If a child has blood group 'A' and his mother has blood group 'A', what are the possiblities of blood group of his father

Options

A. `'A'`
B. `'O'`
C. `'B'`
D. All the above

Answer

To determine the possible blood groups of the father when the child has blood group 'A' and the mother also has blood group 'A', we can analyze the genetic combinations involved in blood group inheritance.

### Step-by-Step Solution:

1. **Understanding Blood Groups**: Blood groups are determined by the presence of antigens on the surface of red blood cells. The main alleles are:
- IA (A antigen)
- IB (B antigen)
- IO (no antigen)

The possible genotypes for blood group A can be:
- IAIA (homozygous A)
- IAIO (heterozygous A)

2. **Mother's Genotype**: Since the mother has blood group A, her possible genotypes are:
- IAIA (homozygous)
- IAIO (heterozygous)

3. **Child's Genotype**: The child has blood group A, which means the possible genotypes for the child are:
- IAIA (homozygous A)
- IAIO (heterozygous A)

4. **Father's Genotype Possibilities**: We will now analyze the possible blood groups of the father based on the mother's genotype.

- **Case 1: Mother is IAIA**
- Possible combinations with the father:
- If the father is IAIA: Child = IAIA (A)
- If the father is IAIO: Child = IAIA (A) or IAIO (A)
- If the father is IBIO: Child = IAIB (AB) or IAIO (A)
- If the father is IOIO: Child = IAIO (A)
- Thus, in this case, the father can be A (IAIA or IAIO) or O (IOIO).

- **Case 2: Mother is IAIO**
- Possible combinations with the father:
- If the father is IAIA: Child = IAIA (A)
- If the father is IAIO: Child = IAIA (A) or IAIO (A)
- If the father is IBIO: Child = IAIB (AB) or IAIO (A)
- If the father is IOIO: Child = IAIO (A)
- Thus, in this case, the father can be A (IAIA or IAIO), B (IBIO), or O (IOIO).

5. **Conclusion**: Therefore, the possible blood groups of the father can be A, B, or O.