Question

Good vision depends on adequate intake of carotene-rich food.
Select the best option from the following statements.
(a)Vitamin A derivatives are formed from carotene.
(b)The photopigments are embedded in the membrane disc of the inner segments.
(c)Retinal is a derivative of Vitamin A.
(d)Retinal is a light-absorbing part of all the visual photopigments.
(A) b, c, and d
(B) a and b
(C) a, c and d
(D) a and c

Answer 1

It's a group of unsaturated nutritional organic compounds. It's needed by the retina of the attention within the sort of retinal, which mixes with protein opsin to make rhodopsin, the light-absorbing molecule. It's important for growth and development, for the upkeep of the system.

Complete answer
Opsin is the protein that occurred in the retina of the eyes and it binds to the retinal. Retinal is the light-sensitive pigment. vitamin A is important for the assembly of retinal, a component of rhodopsin. Rhodopsin is required for sensing dim light. Since insufficiency of nutrient A prompts deficient creation of retinal it brings about bad vision. Carotenes are the pigments present in red-orange products of the vegetables also. Carotenes synthesize vitamin A derivatives.

Additional information
Due to the unique function of the retinal as a visible chromophore, one among the earliest and specific manifestations of vitamin A deficiency is impaired vision, particularly in reduced light – nyctalopia. Persistent deficiency gives rise to a series of changes, the foremost devastating of which occur within the eyes. Other ocular changes are mentioned as xerophthalmia. To start with, there's dryness of the conjunctiva (xerosis) on the grounds that the typical lacrimal and the bodily fluid emitting epithelium is supplanted by a keratinized epithelium. This is regularly trailed by the development of keratin garbage in little hazy plaques (Bitot's spots) and, in the end, the disintegration of the roughened corneal surface with softening and destruction of the cornea (keratomalacia) and resulting in total blindness.

So the correct answer to the above question is option (C) ‘a, c, and d’.

Note: as long as vitamin A is fat-soluble, removing any excess taken in through diet takes much longer than with water-soluble B vitamins and vitamin C . this enables toxic levels of vitamin A to accumulate. These poison levels just happen with preformed (retinoid) vitamin A, (for example, from the liver). The carotenoid forms (for instance, beta-carotene as present in carrots) give no such symptoms, but excessive dietary intake of beta-carotene can cause carotenodermia.