Practice question

Phylum Apicomplexa comprises obligate intracellular parasitic alveolates defined by anterior apical complex ultrastructure visible in electron microscopy consisting of conoid, paired rhoptries secreting adhesins, micronemes for recognition, and dense granules modifying parasitophorous vacuole. Complex mediates sequential attachment, reorientation, formation of moving junction, and active invasion of host cells without triggering endocytosis. Includes genera Plasmodium, Toxoplasma, Cryptosporidium, and Eimeria. Presence of remnant plastid apicoplast derived from secondary endosymbiosis and alveoli sacs distinguishes apicomplexans from other protists, providing therapeutic targets for antiparasitic drugs.