A pair of genes which controls a trait is described as
Answer Details
When we talk about a pair of genes controlling a trait, we are referring to the basic unit of inheritance called "alleles." Each gene has two alleles, one inherited from each parent, that together determine the characteristics or traits of an organism.
In this context, a dominant allele will always be expressed in an organism's traits when present, even if only one copy is inherited. On the other hand, a recessive allele will only be expressed when two copies are inherited, one from each parent.
A variant refers to any alternative form of a gene that may differ from the most common or "wild-type" allele. Finally, a hybrid refers to an offspring resulting from the mating of two organisms from different species or varieties.
So, when we say a pair of genes controls a trait, we are essentially describing how different combinations of dominant and recessive alleles, as well as different variants, can determine an organism's physical or behavioral traits.