Pneumocystis carinii is a

Fugus - possess rigid cell wall containing chitin mannan and other polysaccharides. The cytoplasmic membrane containing sterols. Cytoplasm contains true nuclei with nuclear membrane, mitochondria and endoplasmic reticulum. May be unicellular or multicellular. They divide asexually, sexually or by both processes. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition