question_answer 57)

  If a father and son are both defective in red-green colour vision, is it likely that the son inherited the trait from his father? Comment.

Answer:

                  Gene for colour blindness is X-chromosome linked, 'and sons receive their sole X-chromosome from their mother, not from their father. Male to male inheritances is not possible for X-linked traits in humans. In the given case the mother of the son must bea carrier (heterozygous) for colour blindness gene, thus transmitting the gene to her son.