The member of a pair or series of genes that occupies a specific position on a chromosome is referred to as an allele.

Here's why:

* Genes: Genes are the fundamental units of heredity, responsible for carrying and transmitting traits from parents to offspring.

* Chromosomes: Chromosomes are thread-like structures found in the nucleus of cells, carrying the genetic material (DNA).

* Pairs: Most organisms have two copies of each chromosome, one inherited from each parent. This means they have two copies of each gene.

* Alleles: Alleles are alternate forms of the same gene. They occupy the same locus (position) on homologous chromosomes. For example, the gene for eye color might have an allele for brown eyes and another allele for blue eyes.

Therefore, allele is the term that specifically describes a single variant of a gene located at a particular position on a chromosome.