Question

If mother has blood group B, father has A group, the offspring will be of

• A. A
• B. O
• C. AB
• D. Any of the above

Answer 1

The correct option is D Any of the above

A parent with A blood group can have two possible genotypes: “I${}^A$ I${}^A$” and “I${}^A$ I${}^O$”; similarly parent with B blood group can have two possible genotypes: “I${}^B$ I${}^B$” and “I${}^B$ I${}^O$”. If both the parents are homozygous (I${}^A$ I${}^A$ x I${}^B$ I${}^B$) , all of their children will have AB blood group. But if father is heterozygous (I${}^A$ I${}^O$”) and mother is homozygous (I${}^B$ I${}^B$); the total different types of possible combinations by three alleles (I${}^A$, I${}^B$ and I${}^O$) will be (I${}^A$ I${}^B$ and I${}^B$I${}^O$). But if mother is heterozygous (I${}^B$ I${}^O$) and father is homozygous (I${}^A$ I${}^A$); the total different types of possible combinations by three alleles (I${}^A$, I${}^B$ and I${}^O$) will be (I${}^A$ I${}^B$ and I${}^B$I${}^O$).
Cross 1
Parent generation : I${}^A$ I${}^A$ x (I${}^B$ I${}^B$)

Gametes : I${}^A$ I${}^A$--> (I${}^A$ I${}^B$)	I${}^A$	I${}^A$
I${}^B$	I${}^A$I${}^B$	I${}^A$I${}^B$
I${}^B$	I${}^A$I${}^B$	I${}^A$I${}^B$

F${}_1$ generation phenotypic ratio = All AB group

Cross 2
Parent generation: I${}^A$ I${}^O$ X (I${}^B$ I${}^B$)

Gametes I${}^A$ I${}^O$ --> I${}^B$ I${}^B$	I${}^A$	I${}^O$
I${}^B$	I${}^A$ I${}^B$	I${}^B$ I${}^O$
I${}^B$	I${}^A$ I${}^B$	I${}^B$ I${}^O$

F${}_1$ generation phenotypic ratio = 1 AB group : 1 B group

Cross 3
Parent generation: I${}^A$ I${}^A$ X (I${}^B$ I${}^O$)

Gametes I${}^A$ I${}^A$ --> I${}^B$ I${}^B$	I${}^A$	I${}^A$
I${}^B$	I${}^A$ I${}^B$	I${}^A$ I${}^B$
I${}^O$	I${}^A$ I${}^O$	I${}^A$ I${}^O$

F${}_1$ generation phenotypic ratio = 1 AB group : 1 A group

Cross 4
Parent generation: I${}^A$ I${}^O$ X (I${}^B$ I${}^O$)

Gametes : I${}^A$ I${}^O$ --> I${}^B$ I${}^O$	I${}^A$	I${}^O$
I${}^B$	I${}^A$ I${}^B$	I${}^B$ I${}^O$
I${}^O$	I${}^A$ I${}^O$	I${}^O$ I${}^O$

F${}_1$ generation phenotypic ratio = 1 AB group : 1 B group : 1 A group : 1 O group
Thus, the correct answer is option D.