Which wavelength region is most likely absorbed by rhodopsin according to the transmission experiment?

• A. around 450 nm
• B. around 600 nm
• C. around 507 nm
• D. around 530 nm

Answer: (C)

Rhodopsin absorbs blue‑green light most strongly, with its absorption maximum around 500 nm (about 507 nm in many measurements). In a transmission experiment, the wavelength that shows the greatest absorption is the one where light transmission is lowest. Since 507 nm is closest to rhodopsin’s peak absorption, it will be absorbed most, making this the best match. Wavelengths like 450 nm, 600 nm, or 530 nm sit farther from the peak and would be absorbed less, so they show higher transmission than the peak region. This peak behavior explains why rods are particularly sensitive to blue‑green light in low light.