Which one of the following statements is not correct?
- Retinal is the light absorbing portion of visual photo pigments.
- In retina the rods have the photopigment rhodopsin while cones have three different photopigments.
- Retinal is a derivative of vitamin C.
- Rhodopsin is the purplish red protein present in rods only.
Answer
(3) Retinal is a derivative of vitamin C.
Solution
As per NCERT, the photopigments are composed of opsin (a protein) and retinal (an aldehyde of vitamin A).
⇒ Retinal is the light-absorbing part of the photopigment, so statement (1) is correct.
⇒ Rods contain rhodopsin (visual purple) and cones contain three types of photopigments (for red, green and blue light), so statements (2) and (4) are correct.
∴ Retinal is a derivative of vitamin A, not vitamin C; statement (3) is not correct.
Answer: (3)