A man has blood group O and his mother blood group A. The genotype of mother should be

Options

A. `I^(O)I^(O)`
B. `I^(A)I^(O)`
C. `I^(A)I^(B)`
D. `I^(A)I^(A)`

Answer

To determine the genotype of the mother with blood group A, given that her son has blood group O, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Blood Group Genetics**:
- Blood groups are determined by the presence of specific alleles. The alleles for blood groups are:
- **IA**: A antigen (blood group A)
- **IB**: B antigen (blood group B)
- **i**: No antigen (blood group O)
- Blood group O is represented by the genotype **ii**.

2. **Identifying the Son's Genotype**:
- The man has blood group O, which means his genotype must be **ii**.

3. **Determining Possible Genotypes of the Mother**:
- The mother has blood group A. The possible genotypes for blood group A are:
- **IAIA** (homozygous)
- **IAi** (heterozygous)
- Since the son has blood group O (genotype ii), he must inherit one 'i' allele from his mother.

4. **Analyzing the Inheritance**:
- If the mother were homozygous (IAIA), she could only pass on the IA allele, which means the son could not have blood group O.
- Therefore, the mother must be heterozygous (IAi) to provide the 'i' allele necessary for the son to have blood group O.

5. **Conclusion**:
- The genotype of the mother should be **IAi** (heterozygous).

### Final Answer:
The genotype of the mother should be **IAi**.

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