Identification: hair examination: 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 · Identification: hair examination

Sample item

Microscopic examination of a hair found at a scene shows a medulla that occupies about one-fifth of the shaft diameter. What is the likely origin and the principle used?

AHuman; the medullary index is above about 0.5BAnimal; the medullary index is above about 0.5CHuman; the medullary index is below about 0.33DAnimal; the medullary index is below about 0.33

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

The answer and the reasoning

C. Human; the medullary index is below about 0.33

The medullary index is the ratio of the diameter of the medulla to the diameter of the hair shaft. In human hair it is usually below about one-third (0.33), whereas in many animal hairs the medulla is wide and the index exceeds 0.5. One-fifth is 0.2, which fits human hair.

Option by option

A. Human; the medullary index is above about 0.5
Human hair does not have an index above 0.5, as its medulla is narrow or absent.
B. Animal; the medullary index is above about 0.5
An index above 0.5 is typical of animal hair, but this hair's ratio is 0.2.
C. Human; the medullary index is below about 0.33 (correct)
A ratio of 0.2 is below one-third, which fits human hair.
D. Animal; the medullary index is below about 0.33
Animal hair characteristically has a wide medulla, so a low index does not fit.

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.

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Human; the medullary index is below about 0.33. The medullary index is the ratio of the diameter of the medulla to the diameter of the hair shaft.

Why is "Human; the medullary index is above about 0.5" not the answer?

Human hair does not have an index above 0.5, as its medulla is narrow or absent.

Why is "Animal; the medullary index is above about 0.5" not the answer?

An index above 0.5 is typical of animal hair, but this hair's ratio is 0.2.

Why is "Animal; the medullary index is below about 0.33" not the answer?

Animal hair characteristically has a wide medulla, so a low index does not fit.

What concept does this question test?

It tests Identification: hair examination in Forensic Medicine. In human hair it is usually below about one-third (0.33), whereas in many animal hairs the medulla is wide and the index exceeds 0.5. One-fifth is 0.2, which fits human hair.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Identification: hair examination?

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.