Final answer:
The genotype for the blood type O phenotype is ii, which is answer option D. A woman with blood type B may only donate blood to a husband with blood type A if she is a universal donor (genotype BO). A child with blood type O can be legitimate offspring of parents with blood types A and B, provided they carry the genotype AO and BO respectively.
Step-by-step explanation:
The student's question pertains to the phenotype and genotype relationship in the context of ABO blood groups, which is an example of multiple alleles and codominance. The ABO blood system has four possible phenotypes (A, B, AB, and O) that are determined by three alleles: IA, IB, and i. The alleles IA and IB are both dominant, and i is recessive; hence, blood type O has the genotype ii. If a person exhibits the phenotype of blood type O, their genotype must be ii since both parents would have contributed a recessive allele (i).
To answer the student's questions:
- The genotype that matches the phenotype of blood type O is ii (Option D).
- A couple with blood type A (genotype AO) and blood type B (genotype BO) can have offspring with any of the ABO blood types: A, B, AB, or O. This is due to the possible combinations of their alleles during reproduction.
- A woman with blood type B can donate blood to her husband with blood type A only if her blood type B is BO (making her a universal donor), but not if it is BB, due to the presence of B antigens that would react with the husband's A antibodies.
If we assume an individual has blood type O, they can indeed be a legitimate child of parents who have blood types A and B, provided that each parent contributes the i allele, resulting in an ii genotype for the child.