Question

What is the expected phenotype ratio of the offspring between a man with Type O blood and a woman with homozygous Type A blood?

a) 1:1 (Type O : Type A)

b) 1:2 (Type O : Type A)

c) 2:0 (Type O : Type A)

d) 0:2 (Type O : Type A)

Answer 1

When a man with Type O blood (ii genotype) has children with a woman with homozygous Type A blood (IAIA genotype), all of their children will have Type A blood (IAi genotype). Thus, the expected phenotype ratio is 0:1 (Type O : Type A), corresponding to option d) 0:2 (Type O : Type A).

Step-by-step explanation:

The question pertains to the inheritance of blood types, which is an application of Mendelian genetics. A blood type is determined by the combination of alleles a person inherits. The alleles involved in blood type are IA, IB, and i. The IA and IB alleles express the A and B antigens, respectively, and are codominant to each other. The allele i does not produce any antigen and is recessive to both IA and IB.

The man with type O blood has the genotype ii, and the woman with homozygous type A blood has the genotype IAIA. Their offspring can only inherit an i allele from the father and an IA allele from the mother. Therefore, all of their children will have the genotype IAi, which expresses the phenotype for type A blood. The expected phenotype ratio of the offspring between a man with Type O blood and a woman with homozygous Type A blood is 0:1 (Type O : Type A).