A child has blood group 'O'. If the father has the blood group 'A' and the mother has the blood group 'B' . What will be the genotypes of the parents ?

Options

A. `I^AI^A and I^Bi`
B. `I^Ai^A and I^Bi`
C. `I^Ai^A and ii`
D. `ii and I^B I^B`

Answer

To determine the genotypes of the parents based on the blood group of the child, we can follow these steps:

### Step 1: Understand Blood Group Genetics
Blood groups are determined by alleles. The three alleles for blood groups are:
- **IA** (A antigen)
- **IB** (B antigen)
- **i** (no antigen, which corresponds to blood group O)

### Step 2: Identify the Child's Blood Group
The child has blood group **O**. The genotype for blood group O is **ii** (homozygous recessive). This means the child inherited one **i** allele from each parent.

### Step 3: Analyze the Father's Blood Group
The father has blood group **A**. The possible genotypes for blood group A are:
- **IAIA** (homozygous)
- **IAi** (heterozygous)

Since the child has blood group O, the father must have the **i** allele to pass on to the child. Therefore, the father's genotype must be **IAi**.

### Step 4: Analyze the Mother's Blood Group
The mother has blood group **B**. The possible genotypes for blood group B are:
- **IBIB** (homozygous)
- **IBi** (heterozygous)

Similar to the father, the mother must also have the **i** allele to pass on to the child. Therefore, the mother's genotype must be **IBi**.

### Conclusion
The genotypes of the parents are:
- **Father's genotype:** IAi (A blood group)
- **Mother's genotype:** IBi (B blood group)

### Final Answer
- Father's genotype: **IAi**
- Mother's genotype: **IBi**

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