The eye and the ear are both sense organs that detect stimuli and send nerve impulses to the brain. Explain how the eye detects light and how the ear detects sound, including the roles of the receptor cells in each organ.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Humans rely on two key sense organs — the eye and the ear — to gather information about their environment. Both organs contain specialised receptor cells that convert different types of stimuli into electrical nerve impulses.
Model answer (5 marks)
The eye contains light‑sensitive receptor cells – rods and cones – in the retina. Light enters the eye, is focused by the cornea and lens onto the retina, where it stimulates the rods and cones to generate electrical impulses. These impulses travel via the optic nerve to the brain.
The ear contains hair cells in the cochlea that respond to sound vibrations. Sound waves enter the ear, travel through the ear canal, vibrate the eardrum and ossicles, and are transmitted as fluid waves to the cochlea. The hair cells bend in response to these waves, converting the mechanical vibration into electrical impulses that travel along the auditory nerve to the brain.
The ear contains hair cells in the cochlea that respond to sound vibrations. Sound waves enter the ear, travel through the ear canal, vibrate the eardrum and ossicles, and are transmitted as fluid waves to the cochlea. The hair cells bend in response to these waves, converting the mechanical vibration into electrical impulses that travel along the auditory nerve to the brain.
Examiner tips
- Use the words ‘rods’, ‘cones’, ‘hair cells’, ‘optic nerve’, ‘auditory nerve’ – these are key terms.
- Show the pathway: light → retina → optic nerve → brain; sound → cochlea → hair cells → auditory nerve → brain.
- Mention the role of the lens in focusing light and the cochlea in converting vibration to nerve impulses.
Mark scheme (5 marks)
- The eye contains light receptor cells (rod cells and/or cone cells) located in the retina
- Light entering the eye is focused onto the retina, stimulating the receptor cells to generate nerve impulses
- Nerve impulses from the retina travel along the optic nerve to the brain
- The ear contains hair cells (in the cochlea) that detect sound vibrations
- Nerve impulses from the hair cells travel along the auditory nerve to the brain
Key terms in this question
receptor cells · nerve impulses
Related
- All Edexcel A-Level Biology A: Salters-Nuffield (9BN0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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