Question

Colour blindness is a

• A. Sex limited character
• B. Sex linked character
• C. Sex influenced character
• D. None of the above

Answer 1

The correct option is B Sex linked character

Colour blindness, or colour vision deficiency, is the inability or decreased ability to see colour, or perceive colour differences, under normal lighting conditions. Colour blindness affects a significant percentage of the population. There is no actual blindness but there is a deficiency of colour vision. This type of colour blindness is usually a sex-linked condition. The genes that produce photo-pigments are carried on the X chromosome; if some of these genes are missing or damaged, colour blindness will be expressed in males with a higher probability than in females because males only have one X chromosome (in females, a functional gene on only one of the two X chromosomes is sufficient to yield the needed photo-pigments). Colour blindness can be inherited. It is most commonly inherited from mutations on the X chromosome but the mapping of the human genome has shown there are many causative mutations capable of causing colour blindness, originate from at least 19 different chromosomes and 56 different genes.