A technician must identify red, green and blue warning lights. In a bright room, the technician often confuses the red and green lights but identifies the blue light correctly.
The table shows the mean response of each type of cone cell when the technician and a person with typical colour vision view lights of the same intensity.
| Person tested | Colour of light | Red-sensitive cone response / relative units | Green-sensitive cone response / relative units | Blue-sensitive cone response / relative units |
|---|---|---|---|---|
| typical colour vision | red | 88 | 6 | 4 |
| typical colour vision | green | 7 | 84 | 6 |
| typical colour vision | blue | 3 | 5 | 91 |
| technician | red | 86 | 3 | 4 |
| technician | green | 6 | 4 | 5 |
| technician | blue | 3 | 3 | 89 |
Use the data to explain which type of cone cell is not working properly in the technician's eyes.
The technician's employer suggests making the warning lights brighter.
Explain whether this would restore normal colour vision for the technician.
102 exam-style questions on Edexcel GCSE Biology 2.4 The eye, covering 2.4.1 Structure and function of the eye and 2.4.2 Eye defects and their correction. Each one has a worked solution and a mark scheme showing where the marks go.