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 discs of the inner segment (c) Retinal is a derivative of Vitamin A (d) Retinal is a light absorbing part of all the visual photopigments

• A. (a), (c) and (d)
• B. (a) and (c)
• C. (b), (c) and (d)
• D. (a) and (b)

Answer 1

The Correct Option is A

 Let's delve into the question to understand which options correctly pertain to the role of carotene and Vitamin A in vision.

1. Understanding Carotene and Vitamin A Relationship:
   • Statement (a): "Vitamin A derivatives are formed from carotene" is true. Carotene, particularly beta-carotene, is a precursor of Vitamin A. Once ingested, it is converted in the body to retinal, which is a form of Vitamin A.
2. Understanding Retinal and Photopigments:
   • Statement (b): "The photopigments are embedded in the membrane discs of the inner segment" is incorrect. Photopigments are actually located in the outer segment of the photoreceptor cells in the retina, primarily in the rods and cones, not in the inner segment.
   • Statement (c): "Retinal is a derivative of Vitamin A" is true. Retinal, an aldehyde form of Vitamin A, is crucial for the formation of visual pigments located in the photoreceptor cells in the retina.
   • Statement (d): "Retinal is a light absorbing part of all the visual photopigments" is true. Retinal, when combined with opsin proteins, forms rhodopsin and other related photopigments, making it essential for capturing light.

Based on the above explanations, the correct options are (a), (c), and (d).

Statement	Explanation
(a) Vitamin A derivatives are formed from carotene	True, because carotene converts into Vitamin A.
(b) The photopigments are embedded in the membrane discs of the inner segment	False, as photopigments are located in the outer segment.
(c) Retinal is a derivative of Vitamin A	True, retinal is synthesized from Vitamin A.
(d) Retinal is a light absorbing part of all the visual photopigments	True, retinal is essential for light absorption in vision.

Hence, the correct answer option is (a), (c), and (d).