This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Pneumocystis carinii is a fungus because ? 
Select and explain. 
A. rRNA, mitochondrial protein gene sequence & presence of thymidylate synthase, B. Cell wall contains glucans, C. Angifungals are effective against P. carini, D. All
D: All
Answer: D: All 
Explanation: Ans. is 'a' i.e., rRNA, Mitochondrial protein gene sequence & presence thymidylate synthase; `b' i.e., Cell wall contains glucans; 'c' i.e., Antifungals are effective against p. carinii . The taxonomic classification of Pneumocystis as a fungus is based on factors: 1. Analysis of gene sequence for ribosomal RNA, mitochondria! proteins and major enzymes. 2. Presence of b-1, 3 glucan in the cell wall. 3. The efficacy of antifungal drugs that inhibit b-glucan synthesis. . In contrast to most fungi. 1. Pneumocystis lacks ergosterol 2. Not susceptible to antifungal drugs that inhibit ergosterol synthesis.