What was the five kingdom system of classification based on now that there are six?

Five Kingdoms and two Domains have been expanded in the newest taxonomic classification system for living things into six Kingdoms and three Domains. The original classification was based on morphology and the cells' structural components. All cells that are similar were grouped under a certain "kingdom", this made it easy for scientists to quickly identify certain groupings.

Three criteria on which the five-kingdom classification was based were:

-complexity of the organism's organization

- cell micro structure

- obtaining nutrition

The newest modern classification system is based more on evolutionary relationships at the microscopic level. As described above, it was originally based upon morphology and other physical characteristics and was a two domain system.

Modern scientists have altered the classification to use three domains based upon modern science's ability to better define the genetic structures of living things. A new rDNA comparison analysis led to the development of the three domain system of classification.

It was first described in the Binomial Nomenclature System created by Linneaus, one of the world's premier taxonomists. Linnaeus based his classification system on specific traits such as the structural characteristics (skeleton, body segmenation) and behavioral patterns (abiotic and biotic factors).