, Which of the following is a component of the visual pigment rhodopsin -

Ans. is 'b' i.e., Retinal Vitamin A (Retinol)The retinoids are a family of molecules that are related to retinol (Vitamin A) and are essential for :VisionReproductionGrowthMaintenance of epithelial tissues Structure of vitamin AVitamin A is often used as a collective term for several related biologically active molecules.Vitamin A is essential for vision reproduction, growth and maintenance of epithelial tissues.Vitamin A can exist in several formsRetinol -Retinol is found in animal tissues as a retinyl ester with long chain fatty acids.Retinal (component of the visual pigment rhodopsin)The aldehyde derived from the oxidation of retinol.Retinal and retinol can readily be interconverted.Retinoic acidIt is the acid derived from oxidation of retinal.Retinoic acid cannot be reduced in the body and therefore cannot give rise to either retinal or retinol.b carotenePlant foods contain b carotene, which can be oxidatively cleaved in the intestine to yield two molecules of retinal.Now, the functions associated with each form of vitamin Retinoic acid, derived from oxidation of dietary retinol, mediates most of the actions of the retinoids, except for vision which depends on retinal, the aldehyde derivative of retinol.Note : Retinol acts on the nucleus of the target cells where the vitamin acts in a manner analogous to steroid hormones.