A child has blood groups 'O'. If father has blood group 'A' and mother has blood group 'B'. Work out the genotypes of the partents

Options

A. `I^(A)I^(A) and I^(B) i`
B. `I^(A)i and I^(B) i`
C. `I^(A)i and ii`
D. `ii and I^(B)I^(B)`

Explanation

To determine the genotypes of the parents given that their child has blood group 'O', we can follow these steps:

### Step 1: Understand Blood Group Inheritance
Blood groups are determined by alleles. The alleles for blood groups are:
- A (IA)
- B (IB)
- O (i or IO)

A person with blood group 'O' must have the genotype 'ii' (homozygous recessive).

### Step 2: Identify Possible Genotypes of the Parents
Given that the child has blood group 'O', both parents must carry the 'O' allele. Therefore, we can deduce that:
- The father, who has blood group 'A', can either be homozygous (IAIA) or heterozygous (IAi).
- The mother, who has blood group 'B', can either be homozygous (IBIB) or heterozygous (IBi).

Since the child has blood group 'O', both parents must be heterozygous. Thus:
- Father's genotype = IAi (A blood group, heterozygous)
- Mother's genotype = IBi (B blood group, heterozygous)

### Step 3: Set Up a Punnett Square
To visualize the inheritance, we can set up a Punnett square:

| | IB | i |
|--------|-------|-------|
| **IA** | IAIB | IAi |
| **i** | IBi | ii |

### Step 4: Analyze the Punnett Square
From the Punnett square, we can see the possible offspring:
- IAIB (Blood group AB)
- IAi (Blood group A)
- IBi (Blood group B)
- ii (Blood group O)

### Step 5: Conclusion
Since the child has blood group 'O', the parents' genotypes must be:
- Father: IAi (Blood group A)
- Mother: IBi (Blood group B)

Thus, the genotypes of the parents are:
- Father's genotype: IAi
- Mother's genotype: IBi

### Final Answer
Father's genotype: IAi (Blood group A)
Mother's genotype: IBi (Blood group B)

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