Practice question

Giardia intestinalis synonym Giardia lamblia duodenalis belongs to order Diplomonadida in supergroup Excavata, diagnosed by binucleate trophozoite with adhesive ventral disc composed of microtubule spiral providing attachment to intestinal microvilli, four pairs of flagella, and median bodies. Inhabiting anaerobic duodenum, it lacks conventional mitochondria possessing instead microaerophilic mitosomes. Transmission occurs through quadrinucleate cysts in contaminated water causing malabsorptive diarrhea. SSU rRNA phylogeny places it among diplomonads alongside Spironucleus, distinctly separate from parabasalids containing hydrogenosomes or euglenoids possessing kinetoplast structures found elsewhere in Excavata clade.