Cambridge IGCSE Biology practice

Paper 3 structured question: Sense organs

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Paper

Marks

Topic

Sense organs

Exam-style question

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Paper 3Theory (Core)3 marks

The pupil reflex controls the size of the pupil in response to changes in light intensity.

Description

When a person moves from a dark room to a bright room, the pupil size changes automatically.

a
State what happens to the pupil size when light intensity increases?
Your answer
Aim for approximately 1 distinct marking point.
[1]
b
Explain how the pupil reflex protects the eye when moving into bright light.
Your answer
Aim for approximately 2 distinct marking points.
[2]

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Paper 3Theory (Core)3 marks

Diagram Description

The diagram shows the iris with circular muscles and radial muscles around the pupil.

a
Identify which muscles contract to make the pupil larger in dim light.
Your answer
Aim for approximately 1 distinct marking point.
[1]
b
Explain why the pupil changes size in response to light intensity.
Your answer
Aim for approximately 2 distinct marking points.
[2]