Neurophysiology and special senses: visual acuity at the fovea: practice question

A Physiology 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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Physiology · Neurophysiology and special senses: visual acuity at the fovea

Sample item

Visual acuity is highest at the fovea centralis. Which feature chiefly contributes to this?

AA very high density of rodsBOverlying retinal blood vessels and ganglion cell layersCCones with almost one-to-one connections to bipolar and ganglion cellsDConvergence of many photoreceptors onto each ganglion cell

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

The answer and the reasoning

C. Cones with almost one-to-one connections to bipolar and ganglion cells

The fovea contains only cones, packed tightly, and the overlying layers are displaced to the side. Each foveal cone connects to a single bipolar cell and ganglion cell, so there is no convergence and spatial resolution is high. Rods are absent from the fovea and converge heavily, giving sensitivity at the cost of acuity.

Option by option

A. A very high density of rods
Rods are absent from the fovea and are concentrated in the periphery.
B. Overlying retinal blood vessels and ganglion cell layers
The fovea is free of overlying vessels and layers, which are displaced aside.
C. Cones with almost one-to-one connections to bipolar and ganglion cells (correct)
Correct. Private one-to-one connections give the fovea its acuity.
D. Convergence of many photoreceptors onto each ganglion cell
Convergence increases sensitivity but lowers acuity, as in the rod system.

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 Physiology question

What is the answer to this Physiology question?

The best answer is C, Cones with almost one-to-one connections to bipolar and ganglion cells. The fovea contains only cones, packed tightly, and the overlying layers are displaced to the side.

Why is "A very high density of rods" not the answer?

Rods are absent from the fovea and are concentrated in the periphery.

Why is "Overlying retinal blood vessels and ganglion cell layers" not the answer?

The fovea is free of overlying vessels and layers, which are displaced aside.

Why is "Convergence of many photoreceptors onto each ganglion cell" not the answer?

Convergence increases sensitivity but lowers acuity, as in the rod system.

What concept does this question test?

It tests Neurophysiology and special senses: visual acuity at the fovea in Physiology. Each foveal cone connects to a single bipolar cell and ganglion cell, so there is no convergence and spatial resolution is high. Rods are absent from the fovea and converge heavily, giving sensitivity at the cost of acuity.

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 Neurophysiology and special senses: visual acuity at the fovea?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.