Physiology: dark adaptation: 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: dark adaptation

Sample item

Which photoreceptor and pigment are responsible for scotopic vision?

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

The answer and the reasoning

A. Rods with rhodopsin

Rods contain rhodopsin, which is formed from opsin and 11-cis retinal derived from vitamin A. Deficiency of vitamin A leads to night blindness.

Option by option

  • A. Rods with rhodopsin (correct)

    Correct. Rods mediate dim light vision.

  • B. Ganglion cells with melanopsin only

    Melanopsin ganglion cells control circadian and pupillary responses.

  • C. Bipolar cells with opsin

    Bipolar cells do not contain visual pigment.

  • D. Cones with iodopsin

    Cones function in bright light and give colour vision.

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.

More Ophthalmology questions

Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is A, Rods with rhodopsin. Rods contain rhodopsin, which is formed from opsin and 11-cis retinal derived from vitamin A.

Why is "Ganglion cells with melanopsin only" not the answer?

Melanopsin ganglion cells control circadian and pupillary responses.

Why is "Bipolar cells with opsin" not the answer?

Bipolar cells do not contain visual pigment.

Why is "Cones with iodopsin" not the answer?

Cones function in bright light and give colour vision.

What concept does this question test?

It tests Physiology: dark adaptation in Ophthalmology. Deficiency of vitamin A leads to night blindness.

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 Physiology: dark adaptation?

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.