All 8 questions from UPSC Civil Services Mains Zoology
2025 Paper I (400 marks total). Every stem reproduced in full,
with directive-word analysis, marks, word limits, and answer-approach pointers.
8Questions
400Total marks
2025Year
Paper IPaper
Topics covered
Metagenesis, book lungs, paedomorphosis, torsion, human eye (1)Vertebrate digestive system, sponge reproduction, termite social organization (1)Parental care in amphibians, Pheretima life cycle, protozoan nutrition (1)Mammalian gonads and hormones, reptilian skull types, fish migration (1)Biodiversity hotspots, bird navigation, sickle cell anaemia, circadian rhythms, biome (1)Air pollution, pheromones in alarm spreading, DNA fingerprinting in forensics (1)Student's t-test, fluorescence microscope, prawn culture methods (1)Infectious diseases and filaria, carbon cycle, sexual conflict in animal behaviour (1)
A
Q1
50M150wCompulsorywrite short notesMetagenesis, book lungs, paedomorphosis, torsion, human eye
Write short notes on/Answer the following in about 150 words each: 10×5=50
(a) Metagenesis
(b) Book lungs
(c) Paedomorphosis
(d) Torsion and detorsion in gastropods
(e) Draw a well-labelled diagram of human eye and write its functions.
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर/का लगभग 150 शब्दों में संक्षिप्त टिप्पणी लिखिए/उत्तर दीजिए : 10×5=50
(a) संमेकांतरण
(b) पुस्त फुप्फुस
(c) शावकांतरण
(d) गैस्ट्रोपोड में ऐटन (विमोटन) और अव्यावर्तन
(e) मनुष्य की आँख का एक सुचिहित चित्र बनाइए और उसके कार्यों का वर्णन कीजिए।
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) describe: define > structure or process in order > labelled diagram > significance Full marks: Precise definitions, named taxa, clear diagrams, and functional explanations.
Define metagenesis as alternation of generations
Distinguish asexual (sporic) and sexual (gametic) phases
50MdescribeVertebrate digestive system, sponge reproduction, termite social organization
(a) Describe the comparative anatomy of digestive system in vertebrates. 20
(b) Give an illustrated account of reproduction in sponges. 15
(c) Describe the general features, distribution and social organization in termites. 15
हिंदी में पढ़ें
(a) कशेरुकियों में पाचन तंत्र के तुलनात्मक शारीर का वर्णन कीजिए। 20
(b) स्पंजों में प्रजनन का एक सचित्र विवरण दीजिए। 15
(c) दीमकों में सामान्य लक्षणों, वितरण और सामाजिक संगठन का वर्णन कीजिए। 15
Answer approach & key points
Framework: UPSC Zoology Paper 1. (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: Comprehensive, comparative, and well-illustrated with precise terminology.
50MdescribeParental care in amphibians, Pheretima life cycle, protozoan nutrition
(a) Describe the mechanism of parental care in amphibians with suitable examples. 20
(b) Describe the different stages of life cycle of Pheretima with the help of suitable diagrams. 15
(c) Discuss the various modes of nutrition in protozoa. 15
हिंदी में पढ़ें
(a) उभयचरों (एम्फिबियन) में पैतृक रक्षण की क्रियाविधि का उपयुक्त उदाहरणों सहित वर्णन कीजिए। 20
(b) फेरेटिमा के जीवन-चक्र की विभिन्न अवस्थाओं का उपयुक्त चित्रों की सहायता से वर्णन कीजिए। 15
(c) प्रोटोजोआ में पोषण के विभिन्न तरीकों पर चर्चा कीजिए। 15
Answer approach & key points
(a) describe: define > structure or process in order > labelled diagram > significance | (b) describe: define > structure or process in order > labelled diagram > significance | (c) discuss: intro > 3-4 dimensions > example > balanced close Full marks: Comprehensive, accurate, and well-structured answers with clear diagrams and named examples.
Define parental care in amphibians
Describe specific care mechanisms (e.g., guarding, transport)
Provide suitable examples with named species
Explain the biological significance of the care
Identify *Pheretima* as the taxon
Describe the stages of the life cycle in order
Include suitable labelled diagrams of the life cycle
50MdiscussMammalian gonads and hormones, reptilian skull types, fish migration
(a) Draw a well-labelled diagram of testis and ovary in mammals, and discuss the functions of their hormones. 20
(b) Give an illustrated account of skull types in reptiles. 15
(c) Explain the types and significance of migration in fishes. 15
हिंदी में पढ़ें
(a) स्तनधारियों में वृषण और अंडाशय का सुचिहित चित्र बनाइए और उनके हार्मोनों के कार्यों पर चर्चा कीजिए। 20
(b) सरीसृपों में कपोटि के प्रकारों का एक सचित्र विवरण दीजिए। 15
(c) मछलियों में प्रवास के प्रकार और महत्व की व्याख्या कीजिए। 15
Answer approach & key points
Framework: Zoology Paper 1: Define > Structure/Mechanism > Diagram > Example. (a) discuss: intro > 3-4 dimensions > example > balanced close | (b) account for: state the phenomenon > the causes in order of weight > conclusion | (c) explain: definition/context > points in order > small example > short close Full marks: Accurate diagrams, precise terminology, clear mechanisms, named examples.
Well-labelled diagram of mammalian testis
Well-labelled diagram of mammalian ovary
Functions of testicular hormones (e.g., testosterone)
Functions of ovarian hormones (e.g., estrogen, progesterone)
Definition of skull types (anapsid, diapsid, synapsid)
Write short notes on the following in about 150 words each: 10×5=50
(a) Biodiversity hot spots
(b) Navigation in birds
(c) Sickle cell anaemia
(d) Circadian rhythms
(e) Biome
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणी लिखिए : 10×5=50
(a) जैव विविधता अधिदेशल
(b) पक्षियों में पथ-संचालन (नैविगेशन)
(c) दार (हँसिया) कोशिका अरक्तता
(d) दिवसीय लय
(e) जीवोम
Answer approach & key points
Framework: Zoology, Paper 1. (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, correct mechanisms, named examples, and clear structure.
50MexplainAir pollution, pheromones in alarm spreading, DNA fingerprinting in forensics
(a) Define air pollution. Explain the types, sources, consequences and control measures of air pollution. 20
(b) Define pheromones. Discuss the role of pheromones in alarm spreading in animals with suitable examples. 15
(c) What is DNA fingerprinting? Explain the mechanism and applications of DNA fingerprinting in forensic science. 15
हिंदी में पढ़ें
(a) वायु प्रदूषण को परिभाषित कीजिए। वायु प्रदूषण के प्रकार, स्रोत, परिणाम और नियंत्रण के उपायों की व्याख्या कीजिए। 20
(b) फेरोमोन को परिभाषित कीजिए। जानवरों के संचेतन प्रसार (अलार्म स्प्रेडिंग) में फेरोमोन की भूमिका की उपयुक्त उदाहरणों सहित चर्चा कीजिए। 15
(c) डी० एन० ए० फिंगरप्रिंटिंग क्या है? फोरेंसिक विज्ञान में डी० एन० ए० फिंगरप्रिंटिंग की क्रियाविधि एवं अनुप्रयोगों की व्याख्या कीजिए। 15
Answer approach & key points
(a) explain: definition/context > points in order > small example > short close | (b) discuss: intro > 3-4 dimensions > example > balanced close | (c) explain: definition/context > points in order > small example > short close Full marks: Precise definitions, specific examples, clear mechanisms, and strong forensic/conservation links.
Precise definition of air pollution
Classification of types (e.g., point vs non-point)
Specific sources (industrial, vehicular, domestic)
Consequences (health, environment, climate)
Definition of pheromones (chemical signals)
Mechanism of alarm spreading (diffusion, detection)
Specific example of alarm pheromone (e.g., honeybee)
(a) What is Student's t-test and its significance in biological research? Write the formula of t-test and its various steps using simple data. 20
(b) Explain the principle, instrumentation and applications of fluorescence microscope. 15
(c) Describe the different species suitable for prawn culture with emphasis on the methods of prawn cultivation. 15
हिंदी में पढ़ें
(a) स्टूडेंट का t-परीक्षण क्या है और जैविक अनुसंधान में इसका क्या महत्व है? सरल डेटा का उपयोग करते हुए t-परीक्षण के सूत्र और इसके विभिन्न चरणों का वर्णन कीजिए। 20
(b) प्रतिदीप्ति सूक्ष्मदर्शी के सिद्धांत, यंत्रीकरण एवं अनुप्रयोगों की व्याख्या कीजिए। 15
(c) झींगा पालन के तरीकों पर जोर देते हुए झींगा पालन के लिए उपयुक्त विभिन्न प्रजातियों का वर्णन कीजिए। 15
Answer approach & key points
Framework: null. (a) explain: definition/context > points in order > small example > short close | (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, correct formulas/calculations, labelled diagrams, and specific named examples.
Definition of Student's t-test
Formula for t-value (t = mean diff / SE)
Step-by-step calculation using provided simple data
50MdescribeInfectious diseases and filaria, carbon cycle, sexual conflict in animal behaviour
(a) What do you mean by infectious and communicable diseases? Mention the causative agent and means of spread of filaria. Also describe the symptoms, diagnosis, treatment and preventive measures of filaria. 20
(b) Give an illustrated account of carbon cycle with suitable diagram. 15
(c) Describe the phenomenon of sexual conflict and selfishness in studying animal behaviour with suitable examples. 15
हिंदी में पढ़ें
(a) संक्रामक एवं संचारणीय रोगों से आप क्या समझते हैं? फाइलेरिया के रोगकारक (कारक एजेंट) एवं प्रसार के तरीकों का उल्लेख कीजिए। फाइलेरिया के लक्षणों, निदान, इलाज एवं निवारक उपायों का भी वर्णन कीजिए। 20
(b) कार्बन चक्र का उपयुक्त रेखाचित्र सहित एक स्पष्टीकृत विवरण दीजिए। 15
(c) प्राणी व्यवहार के अध्ययन में यौन संघर्ष एवं स्वार्थ की परिघटना का उपयुक्त उदाहरणों सहित वर्णन कीजिए। 15
Answer approach & key points
(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, named species, labelled diagrams, evolutionary links, and specific examples throughout.
Define infectious vs communicable diseases
Identify Wuchereria bancrofti as causative agent
Explain Culex mosquito vector transmission
List symptoms, diagnosis, treatment, and prevention