Platyfish with spots have an x-linked gene that produces the spots. all platyfish have an autosomal repressor that inhibits the expression of the spot-producing gene. the closely related swordtail lacks both the spot-producing gene and the repressor. in backcrosses between these two species, some hybrids receive the spot-producing gene, but not the repressor. these individuals can develop malignant tumors, because the expression of the spot-producing gene is not properly regulated. this appears to be an example of:

Why is it important that fibrin is insoluble in water?

What does natural resource management aim at ?

Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human x chromosome. the patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. they rarely live past their twenties. how likely is it for a woman to have this condition? a) women can never have this condition.b) one-fourth of the daughters of an affected man would have this condition.c) one-half of the daughters of an affected father and a carrier mother could have this condition.d) only if a woman is xxx could she have this condition.