The Eye as a Receptor Organ · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Your eye turns light into signals

Science · The Human Body · ages 15-16
Name ______________________   Date ____________

  1. What does the iris do?

    • Converts light into signals
    • Controls pupil to dose light
    • Carries signals to the brain

  2. Which order traces light to the retina, then nerve signals leaving the eye?

    • Retina, lens, cornea, brain
    • Cornea, pupil, lens, retina, optic nerve
    • Optic nerve, iris, lens, cornea

  3. Rods and cones turn light into electrical signals for the brain.

    Circle one:   True   False

  4. In dim light you catch shapes but no colour. Why?

    • Rods work dim shapes, cones need bright light
    • The lens closes at night
    • The optic nerve sleeps

  5. How does the eye focus on a near book?

    • Muscles let the lens thicken for close rays
    • The retina slides forward
    • The iris converts the light

  6. Far objects look blurry but near ones are clear. Where is the image, and which lens fixes it?

    • Behind the retina, extra-bending lens
    • In front of retina, spreading lens
    • On the iris, dark lens

  7. A student claims glasses cure the eyeball length itself. What is wrong?

    • Nothing, lenses reshape the eyeball
    • Lenses only rebend rays onto retina
    • Glasses work on the brain directly

  8. Near objects look blurry but far ones are clear. Where is the image, and which lens fixes it?

    • In front of the retina, spreading lens
    • On the cornea, flat lens
    • Behind the retina, extra-bending lens
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Your eye turns light into signals W1-mt_fslwsM3I7F-s1

  1. Controls pupil to dose light · Wider for dim rooms, narrower for bright ones.
  2. Cornea, pupil, lens, retina, optic nerve · Front bending first, conversion on the retina, then signals to the brain.
  3. True · That conversion is the whole job of the retina.
  4. Rods work dim shapes, cones need bright light · Rods serve dim shapes and movement; cones need brightness for colour and detail.
  5. Muscles let the lens thicken for close rays · Thickening shortens the focal length, landing close rays on the retina.
  6. In front of retina, spreading lens · That is short sight: over-bending lands far images early, and spreading corrects it.
  7. Lenses only rebend rays onto retina · Corrections follow from image place; they redirect light, not rebuild the eye.
  8. Behind the retina, extra-bending lens · That is long sight: weak bending lands close images late, and extra bending pulls them forward.
Worksheet · LightMySky