An optician has two lenses, P and Q.
Lens P is thicker in the middle than at the edges.
Lens Q is thinner in the middle than at the edges.
Give the letter of the lens that is used to correct short-sightedness.
Explain your answer.
A person needs lens P to read but does not need a lens to see distant objects.
Explain what this tells you about this person's eyes.
A man is short-sighted. As he gets older, the lens in his eye becomes stiffer and cannot become as thick.
His new glasses have two parts. The upper part is used for looking at distant objects and the lower part is used for reading.
Suggest the type of lens in each part. Give a reason for each answer.
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.