Question

Adaptation of eyes in dark is due to

• A. Depletion of vision pigment in rods.
• B. Depletion of vision pigment in cones.
• C. Repletion of vision pigment in rods.
• D. Repletion of vision pigment in cones.

Answer 1

The correct option is C Repletion of vision pigment in rods.

Adaption by eyes refers to the ability of the eye to adjust to various levels of darkness and light. The three main players in dark adaptation of the eye are the pupil, the cone cells, and the rod cells. While the pupil is the dark hole near the front of the eye that lets the light into the eye, cone cells along the retina are responsible for color vision and the rod cells are responsible for black and white vision. Both Cones and rods contain rhodopsin; a biological pigment which is a highly sensitive photoreceptor which photobleaches in response to light. Rods are more sensitive to light and they take longer to fully adapt to the change in light. Further, the photopigment in the rods regenerate more slowly, do not reach their maximum sensitivity while cone cells take just 10 minutes. However, since there are far more rods in the retina than cone cells it is the repletion of visual pigment in rods that help in the adaptation of eyes to dark.