Forensic Biology: Body Fluid Identification

This mock covers the body-fluid identification toolkit that every forensic-biology student must master before tackling sexual-assault casework, scene-of-crime serology, or the Forensic Biology paper of any Indian university examination. Thirty questions across the presumptive and confirmatory tests for blood (Kastle-Meyer phenolphthalin chemistry, Leucomalachite Green, luminol chemiluminescence and its 1:5,000,000 sensitivity, Hemastix on-scene strips, Takayama and Teichmann crystal confirmations, Ouchterlony precipitin species identification, ABO grouping from dried stains by absorption-elution); semen (acid phosphatase with Brentamine Fast Blue B, prostate-specific antigen / p30 confirming seminal fluid even from azoospermic or vasectomised donors, Christmas Tree stain for spermatozoa morphology); saliva (alpha-amylase by starch-iodine, Phadebas, SALIgAE, and the species-specific RSID-Saliva immunochromatographic strip); urine (creatinine, urea, uric acid spot tests and the DMAC reagent); vaginal fluid (Lugol's iodine on glycogenated squamous epithelial cells, Doderlein lactobacilli on Gram stain, mRNA marker panels including MYOZ1, CYP2B7P1, HBD-1); faeces (urobilinogen with Ehrlich's reagent, the Edelman test); modern mRNA-based multiplex RT-PCR panels and emerging microbiome 16S rRNA approaches; and the Wood's lamp / alternate light source workflow for presumptive scene mapping.

It is pitched at BSc and first-year MSc forensic-science students at NFSU, LNJN-NICFS, and other Indian universities, FACT and FACT Plus aspirants, and UGC-NET candidates who need the body-fluid identification fundamentals locked in before tackling sexual-assault casework, scene reconstruction, or DNA-typing application papers.

Themes covered:

• Presumptive blood tests — Kastle-Meyer (with the phenolphthalin / phenolphthalein distinction), LMG, luminol, Hemastix
• False positives — plant peroxidases (horseradish, potato), bleach, copper, oxidising agents
• Confirmatory blood tests — Takayama and Teichmann crystal tests; species ID by Ouchterlony precipitin and lateral-flow HemaTrace
• ABO grouping from dried stains by absorption-elution
• Semen presumptive (acid phosphatase / Brentamine Fast Blue B) vs confirmatory (PSA / p30, sperm microscopy)
• Christmas Tree (Picroindigocarmine + Nuclear Fast Red) staining for spermatozoa
• Saliva amylase activity (Phadebas, SALIgAE) and species-specific RSID-Saliva
• Urine markers — creatinine, urea, uric acid, DMAC, Tamm-Horsfall protein
• Vaginal fluid — glycogenated cells (Lugol), Doderlein bacilli, mRNA marker panels
• Faeces — urobilinogen (Ehrlich's), Edelman fluorescence
• mRNA-based multiplex body-fluid panels and microbiome 16S rRNA corroboration
• Wood's lamp / alternate light source mapping
• Cross-reactivities and species-specificity caveats

Each question carries a detailed 220+ word explanation citing standard references — Saferstein's Criminalistics, James & Nordby's Forensic Science, Goodwin / Linacre / Hadi's Introduction to Forensic Genetics. Allow 15 minutes; the explanations are long enough to use as study notes by themselves. If you can pass this mock comfortably, you have the body-fluid identification vocabulary that the application-level papers and casework practicals build on.