Weekly Environment and Ecology

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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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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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Questions for 07 July Zoology

Instructions · All questions are compulsory. · Adhere to world limits wherever specified. · Draw neat and well labelled diagrams. No beautification required. · Don’t use colour pens only pencil colour if you are an extraordinary student. · Try to finish all questions within 2 hours in written. · Answers will be reviewed every day at 9 pm. Q:-1 Compare the process of mitosis and meiosis. What are the Cyclins. (20) Q:-2 What is mitotic apparatus? Describe its cycle.(15) Q:-3 Explain the general feature and life cycle of  Plasmodium . Compare the various species specific febrile paroxysm. (20) Q:-4 What is Rb protein? How it regulates cell cycle? (10) Q:-5 Give the morphological features of Leishmania . Discuss its life cycle and briefly explain its pathogenesis. (20)
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Questions for 13 July Zoology

Q:-1 Discuss the characteristic features of phylum Nemathelminthes. Classify the phylum upto Sub classes. (20) Q:-2 Enlist all essential requirements for Translation. How GTP plays regulatory role in process of translation. (10) Q:-3 Compare the process of translation in eukaryotes and prokaryotes. Briefly describe wobble hypothesis. (15) Q:-4 Discuss the life cycle of Wuchereria. Comments on its parasitic adaptations. (20) Q:-5 Discuss the genera features life cycle of Ascaris. Comment on its pathogenic capability and prophylaxis. (20)
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