In humans, as well as in many other animals and some plants, the sex of the individual is determined by sex chromosomes.
The sex chromosomes are one pair of non-homologous chromosomes: XX represents a female, while XY represents a male.
When a gene for a specific trait is attached to the X or Y chromosome, we say it is sex-linked, and when it is attached to the X
chromosome, we say it is X-linked. Alleles for these linked traits, such as hemophilia or color blindness, crosses, may be
recessive or dominant
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Hemophilia is an X-linked, recessive trait. The recessive allele for hemophilia is actually a mutated version of the normal alllele
but it can still be passed on through generations. Imagine a female is a carrier for hemophilia; her genotype is XHxh She is
married to a man who does not have hemophilia. What conclusion is NOT valid concerning this genetic cross?
A)
0% of female offspring will have hemophilia.
100% of the male offspring will have hemophilia.
There is a 50% chance that male offspring will have hemophilia.
The chance that female offspring will have the allele for hemophilia is
50%