Question

Why is colour blindness more common in men than in women?

Answer 1

Hint: Colour blindness is the genetic disorder where the affected individuals are not able to perceive different colours. It is caused either due to damage to the eye, the optic nerve or some parts of the brain. The most common colour blindness is red-green which is followed by yellow-blue.

Complete answer:
Colour blindness is an X-linked genetic disorder that most commonly affects the cone cells of the eye since these cells are associated with colour vision. Colour blindness is more common in men than in women because men have only a single copy of the X chromosome. If the X chromosomes that men receive are mutated it results in colour blindness whereas women contain two copies of the X chromosome.

So even if one of the copies contains the mutation the other copy is normal and the defect is compensated by the normal copy. Colour blindness can either be acquired by inheritance. Acquired colour blindness is caused by drugs, diseases, organic solvents or certain harmful chemicals. Inherited colour blindness is of three types- monochromacy, dichromacy and anomalous trichromacy. Monochromacy is known as total colour blindness where cones are either absent or defective. Dichromacy is the inability to distinguish between blue and green or red and green colours. Anomalous trichromacy occurs when one of the three cone pigments is altered.

Note: Till date there is no cure for colour blindness though special lenses are available that help people having red-green colorblindness. Diagnosis is carried out mostly by the Ishihara colour test or other genetic testing methods.