Which photoreceptor has a peak absorption at 507 nm?

The photoreceptor that has a peak absorption at 507 nm is the rod cell. Rods are specialized for low-light vision and are highly sensitive to light, making them crucial for night vision. They contain the pigment rhodopsin, which is particularly effective at this wavelength, allowing rods to respond to dim light conditions.

Rods are more prevalent than cones in the peripheral regions of the retina and are responsible for detecting light and movement rather than color. Their peak sensitivity at 507 nm falls within the blue-green light spectrum, which corresponds to the optimal wavelength for rod function.

In contrast, the other photoreceptors, which are cones responsible for color vision, have different peak absorption wavelengths. S cones (short-wavelength cones) peak at around 420 nm, M cones (medium-wavelength cones) peak at approximately 530 nm, and L cones (long-wavelength cones) peak around 560 nm. Each type of cone contributes to color perception, whereas rods are primarily focused on sensitivity in lower light levels.