what are the disadvantages of 5 kingdom classification?

(i) The position of virus is not clear.

(ii) Kingdom Protista includes organisms having diverse form, structure and life cycle, hence does not seem to be proper grouping.

(iii) Some organisms included under Protista (e.g. Dinoflagellates) are not eukaryotic rather mesokaryotic.

(iv) Slime moulds placed under Protista differ considerably from the rest of protists.