Hemophilia, color blindness, and duchenne muscular dystrophy occur more often in males than females. why? a these traits are carried only on the x chromosome and since there is no matching gene on the y chromosome, the traits are expressed more readily in males. b these traits are carried only on the x chromosome. c testis-determining factor (tdf causes these diseases. d these diseases develop due to the lack of estrogen and progesterone. e since there is no matching gene on the y chromosome, the traits are expressed more readily in males.

a) these traits are carried only on the x chromosome and since there is no matching gene on the y chromosome, the traits are expressed more readily in males.

Explanation:

Hemophilia, color blindness, and duchenne muscular dystrophy are disorders which are caused by X-linked recessive mutations which means that even if a mutation occurs in a gene of only one X chromosome then the phenotype will be expressed in the males because they are hemizygous for the gene. By hemizygous we mean to say that males have one X and one Y chromosome so a gene present on X chromosome will not find match on the Y chromosome and the mutation will express readily.

In contrast to this, in case of females who have two X chromosomes, the mutation in one X chromosome may be suppressed by another X chromosome in heterozygous condition i.e. if another X chromosome has healthy gene (wild type gene). In case of females the diseased phenotype will only appear if they are homozygous for the mutation.

sex cells are usually half's then they find another half and make a fertilize egg