ZOOLOGY MAINS ANSWER WRITING 2019

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Questions for 21July Zoology

Q:-1Discuss the general features and life history of Pila with suitable diagrams. (20) Q:-2 Explain the process of torsion and detorsion in Gastropods. Discuss its significance and implications on physiology. (15) Q:-3 Compare the life history of Sepia and Lamellidens. (20) Q:-4 With diagrams explain the process of whole animal cloning. Describe various methods of making hybrid organisms. (15) Q:-5 What is transgenic organism? Discuss its significance in modern day society. (15)
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Status of Hemichordata

Hemichordata status                           Introduction Hemichordata was till recently treated as the sub phylum of the phylum Chordate but is now regarded to be the independent phylum of invertebrates very close to the phylum Echinodermata. The peculiar characteristics of the animals belonging to Hemichordata are as follows, Enterocoelus coelom Pharyngeal gill slits Buccal diverticulum (earlier considered as notochord) Vermiform body divisible into three regions – proboscis, collar, trunk The phylum hemichordate includes a small group of soft, primitive and marine chordates called as acron worms or tongue worms. Most familiar genus of this phylum is Balanoglossus which belongs to the class Enteropneusta. Other closely related genera are Saccoglossus, Glossobalanus etc. The class Enteropneusta was established by Gegenbaur in 1870. Since then due to the peculiar anatomical organisation and embryology, Hemichordata have...
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Invertebrate Zoology By Brusca and Brusca

"Invertebrates" 2nd edition presents a modern survey of the 34 animal phyla (plus the Protista) and serves as both a college course text and a reference on invertebrate biology. It is organized around the themes of bauplans (body plans) and evolution (phylogenetics). Detailed classifications, phylogenetic trees, and references for all phyla are provided. The text is accompanied by detailed line drawings and - new to this edition - four-colour photographs. Other key changes from the 1st edition (1990) include: the incorporation of all the new developments in phylogenetics, developmental biology and molecular genetics; major changes at the highest levels among the invertebrates; three phyla that appeared in the original book Pentastomida, Pogonophora and Vestimentifera no longer exist, and an entire new phylum, Cycliophora, has been erected. Moreover, this edition discusses recent work in molecular systematics, and there is a large new section on "Kingdom Protista" (...
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Retrogressive Metamorphosis

Retrogressive Metamorphosis in Urochordates Metamorphosis is a change from the juvenile to adult stage in which larval stage is quite different from the adult stage. In retrogressive metamorphosis the larva possesses advanced characters which are lost during the development and the adult is either sedentary or degenerated with primitive characters. Urochordate adults, being sedentary show degenerative characters while the free swimming tadpole larva shows advanced chordate characters which are lost during metamorphosis. Parasitic crustaceans, like Sacculina and copepod parasites and stylopids and scale insects (Insecta) also show retrogressive metamorphosis. Retrogressive Metamorphosis in Herdmania The tadpole larva of Herdmania is only 1-2 mm long when it hatches out of the egg. It does not feed and hence has only 3 hours of survival during which it has to swim about in search of a suitable substratum for attachment. The larva needs advanced features for its free swimming existence,...
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