USABO Biosystematics Test with Complete Solutions

USABO Biosystematics Test with Complete Solutions Calcarea, Silicea (sponges) - Answer-Lack true tissues; have choanocytes (collar cells-flagellated cells that ingest bacteria and tiny food particles) Cnidaria (hydras, jellies, sea anemones, corals) - Answer-Unique stinging structures (nematocysts) housed in special cells (cnidocytes); diploblastic, radially symmetrical, gastrovascular cavity Plathyhelminthes - Answer-Dorsoventrally flattened, unsegmented acoelomates; gastrovascular cavity or no digestive tract Rotifera (rotifers) - Answer-Pseudocoelomates with alimentary canal (digestive tube with mouth and anus); jaws (trophi) in pharynx; head with ciliated crown Lophophorates: Ectoprocta, Brachipoda - Answer-Coelomates with lophophores (feeding structures bearing ciliated tentacles) Mollusca (clams, snails, squids) - Answer-Coielomates with three main body parts (muscular foot, visceral mass, mantle); coelom reduced; most have hard shell made of calcium carbonate Annelida (segmented worms) - Answer-Coelomates with segmented body wall and internal organs (except digestive tract, which is unsegmented) Nematoda (roundworms) - Answer-Cylindrical, unsegmented pseudocoelomates with tapered ends; no circulator system; undergo ecdysis Arthopoda (crustaceans, insects, spiders) - Answer-Coelomates with segmented body, jointed appendages, and exoskeleton made of protein and chitin