Explain how the structure of the eye enables it to detect light and send information to the brain. In your answer, refer to the role of the cornea, lens, retina, and optic nerve.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
The cornea refracts light as it enters the eye, bending the rays to begin focusing them.
The lens refracts the light further, fine‑tuning the focus so that the rays converge precisely on the retina.
The retina contains light‑sensitive cells (photoreceptors) that detect the light.
These photoreceptors generate electrical impulses in response to the light.
The optic nerve carries these electrical impulses to the brain for visual processing.
The lens refracts the light further, fine‑tuning the focus so that the rays converge precisely on the retina.
The retina contains light‑sensitive cells (photoreceptors) that detect the light.
These photoreceptors generate electrical impulses in response to the light.
The optic nerve carries these electrical impulses to the brain for visual processing.
Examiner tips
- Use the exact terms: cornea, lens, retina, optic nerve. Show the sequence: cornea → lens → retina → optic nerve. Mention refracting and generating impulses. Keep answer concise to fit 5 marks.
Common mistakes
- Confusing the cornea with the lens or vice versa. Forgetting to mention that the retina contains photoreceptors. Using vague phrases like "detects light" without linking to electrical impulses.
Mark scheme (5 marks)
- The cornea refracts (bends) light as it enters the eye
- The lens refracts light further / fine-tunes focusing so that light converges on the retina
- The retina contains light-sensitive cells / receptors that detect light
- The light-sensitive cells generate electrical impulses / signals
- The optic nerve carries the electrical impulses to the brain
Key terms in this question
cornea · lens · retina · optic nerve
Related
- All AQA A-Level Physics (7408) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →