Each person can have one of four possible blood types: A, B, AB, or O....
Each person can have one of four possible blood types: A, B, AB, or O. Blood type A means that the A antigen is present on the red blood cell surface. Blood type B means that the B antigen is present on red blood cells' surfaces. Blood type AB means that both the A antigen and the B antigen are present on the red blood cells' surfaces. Blood type O means that no antigens are present on the red blood cells' surfaces. Someone with genotype A/A or A/O will have type A blood. Someone with genotype B/B or B/O will have type B blood. Someone with genotype A/B will have AB blood, and someone with genotype O/O will have type O blood. Assume that blood type is not a sex-linked trait. A mother with genotype A/O and a father with genotype A/B could NOT have a child with which blood type?
- A. A
- B. B
- C. O
- D. Not enough information
Correct Answer: C. O
Explanation
The easiest way to solve this problem is to draw a punnet square. The genotypes of the parents are AO and AB. The potential genotypes of their children are AA, AO, BA, and BO. Children with genotypes AA and AO will have type A blood. Children with genotype BO will have type B blood. Children with genotype BA will have type AB blood. Genotype O/O is the only one that will result in type O blood. O/O is not a possible product of this punnet square. Both the mother and the father must have the O allele in order for a child to have genotype O/O and type O blood.