A student investigates the effect of light intensity on pupil diameter. In dim light the student views a nearby card. In bright light the student views a distant wall.
Which change would best isolate the effect of light intensity?
Keep the light intensity constant so accommodation conditions remain the same.
Use a different person each time so the starting pupil diameter is different.
Use a different viewing distance each time so the lens changes its curvature.
Keep the viewing distance constant so accommodation conditions remain the same.
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.