This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Special Senses, Subject name: Physiology
[{'content': 'In dark adaptation, there is: \nSelect and explain. \nA. Break down of rhodopsin, B. Increased threshold for vision, C. No role for cones, D. No change in the dioptric power of the eye', 'role': 'user'}, {'content': 'Answer: D \nExplanation: In dark adaptation, there is re-synthesis of the bleached rhodopsin. In the retina, the storage form of vitamin A (all-trans retinol) is conveed to 11-cis retinal which combines with opsin to form rhodopsin. Initial dark adaptation is due to cones; cones form visual pigment faster as compared to rods. Other changes in the dark: (1) dilation of pupil, (2) increased number of impulses in the optic nerve fibers.', 'role': 'assistant'}]