Photoreceptors Practice Test

Color perception comes from cones, not rods. Cones have three types of photopigments sensitive to different parts of the spectrum (roughly short, medium, and long wavelengths), and the brain interprets color by comparing the relative activity of these cone types. Rods, by contrast, use a single pigment and are extremely sensitive to light, but they do not convey color information. In bright light, cones drive vision and color is vivid; in dim light, cones become less active and rods take over, giving mostly grayscale, colorless vision. This is why color vision can be lost when cone function is impaired while rod function remains, illustrating that color is carried by cones rather than rods.