Rods vs. cones in dim light
After walking from bright sunlight into a dark theater, you gradually see better, but colors look washed out. What explains this?
Answer C: explanation for every choice
A
Cones need bright light. They are responsible for color and fine detail, not night vision.
B
The fovea is packed with cones and has no rods, which is why dim objects are easier to see slightly off center.
C
Correct. Rods contain rhodopsin and respond to very low light, but a single rod type cannot distinguish wavelengths, so color vision fades.
D
Lens curvature changes focus (accommodation). The pupil, not the lens, controls how much light enters.
TakeawayRods: dim light, no color, periphery. Cones: bright light, color, fovea.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID ps27.