<prompt> Pneumocystis carinii is a fungus becauserRNA, mitochondrial protein gene sequence and presence of thymidylate synthaseCell wall contains glucansAngifungals are effective against P. CariniCommonest infection in AIDS  <response>: 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. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition 