Answer:
Gene for blood type O is recessive
Gene for blood type A and B is dominant
Gene for blood type AB is neither dominant nor recessive but a form of co-dominance
Step-by-step explanation:
In the ABO blood group,
A and B are dominant genes, O is recessive genes.
So the different genotype and its corresponding phenotype is as follows –
Genotype Phenotype
AO A
BO B
AB AB
AA A
BB B
OO O
Hence, the two alleles AB occur and express together. Therefore, AB blood group is an example of co-dominance.
Blood type also varies with the presence of Rh factor. If Rh factor is present, the blood type will represented with a “+” symbol. And if Rh factor is absent, the blood type will be represented by “-“symbol.