If mother's blood group is A and father blood group is AB , then child 's blood group cannot be

Options

A. A
B. B
C. O
D. AB

Answer

To solve the question regarding the possible blood groups of a child when the mother's blood group is A and the father's blood group is AB, we can follow these steps:

### Step 1: Determine the Genotypes of the Parents
- The mother's blood group is A. This means her genotype can either be:
- Homozygous: \( I^A I^A \)
- Heterozygous: \( I^A i \) (where \( i \) represents the O allele)
- The father's blood group is AB, which means his genotype is:
- \( I^A I^B \)

### Step 2: Perform a Punnett Square Analysis
We will analyze the possible combinations of alleles from both parents.

#### Case 1: Mother is Homozygous \( I^A I^A \)
- Possible gametes from the mother: \( I^A \)
- Possible gametes from the father: \( I^A, I^B \)

| | \( I^A \) | \( I^B \) |
|---------|-----------|-----------|
| \( I^A \) | \( I^A I^A \) (A) | \( I^A I^B \) (AB) |

From this cross, the possible blood groups of the child are:
- A (from \( I^A I^A \))
- AB (from \( I^A I^B \))

#### Case 2: Mother is Heterozygous \( I^A i \)
- Possible gametes from the mother: \( I^A, i \)
- Possible gametes from the father: \( I^A, I^B \)

| | \( I^A \) | \( I^B \) |
|---------|-----------|-----------|
| \( I^A \) | \( I^A I^A \) (A) | \( I^A I^B \) (AB) |
| \( i \) | \( I^A i \) (A) | \( I^B i \) (B) |

From this cross, the possible blood groups of the child are:
- A (from \( I^A I^A \) and \( I^A i \))
- AB (from \( I^A I^B \))
- B (from \( I^B i \))

### Step 3: Conclusion
From both cases, we can summarize the possible blood groups for the child:
- A
- AB
- B

The only blood group that cannot be produced from these combinations is:
- O

### Final Answer
The child’s blood group cannot be O.

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