Protozoa melakukn respirasi melalui resapan ringkas.melakukn pertukaran oksigen dan karbon dioksida yg merentasi membran plasma. oksigen meresap masuk ke dlm sel. karbon dioksida meresap keluar dari sel.
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I'll answer in English because mine is English based. 

Protozoa do not have any organellae for the process of respiration. The limiting permeable membrane acts as a respiratory surface. The free molecular oxy­gen from the surrounding media enters into the body by diffusion. Presence of a cyto­chrome system has been demonstrated in protozoa.

Protozoa which live as parasites in the digestive tube of higher animals do not get molecular oxygen in free state but get it by decomposing complex oxygen bearing substances present in the body of the host.

Anaerobic protozoa include Trypanosoma gambiense of vertebrate blood. While Histomonas meleagridis, a flagellate in the intestine of chicken can grow in presence of air as well as without it and is a ‘facultative aerobe’.