All 8 questions from UPSC Civil Services Mains Zoology 2021 Paper I (400 marks total). Every stem reproduced in full, with directive-word analysis, marks, word limits, and answer-approach pointers.
8Questions
400Total marks
2021Year
Paper IPaper
Topics covered
Animal diversity and morphology (1)Metamorphosis and life cycles (1)Endocrinology and excretory system (1)Circulation and life cycles (1)Applied zoology and ecology (1)Biostatistics and ecology (1)Biotechnology and animal behavior (1)Ecosystem and applied zoology (1)
A
Q1
50M150wCompulsorywrite short notesAnimal diversity and morphology
Write notes in about 150 words each for Q. Nos. 1(a) to 1(d) and answer Q. No. 1(e) :
(a) Canal system in sponges (10 marks)
(b) Nematocysts of Aurelia (10 marks)
(c) Trochophore larva and its evolutionary significance (10 marks)
(d) Origin of tetrapods (10 marks)
(e) Draw a well-labelled diagram of avian brain. (10 marks)
हिंदी में पढ़ें
प्र० सं० 1(a) से 1(d) तक प्रत्येक पर लगभग 150 शब्दों में टिप्पणी लिखिए और प्र० सं० 1(e) का उत्तर दीजिए :
(a) स्पंजों में नाल प्रणाली (10 अंक)
(b) ऑरेलिया के निमेटोसिस्ट (10 अंक)
(c) ट्रोकोफोर लार्वा और इसका विकासवादी महत्व (10 अंक)
(d) चौपायों (टेट्रापोड्स) की उत्पत्ति (10 अंक)
(e) पक्षी (एवियन) मस्तिष्क का एक नामांकित चित्र बनाइए। (10 अंक)
Answer approach & key points
Framework: Zoology Paper 1: Define > Structure/Mechanism > Diagram > Example. (a) write short notes: define > 3-4 key features > one example > one-line significance | (b) write short notes: define > 3-4 key features > one example > one-line significance | (c) write short notes: define > 3-4 key features > one example > one-line significance | (d) write short notes: define > 3-4 key features > one example > one-line significance | (e) map: locate accurately > label > one line on why it matters Full marks: All parts answered with precise definitions, detailed mechanisms, and accurate diagrams.
Ascon, sycon and leucon types with examples
Water path: ostia, canals, choanocyte chambers, osculum
Cnidocyte, capsule, operculum, thread and cnidocil
(a) What is metamorphosis? Describe the hormonal regulation of metamorphosis in insects. (20 marks)
(b) What is alternation of generations? Illustrate this phenomenon with life history of Obelia. (15 marks)
(c) Describe the structure and functions of internal ear in mammals. (15 marks)
हिंदी में पढ़ें
(a) कायांतरण क्या है? कीटों में कायांतरण के हार्मोनल विनियमन का वर्णन कीजिए। (20 अंक)
(b) पीढ़ियों का प्रत्यावर्तन क्या है? ओबेलिया के जीवन-इतिहास के साथ इस परिघटना को स्पष्ट कीजिए। (15 अंक)
(c) स्तनधारियों में आंतरिक कान की संरचना और कार्यों का वर्णन कीजिए। (15 अंक)
Answer approach & key points
Framework: Zoology Paper 1: Define > Structure/Mechanism > Diagram > Example. (a) describe: define > structure or process in order > labelled diagram > significance | (b) explain: definition/context > points in order > small example > short close | (c) describe: define > structure or process in order > labelled diagram > significance Full marks: Precise definitions, detailed mechanisms, labelled diagrams, named examples, and clear hormonal/structural explanations.
Definition and types (incomplete and complete)
PTTH from brain, ecdysone from prothoracic glands
Juvenile hormone from corpora allata and its status-quo role
Metagenesis between polyp and medusa
Polymorphic colony with hydranth and blastostyle
Life cycle: medusa, gametes, zygote, planula, hydrula and colony
Bony and membranous labyrinth with perilymph and endolymph
(a) What is hypothalamo-pituitary axis? Draw a well-labelled diagram of pituitary gland and describe the functions of its hormones. (20 marks)
(b) Define nephridium. Describe the various types of nephridia found in Pheretima. (15 marks)
(c) Describe the respiratory organs and mechanism of respiration in Pila. (15 marks)
हिंदी में पढ़ें
(a) हाइपोथैलेमो-पिट्यूटरी अक्ष क्या है? पीयूष (पिट्यूटरी) ग्रंथि का एक नामांकित चित्र बनाइए और इसके हार्मोनों के कार्यों का वर्णन कीजिए। (20 अंक)
(b) वृक्क नलिका (नेफ्रिडियम) को परिभाषित कीजिए। फेरेटिमा में पाई जाने वाली विभिन्न प्रकार की वृक्क नलिकाओं (नेफ्रिडिया) का वर्णन कीजिए। (15 अंक)
(c) पाइला में श्वसन अंगों और श्वसन की क्रियाविधि का वर्णन कीजिए। (15 अंक)
Answer approach & key points
Framework: Zoology Paper 1: Define > Structure/Mechanism > Diagram > Example. (a) describe: define > structure or process in order > labelled diagram > significance | (b) describe: define > structure or process in order > labelled diagram > significance | (c) describe: define > structure or process in order > labelled diagram > significance Full marks: Precise definitions, fully labelled diagrams, and detailed mechanisms for all parts.
Portal system and neurosecretory tract linking hypothalamus and pituitary
Labelled diagram: adenohypophysis parts and neurohypophysis
Hormones of both lobes with functions
Definition of nephridium
Septal, integumentary and pharyngeal nephridia with locations
Enteronephric versus exonephric and presence of nephrostome
Ctenidium and pulmonary sac in the mantle cavity
Aquatic respiration through the gill with water current
Aerial respiration through the lung and nuchal siphon
(a) Define double circulation. Give a comparative account of heart in reptiles, birds and mammals. (20 marks)
(b) Describe habitat, habits and life history of Branchiostoma. (15 marks)
(c) Give an illustrated account of life cycle of Leishmania. (15 marks)
हिंदी में पढ़ें
(a) दोहरे परिसंचरण को परिभाषित कीजिए। सरीसृपों, पक्षियों और स्तनधारियों में हृदय का तुलनात्मक विवरण दीजिए। (20 अंक)
(b) ब्रांकिओस्टोमा के आवास, आदतों और जीवन-इतिहास का वर्णन कीजिए। (15 अंक)
(c) लीशमैनिया के जीवन-चक्र का सचित्र विवरण दीजिए। (15 अंक)
Answer approach & key points
Framework: UPSC Zoology Paper 1. (a) compare: paired headings or table > key differences > significance > conclusion | (b) describe: define > structure or process in order > labelled diagram > significance | (c) describe: define > structure or process in order > labelled diagram > significance Full marks: Precise definitions, comparative tables, labelled diagrams, specific species names, and clear mechanisms.
Double circulation defined with pulmonary and systemic circuits
Reptilian three-chambered heart with partial septum; crocodile exception
Four-chambered heart of birds and mammals with right or left systemic arch
Marine sandy habitat with burrowing habit
Ciliary filter-feeding with endostyle mucus
Life history: gametes, external fertilisation, larva, metamorphosis
Digenetic cycle in human and sandfly
Amastigote and promastigote forms
Infective metacyclic promastigote and transmission
50M150wCompulsorywrite short notesApplied zoology and ecology
Write notes on the following in about 150 words each :
(a) Vermiculture (10 marks)
(b) FISH (10 marks)
(c) Biological clock (10 marks)
(d) Ecological succession (10 marks)
(e) Biodiversity hotspots (10 marks)
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में टिप्पणी लिखिए :
(a) कृमि संवर्धन/केंचुआ संवर्धन (वर्मीकल्चर) (10 अंक)
(b) एफ० आई० एस० एच० (10 अंक)
(c) जैविक घड़ी (10 अंक)
(d) पारिस्थितिकीय अनुक्रमण/उत्तरवर्तन (10 अंक)
(e) जैव विविधता हॉटस्पॉट (10 अंक)
Answer approach & key points
Framework: Zoology Paper 1: Define > Structure/Mechanism > Diagram > Example. (a) write short notes: define > 3-4 key features > one example > one-line significance | (b) write short notes: define > 3-4 key features > one example > one-line significance | (c) write short notes: define > 3-4 key features > one example > one-line significance | (d) write short notes: define > 3-4 key features > one example > one-line significance | (e) write short notes: define > 3-4 key features > one example > one-line significance Full marks: Precise definitions, named taxa/species, clear mechanisms, and specific examples for all parts.
Epigeic earthworm species (Eisenia, Eudrilus)
Method of vermicomposting
Benefits of vermicompost
Fluorescence in situ hybridisation expanded
Principle: fluorescent probe hybridising to target sequence
Applications in diagnosis and cancer
Circadian rhythm free-running with entrainment by light
SCN as master clock
Feedback loop of CLOCK, BMAL1, PER and CRY
Definition with pioneer, seral and climax stages
Primary versus secondary succession
Examples such as lithosere, hydrosere and abandoned fields
Myers criteria of 1,500 endemic plants and 70% loss
(a) Define correlation. Explain its types and methods of computing coefficient of correlation. (20 marks)
(b) Write a note on ecological pyramids with suitable examples. (15 marks)
(c) What are pheromones? Discuss their role in insects. (15 marks)
हिंदी में पढ़ें
(a) सहसंबंध को परिभाषित कीजिए। सहसंबंध के प्रकार और इसके गुणांक की गणना के तरीकों की व्याख्या कीजिए। (20 अंक)
(b) पारिस्थितिक पिरामिडों पर उपयुक्त उदाहरणों सहित एक टिप्पणी लिखिए। (15 अंक)
(c) फेरोमोन क्या हैं? कीटों में उनकी भूमिका की चर्चा कीजिए। (15 अंक)
Answer approach & key points
Framework: UPSC Zoology Paper 1. (a) explain: definition/context > points in order > small example > short close | (b) write short notes: define > 3-4 key features > one example > one-line significance | (c) discuss: intro > 3-4 dimensions > example > balanced close Full marks: Comprehensive, accurate, with examples and diagrams
Definition and types (positive, negative, linear, simple, partial, multiple)
Karl Pearson's coefficient with formula and range
Spearman rank correlation formula
Pyramids of numbers, biomass and energy
Upright and inverted examples
Energy pyramid always upright with the ten percent law
Definition of pheromone as a species-specific chemical signal
Types: sex, aggregation, alarm and trail
Examples such as bombykol and honey-bee queen substance
(a) What is transgenesis? Describe the methods and applications of transgenesis in animals. (20 marks)
(b) Describe the principle and applications of polymerase chain reaction (PCR). (15 marks)
(c) Explain the process of learning and memory in animals with suitable example. (15 marks)
हिंदी में पढ़ें
(a) ट्रांसजेनेसिस क्या है? जानवरों में ट्रांसजेनेसिस की विधियों और अनुप्रयोगों का वर्णन कीजिए। (20 अंक)
(b) पॉलिमरेज मुंबला अभिक्रिया (पी० सी० आर०) के सिद्धांत और अनुप्रयोगों का वर्णन कीजिए। (15 अंक)
(c) जानवरों में सीखने और स्मृति (याददाश्त) की प्रक्रिया को उपयुक्त उदाहरण सहित समझाइए। (15 अंक)
Answer approach & key points
Framework: Zoology Paper 1: Define > Structure/Mechanism > Diagram > Example. (a) describe: define > structure or process in order > labelled diagram > significance | (b) describe: define > structure or process in order > labelled diagram > significance | (c) explain: definition/context > points in order > small example > short close Full marks: Precise definitions, detailed mechanisms, labelled diagrams, specific examples, and clear applications.
Definition of transgenesis
Methods: pronuclear microinjection, retroviral vectors, ES cells
Applications such as biopharming and disease models
Three steps: denaturation, annealing and extension
(a) Define ecosystem. Discuss the structure and functions of ecosystem. (20 marks)
(b) What is apiculture? Describe the various methods of beekeeping and also add a note on the uses of honey. (15 marks)
(c) Differentiate between SEM and TEM. (15 marks)
हिंदी में पढ़ें
(a) पारिस्थितिकी तंत्र को परिभाषित कीजिए। पारिस्थितिकी तंत्र की संरचना और कार्यों का वर्णन कीजिए। (20 अंक)
(b) मधुमक्खी-पालन क्या है? मधुमक्खी-पालन की विभिन्न विधियों का वर्णन कीजिए और शहद के उपयोगों पर एक टिप्पणी भी लिखिए। (15 अंक)
(c) एस० ई० एम० और टी० ई० एम० के बीच अंतर स्पष्ट कीजिए। (15 अंक)
Answer approach & key points
(a) discuss: intro > 3-4 dimensions > example > balanced close | (b) describe: define > structure or process in order > labelled diagram > significance | (c) compare: paired headings or table > key differences > significance > conclusion Full marks: Comprehensive coverage of all sub-parts with precise terminology, labelled diagrams, and specific examples.
Definition with Tansley
Structure: abiotic and biotic components (producers, consumers, decomposers)
Functions: energy flow and nutrient cycling
Definition and species used in India
Traditional and movable-frame hive methods
Uses of honey
Principle: scanning of surface versus transmission through a section