What term describes the combination of alleles that determine a specific trait?

The term that describes the combination of alleles that determine a specific trait is "genotype." The genotype refers to the genetic makeup of an individual, specifically the alleles that an individual carries for various traits. For example, if a plant has one allele for purple flowers and another for white flowers, its genotype will determine what color flowers it produces, which is a manifestation of its genetic information.

Phenotype refers to the observable characteristics or traits of an organism resulting from the interaction between its genotype and the environment, not the genetic makeup itself. The term "allele pair" may suggest the two alleles that an organism possesses for a specific gene, but it does not encompass the broader concept of the genetic makeup relevant to multiple traits. Similarly, "chromosome set" refers to the complete set of chromosomes in an organism's cells, which includes all the genes, rather than focusing specifically on the alleles that relate to a singular trait. Thus, "genotype" is the most accurate term for the combination of alleles determining a specific trait.