Question

Vitamin A deficiency leads to night-blindness. Which of the following is the reason for the disease?
A. Rod cells are not converted to cone cells.
B. Rhodopsin pigment of rod cells is defective.
C. Melanin pigment is not synthesized in cone cells.
D. Cornea of the eye gets dried.

Answer 1

The vitamins are natural and essential nutrients, required in small quantities and play a major role in growth and development, repair and healing wounds, maintaining healthy bones and tissues, for the proper running/working of an immune system, and other biological functions. Vitamin A is an important vitamin that takes part in a major role in our vision. It helps in the production of certain pigments that are important for the proper functioning of the retina.

Complete answer:
Vitamin A deficiency is the major cause of acute diseases, infections, and preventable blindness in children. It is one of the crucial causes of night blindness in pregnant women. It also affects the immune system and results in deaths from malaria, diarrhea, and measles. Vitamin A Deficiency also results in the growing inability of a body to oppose or confront different types of infections. This results in various diseases. The deficiency of vitamin A critically affects the growth of their bones and also their overall body growth.

Night blindness/nyctalopia is an unusual condition where the individual is not able to see at night. The rods and cones are the photoreceptor cells, which are found in the retina. Rods help in low light vision. Rhodopsin is a pigment that is present in these cells. The photosensitivity of rhodopsin pigment is damaged/diminished which causes night blindness. it can occur due to deficiency of vitamin A. so the correct option is Rhodopsin pigment of rod cells is defective.

Hence, the correct answer is option (B).

Additional information:
The healthy human eye retina contains two light-sensitive cells, rod cells, and cone cells. The rod cells are for low light and the cone cells are for normal and bright light and responsible for color vision. Colour blindness is affected when these two light-sensitive cells fail to perform their functions.

Note: Keep in mind the following important causes of vitamin A deficiency:
- Not taking the required animal food products and vegetables can cause malnutrition.
- This deficiency can cause over excretion of urine.
- Mothers who do not breastfeed their child can put them at major risk of this kind of deficiency. Because breast milk consists of a good amount of Vitamin A for a newborn baby.