Solution :Rhodopsin is a pigment present in the rod cells of the retina.It consists of two components-OPSIN and retinal (=retinene).Retinal is an aldehyde of vitamin A which absorbs light FALLING on the rod and CHANGES its form and separates from the opsin component. This initiates the transmission of a NERVE impulse to the brain.Rhodopsin ALLOWS vision in dim light (night vision).