IAS (UPSC CSE) Mains 2021 Zoology Syllabus

Updated On -

Mar 22, 2021

The IAS (UPSC CSE) is conducted in three stages- Prelims, Mains and Interview. The candidates should choose one optional subject for the IAS (UPSC CSE) exam. Optional subject in the mains exam is playing a major role in uplifting the ranking of the aspirants.

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Zoology is one of the chosen optional subjects out of the list of 48 optional subjects. IAS (UPSC CSE) MAINS Exam 2021 for Zoology will cover all the necessary topics from two parts. Part 1 will consist of Non-chordata and Chordata, Ecology, Ethology, Economic Zoology & Biostatistics and part 2 will consist of Cell Biology, Genetics, Evolution, Systematics, Biochemistry & Physiology. A candidate while preparing must cover all these topics before appearing for the exam.

IAS (UPSC CSE) notification 2021 was scheduled to be released on 10 February 2021, however, due to the pending of Public Interest Litigation (PIL) in Supreme Court, the detailed notifications of IAS (UPSC CSE) will be published shortly. To know more, click here.

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Zoology Syllabus for IAS

Each paper of Zoology carries 250 marks, with a total of 500 marks. If the aspirants (who have completed their graduation in Zoology) choose Zoology as the optional paper for the IAS (UPSC CSE) Mains exam 2021, the probability of their selection will be increased due to the low competition and the specialised nature of the syllabus.


1.Non-chordata and Chordata:

  • 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.
  • Protozoa: Locomotion, nutrition, reproduction, sex; General features and life history of Paramaecium, Monocystis, Plasmodium and Leishmania.
  • Porifera: Skeleton, canal system and reproduction.
  • Cnidaria: Polymorphism, defensive structures and their mechanism; coral reefs and their formation; metagenesis; general features and life history of Obelia and Aurelia.
  • Platyhelminthes: Parasitic adaptation; general features and life history of Fasciola and Taenia and their pathogenic symptoms.
  • Nemathelminthes: General features, life history, parasitic adaptation of Ascaris and Wuchereria.
  • Annelida: Coelom and metamerism; modes of life in polychaetes; general features and life history of Nereis, earthworm and leech.
  • 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); metamorphosis in insect and its hormonal regulation, social behaviour of Apis and termites.
  • Mollusca: Feeding, respiration, locomotion, general features and life history of Lamellidens, Pila and Sepia, torsion and detorsion in gastropods.
  • Echinodermata: Feeding, respiration, locomotion, larval forms, general features and life history of Asterias.
  • Protochordata: Origin of chordates; general features and life history of Branchiostoma and Herdmania.
  • Pisces: Respiration, locomotion and migration.
  • Amphibia: Origin of tetrapods, parental care, paedomorphosis.
  • Reptilia; Origin of reptiles, skull types, status of Sphenodon and crocodiles.
  • Aves: Origin of birds, flight adaptation, migration.
  • 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.
  • 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, urino-genital system, brain and sense organs (eye and ear).

2. Ecology:

  • Biosphere: Concept of biosphere; biomes, Biogeochemical cycles, Human induced changes in atmosphere including green house effect, ecological succession, biomes and ecotones, community ecology.
  • Concept of ecosystem; structure and function of ecosystem, types of ecosystem, ecological succession, ecological adaptation.
  • Population; characteristics, population dynamics, population stabilization.(d) Biodiversity and diversity conservation of natural resources.
  • Wildlife of India.
  • Remote sensing for sustainable development.
  • Environmental biodegradation, pollution and its impact on biosphere and its prevention.

3. Ethology:

  • Behaviour: Sensory filtering, responsiveness, sign stimuli, learning and memory, instinct, habituation, conditioning, imprinting.
  • Role of hormones in drive; role of pheromones in alarm spreading; crypsis, predator detection, predator tactics, social hierarchies in primates, social organization in insects.
  • Orientation, navigation, homing, biological rhythms, biological clock, tidal, seasonal and circadian rhythms.
  • Methods of studying animal behaviour including sexual conflict, selfishness, kinship and altruism.

4. Economic Zoology:

  • Apiculture, sericulture, lac culture, carp culture, pearl culture, prawn culture, vermiculture.
  • Major infectious and communicable diseases (malaria, filaria, tuberculosis, cholera and AIDS) their vectors, pathogens and prevention.
  • Cattle and livestock diseases, their pathogen (helminthes) and vectors (ticks, mites, Tabanus, Stomoxys).
  • Pests of sugar cane (Pyrilla perpusiella) oil seed (Achaea janata) and rice (Sitophilus oryzae).
  • Transgenic animals.
  • Medical biotechnology, human genetic disease and genetic counselling, gene therapy.
  • Forensic biotechnology.

5. Biostatistics:

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:

  • Spectrophotometer, phase contrast and fluorescence microscopy, radioactive tracer, ultra centrifuge, gel electrophoresis, PCR, ELISA, FISH and chromosome painting.
  • Electron microscopy (TEM, SEM).

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1. Cell Biology:

  • 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 movements, chromosome type polytene and lambrush, organization of chromatin, heterochromatin, Cell cycle regulation.
  • Nucleic acid topology, DNA motif, DNA replication, transcription, RNA processing, translation, protein foldings and transport.

2. Genetics:

  • Modern concept of gene, split gene, genetic regulation, genetic code.
  • Sex chromosomes and their evolution, sex determination in Drosophila and man.
  • Mendel's laws of inheritance, recombination, linkage, multiple alleles, genetics of blood groups, pedigree analysis, hereditary diseases in man.
  • Mutations and mutagenesis.
  • Recombinant DNA technology; plasmid, cosmid, artificial chromosomes as vectors, transgenic, DNA cloning and whole animal cloning (principles and methods).
  • Gene regulation and expression in prokaryotes and eukaryotes.
  • Signal molecules, cell death, defects in signaling pathway and consequences.
  • RFLP, RAPD and AFLP and application of RFLP in DNA fingerprinting, ribozyme technologies, human genome project, genomics and proteomics.

3. Evolution:

  • Theories of origin of life.
  • Theories of evolution; Natural selection, role of mutations in evolution, evolutionary patterns, molecular drive, mimicry, variation, isolation and speciation.
  • Evolution of horse, elephant and man using fossil data.
  • Hardy-Weinberg Law.
  • Continental drift and distribution of animals.

4. Systematics: 

Zoological nomenclature, international code, cladistics, molecular taxonomy and biodiversity.

5. Biochemistry:

  • Structure and role of carbohydrates, fats, fatty acids and cholesterol, proteins and amino-acids, nucleic acids. Bioenergetics.
  • Glycolysis and Kreb cycle, oxidation and reduction, oxidative phosphorylation, energy conservation and release, ATP cycle, cyclic AMP – its structure and role.
  • Hormone classification (steroid and peptide hormones), biosynthesis and functions.
  • Enzymes: types and mechanisms of action.
  • Vitamins and co-enzymes
  • Immunoglobulin and immunity.

6. Physiology (with special reference to mammals):

  • Composition and constituents of blood; blood groups and Rh factor in man, factors and mechanism of coagulation, iron metabolism, acid-base balance, thermo-regulation, anticoagulants.
  • Haemoglobin: Composition, types and role in transport of oxygen and carbon dioxide.
  • Digestion and absorption: Role of salivary glands, liver, pancreas and intestinal glands.
  • Excretion: nephron and regulation of urine formation; osmo-regulation and excretory product
  • Muscles: Types, mechanism of contraction of skeletal muscles, effects of exercise on muscles.
  • Neuron: nerve impulse – its conduction and synaptic transmission, neurotransmitters.
  • Vision, hearing and olfaction in man.
  • Physiology of reproduction, puberty and menopause in human. 

7. Developmental Biology:

  • Gametogenesis; spermatogenesis, composition of semen, in vitro and in vivo capacitation of mammalian sperm, Oogenesis, totipotency; fertilization, morphogenesis and morphogen, blastogenesis, 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.
  • Cell lineage, cell-to cell interaction, Genetic and induced teratogenesis, role of thyroxine in control of metamorphosis in amphibia, paedogenesis and neoteny, cell death, aging.
  • Developmental genes in man, in vitro fertilization and embryo transfer, cloning.
  • Stem cells: Sources, types and their use in human welfare.
  • Biogenetic law.
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*The article might have information for the previous academic years, please refer the official website of the exam.