Final answer:
The statement that the wavelengths of light a photoreceptor responds to are determined by the opsin in the photoreceptor is true. Opsins are sensitive to specific wavelengths, which allows for the detection of different colors by rods and cones in the human eye. Retinal, a key component in photopigments, changes shape upon light exposure, activating the photoreceptor's biochemical cascade.
Step-by-step explanation:
The statement that the wavelengths of light a photoreceptor responds to is determined by the opsin in the photoreceptor is true. Photoreceptor cells, which include rods and cones, contain photopigments composed of an opsin protein and a retinal molecule. Different opsins have varying sensitivities to light wavelengths, with rods being more sensitive and primarily active in low-light conditions due to their photopigment rhodopsin, which has a peak sensitivity at 498 nm. Cones, on the other hand, are responsible for color vision and have three types of opsins with peak sensitivities at 564 nm, 534 nm, and 420 nm, corresponding to the colors red, green, and blue, respectively.
When light strikes retinal, it changes the shape which activates the photoreceptor cell. This change leads to a series of biochemical events resulting in a change in membrane potential, the release of neurotransmitters, and eventually the perception of light. Bleaching occurs when intense light exposure causes retinal to change into a form that cannot respond to light energy, requiring enzymatic changes to reverse the photoisomerization.