Scientists investigated two human lens samples affected by cataracts. They directed the same light beam at each sample and measured the percentage of incoming light that passed straight through to a sensor.
| Lens sample | Area of cloudy patch in mm2\text{mm}^2mm2 | Percentage of incoming light passing straight through |
|---|---|---|
| P | 2 | 80 |
| Q | 8 | 40 |
Compare the results for sample P and sample Q.
The incoming light level for sample Q is 500 lux.
Calculate the light level that passes straight through sample Q.
Name the light-sensitive layer at the back of the eye.
A person with a cataract sees blurred edges around printed letters.
Suggest why the edges do not appear sharp.
During cataract treatment, an artificial lens is fitted into the eye.
Suggest why it is important that the artificial lens is transparent.
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.