Question

A man of A blood group marries a woman of AB blood group. Which type of progeny would indicate that man is heterozygous A?

• A. AB
• B. A
• C. O
• D. B

Answer 1

Answer: (D)

The correct option is D B
Genotype of a heterozygous man with A blood group I${}^A$I and that of a homozygous man with A blood group I${}^A$I${}^A$.

A cross between heterozygous man with A blood group and woman of AB blood group produce progeny with A, AB and B blood groups.

Gametes I${}^A$I I${}^A$I${}^B$	I${}^A$	I
I${}^A$	I${}^A$I${}^A$	I${}^A$I
I${}^B$	I${}^A$I${}^B$	I${}^B$I

On the other hand, a cross between homozygous man with A blood group, I${}^A$I${}^A$ and woman of AB blood group, $I^A$I${}^B$ produce progeny with A, AB blood groups, none of the child will have B blood group.

Gametes I${}^A$I${}^A$ I${}^A$I${}^B$	I${}^A$	I${}^A$
I${}^A$	I${}^A$I${}^A$	I${}^A$I${}^A$
I${}^B$	I${}^A$I${}^B$	I${}^A$I${}^B$

Hence, a child with B blood group would indicate that man is heterozygous A.

Thus, the correct answer is option D.