What is the phenomenon called where factors produce independent effects in their heterozygous condition?

Define/Explain: Co-dominance.

When two genes with independent expression are present together, they both express their characteristics, and when they are separate, they express their individual characteristics. This phenomenon is observed in which of the following?

The $AB$ blood group exhibits which of the following phenomena?

When dominant and recessive alleles express themselves together,it is called

In shorthorn cattle,genes for red $(R_1)$ and white $(R_2)$ coat colour occur. Crosses between red $(R_1R_1)$ and white $(R_2R_2)$ produced $(R_1R_2)$ roan. This is an example of