A student tests two people using equally bright coloured patches. Both people see patch outlines clearly. Person P confuses some colours, while person Q identifies all colours correctly.
Which conclusion is supported?
P must have abnormal rod function, even though light is focused correctly.
P must have a cloudy lens, because light cannot reach any receptor cells.
P may have abnormal cone function, even though light is focused correctly.
P may have an elongated eyeball, because all wavelengths focus differently.
42 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.