Date | May 2018 | Marks available | 6 | Reference code | 18M.3.HL.TZ1.8 |
Level | Higher level | Paper | Paper 3 | Time zone | Time zone 1 |
Command term | Explain | Question number | 8 | Adapted from | N/A |
Question
Explain how the human eye is able to distinguish between different colours of light.
Markscheme
a. (white) light is a mix of different wavelengths which correspond to different colours seen
b. light hits the back of the eye /retina
c. cones are photoreceptors in the retina/concentrated in fovea
d. cone cells are sensitive to a specific wavelength/specific colours/contain different pigments
e. three types of cone cells respond to red, blue or green light
f. different colours are perceived by the relative degree of stimulation of different cone cells
g. single cone cell passes impulses to a single nerve fibre/ganglion cell
h. (stimulation of) cones require bright light/ colour vision is less in dim light
i. genetic disorders can cause absence of red/green/some pigments / colour blindness