Question

Night blindness is caused due to deficiency of

• A. Vitamin A
• B. Vitamin C
• C. Vitamin D
• D. Vitamin E

Answer 1

The correct option is A

Vitamin A

The correct option is A

Explanation of the correct option:

Night blindness

1. Night blindness is poor vision at night or in dim light
2. Rhodopsin is a pigment found in the rods of the retina.
3. Rhodopsin is required for vision in dim light.
4. It is made up of opsin and retinal.
5. Opsin is a protein that on detecting light change shapes and activated the photoreceptor and send indications to the brain that light is detected.
6. Retinal in the eye is phototransduction means it converts the light energy detected to electrical energy and sends signals to the brain by the optic nerve.

Vitamin A

1. Vitamin A is the precursor of rhodopsin.
2. Vitamin A is required for the production of retinal.
3. So in its deficiency retinal is not formed.
4. Causing improper vision in dim light leading to night blindness.

Explanation of the incorrect options:

Option B

1. Vitamin C is found in citrus fruits and vegetables.
2. Vitamin C is water soluble and can get excreted out by urine if present in excess.
3. Vitamin C helps in the protection of cells, wound healing, and proper functioning of the immune system.
4. Scurvy is caused by a deficiency of vitamin C.
5. Scurvy symptoms are bleeding gums, weakness, fatigue, and rash.

Option C

1. We get vitamin D through food and by exposure to sunlight.
2. It helps in the absorption of phosphorus and calcium.
3. In adults its deficiency causes osteomalacia.
4. Osteomalacia causes weak bones and muscle weakness.
5. Rickets is caused by a deficiency of vitamin D in children.
6. Ricket results from inadequate mineralization of growing bone.

Option D:

1. Vitamin E is also called Tocopherol.
2. It helps in the proper functioning of muscles and nerves.
3. It is an antioxidant that protects the cell from damage.
4. Can also cause a weak immune system in its deficiency.
5. Vitamin E deficiency may cause impaired reflexes and coordination, difficulty walking, and weak muscles.

Final answer: Night blindness is caused due to deficiency of Vitamin A.