Biology Quiz A Q4

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Biology Quiz A Q4 The Schizont developmental stage is the asexual replication stage that some trophozoites follow (others enter sexual development as gametocytes). During this stage the parasite undergoes a number of cycles of division to generate between 8 1n3 32 daughter parasites (1-3 on image) depending on species. The stage ends when the red cell membrane lyses releasing these daughter "merozoites" to enter other red cells (4&5 on image). File:Biology Gmaetocyte.jpg Concerning schizonts which statements are correct? (select all true statements) The stage gives rise to gametocytes Schizont release causes pyrexia P.malariae" typically forms 32 merozoites In P.falciparum they are rarely seen The stage is morphologically variable Explanation of correct answer (click "Expand") Short answer taken from section "Schizont Biology" (see the section for full details and links). Schizonts make repeated cycles of asexual development to generate muliple daughter "merozoites". The number of replication cycles differs between species: the typical number of merozoites formed differs between species with as few as 8 (in P.malariae) up to a possible 32 (in P.vivax). This stage may not be seen in blood films: the schizonts of P.falciparum adhere within the small vessels so is not seen in blood unless infection is very severe This progressive maturation means that they have a wide range of morphological forms (as shown in the diagram at the top of this page). When the merozoites are released this exposes the body to large amounts of free parasite antigens and can result is an immune response causing high fever and illness symptoms. In some cases the development of parasites is synchronous so that all schizonts mature and release their merozoites at the same time - although rarely seen now, this pattern of development may produce a pattern of remitting fever with a distinct periodicity depending on species: underlying the older descriptive terms tertian or quartan malaria. Go to next question (5 of 5)