Zoology 2022 Paper I 50 marks 150 words Compulsory Write short notes

Q1

Write short notes on each of the following in about 150 words: (a) Structure of visual organs of cockroach. (10 marks) (b) What is meant by symmetry? Write about different types of symmetry in animals. (10 marks) (c) Structure and functions of endocrine pancreas. (10 marks) (d) "Cnidoblasts as defensive organs in coelenterates". Justify. (10 marks) (e) Evolutionary status of Sphenodon. (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित प्रत्येक पर लगभग 150 शब्दों में टिप्पणी लिखिए : (a) कॉकरोच के चाक्षुष अंगों की संरचना । (10 अंक) (b) सममिति से क्या अभिप्राय है ? प्राणियों में विभिन्न प्रकार की सममिति के बारे में लिखिए । (10 अंक) (c) अंतःस्रावी अग्न्याशय की संरचना एवं उसके कार्य । (10 अंक) (d) "सीलेंटेरेटा में दंशकोरक रक्षात्मक अंगों के रूप में" । औचित्य सिद्ध कीजिए । (10 अंक) (e) स्फीनोडॉन की विकासीय स्थिति । (10 अंक)

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Directive word: Write short notes

This question asks you to write short notes. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The directive 'write short notes' demands concise, information-dense responses for each sub-part. Allocate approximately 30 words per mark, giving roughly 30 words to each 10-mark sub-part. Structure each note with a precise definition or opening statement, followed by 2-3 key structural/functional points, and end with significance. For (a), emphasize compound eye structure; for (b), contrast symmetry types with animal examples; for (c), balance islets of Langerhans anatomy with hormone functions; for (d), focus on cnidocil mechanism and nematocyst discharge; for (e), highlight Sphenodon as a living fossil with primitive and derived traits.

Key points expected

  • (a) Cockroach visual organs: compound eyes with ~2000 ommatidia, structure of ommatidium (cornea, crystalline cone, retinular cells, rhabdome), mosaic vision vs. apposition image formation, ocelli as simple eyes for light detection
  • (b) Symmetry: definition (body arrangement around central axis), radial symmetry (cnidarians, echinoderms), bilateral symmetry (most triploblasts), biradial symmetry (ctenophores), asymmetry (sponges); evolutionary significance with grade of organization
  • (c) Endocrine pancreas: islets of Langerhans histology (alpha, beta, delta, PP cells), insulin and glucagon antagonistic functions, blood glucose regulation, clinical relevance to diabetes mellitus
  • (d) Cnidoblasts: structure of cnidocyte with cnidocil and nematocyst, explosive discharge mechanism (osmotic pressure/hydraulic hypothesis), defensive and offensive functions, specificity to Cnidaria as synapomorphy
  • (e) Sphenodon: sole surviving genus of Rhynchocephalia, 'living fossil' status, primitive features (parietal eye, lack of external ear opening, amphicoelous vertebrae), restricted distribution to New Zealand offshore islands, evolutionary significance for understanding lepidosaur divergence

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness20%10All five sub-parts demonstrate accurate anatomical and physiological facts: for (a) correctly describes ommatidial structure and image formation; for (b) precisely defines symmetry types with correct taxonomic associations; for (c) accurately identifies four islet cell types and their hormones; for (d) correctly explains cnidocil trigger and discharge mechanics; for (e) accurately places Sphenodon in Rhynchocephalia with correct primitive traitsMostly correct facts with minor errors: vague on ommatidial ultrastructure, confuses biradial with bilateral, mixes alpha/beta cell functions, oversimplifies cnidoblast mechanism, or misidentifies Sphenodon's taxonomic positionSignificant factual errors: describes simple eyes instead of compound eyes in (a), conflates all symmetry types in (b), confuses exocrine with endocrine pancreas in (c), fails to identify cnidoblast uniqueness in (d), or calls Sphenodon a lizard in (e)
Diagram / labelling20%10Includes at least 3 well-executed diagrams: ommatidium longitudinal section with labelled parts (cornea, crystalline cone, retinular cells, rhabdome); symmetry types illustrated with body plans; islet of Langerhans cellular composition; cnidocyte with nematocyst in discharged and undischarged states; all diagrams neat, proportionate, and properly labelled with leader linesIncludes 1-2 diagrams with partial labelling, or describes diagrams in text without actual drawing; labels may be incomplete or misaligned; symmetry types described verbally without illustrationNo diagrams attempted, or diagrams are unrecognizable scribbles without labels; fails to utilize the 10-mark allocation for visual representation where expected (especially for (a), (c), and (d))
Examples & nomenclature20%10Precise scientific nomenclature throughout: for (a) uses Periplaneta americana and terms like rhabdome, retinular cells; for (b) cites Aurelia (radial), Asterias (pentaradial), Planaria (bilateral), Pleurobrachia (biradial); for (c) names glucagon, insulin, somatostatin, pancreatic polypeptide with cell types; for (d) uses cnidocyte, nematocyst, cnidocil, hypotome; for (e) cites Sphenodon punctatus, Tuatara, RhynchocephaliaUses common names or partial scientific names; generic references like 'pancreas cells' instead of specific islet cells; mentions 'jellyfish' instead of Aurelia; refers to 'living fossil' without naming Sphenodon punctatusIncorrect or invented terminology; confuses cnidoblast with cnidocyte; uses 'Sphenodon' as common name; fails to distinguish between endocrine and exocrine pancreas terminology; misspells critical terms affecting meaning
Process explanation20%10Clear mechanistic explanations: for (a) explains apposition image formation through rhabdome function; for (b) explains how symmetry relates to locomotion and cephalization; for (c) explains feedback regulation of blood glucose; for (d) explains osmotic discharge hypothesis of nematocyst; for (e) explains why Sphenodon survived as relict through geographic isolationDescribes structures without explaining function; states that nematocysts 'sting' without explaining trigger mechanism; mentions hormones without explaining antagonistic action; lists primitive traits without explaining evolutionary significanceNo process explanation; purely descriptive without causal mechanisms; confuses structure with function; fails to explain 'why' for any of the five sub-parts; static description without dynamic biological processes
Evolutionary / applied context20%10Integrates evolutionary and applied significance: for (a) compares insect vision with vertebrate; for (b) traces symmetry evolution from radial (sessile) to bilateral (active); for (c) connects endocrine pancreas to diabetes mellitus treatment (Banting-Best, Indian context of rising diabetes); for (d) explains cnidoblast as Cnidaria synapomorphy and ecological success; for (e) emphasizes Sphenodon as window to Mesozoic reptile evolution and conservation statusBrief mention of evolutionary trends without integration; notes Sphenodon as 'living fossil' without elaboration; mentions diabetes without Indian context; superficial treatment of adaptive significanceNo evolutionary or applied context; treats all topics as isolated facts; misses the 'living fossil' significance of Sphenodon entirely; no mention of clinical relevance of pancreatic endocrinology; fails to justify cnidoblasts as defensive in ecological context

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