The best description of expression gene process is constitutive. this is because it is the partial diploid strain whereby the strain containing a beta-galactosidase gene which is constitutive.
Gene expression process is the process by which information from a gene is being used in the synthesis of the functional gene product. The process gene expression is used by different known life. For example, we eukaryotes, prokaryotes and utilized by viruses which are used to generate the macromolecular machinery which is for life.