The contrasting pairs of factors in Mendelian crosses are called

The contrasting pairs of factors in Mendelian crosses are called Allelomorphs.
Allelomorph is (genetics) one of several alternative forms of the same gene occupying a given position on a chromosome.
An allele also termed an allelomorph that is any one of two or more genes that may occur alternatively at a given site (locus) on a chromosome.
Alleles may occur in pairs, or there may be multiple alleles affecting the expression (phenotype) of a particular trait.