Final answer:
The mother's genotype could be either IBi or ii for the son with blood type B (IBi) to donate blood to her. A child with blood type O (ii) can be born to parents with A (IAi) and B (IBi) blood types, showcasing codominant inheritance patterns.
Step-by-step explanation:
The subject of this question is Biology, specifically genetics and the inheritance patterns of ABO blood types. In order for a son with blood type B (IBi) to donate blood to his mother without knowing her blood type directly, we need to infer her genotype based on the information given about the father's genotype (IAIB, since he has AB blood type). The son must have inherited the i allele from his mother because he received IB from his father. Therefore, the mother's genotype cannot contain an IA allele, meaning she could be either genotype IBi or genotype ii. Thus, the son can donate blood to his mother if she has B or O blood type.
To address the question related to the possibility of an individual with blood type O (ii) being a legitimate child of parents with blood types A and B, if both parents are heterozygous (genotype IAi and IBi, respectively), they could indeed produce a child with blood type O (ii). This situation aligns with the principle of codominance and simple Mendelian inheritance.