The ABO blood groups in humans are determined by a multiple-allele system in which IA and IB are codominant and are both dominant to IO. A newborn infant is type A. The mother is type O. Possible phenotypes of the father are

The possible phenotypes of the father include type A blood (genotype AA or genotype AO) or type AB blood (genotype AB).

Human blood type is determined by a single gene that has three different alleles: A, B and O.

The A and B alleles are codominant, which means that both alleles are expressed in heterozygous individuals (type AB blood).

On the other hand, A and B alleles are dominant over O allele.

Therefore, individuals who show an AO genotype have a type A phenotype, while individuals who show a BO genotype have a type B phenotype.

In this case, the phenotype of the mother is type O (genotype OO), while the newborn infant is type A (genotype AO), thereby the infant inherited the A allele from the father.

In conclusion, the possible phenotypes of the father include type A blood (genotype AA or genotype AO) or type AB blood (genotype AB).

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The possible genotype of the father will be AA or AO meaning of type A blood

Explanation:

The ABO blood group system can be regarded as the classification of human blood which is determined by the presence or absence of the antigens A and B, which are carried on the surface of the red cells (erythrocytes). An individual may therefore have type A, type B, type O, or type AB blood.

For a mother to be of type O blood, it means her genotype is OO and is inherited in the recessive form. The infant of type A can have a genotype of AO or AA. Thus, the possible genotype of the father will be AA or AO meaning of type A blood

           IO        IO                      IO         IO

IA        IAIO     IAIO         IA      IAIO      IAIO

IA        IAIO     IAIO         IO      IOIO     IOIO

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