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UPSC Zoology — Previous Year Questions

Every question from Zoology papers in UPSC Civil Services Mains (2021–2026), organised by year. 96 questions in total, each with directive-word analysis, model answer points, and a full evaluation rubric.

96Questions
6Years covered

2026 Mains

16 questions · 800 marks

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Paper I 8 Qs · 400 marksPaper II 8 Qs · 400 marks
All 16 questions from 2026

Paper I

  1. Q1 (a) Structure of gemmules in Porifera and their importance. (10 marks) (b) Structure and functions of parathyroid… 50 marks
  2. Q2 (a) Write peculiar characters of phylum Annelida. Classify this phylum into different classes and mention features of… 50 marks
  3. Q3 (a) Give a comparative account of aortic arches in vertebrates. (20 marks) (b) Explain different ways of locomotion in… 50 marks
  4. Q4 (a) Explain types of fins in fishes and their role in locomotion. (20 marks) (b) Describe the functions of various… 50 marks
  5. Q5 (a) Green house effect. (10 marks) (b) Sign stimuli in animals and their significance. (10 marks) (c) Gene therapy and… 50 marks
  6. Q6 (a) Enumerate various population characteristics. Explain the following characteristics in detail : (i) Natality and… 50 marks
  7. Q7 (a) Differentiate among alpha, beta and gamma diversity. Explain various factors which threaten the biodiversity. (20… 50 marks
  8. Q8 (a) Explain the following human genetic diseases : (i) Haemophilia (ii) Thalassemia (20 marks) (b) Explain various… 50 marks

Paper II

  1. Q1 (a) Semiconservative replication of DNA (10 marks) (b) Difference between pinocytosis and phagocytosis (10 marks) (c)… 50 marks
  2. Q2 (a) What is DNA transcription? Explain the process of DNA transcription in eukaryotes. (20 marks) (b) What is primary… 50 marks
  3. Q3 (a) What is recombinant DNA technology? Describe the different vectors used in DNA cloning. (20 marks) (b) Describe the… 50 marks
  4. Q4 (a) What is Oparin concept? Comment on the chemical theory of origin of life. (20 marks) (b) Explain the functional… 50 marks
  5. Q5 (a) Role of calcium in muscle contraction (10 marks) (b) How is excretion different from osmoregulation in mammals? (10… 50 marks
  6. Q6 (a) Explain various levels of protein organization with suitable examples. (20 marks) (b) What is nerve impulse? How is… 50 marks
  7. Q7 (a) Name the proteins and their functions involved in skeletal muscle contraction. Unlike skeletal muscles, why do… 50 marks
  8. Q8 (a) Define apoptosis. Explain the characteristics, molecular pathways and significance of apoptosis. (20 marks) (b)… 50 marks

2025 Mains

16 questions · 800 marks

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Paper I 8 Qs · 400 marksPaper II 8 Qs · 400 marks
All 16 questions from 2025

Paper I

  1. Q1 (a) Metagenesis (b) Book lungs (c) Paedomorphosis (d) Torsion and detorsion in gastropods (e) Draw a well-labelled… 50 marks
  2. Q2 (a) Describe the comparative anatomy of digestive system in vertebrates. 20 (b) Give an illustrated account of… 50 marks
  3. Q3 (a) Describe the mechanism of parental care in amphibians with suitable examples. 20 (b) Describe the different stages… 50 marks
  4. Q4 (a) Draw a well-labelled diagram of testis and ovary in mammals, and discuss the functions of their hormones. 20 (b)… 50 marks
  5. Q5 (a) Biodiversity hot spots (b) Navigation in birds (c) Sickle cell anaemia (d) Circadian rhythms (e) Biome 50 marks
  6. Q6 (a) Define air pollution. Explain the types, sources, consequences and control measures of air pollution. 20 (b) Define… 50 marks
  7. Q7 (a) What is Student's t-test and its significance in biological research? Write the formula of t-test and its various… 50 marks
  8. Q8 (a) What do you mean by infectious and communicable diseases? Mention the causative agent and means of spread of… 50 marks

Paper II

  1. Q1 (a) Protein sorting in Golgi apparatus (10 marks) (b) Structure and function of Lampbrush chromosome (10 marks) (c)… 50 marks
  2. Q2 (a)(i) Describe composition of plasma membrane. (10 marks) (a)(ii) Differentiate between facilitated and passive… 50 marks
  3. Q3 (a)(i) Describe the synthetic theory of evolution. (10 marks) (a)(ii) Describe common types of mimicry in insects with… 50 marks
  4. Q4 (a) Describe the steps of constructing a recombinant DNA and its cloning. (20 marks) (b) Discuss the major… 50 marks
  5. Q5 (a) Block to polyspermy (10 marks) (b) Fate map of frog embryo (10 marks) (c) Activation energy based mechanism of… 50 marks
  6. Q6 (a)(i) Write down the reactions that produce NADH during Krebs cycle. (10 marks) (a)(ii) Explain the role of proton… 50 marks
  7. Q7 (a)(i) Explain sigmoidal nature of oxygen dissociation curve for hemoglobin. (10 marks) (a)(ii) Describe differences… 50 marks
  8. Q8 (a) Describe the stages of fertilization in chick with diagram. (20 marks) (b) Draw structure of cholesterol and… 50 marks

2024 Mains

16 questions · 800 marks

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Paper I 8 Qs · 400 marksPaper II 8 Qs · 400 marks
All 16 questions from 2024

Paper I

  1. Q1 (a) Concept and organization of Coelom (10 marks) (b) Metamorphosis in Insects (10 marks) (c) Thyroid gland and its… 50 marks
  2. Q2 (a) Explain the general features, life cycle and pathogenicity of Fasciola. (20 marks) (b) Define Autogamy. Explain the… 50 marks
  3. Q3 (a) Describe the different larval forms of Crustaceans with suitable diagrams. (20 marks) (b) What are coral reefs ?… 50 marks
  4. Q4 (a) Give an illustrated account of integument and its derivatives in vertebrates with suitable diagrams. (20 marks) (b)… 50 marks
  5. Q5 (a) Food Web (10 marks) (b) Biological Rhythms (10 marks) (c) AIDS (10 marks) (d) Chromosome Painting (10 marks) (e)… 50 marks
  6. Q6 (a) What is ecological succession ? Explain the different types and theories of ecological succession. (20 marks) (b)… 50 marks
  7. Q7 (a) Mention the causative agent and means of spread of malaria. Also describe symptoms, diagnosis, treatment and… 50 marks
  8. Q8 (a) Describe the various measures of central tendency of data with suitable examples and discuss their merits and… 50 marks

Paper II

  1. Q1 (a) Polytene chromosome (10 marks) (b) Difference between male heterogamety and female heterogamety with examples (10… 50 marks
  2. Q2 (a) Give an account of ultrastructure of rough and smooth endoplasmic reticulum. Also discuss the role of endoplasmic… 50 marks
  3. Q3 (a) What is sex-determination? Give an account of genic balance theory of sex-determination in Drosophila with examples… 50 marks
  4. Q4 (a) Describe the stages of human evolution and mention the major hominid forms giving their time of origin. (20 marks)… 50 marks
  5. Q5 (a) Functions of immunoglobulins (10 marks) (b) ABO system of blood groups and its basis, and erythroblastosis foetalis… 50 marks
  6. Q6 (a) Explain the structure of nephron and its role in urine formation. Add a note on hormonal regulation of urine… 50 marks
  7. Q7 (a) Describe the process of spermatogenesis. Add a note on the role of Golgi bodies in the formation of acrosome… 50 marks
  8. Q8 (a) Write about the role of liver and pancreas in digestion. Add a note on neural and hormonal regulation of their… 50 marks

2023 Mains

16 questions · 800 marks

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Paper I 8 Qs · 400 marksPaper II 8 Qs · 400 marks
All 16 questions from 2023

Paper I

  1. Q1 (a) Erythrocytic schizogony (10 marks) (b) Statocyst of medusa (10 marks) (c) Evolutionary status of Onychophora (10… 50 marks
  2. Q2 (a) Define conjugation. Explain the mechanism of conjugation in Paramecium. Also give its significance. (20 marks) (b)… 50 marks
  3. Q3 (a) Explain the general features, life cycle and pathogenicity of Taenia. (20 marks) (b) Give an illustrated account of… 50 marks
  4. Q4 (a) Draw a well-labelled diagram of adrenal gland and discuss the functions of its hormones. (20 marks) (b) Describe… 50 marks
  5. Q5 (a) Ecological niche (10 marks) (b) Instinct behaviour in animals (10 marks) (c) Pathogenesis of cholera (10 marks) (d)… 50 marks
  6. Q6 (a) Define regression. Explain different methods and applications of regression analysis. (20 marks) (b) Define food… 50 marks
  7. Q7 (a) What is lac culture? Explain the life cycle of lac insect and describe cultivation and processing of lac in India… 50 marks
  8. Q8 (a) What is ELISA? Explain the principle, types, procedure and applications of ELISA. (20 marks) (b) Describe the… 50 marks

Paper II

  1. Q1 (a) Write about different ways by which biodiversity is being threatened. (10 marks) (b) How is hn RNA (primary… 50 marks
  2. Q2 (a) Give structure of t-RNA. Write role of different RNAs in the translation process. (20 marks) (b) Describe the… 50 marks
  3. Q3 (a) Describe the structure of mitochondrion. Why is it known as powerhouse of the cell? (20 marks) (b) Explain the… 50 marks
  4. Q4 (a) Explain the following: (10×2=20 marks) (i) Haemophilia (ii) Red-green colour blindness (b) Describe various stages… 50 marks
  5. Q5 (a) Highlight role of various hormones in the regulation of digestive secretions. (10 marks) (b) Describe the balance… 50 marks
  6. Q6 (a) Classify carbohydrates by giving suitable examples. Also, mention characteristics of each category. (20 marks) (b)… 50 marks
  7. Q7 (a) Give an account of hormonal regulation of menstruation in human females. (20 marks) (b) Explain the source(s) and… 50 marks
  8. Q8 (a) Explain enzymes, their characteristics as well as induced-fit model of mechanism of enzyme action. (20 marks) (b)… 50 marks

2022 Mains

16 questions · 800 marks

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Paper I 8 Qs · 400 marksPaper II 8 Qs · 400 marks
All 16 questions from 2022

Paper I

  1. Q1 (a) Structure of visual organs of cockroach. (10 marks) (b) What is meant by symmetry? Write about different types of… 50 marks
  2. Q2 (a) Explain asexual and sexual modes of reproduction in Paramecium. (20 marks) (b) Write general features of egg laying… 50 marks
  3. Q3 (a) Explain habitat, habits, general features and life cycle of Wuchereria. (20 marks) (b) Describe different types of… 50 marks
  4. Q4 (a) Give an account of the origin as well as adaptive radiation of reptiles. (20 marks) (b) Describe general structure… 50 marks
  5. Q5 (a) What are ecotones? Explain by giving examples. Also write a note on 'edge effect'. (10 marks) (b) Comment on… 50 marks
  6. Q6 (a) Describe various types of social groupings in primates. Write a note on importance of social grouping. (20 marks)… 50 marks
  7. Q7 (a) What is meant by biodiversity? Explain various means of in situ conservation of biodiversity. (20 marks) (b)… 50 marks
  8. Q8 (a) Mention the causative agent and means of spread of tuberculosis. Also describe symptoms, diagnosis, treatment and… 50 marks

Paper II

  1. Q1 (a) Draw the structure of a microtubule and explain its role in chromosomal movements during cell division. (b) What is… 50 marks
  2. Q2 (a) What is rough endoplasmic reticulum (RER)? Describe in detail the various modifications of secretory proteins… 50 marks
  3. Q3 (a) Sketch out a basic transcription unit and illustrate the RNA polymerase II associated assembly of a transcription… 50 marks
  4. Q4 (a) What is fossil? Describe the origin and evolution of horse based on the fossil records. 20 (b) Define variation… 50 marks
  5. Q5 (a) Define immunity. Explain cell-mediated immune response in vertebrates with suitable diagram. (b) Describe the… 50 marks
  6. Q6 (a) Draw the molecular structure of ATP synthase and diagrammatically explain the chemiosmotic concept of ATP… 50 marks
  7. Q7 (a) What are intestinal glands? Describe the roles of intestinal juices in digestion and absorption of food. 20 (b)… 50 marks
  8. Q8 (a) What is stem cell? Discuss the types of stem cells and their application in therapeutic uses in human. 20 (b)… 50 marks

2021 Mains

16 questions · 800 marks

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Paper I 8 Qs · 400 marksPaper II 8 Qs · 400 marks
All 16 questions from 2021

Paper I

  1. Q1 (a) to 1(d) and answer Q. No. 1(e) : (a) Canal system in sponges (10 marks) (b) Nematocysts of Aurelia (10 marks) (c)… 50 marks
  2. Q2 (a) What is metamorphosis? Describe the hormonal regulation of metamorphosis in insects. (20 marks) (b) What is… 50 marks
  3. Q3 (a) What is hypothalamo-pituitary axis? Draw a well-labelled diagram of pituitary gland and describe the functions of… 50 marks
  4. Q4 (a) Define double circulation. Give a comparative account of heart in reptiles, birds and mammals. (20 marks) (b)… 50 marks
  5. Q5 (a) Vermiculture (10 marks) (b) FISH (10 marks) (c) Biological clock (10 marks) (d) Ecological succession (10 marks)… 50 marks
  6. Q6 (a) Define correlation. Explain its types and methods of computing coefficient of correlation. (20 marks) (b) Write a… 50 marks
  7. Q7 (a) What is transgenesis? Describe the methods and applications of transgenesis in animals. (20 marks) (b) Describe the… 50 marks
  8. Q8 (a) Define ecosystem. Discuss the structure and functions of ecosystem. (20 marks) (b) What is apiculture? Describe the… 50 marks

Paper II

  1. Q1 (a) Describe the requirement of proteins for the initiation of transcription in an eukaryote. 10 (b) What is modern… 50 marks
  2. Q2 (a) What is cell cycle ? Draw an overview of molecular events during cell cycle. Discuss the role of protein kinases in… 50 marks
  3. Q3 (a) What is chromosome mutation ? Describe various types of polyploidy with suitable examples. Add a note on phenotypic… 50 marks
  4. Q4 (a) What is isolation ? Describe the major isolating mechanisms which lead to speciation. 20 (b) Enlist theories of… 50 marks
  5. Q5 (a) Fatty acids regulate the nature of lipids, justify. 10 (b) Define coenzyme. Explain the role of coenzymes in the… 50 marks
  6. Q6 (a) What are peptide hormones ? With the help of schematic diagram, discuss the epinephrine cascade for the glucose… 50 marks
  7. Q7 (a) Explain the basic stimuli causing pancreatic secretion. Discuss the role of pancreas in major food digestion. 20… 50 marks
  8. Q8 (a) What are morphogens ? Describe the cellular differentiation during morphogenesis. 20 (b) What are gap junction… 50 marks

How Zoology answers are marked

The shape the examiner expects, what earns the marks and the traps that lose them: the same card our rubrics for this subject are written from.

Answer skeleton

  1. Define
  2. Structure or mechanism
  3. Diagram
  4. Example taxon

What earns the marks

  • Name the taxon precisely and place it
  • Draw labelled life cycles and systems
  • Give the mechanism, not just description
  • Link to vectors, fisheries or conservation

What earns the extra mark

  • Named species
  • Recent conservation status

Traps that cost marks

  • Common names alone
  • Diagrams without labels
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