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IGCSEBiology
Trial Class

Original practice · 5 questions · 16 marks · about 18 minutes

Eye Structure and Function Practice Questions

Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.

These questions test your knowledge of the structure of the eye and how it focuses light on the retina.

Before you open the answers

  • Attempt every question without notes.
  • Show working for calculations and write complete biological statements.
  • Use the suggested time as a guide, not a strict limit on the first attempt.

These are original practice questions. They do not reproduce an official Cambridge paper or official mark scheme.

  1. Question 1

    Paper 4 Both 4 marks Difficulty 3/5

    State the function of each of these parts of the eye: (a) cornea, (b) iris, (c) lens, (d) retina.

    Show model answer and marking guidance
    1. (a) Cornea: refracts (bends) light entering the eye.
    2. (b) Iris: controls the amount of light entering the eye by adjusting the pupil size.
    3. (c) Lens: focuses light onto the retina by changing shape (accommodation).
    4. (d) Retina: contains light-sensitive receptor cells (rods and cones) that detect light.

  2. Question 2

    Paper 4 Extended 4 marks Difficulty 4/5

    Describe how the eye focuses on a near object (accommodation).

    Show model answer and marking guidance
    1. Ciliary muscles contract.
    2. Tension in the suspensory ligaments decreases / ligaments slacken.
    3. The lens becomes thicker / more curved / more convex.
    4. This increases the refraction of light, focusing the image on the retina.

    Watch for: Getting the ciliary muscle action backwards: they contract for near vision, not relax.

  3. Question 3

    Paper 4 Both 3 marks Difficulty 3/5

    Explain how the iris controls the amount of light entering the eye in bright conditions.

    Show model answer and marking guidance
    1. In bright light, the circular muscles of the iris contract.
    2. The radial muscles relax.
    3. The pupil becomes smaller: less light enters, protecting the retina.

  4. Question 4

    Paper 2 Core 2 marks Difficulty 1/5

    Name the nerve that carries impulses from the eye to the brain.

    Show model answer and marking guidance
    1. The optic nerve.
    2. It transmits electrical impulses from the retina to the brain for processing.

  5. Question 5

    Paper 4 Extended 3 marks Difficulty 4/5

    Explain why the pupil reflex is an example of a reflex action.

    Show model answer and marking guidance
    1. It is rapid and automatic: does not require conscious thought.
    2. It follows a reflex arc: light receptor (retina) → sensory neurone → brain → motor neurone → iris muscles.
    3. It protects the retina from damage by bright light.

Mark the set consistently

Award a point only when the idea is clearly present in the written answer. Correct any missed point in a complete sentence, then test the same skill on a different question several days later.

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