The following question is a sex-linked trait. Review the patterns of inheritance of sex-linked traits before answering the following questions. Make sure to indicate chromosomes and alleles in your answers when necessary.
Hemophilia is a caused by a recessive mutation found on the X chromosome in humans. The recessive allele (Xh) is associated with abnormal blood clotting (hemophilia), while the dominant allele (XN) causes normal blood clotting.
A man with normal blood clotting and woman who is heterozygous are going to have a child. What is the probability of an offspring who is a carrier of hemophilia, and if so, the sex(es) of the offspring?
A. Chances are 25% of a son who is a carrier
B. There is no chance of an offspring who is a carrier
C. Chances are 50% of either a son or a daughter who is a carrier
D. All offspring, male or female, will be carriers
E. Chances are 1 in 4 of a daughter who is a carrier
2. Two fruit flies, one with red eyes and one with white eyes mate and have an offspring with white eyes. Having red eyes is a dominant trait (R) while white eyes (w) is recessive. Based on this information, what must be the genotypes of the parental white-eyed fruit fly and the parental red-eyed fruit fly?
A. Red-Eyed fruit fly: Rw
White-eyed fruit fly: ww
B. Red-Eyed fruit fly: RR
White-eyed fruit fly: wR
C. Red-Eyed fruit fly: R
White-eyed fruit fly: w
D. Red-Eyed fruit fly: rr
White-eyed fruit fly: wr
E. Red-Eyed fruit fly: RR
White-eyed fruit fly: ww