Which microscopic appearance identifies a cotton fibre recovered from a crime scene?
- A Smooth cylindrical shaft with a central lumen and no twist
- B Flat twisted ribbon with periodic convolutions ✓
- C Serrated overlapping scales along the entire length
- D Uniform synthetic filament with regular cross markings
Correct answer: B. Flat twisted ribbon with periodic convolutions
Explanation
Cotton is a natural vegetable fibre of nearly pure cellulose that dries into a flat, twisted ribbon showing characteristic convolutions along its length. Wool and other animal fibres show serrated scales, while smooth uniform filaments without twist suggest man-made fibres such as polyester or nylon. Recognising natural versus synthetic class characteristics is the first step in fibre comparison before instrumental confirmation.
Reference: Saferstein, Criminalistics: An Introduction to Forensic Science, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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