FREE AP-MICRO Mycology and Parasitology Questions and Answers

Question 1

A patient with a history of cave exploration in the Ohio River Valley presents with respiratory symptoms.
A fungal culture of a lung biopsy grows a mold at 25°C and a yeast at 37°C.
Microscopic examination of the mold phase reveals large, thick-walled, tuberculate macroconidia.
Which organism is most likely the cause of the infection?

Accepted Answer

Histoplasma capsulatum

Answer

Coccidioides immitis

Answer

Blastomyces dermatitidis

Answer

Sporothrix schenckii

Question 2

A Giemsa-stained peripheral blood smear reveals multiple ring-form trophozoites in some red blood cells (RBCs), including appliqué forms (rings on the periphery of the cell). Several crescent-shaped gametocytes are also observed. The infected RBCs are normal in size. Which species of Plasmodium is most likely present?

Accepted Answer

Plasmodium falciparum

Answer

Plasmodium vivax

Answer

Plasmodium malariae

Answer

Plasmodium ovale

Question 3

A fungal culture from a sinus biopsy of an immunocompromised patient grows a rapidly spreading, woolly, gray-to-brown mold. Microscopic examination reveals broad, ribbon-like, pauciseptate (aseptate) hyphae with right-angle branching. What class of fungi is described?

Accepted Answer

Zygomycetes

Answer

Ascomycota

Answer

Dermatophytes

Answer

Basidiomycota

Question 4

A trichrome-stained stool smear from a patient with dysentery reveals amoebic trophozoites measuring approximately 20 µm. The cytoplasm is finely granular and contains ingested red blood cells. The single nucleus has even, peripheral chromatin and a small, central karyosome. Based on these observations, what is the most likely identification?

Accepted Answer

Entamoeba histolytica

Answer

Endolimax nana

Answer

Entamoeba coli

Answer

Iodamoeba bütschlii

Question 5

In the Lactophenol Cotton Blue (LPCB) stain used for microscopic examination of fungi, which component acts as a killing agent, deactivating lytic enzymes and preserving the organism's morphology?

Accepted Answer

Phenol

Answer

Lactic acid

Answer

Glycerol

Answer

Cotton blue

Question 6

Which of the following is the specimen of choice for the laboratory diagnosis of an Enterobius vermicularis infection?

Accepted Answer

Cellulose tape paddle preparation

Answer

Stool specimen in preservative

Answer

Peripheral blood smear

Answer

Duodenal aspirate