Forensic serology: species identification: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Forensic serology: species identification

Sample item

A dried stain on a knife is confirmed as blood. The accused says it came from a slaughtered goat. Which test establishes the species of origin of the blood?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Precipitin test using species-specific antiserum

The precipitin test (Uhlenhuth) uses antiserum raised against the proteins of a species; a precipitate at the interface shows that the stain contains protein from that species. The other tests identify blood but not the species. The phenolphthalein test is presumptive, while the crystal tests are confirmatory for blood.

Option by option

  • A. Takayama haemochromogen test

    Takayama crystals confirm blood pigment, but give no species information.

  • B. Teichmann haemin crystal test

    Teichmann crystals show that blood is present, but do not identify the animal.

  • C. Precipitin test using species-specific antiserum (correct)

    Correct. The precipitin reaction is species-specific.

  • D. Kastle-Meyer (phenolphthalein) test

    The phenolphthalein test is a presumptive test for blood and cannot name the species.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Precipitin test using species-specific antiserum. The precipitin test (Uhlenhuth) uses antiserum raised against the proteins of a species; a precipitate at the interface shows that the stain contains protein from that species.

Why is "Takayama haemochromogen test" not the answer?

Takayama crystals confirm blood pigment, but give no species information.

Why is "Teichmann haemin crystal test" not the answer?

Teichmann crystals show that blood is present, but do not identify the animal.

Why is "Kastle-Meyer (phenolphthalein) test" not the answer?

The phenolphthalein test is a presumptive test for blood and cannot name the species.

What concept does this question test?

It tests Forensic serology: species identification in Forensic Medicine. The other tests identify blood but not the species. The phenolphthalein test is presumptive, while the crystal tests are confirmatory for blood.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Forensic serology: species identification?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.