A passenger first looks through a train window at a sign on a distant platform. The passenger then looks at a nearby information screen.
| condition | light intensity at the eye in lux | distance of object from eye in m |
|---|---|---|
| looking at the sign | 60 | 20 |
| looking at the screen | 800 | 0.30 |
Assume that the passenger's iris and focusing structures respond normally during this change.
Using the information in the table, explain how the iris and the focusing structures of the eye respond when the passenger changes from looking at the sign to looking at the screen.
On a later journey, a fault in the passenger's suspensory ligaments causes nearby text to appear blurred. Suggest a mechanism by which this fault could cause the blurred vision.
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.