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Chapter 9 1. One proposed mechanism for the evolution of multicellularity involves an ancestral multinucleate cell in which plasma membranes formed between nuclei, resulting in a multicellular organism. This proposed mechanism is referred to as the __________ hypothesis. A) colonial B) syncytial C) polyphyletic D) metazoan E) synthetic 2. A) B) C) D) E) Which of the following items is not found in sponges? choanocytes tissues pinacocytes porocytes mesohyl 3. A) B) C) D) E) Contractile pinacocytes that can regulate water circulation in some sponges are called spongiocytes. choanocytes. porocytes. archeocytes. amebocytes. 4. A) B) C) D) E) Just underneath the pinacocyte layer of a sponge is a jellylike layer referred to as the ectoderm. endoderm. mesoderm. mesohyl. endochyme. 5. A) B) C) D) E) The collar of a choanocyte regulates the diameter of the osculum. filters food from the water. creates currents in the water. regulates the diameter of the ostia. secretes digestive enzymes. Page 1 6. A) B) C) D) E) The taxonomy of sponges is determined by the shape of the choanocytes. the complexity of the osculum. the material that composes the skeleton. the presence or absence of porocytes. the shape of the body of the sponge. 7. A) B) C) D) E) The __________ is the simplest, but least common body form of sponge. leucon sycon demosponge ascon sclerosponge 8. A) B) C) D) E) The porocytes of ascon sponges lead to the outside via openings called spongocoels. atriopores. blastopores. oscula. ostia. 9. A) B) C) D) E) The single large opening at the top of the spongocoel is the osculum. atriopore. ostium. mouth. anus. 10. A) B) C) D) E) __________ sponges have incurrent canals formed by infoldings of the body wall. Sclerosponge Sycon Leucon Calcisponge Ascon 11. A) B) C) D) E) Sponges may gain nutrition by all of the following modes except filtration. trapping of food items by the collar. active transport of nutrients. phagocytosis. active predation. Page 2 12. A) B) C) D) E) The unique adhesive cells of ctenophores are statoblasts. cnidoblasts. colloblasts. pleuroblasts. statoliths. 13. The most complex sponge body form, the __________, is characterized by multiple oscula and a complex canal system where choanocytes reside in small chambers. A) leucon B) ascon C) sycon D) polyp E) medusa 14. A) B) C) D) E) Excretion and gas exchange in sponges are accomplished by active transport. diffusion. contractile vacuoles. nephridia. osmosis. 15. A) B) C) D) E) Eggs and sperm of sponges are commonly formed from pinacocytes. porocytes. choanocytes. spongiocytes. sclerocytes. 16. A) B) C) D) E) Ctenophores move via bands of cilia called lappets. rhopalia. comb rows. acontia. tentacles. 17. Freshwater (and some marine) sponges form resistant structures which function in asexual reproduction, called A) brown bodies. B) larvae. C) statoblasts. D) spores. E) gemmules. Page 3 18. A) B) C) D) E) Gemmules contain masses of __________ which can survive freezing or drying. amoeboid cells porocytes choanocytes spongin pinacocytes 19. A) B) C) D) E) Members of class __________ are those historically used as commercial sponges. Calcarea Demospongiae Hexactinellida Syconidae Leuconidae 20. Members of the phylum __________ are characterized by radial (or biradial) symmetry, diploblastic organization, a gastrovascular cavity, and cnidocytes. A) Mesozoa B) Placozoa C) Cnidaria D) Porifera E) Ctenophora 21. A) B) C) D) E) Members of the cnidarian class __________ never have a medusa stage. Mesozoa Hydrozoa Scyphozoa Anthozoa Cubozoa 22. A) B) C) D) E) Cnidarians exchange respiratory gases and nitrogenous wastes via active pumping. movement of cilia. active transport. movement of microvilli. diffusion. 23. An intracellular structure made of a fluid-filled capsule holding a coiled, hollow tube is the A) cnidocyte. B) choanocyate. C) cnidocil. D) nematocyst. E) pinacocyte. Page 4 24. A) B) C) D) E) The __________ body form of a cnidarian is typically asexual and sessile. sycon polyp ascon leucon medusa 25. A) B) C) D) E) The __________ body form of a cnidarian is typically dioecious and free swimming. sycon polyp ascon leucon medusa 26. The __________ cavity of cnidarians serves in digestion and as a site for exchange of respiratory gases and wastes. A) intestine B) spongocoel C) gastrocoel D) gastrovascular cavity E) archenteron 27. A) B) C) D) E) The free swimming larva of cnidarians is the planula. pilidium. trochophore. bipinnaria. veliger. 28. A) B) C) D) E) The feeding polyps of an Obelia colony are called hydranths. gastrozooids. gonozooids. statocysts. statoblasts. 29. A) B) C) D) E) The Portuguese man-of-war is a colonial scyphozoan. anthozoan. mesozoan. hydrozoan. cubozoan. Page 5 30. A) B) C) D) E) Members of the cnidarian class __________ are called the “true jellyfish.” Cubozoa Anthozoa Hydrozoa Scyphozoa Mesozoa 31. A) B) C) D) E) Sensory structures located in 8 notches around the bell of jellyfish medusae are statoliths. colloblasts. manubri. nematocysts. rhopalia. 32. A) B) C) D) E) The main source of nutrient carbohydrates in coral come from zooxanthellae. captured prey. rhopalia. acontia. ephyrae. 33. A) B) C) D) E) Members of the phylum Ctenophora are commonly called jellyfish. comb jellies. water bears. ephyrae. polyps. Page 6