A person can focus a coloured pattern sharply but repeatedly confuses red and green areas. Increasing the brightness does not remove the difficulty.
Which explanation is most likely?
Some cone cells do not distinguish the colours normally.
Some rod cells refract the coloured light too strongly.
The cornea focuses the coloured light behind the retina.
The lens focuses the coloured light in front of the retina.
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.