6. What are the missing categories in the classification system that follows: kingdom, phylum, class, order, family,

The modern taxonomic classification system has eight main levels (from most inclusive to most exclusive) : Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species Identifier. Every different species has a unique species identifier and the more closely a species is related to it on the evolutionary tree of life, it will be included in a more inclusive group with the species being classified.