Protozoa are classified on the basis of:

Step-by-step solution

Protozoa include all single-celled, eukaryotic organisms without a cell wall and they also show the heterotrophic mode of nutrition, but main reason for classifying these organisms into separate phylum is due to presence of locomotory organelles. Amoeboid protozoa form cytoplasmic extensions called pseudopodia for locomotion. Trypanosoma, Trichomonas vaginalis and Leishmania donovani possess flagella for locomotion and Ciliated Protozoans ( Paramoecium ) moves with the help of cilia.