In humans, the ABO blood type is under the control of autosomal multiple alleles. Color blindness is a recessive X-linked trait. If two parents who are both type A and have normal vision produce a son who is color-blind and is type O, what is the probability that their next child will be a female who has normal vision and is type O?

In fruit flies, yellow body (y) is recessive to gray body , and the trait of body color is inherited on the X chromosome. Vestigial wing (v) is recessive to full-sized wing (v⁺), and the trait has autosomal inheritance. A cross of a male with yellow body and full wings to a female with gray body and full wings is made. Based on an analysis of the progeny of the cross shown below, determine the genotypes of parental and progeny flies.
[Table below appears at this point containing crosses and results]
Phenotype                               Number of     Number of
                                                 Males            Females    _
Yellow body, full wing                296                   301
Yellow body, vestigial wing        101                    98
Gray body, full wing                   302                   298
Gray body, vestigial wing           101                   103 _
                                                   800                   800

In a species of fish, a black spot on the dorsal fin is observed in males and females. A fish breeder carries out a pair of reciprocal crosses and observes the following results.

    Cross I      Parents: black-spot male x nonspotted female
                      Progeny: 22 black-spot male
                                     24 black-spot females
                                     25 nonspotted males
                                     21 nonspotted females
     Cross II     Parents: nonspotted male x black-spot female
                       Progeny: 45 black-spot males
                                      53 nonspotted females

Identify which sex is heterogametic. Give genotypes for the parents in each cross, and explain the progeny proportions in each cross.

In a species of fish, a black spot on the dorsal fin is observed in males and females. A fish breeder carries out a pair of reciprocal crosses and observes the following results.

    Cross I      Parents: black-spot male x nonspotted female
                      Progeny: 22 black-spot male
                                     24 black-spot females
                                     25 nonspotted males
                                     21 nonspotted females
     Cross II     Parents: nonspotted male x black-spot female
                       Progeny: 45 black-spot males
                                      53 nonspotted females

Why does this evidence support the hypothesis that a black spot is sex linked?

Lesch–Nyhan syndrome (OMIM 300322) is a rare X-linked recessive disorder that produces severe mental retardation, spastic cerebral palsy, and self-mutilation.

What is the probability that the first son of a man whose brother has Lesch–Nyhan syndrome will be affected?

Lesch–Nyhan syndrome (OMIM 300322) is a rare X-linked recessive disorder that produces severe mental retardation, spastic cerebral palsy, and self-mutilation.

If the first son of the woman described in (a) is affected, what is the probability that her second son is affected?

Lesch–Nyhan syndrome (OMIM 300322) is a rare X-linked recessive disorder that produces severe mental retardation, spastic cerebral palsy, and self-mutilation.

What is the probability that the first son of a woman whose brother has Lesch–Nyhan syndrome will be affected?