Question

What is the possible blood group of children whose parents are heterozygous for A & B blood groups ?

• A. A, B only
• B. A, B, AB & O
• C. AB only
• D. A, B & AB only

Answer 1

The Correct Option is B

We are asked to find the possible blood groups (phenotypes) of children when both parents are heterozygous for A and B blood groups respectively.

1. Determine the genotypes of the parents: 

• Parent 1 is heterozygous for A blood group. The genotype is I^AI^O (or I^Ai).
• Parent 2 is heterozygous for B blood group. The genotype is I^BI^O (or I^Bi).

The alleles involved are I^A, I^B, and I^O (or i). I^A and I^B are codominant, and both are dominant over I^O.

2. Determine the possible gametes produced by each parent:

• Parent 1 (I^AI^O) can produce gametes containing either the I^A allele or the I^O allele.
• Parent 2 (I^BI^O) can produce gametes containing either the I^B allele or the I^O allele.

3. Use a Punnett square to find the possible genotypes of the children:

	Parent 2 (IBIO) Gametes
Parent 1 (IAIO) Gametes	IB	IO
IA	IAIB	IAIO
IO	IBIO	IOIO

4. Determine the phenotype (blood group) for each possible genotype:

• I^AI^B → Blood group AB
• I^AI^O → Blood group A
• I^BI^O → Blood group B
• I^OI^O → Blood group O

5. List all possible blood groups (phenotypes) of the children:

The children can have blood groups A, B, AB, and O.

Comparing this result with the given options:

• A, B only
• A, B, AB & O
• AB only
• A, B & AB only

The correct option is A, B, AB & O.

Answer 2

When both parents are heterozygous for blood groups A and B, their genotypes are IAi (blood group A) and IBi (blood group B), respectively. The possible combinations of alleles from these parents can be determined using a Punnett square:​

	IA (Father)	i (Father)
IB (Mother)	IAIB (AB)	IBi (B)
i (Mother)	IAi (A)	ii (O)

Possible Genotypes and Corresponding Blood Groups:

1. IAIB: Blood group AB​
2. IBi: Blood group B​
3. IAi: Blood group A​
4. ii: Blood group O​

The correct answer is (B) : A, B, AB & O.