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UPSC Zoology Optional Syllabus 2025, Preparation Strategy, Booklist, PYQs

UPSC Zoology Optional Syllabus 2025 covers a comprehensive range of topics related to animal biology. Read on for UPSC Zoology Optional Syllabus 2025, preparation tips, PYQs, booklist, and more.
authorImageAnil Solonki18 Aug, 2025
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UPSC Zoology Syllabus

UPSC Zoology Optional Syllabus 2025: The Union Public Service Commission (UPSC) promotes diversity in subject choices by offering 48 optional subjects for the Civil Services Mains Examination. Among these are science-based subjects designed for candidates with relevant academic backgrounds.

Zoology is one such optional subject under the natural sciences, widely chosen by aspirants with a background in life sciences or related fields. Find a detailed overview of the Zoology optional syllabus, recommended books, previous years’ question papers, and other essential resources here.

UPSC Mains Zoology Optional 2025

Zoology is the scientific study of animals and a branch of biology. It is a popular optional subject among candidates with a background in medicine or life sciences. While others can also choose it, the syllabus is somewhat technical. The Zoology optional has two papers, each worth 250 marks.

Both papers are divided into two sections with four questions each. Questions 1 and 5 are compulsory, and candidates can choose any three from the remaining. Here's the exam pattern for Zoology optional in UPSC:

UPSC Zoology Optional Exam Pattern 2025
Number of Papers 2 (Paper I and Paper II)
Marks per Paper 250 marks
Total Marks 500 marks
Paper Structure Each paper has 2 sections: Section A and Section B
Number of Questions per Paper 8 questions total (4 in each section)
Compulsory Questions Question 1 (Section A) and Question 5 (Section B) in both papers
Choice of Questions Attempt 3 more questions from the remaining 6 (total 5 questions per paper)
Time Allowed  3 Hours for each Paper

UPSC Zoology Optional Syllabus 2025

The Zoology optional syllabus is provided in detail in the official notification of the UPSC. The syllabus of Zoology Optional is divided accordingly between Papers 1 and 2. While the syllabus is huge, it can be covered by a systematic approach. 

UPSC Zoology Optional Syllabus Paper 1

The paper 1 syllabus of Zoology optional consists of topics like Chordata, Ecology, Wildlife of India, Ethology, etc. The Zoology optional syllabus for Paper 1 is provided in the table below for candidates:
Topic Subtopic
1. Non-chordata and Chordata
  1. Classification and relationship of various phyla up to subclasses: Acoelomate and Coelomate, Protostomes and Deuterostomes, Bilateria and Radiata; Status of Protista, Parazoa, Onychophora and Hemichordata; Symmetry.
  2. Protozoa: Locomotion, nutrition, reproduction, sex; General features and life history of Paramaecium, Monocystis. Plasmodium and Leishmania.
  3. Porifera: Skeleton, canal system, and reproduction.
  4. Cnidaria: Polymorphism, defensive structures, and their mechanism; coral reefs and their formation; metagenesis; general features and life history of Obelia and Aurelia.
  5. Platyhelminthes: Parasitic adaptation; general features and life history of Fasciola and Taenia and their pathogenic symptoms.
  6. Nemathelminthes: General features, life history, parasitic adaptation of Ascaris andWuchereria.
  7. Annelida : Coelom and metamerism; modes of life in polychaetes; general features and life history of Nereis, earthworm, and leach.
  8. Arthropoda: Larval forms and parasitism in Crustacea; vision and respiration in arthropods (Prawn, cockroach, and scorpion); modification of mouth, parts in insects (cockroach, mosquito, housefly, honey bee, and butterfly), metapmor phosis in insect and its hormonal regulation, the social behaviour of Apis and termites.
  9. Molluscs: Feeding, respiration, locomotion, general features, and life history of Lamellidens, Pila, and Sepia. Torsion and detorsion in gastropods.
  10. Echinodermata: Feeding, respiration, locomotion, larval forms, general features, and life history of Asterias.
  11. Protochordata: Origin of chordates; general features and life history of Branchiostoma and Herdmania.
  12. Pisces: Respiration, locomotion, and migration.
  13. Amphibia: Origin of tetrapods, parental care, paedomorphosis.
  14. Reptilia; Origin of reptiles, skull types, status of Sphenodon and crocodiles.
  15. Aves: Origin of birds, flight adaptation, migration.
  16. Mammalia: Origin of mammals, dentition, general features of egg-laying mammals, pouched mammals, aquatic mammals and primates, endocrine glands (pituitary, thyroid, parathyroid, adrenal, pancreas, gonads) and their interrelationships.
  17. Comparative functional anatomy of various systems of vertebrates . (integument and its derivatives, endoskeleton, locomotory organs, digestive system, respiratory system, circulatory system including heart and aortic arches, urinogenital system, brain, and sense organs (eye and ear).
2. Ecology
  1. Biosphere: concept of biosphere; biomes, Biogeochemical cycles, Human induced changes in atmosphere including greenhouse effect, ecological succession, biomes and ecotones, community ecology.
  2. Concept of ecosystem ; structure and function of ecosystem, types of ecosystem, ecological succession, ecological adaptation.
  3. Population ; characteristics, population dynamics, population stabilization.
  4. Biodiversity and diversity conservation of natural resources.
  5. Wildlife of India.
  6. Remote sensing for sustainable development.
  7. Environmental biodegradation; pollution and its impact on biosphere and its prevention.
3. Ethology
  1. Behaviour: Sensory filtering, responsiveness, sign stimuli, learning, and memory, instinct, habituation, conditioning, imprinting.
  2. Role of hormones in drive; role of pheromones in alarm spreading; crypsis, predator detection, predator tactics, social hierarchies in primates, social organization in insects;
  3. Orientation, navigation, homing; biological rhythms: biological clock, tidal, seasonal, and circadian rhythms.
  4. Methods of studying animal behaviour including sexual conflict, selfishness, kinship, and altruism.
4. Economic Zoology
    1. Apiculture, sericulture, lac culture, carp culture, pearl culture, prawn culture, vermiculture.
    2. Major infectious and communicable diseases (malaria, filaria, tuberculosis, cholera, and AIDS) their vectors, pathogens, and prevention.
    3. Cattle and livestock diseases , their pathogen (helminths), and vectors (ticks, mites, Tabanus, Stomoxys).
    4. Pests of sugar cane (Pyrilla perpusiella), oil seed (Achaeajanata) and rice (Sitophilus oryzae).
  • Transgenic animals.
  1. Medical biotechnology , human genetic disease and genetic counselling, gene therapy.
  2. Forensic biotechnology.
5. Biostatistics
  1. Designing of experiments; null hypothesis; correlation, regression, distribution and measure of central tendency, chi square, student-test, F-test (one-way & two-way F-test).
6. Instrumentation methods
  1. Spectrophotometer, phase contrast and fluorescence microscopy , radioactive tracer, ultra centrifuge, gel. Electrophoresis, PCR, ELISA, FISH and chromosome painting.
  2. Electron microscopy (TEM, SEM).

UPSC Zoology Optional Syllabus Paper 2

Paper 2 of the UPSC Zoology Optional subject is concentrated primarily on Cell Biology, Genetics, Evolution, Biochemistry, and Developmental Biology. The detailed syllabus for Zoology Optional Paper 2 is as follows:
Topics Subtopics
1. Cell Biology
  1. Structure and function of cell and its organelles (nucleus, plasma membrane, mitochondria, Golgi bodies, endoplasmic reticulum, ribosomes and lysosomes), cell division (mitosis and meiosis), mitotic spindle and mitotic apparatus, chromosome movement chromosome type ploytene and lambrush, organization of chromatin, heterochromatin, Cell cycle regulation.
  2. Nucleic acid topology , DNA motif, DNA replication, transcription, RNA processing, translation, protein foldings and transport.
2. Genetics
  1. Modern concept of gene , split gene, genetic regulation, genetic, code.
  2. Sex chromosomes and their evolution, sex determination in Drosophila and human.
  3. Mendel’s laws of inheritance, recombination, linkage, multiple alleles, genetics of blood groups, pedigree analysis, hereditary diseases in human.
  4. Mutations and mutagenesis.
  5. Recombinant DNA technology, plasmid, cosmid, artificial chromosomes as vectors, transgenics, DNA cloning and whole animal cloning (principles and methods).
  6. Gene regulation and expression in prokaryotes and eukaryotes.
  7. Signal molecules, cell death, defects in signaling pathway and consequences.
  8. RFLP, RAPD and AFLF and application of RFLP in DNA finger-printing, ribozyme technologies, human genome project, genomics and protomics.
3. Evolution
    1. Theories of origin of life .
    2. Theories of evolution; Natural selection, role of mutation in evolution, evolutionary patterns, molecular drive, mimicry, variation, isolation and speciation.
    3. Evolution of horse, elephant and human using fossil data.
  • Hardy-Weinberg Law.
  1. Continental drift and distribution of animals.
4. Systematics
  • Zoological nomenclature, international code, cladistics, molecular taxonomy and biodiversity.
5. Biochemistry
  1. Structure and role of carbohydrates, fats , fatty acids, cholesterol, proteins and amino-acids, nucleic acids. Bioenergetics.
  2. Glycolysis and Krebs cycle, oxidation and reduction, oxidative phosphorylation; energy conservation and release, ATP, cycl cyclic AMP-its structure and role.
  3. Hormone classification (steroid and peptide hormones), biosynthesis and functions.
  4. Enzymes: types and mechanisms of action.
  5. Vitamins and co-enzymes.
  6. Immunoglobulin and immunity.
6. Physiology (with special reference to mammals) :
  1. Composition and constituents of blood; blood groups and Rh factor in human; factors and mechanism of coagulation; iron metabolism, acid-base balance, thermo regulation, anticoagulants.
  2. Haemoglobin: Composition, types and role in transport of oxygen and carbon dioxide.
  3. Digestion and absorption: Role of salivary glands, liver, pancreas and intestinal glands.
  4. Excretion: nephron and regulation of urine formation; osmo-regulation and excretory product.
  5. Muscles: Types, mechanism of contraction of skeletal muscles, effects of exercise on muscles.
  6. Neuron: nerve impulse—its conduction and synaptic transmission; neurotransmitters.
  7. Vision, hearing and olfaction in human.
  8. Physiology of reproduction puberty and menopause in human.
7. Developmental Biology
  1. Gametogenesis; spermatogenesis, composition of semen, in vitro and in vivo capacitation of mammalian sperm, Oogenesis, totipotency; fertilization, morphogenesis and morphogen; blastogeneis, establishment of body axes formation, fate map, gestulation in frog and chick; genes in development in chick homeotic genes, development of eye and heart, placenta in mammals.
  2. Cell lineage , cell to cell interaction, Genetic and induced teratogenesis, role of thyroxine in control of metamorphosisin amphibia, paedogenesis and neoteny, cell death, aging.
  3. Developmental genes in human, in vitro fertilization; and embryo transfer; cloning.
  4. Stem cells : Sources, types and their use in human welfare.
  5. Biogenetic law.

Pros and Cons of Taking Zoology Optional in UPSC

The Zoology optional is one of the science subjects; hence, prior knowledge of concepts is necessary. Candidates are required to give some extra effort in this subject, but they can score good marks as a reward in Zoology Optional. The pros and cons of Zoology as an optional subject are discussed here for aspirants:

Zoology Optional Advantages

The benefits of selecting Zoology as an optional subject are as follows:
  1. Precise concepts and defined subjects make it easier to cover the syllabus.
  2. Scope of good marks due to less subjectivity in answers, unlike in the humanities.
  3. Scope of presentation, such as making a well-labelled diagram in the answer to earn extra points.
  4. Helpful in the environment section of the UPSC prelims syllabus and GS 3 paper.
  5. Straightforward questions and candidates can achieve good scores after hard work.
  6. It is useful for candidates who are simultaneously appearing in the UPSC Indian Forest Services exam.

Zoology Optional Disadvantages

The reasons that might make Zoology a less attractive optional subject are:
  1. The Zoology syllabus is not just vast but also requires in-depth preparation.
  2. The technical nature of the subject makes it challenging for candidates from other backgrounds to opt for it.
  3. The overlap is minimal and limited to ecology, environment, and some parts of the agriculture section of the UPSC syllabus.
  4. It requires significant preparation time from aspirants, making it difficult to balance other subjects.
  5. A lot of revision is required to learn technical terms, definitions, and theories in zoology.
  6. There is almost zero scope for writing anything from our own understanding in non-familiar questions like humanities optional subjects.

UPSC Zoology Optional PYQs

The previous year's question papers on Zoology optional are the best way to decide on choosing this subject and start preparation. Candidates can go through the most recent Zoology optional previous year question papers to understand the nature of the questions asked. Here is a direct link to access the previous year's Zoology optional:
Zoology Optional Previous Year Question Papers
Year Paper Download Link
2024
 		  Zoology Paper I  Click Here
Zoology Paper II Click Here
 2023
 		  Zoology Paper I   Click Here
Zoology Paper II Click Here
2022 Zoology Paper I Click Here
Zoology Paper II Click Here
2021 Zoology Paper I Click Here
Zoology Paper II Click Here

How to Prepare Zoology Optional for UPSC? 

Once you have made up your mind, start preparing for the Zoology Optional by making a foolproof strategy. Try making a short-term and long-term plan, including the total number of hours you are dedicating to studying this optional during preparation. Here are some tips to prepare Zoology Optional for UPSC:
  • Beginning: Go through the syllabus and previous year’s Zoology question papers. This will help you get familiar with the subject.
  • Collect Material: The next step is to collect quality books and study materials such as Zoology optional notes of toppers. For basic understanding, candidates can start with books like Modern Zoology by Ramesh Gupta.
  • Fundamentals: Develop a good understanding of basic concepts, such as the basics of cell biology, and then proceed to the application part. Try studying by interconnecting the concepts.
  • Learn to Draw: Since neat and labelled diagrams are highly important in this subject, students should practice them from the very beginning.
  • Paper I: Cover all theories and concepts from standard books. Focus scoring topics such as bio instrumentation and biostatistics in economic zoology.
  • Paper II: Take a subject-based approach, such as writing human welfare applications in genetics and making biochemical pathways in biochemistry. Make a list of predictable topics, such as Hardy-Weinberg Law, which comes in 15-marker questions.
  • Test Series: Join a good coaching or Zoology optional test series for mains to practice well before the exam.
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UPSC Zoology Syllabus

Zoology Optional Booklist 

The candidates must use experts' recommended books for UPSC Zoology optional. Since books are a core part of study material for zoology, optional candidates should ensure that they have a standard booklist with them before starting preparation. Here is the list of paper-wise Zoology optional books:
Paper 1 Books
Book Name Author
Invertebrate Zoology P S Verma and E L Jordan
Chordate Zoology P S Verma and E L Jordan
Vertebrates Comparative Anatomy, Function, Evolution K. Kardong
Ecology and Environment Dr. P.D. Sharma
Animal Behaviour (Ethology) Agarwal V.K.
Applied And Economic Zoology Dr. V.B. Upadhyay and Dr. G.S. Shukla
Fundamentals of Biostatistics Veer Bala Rastogi
Bioinstrumentation Bhawana Pandey and M.H. Fulekar
Paper 2 Books
Book Name Author
Karp's Cell Biology Karp Gerald
Concepts of Genetics Klug and Cummings
Molecular Cell Biology David Baltimore and Harvey Lodish
Organic Evolution Veer Bala Rastogi
Biochemistry U. Satyanarayana
Lehninger Principles of Biochemistry David L. Nelson, Michael M. Cox
Developmental Biology Scott F. Gilbert
Tortora's Principles of Anatomy and Physiology Bryan H. Derrickson, Gerard J. Tortora

Candidate can check UPSC Mains Syllabus 2025 Here!

UPSC Zoology Optional Toppers 

As of the latest information, the record for the highest marks in Zoology Optional is held by Pooja Yadav in 2018. She scored 325 marks in Zoology. Her score is evidence that candidates can score well in this subject with good performance. Here is a list of Zoology optional toppers:
Zoology Optional Toppers  
Name Rank Marks Year
Anup Das AIR 38 303 2022
Pusapati Sahitya AIR 24 278 2021
Prasad Shinde AIR 287 274 2019
Kajal Jawla AIR 28 303 2018
Pooja Yadav AIR 174 325 2018
Have you decided to take up this optional subject? Balance your preparation with the upsc online course at Physics Wallah!

UPSC Zoology Optional Syllabus FAQs

Is Zoology optional scoring in UPSC?

Yes, toppers like Pooja Yadav have scored as high as 325 marks in this optional subject.

How many students take the zoology optional in the UPSC exam?

Very few students take the zoology optional in the UPSC exam. In 2017, only 55 candidates opted for this subject.

What is the benefit of taking Zoology as an optional?

The scope of getting marks is good, and candidates can prepare for the UPSC IFoS exam with this subject.

What is the success rate of the zoology optional in UPSC?

The success rate of zoology optional varies from 1.8% to 12.7% based on the number of candidates opting for this subject.

Can medical science students take Zoology optional?

Anyone with a passion and prior knowledge can take Zoology optional.
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