UGC NTA NET/JRF Exam, Forensic Science, June-2025

In the submission of biological exhibits to an FSL, the process is methodical to ensure security and authenticity. The first step is checking whether the case falls under the jurisdiction of the concerned laboratory (A).

Next, the submission letter or authorization from the investigating authority is verified (D). After authorization, the exhibits are examined for proper sealing and the presence of a sample seal to confirm integrity (B).

Finally, after these formalities, the exhibits are photographed for record and documentation (C).

The greenish discoloration of the lower abdomen seen in the early stage of putrefaction is due to sulphmethaemoglobin. When decomposition begins, bacteria release hydrogen sulphide, which reacts with haemoglobin in the blood to form this greenish pigment.

This color change is one of the earliest external signs of putrefaction and helps forensic experts estimate the post-mortem interval.

The Solanaceae family, or nightshade family, includes several poisonous plants. Atropa (deadly nightshade) contains atropine, Hyoscyamus (henbane) contains hyoscyamine and scopolamine, and Nicotina (tobacco) produces nicotine.

These belong to Solanaceae and are medically significant due to their alkaloids. Digitalis, however, belongs to Scrophulariaceae, and Lamium belongs to Lamiaceae, so they are not included. Hence, Atropa, Hyoscyamus, and Nicotina are the correct members.

Anabolic steroids are artificial substances derived from testosterone and used to promote muscle  growth.

Oxandrolene is a steroid used in weight gain treatments, Stanoxolol is a synthetic anabolic steroid commonly misused by athletes, and Nandrolene is another anabolic steroid enhancing protein synthesis.

On the other hand, Dilaudid is an opioid painkiller, while Freon is an industrial refrigerant, not related to steroids. Thus, the true anabolic steroids in the list are Oxandrolene, Stanoxolol, and Nandrolene.

Photon energy E is E = λ/hc. Hence it is inversely proportional to wavelength (A). A shorter wavelength therefore means higher photon energy (C), while a longer wavelength means lower energy (E). Statements B and D contradict this fundamental relation.

"Separation" methods physically resolve components of a mixture: simple distillation (B) separates by volatility; paper chromatography (C) separates by differential partition; capillary electrophoresis (E) separates by charge-to-size in an electric field.

A visible spectrophotometer (A) and polarography (D) are detection/measurement techniques, not primary separation tools.

Characteristic putrefaction gases from a cadaver include methane (A) and hydrogen sulphide (C)-the latter gives the classic foul odour.

Carbon dioxide can be present, but among the given pairings, methane plus hydrogen sulphide best represents gases specifically associated with decomposition odour profiles.

Sequence of ignition phenomena: an external stimulus ignites the explosive material (C) → temperature rise triggers pre-ignition reactions (A)→ these reactions drive phase/crystal transitions and thermal decomposition (D) → the reaction front becomes self-sustaining, leading to combustion (B).

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