In the context of genetics, what is simply the set of genes in a particular organism?

The term that refers to the complete set of genes within a particular organism is the genome. The genome encompasses all of the genetic material, including both the coding regions that produce proteins (genes) and the non-coding regions that may have regulatory functions or other roles. In essence, it serves as the blueprint for the organism, dictating traits, development, and biological processes.

The other options provided do not accurately capture this definition. Phenotype refers to the observable physical characteristics or traits of an organism, which are influenced by the organism's genetic makeup but are not synonymous with the complete genetic information itself. Phenotypic expression refers to the way an organism's genotype manifests in its physical traits, demonstrating that while linked, genotype and phenotype represent different concepts in genetics. Genetic variance speaks to the differences in genetic information between individuals or populations, which may affect traits but does not define the entirety of an organism's genetic makeup. Overall, "genome" is the precise term that encapsulates all genetic material present within an organism.