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Exam questions · Biology · The Nervous System

The Eye

  • 7 exam questions
  • 21 marks
  • 8 quick checks
  1. 1 State [2 marks]

    State the function of the iris and the function of the retina.

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    Model answer

    The iris controls the amount of light entering the eye. The retina contains the receptor cells that detect light.

    Mark scheme

    • Iris controls the amount of light entering — 1 mark
    • Retina contains the light receptor cells — 1 mark
  2. 2 Name [3 marks]

    Figure 1 shows a section through the eye. Name the parts shown at A, B and C.

    The eye in cross-section with three parts marked A, B and C.
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    Model answer

    A is the cornea. B is the lens. C is the optic nerve.

    Mark scheme

    • A: cornea — 1 mark
    • B: lens — 1 mark
    • C: optic nerve — 1 mark
  3. 3 Explain [3 marks]

    Explain how the pupil changes when a person moves from a dim room into bright sunlight.

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    Model answer

    The circular muscles of the iris contract and the radial muscles relax. The pupil gets smaller. This reduces the amount of light that enters, which protects the retina from damage.

    Mark scheme

    • Circular muscles contract and radial muscles relax — 1 mark
    • Pupil gets smaller — 1 mark
    • Less light enters, protecting the retina — 1 mark
  4. 4 Explain [4 marks]

    Explain how the eye focuses on a near object.

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    Model answer

    The ciliary muscles contract. This slackens the suspensory ligaments. The lens becomes thicker and more curved. It refracts the light more, so that the light is focused on the retina.

    Mark scheme

    • Ciliary muscles contract — 1 mark
    • Suspensory ligaments slacken — 1 mark
    • Lens becomes thicker — 1 mark
    • Light is focused on the retina — 1 mark
  5. 5 Explain [3 marks]

    A person is short-sighted. Explain why distant objects look blurred and how the problem can be corrected.

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    Model answer

    The lens is too strong or the eyeball is too long, so the light from distant objects is focused in front of the retina. The image on the retina is blurred. A concave lens in spectacles spreads the light out so that it is focused on the retina.

    Mark scheme

    • Light focused in front of the retina — 1 mark
    • Image on the retina is blurred — 1 mark
    • Concave lens corrects it — 1 mark
  6. 6 Describe [3 marks]

    Describe three ways in which a focusing problem in the eye can be overcome.

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    Model answer

    Wearing spectacles with the correct lenses, wearing contact lenses, laser eye surgery to reshape the cornea, or replacing the lens with an artificial one.

    Mark scheme

    • Any three of spectacles, contact lenses, laser surgery, replacement lens — 3 marks
  7. 7 Explain [3 marks]

    Explain why a person who is colour blind cannot be helped by spectacles.

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    Model answer

    Colour blindness is caused by faulty cone cells in the retina, which cannot detect one or more colours. Spectacles only change how light is focused, so they cannot fix the receptor cells.

    Mark scheme

    • Caused by faulty cone cells — 1 mark
    • Spectacles only change how the light is focused — 1 mark
    • They cannot repair the receptor cells — 1 mark

Quick check

  1. 1

    Which part of the eye controls the amount of light that enters?

    1. AThe cornea
    2. BThe lens
    3. CThe iris
    4. DThe retina
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    C: The iris

    The iris changes the size of the pupil.

  2. 2

    Which part of the eye contains the light receptor cells?

    1. AThe retina
    2. BThe cornea
    3. CThe pupil
    4. DThe lens
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    A: The retina

    The retina contains the rods and cones.

  3. 3

    What happens to the pupil in bright light?

    1. AIt gets larger
    2. BIt disappears
    3. CIt changes colour
    4. DIt gets smaller
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    D: It gets smaller

    The circular muscles contract, so the pupil gets smaller.

  4. 4

    When the eye looks at a near object, what happens to the lens?

    1. AIt becomes thinner
    2. BIt becomes thicker
    3. CIt stays the same
    4. DIt moves forward
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    B: It becomes thicker

    The ciliary muscles contract, the ligaments slacken and the lens becomes thicker.

  5. 5

    Which lens corrects short-sightedness?

    1. AA convex lens
    2. BA flat lens
    3. CA concave lens
    4. DA cylindrical lens
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    C: A concave lens

    A concave lens spreads the light before it enters the eye.

  6. 6

    What are rod cells used for?

    1. ASeeing in dim light
    2. BSeeing colour
    3. CFocusing the light
    4. DControlling the pupil
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    A: Seeing in dim light

    Rods are sensitive to dim light but do not detect colour.

  7. 7

    What causes colour blindness?

    1. AA lens that is too thick
    2. BAn eyeball that is too long
    3. CA damaged cornea
    4. DFaulty cone cells
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    D: Faulty cone cells

    One or more types of cone cell do not work.

  8. 8

    What do the suspensory ligaments connect?

    1. AThe retina to the optic nerve
    2. BThe ciliary body to the lens
    3. CThe iris to the cornea
    4. DThe pupil to the lens
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    B: The ciliary body to the lens

    The suspensory ligaments connect the ciliary body to the lens.