Detection of light by mammals Quiz
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5 questions, one answer each
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1. Which cells have axons that form the optic nerve?
- A. Rods
- B. Cones
- C. Bipolar neurones
- D. Ganglion cells
2. What effect does light have on a rod?
- A. Hyperpolarises it as Na⁺ channels close
- B. Depolarises it as Na⁺ channels open
- C. Increases release of inhibitory transmitter
- D. Opens K⁺ channels in the bipolar neurone
3. Why do rods work better than cones in dim light?
- A. Rods have no pigment
- B. Many rods synapse with one bipolar neurone, so summation reaches threshold
- C. Rods are concentrated at the fovea
- D. Rods have a bipolar neurone each
4. Which feature explains high visual acuity in the fovea?
- A. Many cones share one bipolar neurone
- B. The fovea has many rods
- C. Each cone has its own bipolar neurone
- D. There are no photoreceptors at the fovea
5. A patient has lost all cones in the fovea. Which symptom is most likely?
- A. Loss of vision in dim light
- B. Loss of detailed, coloured central vision
- C. Loss of peripheral vision
- D. Total blindness