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A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively.

Which of the following is a possible genotype for the mother?

a. IAIB

b. IAIA

c. ii

d. IAi

e. IBIB

Respuesta :

Answer:

option D

Explanation:

There are four possible blood groups (A, B, AB, O)  and six possible genotypes (AA, AO, BB, BO, AB, OO). Since the mother's bloodgroup is blood type A, then her genotype cannot be IAIB, ii(OO) or IBIB. Thus, we are left with the possible genotypes of IAIA (AA) and IAi (AO).

For her to produce a daughter with blood type O (OO), she has to be an heterozygote with the AO, contributing O so that the father assuming he is of blood type A or B negative (AO or BO) can contribute the second O.

For her to produce a son with type B negative which can only be of genotype BO since the mother is an AO (type A positive), he can only get the type B negative (BO) if his father is blood type B negative. this occurs with the mother contributing the O and the father contributing the B and the rhesus negative factor.

luisvaschetto

The genotype for the mother is IAi, while the genotype for the father is IBi.

  • In this case, there are two different genes that determine two blood group systems: the ABO blood system and the Rh group.

  • The ABO blood group system exhibit three different alleles. A and B alleles are codominant (genotype IAIB), while the O allele is recessive over the A and B alleles.

  • Thus, the O allele is only expressed in a homo-zygous condition (genotype ii).

  • Moreover, the Rh- group factor is a recessive trait, thereby this phenotypic feature is also expressed only in homo-zygous condition (genotype -/-).

  • In this case, the mother has a daughter O positive (genotype ii positive) and a son who is type B negative (genotype B_ negative).

  • The only way for which the mother can produce these offspring is if she has the genotype IAi (+/-), thereby she can produce four types of gametes: IA negative (-); i negative (-); IA positive (+); and i positive (+).

  • In consequence, the father would be the genotype IBi (+/-).

The Punnett square for this cross is:

                IA (-)               i (-)                      IA (+)                               i (+)

IB (+)     IAIB (+/-)         IAi (+/-)                IAIB (+/-)                         IBi (+/+)

IB (-)      IAIB (-/-)      son IBi (-/-)           IAIB (+/-)                         IBi (+/-)

i (+)       IAi (+/-)            ii (+/-)                  IAi (+/+)          daughter ii (+/+)

i (-)         IAi (-/-)            ii (+/-)                   IAi (+/-)                           ii (+/-)

In conclusion, the genotype for the mother is IAi, while the genotype for the father is IBi.

Learn more in:

https://brainly.com/question/10253374

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