flame-sterilize the surface
D. Air-dry for days then scrape

A: Water causes loss/contamination.
B: Slightly moistened swab increases epithelial cell capture.
C: Flames destroy DNA and evidence.
D: Delays risk contamination/degradation.

Q10. Spermatozoa are best visualized in a semen stain using:

A. Gram stain
B. Christmas tree stain (KPIC: kernechtrot–picroindigocarmine) ✅
C. Ziehl–Neelsen stain
D. Hematoxylin–eosin only

A: Gram is for bacteria.
B: Heads stain red; tails green—classic confirmatory stain.
C: Acid-fast organisms, not sperm.
D: H&E can show cells but not as specific.

Q11. The CODIS core loci are:

A. SNPs across the genome
B. A standardized set of autosomal STRs ✅
C. Y-STRs only
D. mtDNA control region sites only

A/C/D: CODIS relies mainly on autosomal STRs.
B: Standardized STR panel enables national database compatibility.

Q12. In a two-person mixture, a tri-allelic pattern at one STR locus most likely indicates:

A. Homozygosity
B. Presence of at least two contributors ✅
C. Null allele only
D. Contamination with animal DNA

A: Homozygotes show one peak.
B: Three peaks at a locus suggests multiple contributors (or rare tri-allelic variant).
C: Null alleles cause dropout, not extra peaks.
D: Animal DNA won’t co-amplify human STR kit targets.

Q13. Which estimation helps in postmortem interval (PMI) using vitreous humor?

A. Sodium concentration
B. Potassium concentration ✅
C. Calcium concentration
D. Urea concentration

A/C/D: Less reliable for PMI.
B: Vitreous K⁺ rises after death as cells lyse—used for PMI models.

Q14. The “thanatomicrobiome” refers to:

A. Microbes on living skin
B. Postmortem microbial communities in body/soil ✅
C. Microbes in hospital ICU
D. Ancient bone microbiome only

A: That’s normal microbiome.
B: Succession of microbes after death can inform PMI.
C/D: Not the definition.

Q15. A confirmatory test for blood based on heme crystals is:

A. Teichmann (hemin) test ✅
B. Kastle–Meyer test
C. Luminol
D. Bluestar

A: Forms brown hemin crystals—confirmatory, though less used than modern immuno/RS methods.
B/C/D: Presumptive/screening methods.

Q16. Mitochondrial heteroplasmy may complicate interpretation because:

A. It eliminates all maternal matches
B. Multiple mtDNA variants can coexist within one person ✅
C. It proves sample contamination
D. It prevents sequencing

A: Matches remain interpretable with caution.
B: Different mtDNA haplotypes in tissues/cells can cause mixed sequences.
C: Heteroplasmy is biological, not necessarily contamination.
D: Sequencing is still feasible.

Q17. In forensic entomology, the earliest colonizers on remains are often:

A. Dermestid beetles
B. Blowflies (Calliphoridae) ✅
C. House crickets
D. Termites

A: Dermestids arrive later in dry stages.
B: Blowflies oviposit quickly; larval age informs PMI(min).
C/D: Not typical colonizers of remains.

Q18. A key advantage of mini-STRs is:

A. Better phenotyping of eye color
B. Improved amplification of degraded DNA ✅
C. Ability to type plant pollen
D. Direct age estimation

A/D: Not what STRs provide.
B: Shorter amplicons survive fragmentation better.
C: Pollen typing uses botany/plant markers, not human STRs.

Q19. To minimize allelic dropout in low-template DNA:

A. Reduce PCR cycles
B. Replicate amplifications and consensus calling ✅
C. Skip negative controls
D. Use longer amplicons

A: Fewer cycles reduce sensitivity.
B: Replicates help confirm true alleles versus stochastic loss.
C: Controls are essential to detect contamination.
D: Longer targets fail more in degraded samples.

Q20. The most reliable anatomical source for nuclear DNA in a long-decomposed skeleton is:

A. Rib cartilage
B. Tooth pulp/compact bone of femur ✅
C. Hair shaft
D. Fingernail surface

A: Cartilage yields can be low.
B: Dense bone and teeth protect DNA from environment.
C: Hair shaft lacks nuclei (mtDNA only).
D: Nails mostly keratin; low nuclear DNA.

Q21. Diatom testing in suspected drowning relies on:

A. Chloride levels in blood
B. Presence of diatoms in bone marrow matching water source ✅
C. Lung weight alone
D. Hemoglobin oxygen affinity

A/C/D: Non-specific.
B: Inhaled water can carry diatoms crossing alveolar barrier; matching species supports drowning.

Q22. A confirmatory test for semen other than sperm microscopy is:

A. Phadebas test
B. p30/PSA immunochromatographic test ✅
C. Acid phosphatase color test only
D. Luminol

A: Phadebas detects amylase (saliva).
B: PSA (p30) is prostate-specific; confirms seminal fluid even in azoospermic males.
C: Acid phosphatase is presumptive.
D: Luminol screens for blood.

Q23. Which step best prevents DNA contamination at a scene?

A. Reuse gloves to save time
B. Change gloves between items; use masks/coveralls ✅
C. Blow on swabs to dry faster
D. Package all items together

A/C/D: Increase contamination risk.
B: PPE and item separation maintain integrity.

Q24. mRNA body fluid identification can distinguish:

A. Human vs. animal only
B. Specific fluids (e.g., blood vs. saliva) via tissue-specific transcripts ✅
C. Age of donor
D. Time since deposition precisely

A: Species test is different (e.g., mtDNA, immuno).
B: Markers like HBB (blood), PRM2 (semen), HTN3 (saliva) indicate fluid type.
C/D: mRNA ID does not accurately give donor age or exact deposition time.

Q25. A limitation of phenotypic DNA prediction (forensically) is that:

A. It replaces STR identity statistics
B. It cannot predict any traits
C. It provides probabilistic traits (e.g., eye/skin color), not individual identity ✅
D. It is admissible only with mtDNA

A: It complements, not replaces identity STRs.
B: Validated models predict some traits with probabilities.
C: Predictions are probabilistic and population-dependent—insufficient for unique ID.
D: Admissibility is jurisdiction-specific; not limited to mtDNA.

Forensic Biology MCQs — Part 2 (Q26–Q50)

Q26. Which DNA profiling technique preceded STR typing in forensic work?

A. SNP typing
B. RFLP (Restriction Fragment Length Polymorphism) ✅
C. RAPD profiling
D. Next-generation sequencing

A: SNP typing is newer and less discriminatory per locus.
B: RFLP using VNTRs was the original forensic DNA method before STR PCR kits.
C: RAPD is not validated due to reproducibility issues.
D: NGS is a current frontier, not a predecessor.

Q27. The “Amelogenin locus” in forensic DNA analysis is used for:

A. Species identification
B. Sex determination (X vs. Y allele) ✅
C. Blood group typing
D. Ancestry prediction

A: Other loci (cytochrome b, mtDNA) are used for species ID.
B: Amelogenin has different fragment sizes on X vs. Y → reveals sex.
C: ABO typing is serology-based.
D: Ancestry uses autosomal SNPs, not amelogenin.

Q28. Which technique is used for detecting gunshot residue (GSR) on hands?

A. Immunoassay
B. Scanning electron microscopy with energy dispersive X-ray (SEM–EDX) ✅
C. PCR amplification
D. Flame photometry

A: Immunoassay not used for inorganic residues.
B: SEM–EDX detects morphology and elemental signature (Pb, Ba, Sb).
C: PCR is for DNA, not GSR.
D: Flame photometry is for alkali metals, not GSR.

Q29. Which of the following is a presumptive test for saliva?

A. Acid phosphatase
B. Phadebas test (starch–iodine for α-amylase activity) ✅
C. p30/PSA
D. Kastle–Meyer

A: Acid phosphatase → presumptive semen.
B: Phadebas detects amylase in saliva stains.
C: PSA → semen confirmatory.
D: Kastle–Meyer → blood.

Q30. Which is a common confirmatory method for human hair species identification?

A. Simple visual microscopy
B. Mitochondrial DNA sequencing ✅
C. Keratin immunoassay
D. Fluorescent dye uptake

A: Microscopy may indicate species, but overlaps exist.
B: mtDNA sequencing confirms species (human vs. animal).
C/D: Not standard confirmatory approaches.

Q31. Which skeletal feature is most reliable for sex determination?

A. Femur length
B. Pelvic morphology ✅
C. Skull suture closure
D. Vertebral count

A: Femur length estimates stature, not sex with certainty.
B: Pelvis shows dimorphic traits (subpubic angle, sciatic notch) → most reliable.
C: Suture closure → age, not sex.
D: Vertebral number is generally constant in both sexes.

Q32. The diatom test is not reliable if:

A. Water contains diatoms
B. Body was immersed postmortem but not drowned ✅
C. Diatoms are present in marrow
D. Diatoms species match local water

A: Presence in water is normal.
B: Postmortem immersion may introduce diatoms superficially but not in circulation → false negative/positive.
C/D: These findings support drowning.

Q33. In forensic palynology, the primary evidence studied is:

A. Starch granules
B. Pollen and spores ✅
C. Fungal hyphae
D. Charcoal particles

A: Starch relates to food, not palynology.
B: Palynology = study of pollen/spores; used to trace geographic origin.
C/D: Fungi and charcoal are ancillary, not core.

Q34. The presence of “Wallerian degeneration” in nerves can help:

A. Identify sex
B. Estimate time since injury before death ✅
C. Establish species origin
D. Detect poisoning

A/C/D: Not related.
B: Nerve fiber degeneration begins hours after trauma → timing of ante-mortem injuries.

Q35. Which technique is often used for DNA quantification in forensic samples?

A. SDS-PAGE
B. Real-time quantitative PCR (qPCR) ✅
C. Southern blot
D. Flow cytometry

A: SDS-PAGE is for proteins.
B: qPCR quantifies DNA amount and assesses degradation/inhibition.
C: Southern blot detects fragments, not quantification.
D: Flow cytometry not used here.

Q36. “Locard’s Exchange Principle” states:

A. Blood always leaves a stain
B. Every contact leaves a trace ✅
C. DNA never degrades completely
D. Fingerprints are always visible

A/D: Not universally true.
B: Foundational forensic principle—perpetrator transfers material and takes some away.
C: DNA can degrade.

Q37. Which insect evidence helps estimate PMI beyond 1 year?

A. Blowfly larvae
B. Beetles (e.g., dermestids) ✅
C. Mosquitoes
D. Fleas

A: Blowflies colonize early.
B: Beetles colonize in later decomposition → useful for longer PMIs.
C/D: Not typically colonizers of remains.

Q38. Which molecular method is used for ancestry inference in forensic biology?

A. ABO typing
B. Population-specific SNP panels ✅
C. Blood protein electrophoresis
D. Microscopy of cells

A: ABO lacks resolution for ancestry.
B: SNP panels can infer biogeographic ancestry with probability.
C/D: Obsolete methods.

Q39. Which of the following is a confirmatory test for blood?

A. Luminol
B. Takayama (hemochromogen) crystal test ✅
C. Kastle–Meyer
D. Bluestar

A/C/D: Presumptive/screening tests.
B: Takayama forms pink hemochromogen crystals = confirmatory.

Q40. What is the main advantage of using mtDNA in old skeletal remains?

A. Faster than STRs
B. High copy number per cell increases recovery ✅
C. Less prone to contamination
D. Predicts phenotype accurately

A: Not always faster; sequencing still required.
B: Thousands of mtDNA copies per cell persist when nuclear DNA is gone.
C: Contamination risk remains.
D: mtDNA is for lineage, not phenotype.

Q41. Which test detects uric acid in bird droppings (for wildlife forensics)?

A. Kastle–Meyer
B. Murexide test ✅
C. Benedict’s test
D. Phadebas test

A: Kastle–Meyer → blood.
B: Murexide identifies uric acid, useful in wildlife enforcement.
C: Benedict’s detects reducing sugars.
D: Phadebas → saliva.

Q42. The CODIS system is maintained by:

A. INTERPOL
B. FBI (Federal Bureau of Investigation) ✅
C. World Health Organization
D. National Academy of Sciences

A/C/D: Not custodians.
B: FBI manages CODIS in the U.S.

Q43. Which of the following is most resistant to environmental degradation?

A. mRNA
B. mtDNA ✅
C. Proteins
D. Nuclear DNA

A: mRNA degrades rapidly.
B: mtDNA is protected within mitochondria, high copy number.
C: Proteins degrade variably.
D: Nuclear DNA is single-copy and more fragile.

Q44. In forensic odontology, the most reliable identifier is:

A. Tooth color
B. Dental restorations and records ✅
C. Enamel porosity
D. Tooth size

A/C/D: Less specific.
B: Restorations (fillings, crowns) and dental charts are unique and durable.

Q45. The sperm hyaluronidase test is used to:

A. Determine blood group
B. Confirm semen presence by enzyme detection ✅
C. Detect saliva stains
D. Identify urine

A/C/D: Not related.
B: Hyaluronidase is semen-specific enzyme; supports confirmatory testing.

Q46. Which phenomenon describes DNA alleles appearing at different peak heights in low-template samples?

A. Stutter
B. Allelic imbalance (peak height imbalance) ✅
C. Null allele
D. Contamination

A: Stutter = small extra peak from slippage.
B: In low template, true alleles may amplify unequally.
C: Null allele = failure to amplify.
D: Contamination = unrelated profile.

Q47. Which isotope analysis is useful for geographic origin of human hair/nails?

A. Carbon-12/Carbon-13
B. Strontium and oxygen isotopes ✅
C. Iron isotopes
D. Nickel isotopes

A: C isotopes → diet info.
B: Sr and O isotope ratios vary with geology/water → geographic signature.
C/D: Not typically used in forensic human origin.

Q48. Which body fluid fluoresces strongly under UV light due to flavins?

A. Blood
B. Urine ✅
C. Semen
D. Saliva

A: Blood absorbs rather than fluoresces.
B: Urine fluoresces under UV due to riboflavin/urochrome.
C: Semen also fluoresces but less consistently.
D: Saliva doesn’t reliably fluoresce.

Q49. Which software is commonly used for mixture interpretation in forensic DNA?

A. BLAST
B. STRmix ✅
C. MUSCLE
D. PHYLIP

A: BLAST aligns DNA sequences, not STR profiles.
B: STRmix is probabilistic genotyping software for DNA mixtures.
C: MUSCLE aligns protein/nucleotide sequences.
D: PHYLIP is for phylogenetics.

Q50. Which insect developmental stage is most reliable for short PMI estimation?

A. Adult beetle
B. Blowfly larvae (maggots) ✅
C. Beetle pupae
D. House fly adult

A/C/D: Less useful for immediate PMI.
B: Blowfly larvae growth rates provide accurate PMI in first days after death.

Forensic Biology MCQs — Part 3 (Q51–Q75)

Q51. Which of the following blood group systems is most important in forensic serology?

A. Kell system
B. Duffy system
C. ABO system ✅
D. Kidd system

A: Kell is clinically significant in transfusion, less common in forensics.
B: Duffy is used in malaria studies, not routine forensics.
C: ABO grouping is widely used in forensic serology for exclusion and population statistics.
D: Kidd system is not commonly applied in forensic biology.

Q52. What is the main limitation of ABO blood grouping in forensic cases?

A. Difficult to detect in stains
B. Low discrimination power compared to DNA ✅
C. Cannot be determined from saliva
D. No genetic basis

A: Techniques exist for stains.
B: ABO typing cannot uniquely identify an individual due to high frequency groups.
C: Secretors can reveal ABO from saliva.
D: ABO is genetically inherited.

Q53. Which genetic marker is most useful for maternal lineage analysis?

A. Y-STR
B. Mitochondrial DNA (mtDNA) ✅
C. Autosomal STR
D. X-STR

A: Y-STRs trace paternal lineage.
B: mtDNA is maternally inherited; all maternal relatives share haplotypes.
C/D: Autosomal and X-STRs don’t directly show maternal lineage.

Q54. Which protein is used as a marker for saliva identification?

A. Albumin
B. α-amylase ✅
C. Hemoglobin
D. PSA (p30)

A: Albumin is nonspecific.
B: Saliva contains high α-amylase activity → main marker.
C: Hemoglobin → blood.
D: PSA → semen.

Q55. Which DNA sequencing approach allows analysis of highly degraded forensic DNA?

A. RFLP
B. Next-Generation Sequencing (NGS) ✅
C. Sanger sequencing only
D. Flow cytometry

A: RFLP requires high-quality DNA.
B: NGS works on shorter fragments, allows SNP/mini-STR typing.
C: Sanger works but less efficient for degraded samples.
D: Flow cytometry isn’t for sequencing.

Q56. The rate of stomach emptying can provide:

A. Cause of death
B. Rough estimate of time of last meal before death ✅
C. Blood group of victim
D. Victim’s ancestry

A: Not directly.
B: Gastric contents (volume/digestion stage) can suggest time of last meal.
C/D: Not related.

Q57. The “blue-green” discoloration of body after death is due to:

A. Hemoglobin oxidation to methemoglobin
B. Sulfhemoglobin formation by bacterial hydrogen sulfide ✅
C. Bilirubin accumulation
D. Myoglobin breakdown

A: Methemoglobin is brownish.
B: Postmortem hydrogen sulfide reacts with hemoglobin → sulfhemoglobin (blue-green).
C: Bilirubin → jaundice, not postmortem change.
D: Myoglobin breakdown leads to reddish staining.

Q58. Which insect evidence is most valuable in toxicological analysis when tissues are decomposed?

A. Adult blowflies
B. Maggots (fly larvae) ✅
C. Beetle shells
D. Spider webs

A: Adults may not retain toxins reliably.
B: Maggots bioaccumulate drugs/poisons → used for toxicological analysis.
C: Beetle shells rarely show toxins.
D: Spider webs irrelevant.

Q59. Which bone feature is most useful for estimating age at death in subadults?

A. Dental restorations
B. Epiphyseal union of long bones ✅
C. Cranial suture closure
D. Pubic symphysis morphology

A: Dental restorations → ID, not age.
B: Epiphyseal closure patterns are well-studied in adolescents.
C: Sutures useful in older adults.
D: Pubic symphysis used in adults, not children.

Q60. Which chemical test is used to identify gunpowder residues on clothing?

A. Kastle–Meyer
B. Griess test (for nitrites) ✅
C. Takayama test
D. Luminol

A: Blood test.
B: Griess detects nitrite residues in GSR patterns on fabrics.
C: Takayama is confirmatory blood test.
D: Luminol is for latent blood.

Q61. Which enzyme deficiency increases risk of DNA contamination from analysts’ saliva?

A. DNA polymerase deficiency
B. Amylase activity in saliva contaminating samples ✅
C. Catalase deficiency
D. RNase deficiency

A: Not relevant.
B: High amylase in saliva → saliva cells can deposit DNA easily.
C/D: Not connected.

Q62. Which physiological fluid contains urobilinogen as a marker?

A. Saliva
B. Semen
C. Urine ✅
D. Blood

A: Not in saliva.
B: Not in semen.
C: Urobilinogen is characteristic of urine (heme metabolism product).
D: Blood contains bilirubin but not urobilinogen.

Q63. The most stable anatomical structure for age estimation in adults is:

A. Pubic symphysis
B. Cranial sutures
C. Teeth ✅
D. Finger length

A: Pubic symphysis useful but variable.
B: Cranial sutures close variably with age.
C: Teeth resist postmortem changes, preserve records → reliable.
D: Finger length not age-related.

Q64. The “blue fluorescence” of semen stains under UV is mainly due to:

A. Hemoglobin
B. Flavins in seminal fluid ✅
C. Urobilinogen
D. Lipid oxidation

A: Hemoglobin → blood, not semen.
B: Flavin molecules fluoresce under UV → semen detection.
C: Urobilinogen is urine.
D: Lipid oxidation not relevant.

Q65. Which isotope ratio is most useful in determining dietary history from human bone?

A. Nickel isotopes
B. Carbon (C¹²/C¹³) and Nitrogen (N¹⁴/N¹⁵) ✅
C. Strontium isotopes only
D. Oxygen isotopes only

A: Nickel rarely used.
B: C/N ratios reflect plant vs. animal protein intake.
C: Strontium → migration, not diet.
D: Oxygen → climate/geography.

Q66. The Hyoid bone fracture is most indicative of:

A. Suicide
B. Manual strangulation ✅
C. Poisoning
D. Natural death

A: Hyoid fractures are rare in suicides.
B: Strong sign of throttling/manual strangulation.
C/D: Not associated.

Q67. Which DNA database system is widely used in Europe?

A. CODIS
B. EDNAP/ENFSI databases (European Standard Set STRs) ✅
C. NDIS
D. UK Census

A: CODIS is U.S.-based.
B: European databases use standardized STR panels agreed by EDNAP/ENFSI.
C: NDIS = U.S. national DNA index.
D: Census is not forensic DNA.

Q68. Which blood test can distinguish human from animal origin?

A. Kastle–Meyer
B. Precipitin test (species-specific antibodies) ✅
C. Luminol
D. Bluestar

A: Kastle–Meyer detects heme peroxidase, not species.
B: Precipitin uses antisera against human proteins → distinguishes species.
C/D: Screening for blood only.

Q69. What is the primary cause of stutter peaks in STR analysis?

A. Contamination
B. DNA polymerase slippage during PCR ✅
C. Null alleles
D. Mixture interpretation

A: Contamination gives unrelated profiles.
B: Taq polymerase can slip on repeats → minor stutter peaks one repeat shorter.
C: Null alleles = dropout.
D: Mixtures cause multiple peaks but not stutter artifact.

Q70. Which is the most reliable bone for determining sex in fragmented remains?

A. Skull fragment
B. Pelvis fragment ✅
C. Rib fragment
D. Vertebra fragment

A: Skull helps but pelvis more reliable.
B: Pelvic fragments retain dimorphic features even when incomplete.
C/D: Less diagnostic.

Q71. Which chemical enhances fingerprints on paper by reacting with amino acids?

A. Silver nitrate
B. Iodine fumes
C. Ninhydrin ✅
D. Superglue fuming

A: Silver nitrate reacts with chlorides.
B: Iodine is temporary visualization.
C: Ninhydrin reacts with amino acids → purple (Ruhemann’s purple).
D: Superglue works on non-porous surfaces.

Q72. Which entomological evidence indicates a body was moved postmortem?

A. Multiple insect species present
B. Colonizing insects inconsistent with current environment ✅
C. Advanced maggot stage
D. Pupal casings

A: Normal.
B: Insect succession differs by environment; mismatch suggests relocation.
C/D: Indicate PMI, not movement.

Q73. The “snowstorm appearance” in lung histology after drowning is due to:

A. Hemoglobin denaturation
B. Frothy fluid and surfactant admixture ✅
C. Collapsed alveoli
D. Myelin degeneration

A: Not cause.
B: Inhaled water + surfactant → foam in alveoli (“snowstorm”).
C: Collapse = asphyxia, not drowning signature.
D: Myelin degeneration is neural.

Q74. Which forensic marker can help identify the time since deposition of semen?

A. ABO typing
B. Sperm motility and protein degradation ✅
C. Blood group secretor status
D. DNA STR profile

A: ABO typing not time-sensitive.
B: Progressive loss of sperm motility and breakdown of seminal proteins help estimate deposition interval.
C: Secretor status indicates ABO in fluids, not time.
D: DNA profiles persist regardless of age of stain.

Q75. Which poison causes characteristic line on gums (“lead line”) useful in forensic diagnosis?

A. Arsenic
B. Mercury
C. Lead ✅
D. Cyanide

A: Arsenic → Mees’ lines on nails, not gums.
B: Mercury → tremors, gingivitis.
C: Lead → “Burton’s line” (blue-black gingival margin).
D: Cyanide → bitter almond odor, not gum lines.

Forensic Biology MCQs — Part 4 (Q76–Q100)

Q76. Which poison produces “raindrop pigmentation” on skin?

A. Lead
B. Arsenic ✅
C. Mercury
D. Cyanide

A: Lead → gum line, anemia, neuropathy.
B: Chronic arsenic → patchy hyperpigmentation resembling raindrops.
C: Mercury → tremors, gingivitis, neurotoxicity.
D: Cyanide → hypoxia, bitter almond odor.

Q77. Which substance causes “cherry-red” postmortem lividity?

A. Cyanide
B. Carbon monoxide ✅
C. Hydrogen sulfide
D. Methanol

A: Cyanide → cellular hypoxia but not cherry-red color.
B: Carboxyhemoglobin imparts bright red/pink discoloration.
C: H₂S → dark greenish-black.
D: Methanol → optic nerve damage, not red lividity.

Q78. Which of the following is a confirmatory test for semen?

A. Acid phosphatase test
B. Luminol test
C. p30 (prostate-specific antigen) test ✅
D. Phadebas test

A: Acid phosphatase is only presumptive.
B: Luminol detects blood, not semen.
C: PSA (p30) is confirmatory for semen, even in azoospermic males.
D: Phadebas → saliva.

Q79. Which bone is most reliable for estimating stature?

A. Skull
B. Femur ✅
C. Clavicle
D. Sternum

A: Skull less accurate.
B: Femur length strongly correlates with height.
C/D: Less predictive.

Q80. What is the function of the “DNA ladder” in forensic gel electrophoresis?

A. Detect inhibitors
B. Provide fragment size reference ✅
C. Increase DNA yield
D. Detect contamination

A/C/D: Not functions of ladder.
B: Ladder is molecular weight marker for fragment sizing.

Q81. Which forensic test detects blood origin as human vs. animal?

A. Luminol
B. Precipitin test ✅
C. Kastle–Meyer
D. Takayama

A/C/D: Detect presence of blood, not species.
B: Precipitin uses human-specific antisera.

Q82. Which insect is used for estimating long-term PMI (months to years)?

A. Blowflies
B. Dermestid beetles ✅
C. Flesh flies
D. Mosquitoes

A: Blowflies → early PMI.
B: Dermestids colonize dry remains, useful for longer PMIs.
C: Flesh flies are early colonizers.
D: Mosquitoes irrelevant.

Q83. Which biomolecule is visualized with ninhydrin in fingerprints?

A. Lipids
B. Carbohydrates
C. Amino acids ✅
D. Fatty acids

A/B/D: Do not react with ninhydrin.
C: Ninhydrin reacts with amino acids → purple color (Ruhemann’s purple).

Q84. Which method is best for estimating age of bloodstains?

A. ABO typing
B. STR profiling
C. RNA/DNA degradation analysis and hemoglobin breakdown ✅
D. Blood group secretor status

A/B/D: Provide identity but not age of stain.
C: Molecular degradation patterns inform time since deposition.

Q85. Which poison causes “Mee’s lines” on fingernails?

A. Cyanide
B. Lead
C. Arsenic ✅
D. Mercury

A: Cyanide has no nail sign.
B: Lead → gum line.
C: Arsenic → transverse white bands (Mee’s lines).
D: Mercury → tremors, gingivitis.

Q86. Which tissue is best for detecting chronic heavy metal poisoning?

A. Blood
B. Hair and nails ✅
C. Liver only
D. Muscle

A: Blood → acute exposure only.
B: Hair/nails incorporate metals over time, reflect chronic exposure.
C/D: Less informative long-term.

Q87. Which entomological evidence is most useful in the fresh stage of decomposition?

A. Beetles
B. Blowflies (Calliphoridae) ✅
C. Moths
D. Cockroaches

A: Beetles → later stages.
B: Blowflies oviposit within hours, useful in early PMI.
C/D: Not major forensic colonizers.

Q88. Which poison causes “garlic odor” from the body?

A. Cyanide
B. Arsenic ✅
C. Lead
D. Methanol

A: Cyanide → bitter almond odor.
B: Arsenic ingestion produces garlic-like odor.
C: Lead has no odor.
D: Methanol odorless.

Q89. Which confirmatory test detects blood heme via crystal formation?

A. Kastle–Meyer
B. Luminol
C. Takayama test ✅
D. Bluestar

A/B/D: Presumptive tests.
C: Takayama forms pink hemochromogen crystals (confirmatory).

Q90. Which forensic sample type contains only mitochondrial DNA?

A. Buccal swab
B. Bloodstain
C. Hair shaft (without root) ✅
D. Semen stain

A/B/D: Contain nuclear DNA.
C: Hair shaft lacks nuclei, has only mtDNA.

Q91. Which poison produces “bitter almond” odor in cadavers?

A. Methanol
B. Lead
C. Cyanide ✅
D. Mercury

A: Methanol odorless.
B/D: No characteristic odor.
C: Cyanide → bitter almond odor (not sensed by all people).

Q92. Which of the following can best identify time since death within hours?

A. Blowfly colonization
B. Algor mortis (body cooling) ✅
C. Dental records
D. Isotope analysis

A: Blowflies → days.
B: Body cooling rate is accurate in early hours postmortem.
C/D: Not time-of-death tools.

Q93. Which is the most dimorphic bone for sex determination?

A. Skull
B. Pelvis ✅
C. Femur
D. Sternum

A/C/D: Useful but less reliable.
B: Pelvis shows >95% accuracy due to childbirth adaptations.

Q94. Which poison causes “dark brown postmortem staining” of the gastric mucosa?

A. Nitric acid ✅
B. Sulphuric acid
C. Hydrochloric acid
D. Carbolic acid

A: Nitric acid ingestion → brown/yellow staining.
B: Sulphuric → black charring.
C: HCl → gray/white.
D: Carbolic → white leathery patches.

Q95. Which marker gene is specific for semen in RNA profiling?

A. HBB
B. PRM2 (Protamine 2) ✅
C. HTN3
D. AMELY

A: HBB → blood.
B: PRM2 expressed in spermatozoa → semen marker.
C: HTN3 → saliva.
D: AMELY → sex typing.

Q96. Which forensic method is used to identify latent fingerprints on non-porous surfaces?

A. Ninhydrin
B. Cyanoacrylate fuming (superglue) ✅
C. Phadebas test
D. Precipitin test

A: Ninhydrin → porous (paper).
B: Superglue vapors polymerize on sweat → latent prints visible.
C: Saliva test.
D: Species test.

Q97. Which insect succession is typical in advanced decomposition?

A. Blowflies only
B. Beetles (dermestids, carrion beetles) ✅
C. Mosquitoes
D. Crickets

A: Blowflies decline in advanced decay.
B: Beetles dominate advanced/dry stages.
C/D: Not colonizers.

Q98. Which poison causes “rice-water stools” in forensic cases?

A. Arsenic ✅
B. Lead
C. Mercury
D. Cyanide

A: Arsenic poisoning → severe GI irritation, rice-water diarrhea.
B: Lead → constipation, anemia.
C: Mercury → tremors, gingivitis.
D: Cyanide → rapid death, no diarrhea.

Q99. Which insect life stage is most accurate for PMI estimation in early decomposition?

A. Larvae (maggots) ✅
B. Pupae
C. Adult beetles
D. Empty casings

A: Larval growth rates directly correlate with PMI in early stages.
B-D: Useful later.

Q100. Which modern forensic approach allows simultaneous typing of STRs, SNPs, and mtDNA?

A. Capillary electrophoresis
B. Massively Parallel Sequencing (Next-Generation Sequencing, NGS) ✅
C. RFLP
D. Sanger sequencing

A: CE limited to STR sizing.
B: NGS allows multi-marker, high-resolution analysis.
C: RFLP is outdated.
D: Sanger is limited to single loci.

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