Locate the fovea in an original eye diagram and explain its function
Trace H separately from the optic-disc blind spot.
Section B13.1 · Coordination and response
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Recall receptors, electrical impulses, CNS organisation and the distinction between a stimulus and an effector response.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which original label identifies the fovea?
What you will learn
- Identify a distinct retinal region
- Connect dense cones with detailed central colour vision
Locate the fovea in an original eye diagram and explain its function
| Feature | Meaning |
|---|---|
| H | Fovea within posterior retina |
| Function | Detailed central colour vision |
| Receptors | Densely packed cones |
| G comparison | Optic-disc blind spot has no light receptors |
Identify a distinct retinal region
In the original left-front eye section, H points to the foveal region on the posterior retina. G points separately to the optic disc, the nerve-exit region corresponding to the blind spot. Follow the endpoints: two labels near the back of the eye do not mean they identify the same structure.
The fovea contains a high density of cones, especially in its central region, and supports sharp, detailed central colour vision. This functional description depends on its receptor population rather than saying that the fovea is an opening for light entry or the structure carrying impulses out of the eye. Those other roles belong to the pupil and optic nerve respectively.
Connect dense cones with detailed central colour vision
The optic disc has no light receptors, so it cannot be assigned the fovea’s receptor-rich function. It lies where optic nerve fibres leave the eye, whereas the fovea is a separate specialised retinal region. The original drawing intentionally separates H from G without representing an exact anatomical distance or angular field for an individual.
Identify the location first and then explain the function. A label-only answer omits how dense cones relate to central detailed colour vision. A functional answer without tracing the leader can still identify the wrong retinal site. The diagram uses simplified proportions and teaching colours and should not be treated as a clinical image or a measured receptor-density map.
Sources for this lesson
Pause and explain
Which function matches the fovea?
Worked example
Identify H and contrast it with G.
Show the worked solution
- H is the cone-rich fovea supporting detailed central colour vision.
- G is the receptor-free optic-disc blind spot.
Answer H fovea: dense cones for detailed central colour vision; G optic-disc blind spot: no light receptors.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Identify H in the diagram and give its function.
Give me a hint
Trace the posterior retinal endpoint.
Compare my reasoning
- H marks the fovea.
- Dense cones support detailed central colour vision.
H is the fovea, a cone-rich retinal region supporting detailed central colour vision.
Look for these in your work
- Name fovea
- Connect cones with function
Distinguish G and H using receptor presence and function.
Give me a hint
Compare nerve exit and specialised retina.
Compare my reasoning
- G is optic disc, with no light receptors.
- H is cone-rich fovea for detailed central colour vision.
G marks the receptor-free optic-disc blind spot; H marks the cone-rich fovea supporting detailed central colour vision.
Look for these in your work
- Separate both sites
- Match receptor state and function
Does the schematic position of H establish exact fovea-to-disc distance in an individual?
Give me a hint
A simplified drawing has no calibrated individual scale.
Compare my reasoning
- It establishes distinct locations.
- It gives no measured personal distance.
No. The schematic distinguishes fovea from optic disc but does not measure their exact separation in an individual.
Look for these in your work
- Use location distinction
- Avoid an unsupported personal measurement
Common mistakes
- Giving H as the optic nerve exit.
- Giving the fovea a light-entry aperture function.
What can you explain now?
Which function matches the fovea?
Compare with the explanation
Detailed central colour vision through densely packed cones
It connects location, receptors and function.
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Make it stick
Identify the fovea and explain dense-cone central vision without confusing it with the blind spot.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.