Q11 of 805 Page 1

One of the twins born to parents having normal colour vision was colour blind whereas the other twin had normal vision. Work out the cross. Give two reasons how it is possible.

Colour blindness is a sex-linked disorder with the carrier gene present on the X chromosome. The probable reason for one of the twins to be colour blind is that the mother was a carrier of the gene and the offspring was a male i.e., the dominant X gene was received from the father.


2. Cross showing affected colour-blind individual (in red)


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