Zoology 2023 Paper I 50 marks 150 words Compulsory Write short notes

Q1

Write short notes on the following in about 150 words each: (a) Erythrocytic schizogony (10 marks) (b) Statocyst of medusa (10 marks) (c) Evolutionary status of Onychophora (10 marks) (d) Neoteny (10 marks) (e) Migration in birds (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित में से प्रत्येक पर 150 शब्दों में संक्षिप्त टिप्पणी लिखिए : (a) रक्ताण्विक विखण्डनिजन (10 अंक) (b) मेड्यूसा की संतुलन-पुटी (स्टैटोसिस्ट) (10 अंक) (c) ओनिकोफोरा की विकासवादी स्थिति (10 अंक) (d) चिरभूणता (10 अंक) (e) पक्षियों में प्रवास (10 अंक)

Evaluate your answer to this question → See all 2023 Zoology questions

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 with equal weightage (10 marks each). Allocate approximately 30 words per sub-part (150 words total), spending roughly 3-4 minutes per part. Structure each note with: (1) precise definition/identification, (2) key structural/functional details, (3) biological significance. No introduction or conclusion is needed; begin directly with sub-part (a). Prioritize accuracy over elaboration—each word must carry technical value.

Key points expected

(a) Erythrocytic schizogony: Occurs in Plasmodium within RBCs; mention trophozoite → schizont → merozoites; significance in malaria pathogenesis (fever cycles); contrast with exo-erythrocytic schizogony in liver
(b) Statocyst of medusa: Balance organ in Cnidaria; structure—statolith (calcium carbonate/statoconia) within sensory hair cells; function in geotaxis and orientation; location at base of tentacles or rhopalia
(c) Evolutionary status of Onychophora: 'Living fossil' connecting Annelida and Arthropoda; unique features—slime glands, tracheal respiration, unjointed legs with claws; molecular phylogeny places as sister group to Arthropoda (Panarthropoda)
(d) Neoteny: Retention of juvenile traits in adult; classic example—Axolotl (Ambystoma mexicanum) retaining gills and aquatic life; significance in human evolution (cranial features); distinction from paedomorphosis/progenesis
(e) Migration in birds: Seasonal, directed movement; Indian examples—Siberian Crane (Keoladeo), Amur Falcon (Nagaland); proximate (photoperiod, hormonal) and ultimate (resource tracking, breeding) causes; navigation mechanisms (magnetic, celestial)

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	20%	10	All five sub-parts demonstrate precise, error-free understanding: correctly identifies erythrocytic schizogony as RBC phase in Plasmodium life cycle; statocyst as gravity receptor with correct cellular components; Onychophora's transitional phylogenetic position; neoteny as heterochronic process distinct from progenesis; bird migration as obligate/partial with accurate trigger mechanisms	Mostly correct with minor errors: confuses schizogony with gametogony; describes statocyst functionally but misses statolith composition; vaguely calls Onychophora 'primitive' without phylogenetic placement; conflates neoteny with paedomorphosis broadly; lists bird examples without explaining navigation	Fundamental misconceptions: describes schizogony in mosquitoes; calls statocyst a visual organ; places Onychophora within Arthropoda; defines neoteny as 'rapid development'; describes migration as 'random wandering' without directionality
Diagram / labelling	20%	10	Includes at least 2-3 quick, accurate sketches: schizont with merozoites budding from RBC; statocyst cross-section showing statolith and sensory cilia; Onychophora external morphology; neotenic salamander with external gills; bird migration route map or flight muscle-wing diagram—all properly labelled with 3-4 key structures each	Attempts 1-2 diagrams with partial accuracy: rough RBC with dots inside; statocyst drawn as simple circle; stick-figure Onychophora without diagnostic features; mentions 'draw axolotl' without execution; no migration diagram	No diagrams, or diagrams entirely wrong: draws liver stage for erythrocytic schizogony; labels eye as statocyst; draws earthworm for Onychophora; no visual representation for neoteny or migration despite structural questions
Examples & nomenclature	20%	10	Precise scientific nomenclature throughout: Plasmodium vivax/falciparum; Aurelia/Obelia for medusa; Peripatus/Peripatoides with family Peripatidae; Ambystoma mexicanum, Thyroid hormone (T3/T4) role; Indian migratory species—Siberian Crane (Grus leucogeranus), Amur Falcon (Falco amurensis), Bar-headed Goose (Anser indicus) with specific wintering sites	Generic or partially correct examples: 'malaria parasite' without species; 'jellyfish' without genus; 'velvet worm' without Peripatus; 'salamander' without Axolotl; 'Siberian birds' without specific Indian locations	Wrong examples or no nomenclature: Toxoplasma for Plasmodium; 'fish ear' for statocyst; earthworm for Onychophora; tadpole for neoteny; 'crow flying south' as migration example
Process explanation	20%	10	Clear sequential mechanisms: schizogony stages (ring form → amoeboid trophozoite → schizont → merozoite release with hemozoin); statocyst mechanotransduction (statolith displacement → hair cell bending → nerve impulse); Onychophoran locomotion via hydrostatic skeleton and leg waves; hormonal basis of neoteny (thyroid deficiency); migration physiology (fat deposition, Zugunruhe, navigation integration)	Vague process descriptions: 'parasite divides in blood'; 'helps balance'; 'crawls with legs'; 'stays young'; 'flies when cold comes'—lacks mechanistic detail	No process explanation or entirely wrong: describes sexual reproduction for schizogony; claims statocyst produces light; states Onychophora swim; says neoteny is 'evolution of new species'; describes migration as 'instinct' without physiological basis
Evolutionary / applied context	20%	10	Explicit significance for each: schizogony—cause of malarial fever/relapse, drug target (chloroquine); statocyst—evolution of proprioception, cnidarian neural net integration; Onychophora—Ecdysozoa debate, conservation of 'living fossils' in Gondwana; neoteny—human evolution (retention of juvenile ape features), breeding applications; migration—conservation challenges (Keoladeo wetland loss, Amur Falcon hunting), climate change impacts	Brief mention of significance without depth: 'causes disease'; 'helps survival'; 'shows evolution'; 'interesting phenomenon'; 'important for ecosystem'—generic statements	No context or wrong significance: schizogony 'cures malaria'; statocyst 'for digestion'; Onychophora 'extinct'; neoteny 'causes cancer'; migration 'harms agriculture'

Practice this exact question

Write your answer, then get a detailed evaluation from our AI trained on UPSC's answer-writing standards. Free first evaluation — no signup needed to start.

Evaluate my answer →