Physiology: cone pigment sensitivity: practice question

A Ophthalmology 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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Ophthalmology · Physiology: cone pigment sensitivity

Sample item

A student is asked about the peak absorption wavelengths of cone pigments. Which pairing is correct?

ABlue cone about 420 nm, red cone about 560 nmBBlue cone about 380 nm, red cone about 700 nmCBlue cone about 560 nm, red cone about 420 nmDBlue cone about 500 nm, red cone about 650 nm

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

The answer and the reasoning

A. Blue cone about 420 nm, red cone about 560 nm

Short wavelength cones peak near 420 nm, medium (green) near 530 nm and long (red) near 560 nm. Rhodopsin peaks near 500 nm. Colour vision defects arise from abnormalities in these pigments.

Option by option

A. Blue cone about 420 nm, red cone about 560 nm (correct)
Correct. S cones near 420 nm and L cones near 560 nm.
B. Blue cone about 380 nm, red cone about 700 nm
The values are outside the visible peaks of human cones.
C. Blue cone about 560 nm, red cone about 420 nm
The pairing is reversed.
D. Blue cone about 500 nm, red cone about 650 nm
These values are too high for blue and red cone peaks.

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 Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is A, Blue cone about 420 nm, red cone about 560 nm. Short wavelength cones peak near 420 nm, medium (green) near 530 nm and long (red) near 560 nm.

Why is "Blue cone about 380 nm, red cone about 700 nm" not the answer?

The values are outside the visible peaks of human cones.

Why is "Blue cone about 560 nm, red cone about 420 nm" not the answer?

The pairing is reversed.

Why is "Blue cone about 500 nm, red cone about 650 nm" not the answer?

These values are too high for blue and red cone peaks.

What concept does this question test?

It tests Physiology: cone pigment sensitivity in Ophthalmology. Rhodopsin peaks near 500 nm. Colour vision defects arise from abnormalities in these pigments.

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 Physiology: cone pigment sensitivity?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology 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.