Question

Colour blindness in human being is due to

• A. Vitamin A deficiency
• B. Sex linked inheritance
• C. Over activity of adrenal gland
• D. Excessive drinking of alcohol

Answer 1

The correct option is B Sex linked inheritance

Colour blindness is a usually a genetic (hereditary) condition. Red / green and blue colour blindness is usually passed down from our parents. The gene, which is responsible for the condition is carried on the X chromosome and this is the reason why many more men are affected than women. The retina of the eye has two types of light-sensitive cells called as rods and cones. Rods work in low light conditions to help night vision, but cones work in daylight and are responsible for colour discrimination. There are three types of cone cells and each type has a different sensitivity to light wavelengths. One type of cone perceives blue light, another perceives green and the third perceives red. People with normal colour vision have all three types of cone/pathway working correctly but colour blindness occurs when one or more of the cone types are faulty.