Mother and father of a person with 'O' blood group have 'A' and 'B' blood group respectively. What would be the genotype of both mother and father ?

Options

A. Mother is homozygous for 'A' blood groups and father is heterozygous for 'B'
B. Mother is heterozygous for 'A' blood group and father is homozygous for 'B'
C. Both mother and father are heterozygous for 'A' and 'B' blood group, respectively.
D. Both mother and father are homozygous for 'A' and 'B' blood group respectively.

Explanation

To solve the question regarding the genotypes of the mother and father of a person with 'O' blood group, we need to understand the inheritance of blood groups and the corresponding genotypes.

### Step-by-Step Solution:

1. **Understand Blood Group Inheritance**:
- Human blood groups are determined by the ABO blood group system, which includes four main types: A, B, AB, and O.
- The alleles responsible for these blood groups are:
- A blood group: Genotype can be either AA (homozygous) or AO (heterozygous).
- B blood group: Genotype can be either BB (homozygous) or BO (heterozygous).
- AB blood group: Genotype is AB (co-dominance).
- O blood group: Genotype is OO (homozygous recessive).

2. **Identify the Child's Genotype**:
- The child has an 'O' blood group, which means the genotype must be OO. This indicates that the child has inherited one 'O' allele from each parent.

3. **Determine Possible Genotypes of Parents**:
- The mother has an 'A' blood group. Her possible genotypes are:
- Homozygous: AA (cannot contribute an O allele)
- Heterozygous: AO (can contribute an O allele)
- The father has a 'B' blood group. His possible genotypes are:
- Homozygous: BB (cannot contribute an O allele)
- Heterozygous: BO (can contribute an O allele)

4. **Analyze the Inheritance**:
- Since the child has an OO genotype, it is necessary for both parents to contribute an O allele.
- Therefore, the mother must be heterozygous (AO) to provide the O allele.
- Similarly, the father must also be heterozygous (BO) to provide the O allele.

5. **Conclusion**:
- The genotypes of the parents are:
- Mother: AO (heterozygous for A)
- Father: BO (heterozygous for B)

### Final Answer:
- The mother is heterozygous (AO) for A blood group, and the father is heterozygous (BO) for B blood group.