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CANAL SYSTEM IN Porifera

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Canal system in Porifera (sponges) Body of all sponges is the perforated by large number of apertures through which water enters Inside body and flows through a system of criss-crossing canals collectively forming the canal system which is a characteristic feature of poriferans. Following types of canal systems are found in sponges: Ascon type, with flagellated spongocoel Sycon type, with flagellated radial canals Leucon type, with flagellated chambers Rhagon type, with conical shape and broad base ASCON TYPE This is the simplest type of canal system and is found in  Leucosolenia  and other homocoela. Ostia are present on the surface of body and lead directly into the spongocoel, which is lined by flagellated choanocyte cells. Spongocoel opens to the outside through a narrow circular opening, the  osculum  located at the distal free end of the sponge body. Water enters through ostia into spongocoel and goes out of body through the  osculum . SYCO...
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Questions for 16 July zoology

Q:-1 Describe the general feature and life cycle of Nereis and compare its general body plan with earthworm. (20) Q:-2 Define linkage. How concept of linkage had  established? Discuss its significance with examples. (15) Q:-3 Female Drosophila with cinnabar eye (cn) and vestigial wings (vg) were mated to males with roof wings (rf). The F1 were all wild-type. When the F1 females were test crossed with males homozygous for all three traits the following result were obtained. 382 cinnabar, vestigial P 401 roof       P 3 cinnabar DCO   4 roof, vestigial DCO 59 cinnabar, roof, vestigial SCO1 67 wild SCO1 44 cinnabar, roof SCO2 40 vestigial SCO2 Calculate following a) gene order b) Interference Draw gene map.  (20) Q:-4 What is recombination? Discuss its significance. (10) Q:-5 Describe the life cycle of Leach with well labelled diagrams. (15)
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