Describe the roles of rod cells and cone cells in the retina.

Cambridge International IGCSE Biology (0610) — 14.1 Nervous control in humans · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Rod cells:
1. Function in low light intensity – used for night vision.
2. Provide monochromatic vision – cannot distinguish colour.

Cone cells:
1. Function in bright light – responsible for colour vision.
2. Three types, each sensitive to a different colour (red, green, blue).
3. Concentrated at the fovea.

Examiner tips

Use the word "function" to show role; list each point clearly.
Mention the fovea for cones – examiners look for this detail.
Keep answer concise – 4 marks, so 2 points per cell type.

Common mistakes

Mixing up rod and cone functions (e.g., saying rods are for colour).
Omitting the fovea detail for cones.
Using vague terms like "help see" instead of "function in".

Mark scheme (4 marks)

Rod cells function in low light intensity / are used for night vision
Rod cells are responsible for monochromatic vision (cannot distinguish colour)
Cone cells function in bright light and are responsible for colour vision
There are three types of cone cell, each sensitive to a different colour (red, green or blue); cone cells are concentrated at the fovea

Key terms in this question

rod cells · cone cells · retina