Linnaeus recognized two kingdoms of living things, plants and animals. Why do today's classification systems now include six kingdoms?

The Six Kingdoms. When Linnaeus developed his system of classification, there were only two kingdoms, Plants and Animals. But the use of the microscope led to the discovery of new organisms and the identification of differences in cells. Today the system of classification includes six kingdoms.

Explanation:

there are mainly three domains in biological classification namely; archaea, bacteria, and eukarya.

archaea includes all the prokaryotic cells which are characterized by their lipid membranes. they have branched hydrocarbon which is attached to glycerol through an ether linkage.

bacteria includes all the prokaryotic cells, the cell membrane of which are made up of the unbranched fatty acid chain. in addition, they are attached to glycerol through an ester bond.

eukarya includes all the eukaryotic cells, that is, the cells contain a nucleus and other membrane-bound cell organelles.

they can be autotrophic as well as heterotrophic, unicellular as well as multicellular

they include kingdoms like protista, plantae, animalia, fungi et cetera.

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