Zoology Optional PYQs – Topic-wise (2004–2026)

Zoology Optional PYQs Topic-wise for UPSC Mains (2004–2026) are listed below unit by unit, in the order of the official syllabus – 1138 questions in all. Click any unit to open all its previous year questions, arranged topic-wise with the latest first.

Want full papers instead? Open the Zoology Optional year-wise question papers for Paper I and Paper II.

Paper I

Unit	Topic (click to open PYQs)	Sub-topics	Questions	Link
1	Non-Chordata and Chordata	17	275	Click here →
2	Ecology	7	83	Click here →
3	Ethology	4	62	Click here →
4	Economic Zoology	7	61	Click here →
5	Biostatistics	2	32	Click here →
6	Instrumentation Methods	3	40	Click here →

Trend: Non-chordata and Chordata is by far the largest unit of Paper I, with half of all the marks both since 2013 and in the last five years. It is followed by Ecology (about 14–16%), Economic Zoology (12–14%), Ethology (10–12%), Instrumentation methods (6–7%) and Biostatistics (about 5%). Within the units, comparative anatomy of vertebrates (topic 1.17), Mammalia including endocrine glands (1.16) and Arthropoda (1.8), biosphere and community ecology (2.1), hormones, pheromones and social behaviour (3.2), animal culture (4.1) and medical biotechnology (4.6), and molecular techniques such as PCR, ELISA and electrophoresis (6.2) have been asked most often since 2013. In 2022–2026 Protozoa (1.2), biodiversity and population ecology (2.4, 2.3), learning and behaviour (3.1) and human infectious diseases (4.2) have come up more often.

Paper II

Unit	Topic (click to open PYQs)	Sub-topics	Questions	Link
1	Cell Biology	5	86	Click here →
2	Genetics	8	113	Click here →
3	Evolution	5	78	Click here →
4	Systematics	–	28	Click here →
5	Biochemistry	6	90	Click here →
6	Physiology (with Special Reference to Mammals)	8	93	Click here →
7	Developmental Biology	6	97	Click here →

Trend: Paper II is spread fairly evenly: Genetics (about 18%), Cell Biology, Biochemistry and Physiology (about 16–17% each), Developmental Biology (about 15–16%), Evolution (13–14%) and Systematics (about 4%). The most-asked topics since 2013 are cell organelles (1.1), transcription and translation (1.5), Mendelian genetics and linkage (2.3) and recombinant DNA technology (2.5), theories of evolution and speciation (3.2) and the evolution of horse, elephant and human (3.3), metabolism and ATP (5.2) and hormones (5.3), blood (6.1) and digestion (6.3), and gametogenesis and fertilization (7.1). In 2022–2026 transcription and translation (1.5), sex determination (2.2), biomolecules (5.1) and gametogenesis (7.1) have come up more often.

More questions

Other questions (outside the present syllabus) – 2 questions

How this collection is organised

Considering the changing exam pattern over the years, we felt it necessary to declare some practices we’ve adopted in this collection.

1. Units follow the official syllabus – Paper 1: 1 Non-chordata and Chordata, 2 Ecology, 3 Ethology, 4 Economic Zoology, 5 Biostatistics, 6 Instrumentation methods; Paper 2: 1 Cell Biology, 2 Genetics, 3 Evolution, 4 Systematics, 5 Biochemistry, 6 Physiology, 7 Developmental Biology. The official syllabus has been divided into numbered topics (e.g. Paper 1 – 1.8 Arthropoda) to arrange the questions.

2. Questions on areas the syllabus does not name separately are placed under the nearest topic: for example, hemichordates under classification of phyla (Paper 1 – 1.1); human sense organs under comparative anatomy (1.17); ozone depletion under pollution (2.7); in Paper 2, transposons under the concept of gene (2.1); regeneration under cell interactions and metamorphosis (7.4); and von Baer’s law under the biogenetic law (7.6).

3. Until 2008 the two papers followed an older syllabus, and a few subjects (for example blotting techniques, insect metamorphosis and pheromones) appeared in Paper 2. Such questions of 2004–2007 are placed under the topic of the present syllabus, even when that topic is now in the other paper; Part III shows each paper as set. From 2009 every question is kept in its own paper.

4. Questions on subjects no longer in the syllabus (fossil formation and dating) are placed at the end of Paper 2 under “Other Questions (Outside the Present Syllabus)”.

5. Some questions cover more than one topic. We’ve kept such questions in each topic of relevance.

6. Every diagram printed with a question is given as a complete description in square brackets – [Figure: …] – with every numbered pointer and label shown, so that the question can be solved from the description. Standard tables attached to a paper are not reproduced.

7. Graphs at the start of each paper show the weightage of every unit in that paper, and graphs for each unit show the weightage of its topics. Weightage is the share of marks asked from a unit or topic, compared for 2013–2026 (white bars) and the last five years, 2022–2026 (black bars). A question placed under two topics has its marks split equally between them.

8. Each of the topicwise question is suffixed by a question code like this [2024/20m/2a]. This code indicates a) year in which the question was asked, b) maximum marks the question carried, c) prescribed word limit (where UPSC set one, e.g. 200w) and, d) the question number in actual paper, in given order.

9. Until 2012, each paper carried 300 marks (60 per question); since 2013 each paper carries 250 marks (50 per question). Where a compulsory question offered more parts than were to be answered (“any three” of four), every part is included with its own marks. Where a retyped copy of an older paper prints no marks for a part, the code carries the marks implied by the question. Split marks such as 15+5=20 are kept as printed.

10. 2018–2020 and 2024–2026 papers are transcribed from the official UPSC question papers, 2009–2017 and 2021–2023 from scans of the printed papers, and 2004–2007 from a single typed copy each. No copy of the 1995–2003 or 2008 papers could be found, so they are not included.

11. The wording, figures and data of the questions are as printed, including the papers’ own grammar and apparent misprints such as wrong units.

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Last updated: 31 October 2026