Final answer:
Adjustment to low-light conditions is primarily facilitated by changes in rhodopsin concentration. Rhodopsin is found in rod cells and requires the retinal derived from vitamin A to change its structure in response to light, enabling the rods to function adequately in dim light.
Step-by-step explanation:
Adjustment to low-light conditions is primarily facilitated by changes in rhodopsin concentration. Rod cells in the retina contain rhodopsin, which is crucial for vision in dim light. Rhodopsin consists of the protein opsin and the cofactor retinal, which is derived from vitamin A. When light strikes the retina, rhodopsin undergoes a biochemical change, enabling vision in changing light conditions.
The rods are photoreceptors sensitive to low levels of light, thus dominating vision in low-light conditions, whereas cones are responsible for vision at higher light levels and color vision. The transition from a well-lit to a dimly lit environment initiates a shift in photoreceptor activity from cones to rods. The conversion of retinal from its active 'cis' form to an inactive 'trans' form and then back again in the dark is a vital process that continues the cycle of rhodopsin synthesis, therefore enabling normal vision in various lighting.
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