Zoology Optional Syllabus

Here is the official UPSC Zoology Optional syllabus for Paper I and Paper II, arranged paper by paper and unit by unit. Under each unit we give the official text first, then break it into numbered topics, so you can track your preparation and match every previous year question to its topic.

Source. UPSC Civil Services Examination 2026 notification (Examination Notice No. 05/2026-CSE, dated 04.02.2026, pp. 152–155), upsc.gov.in. The Zoology syllabus has been unchanged in recent years.

Scheme. Two papers of 250 marks each (total 500), 3 hours each. Each paper has two sections (A and B) of four questions each; Questions 1 and 5 are compulsory, and three more are attempted with at least one from each section. The syllabus itself is not divided into sections. Paper I has six units (Non-chordata and Chordata; Ecology; Ethology; Economic Zoology; Biostatistics; Instrumentation methods); Paper II has seven (Cell Biology; Genetics; Evolution; Systematics; Biochemistry; Physiology; Developmental Biology). Most units are divided into lettered sub-heads (a), (b) ….

Syllabus at a glance

Paper	Unit	Topics
Paper I	1. Non-chordata and Chordata	17
Paper I	2. Ecology	7
Paper I	3. Ethology	4
Paper I	4. Economic Zoology	7
Paper I	5. Biostatistics	2
Paper I	6. Instrumentation methods	3
Paper II	1. Cell Biology	5
Paper II	2. Genetics	8
Paper II	3. Evolution	5
Paper II	4. Systematics	1
Paper II	5. Biochemistry	6
Paper II	6. Physiology (with special reference to mammals)	8
Paper II	7. Developmental Biology	6

Paper I

1. Non-chordata and Chordata

1.1 Classification and relationships of phyla

• Acoelomate and coelomate
• Protostomes and deuterostomes
• Bilateria and Radiata
• Status of Protista, Parazoa, Onychophora and Hemichordata
• Symmetry

1.2 Protozoa

• Locomotion, nutrition, reproduction, sex
• Paramaecium, Monocystis, Plasmodium, Leishmania

1.3 Porifera

• Skeleton
• Canal system
• Reproduction

1.4 Cnidaria

• Polymorphism
• Defensive structures
• Coral reefs
• Metagenesis
• Obelia and Aurelia

1.5 Platyhelminthes

• Parasitic adaptation
• Fasciola and Taenia, pathogenic symptoms

1.6 Nemathelminthes

• Ascaris and Wuchereria
• Parasitic adaptation

1.7 Annelida

• Coelom and metamerism
• Modes of life in polychaetes
• Nereis, earthworm and leech

1.8 Arthropoda

• Larval forms and parasitism in Crustacea
• Vision and respiration in arthropods
• Mouth parts of insects
• Metamorphosis and its hormonal regulation
• Social behaviour of Apis and termites

1.9 Mollusca

• Feeding, respiration, locomotion
• Lamellidens, Pila and Sepia
• Torsion and detorsion

1.10 Echinodermata

• Feeding, respiration, locomotion
• Larval forms
• Asterias

1.11 Protochordata

• Origin of chordates
• Branchiostoma and Herdmania

1.12 Pisces

• Respiration
• Locomotion
• Migration

1.13 Amphibia

• Origin of tetrapods
• Parental care
• Paedomorphosis

1.14 Reptilia

• Origin of reptiles
• Skull types
• Status of Sphenodon and crocodiles

1.15 Aves

• Origin of birds
• Flight adaptation
• Migration

1.16 Mammalia

• Origin of mammals
• Dentition
• Egg-laying, pouched and aquatic mammals, primates
• Endocrine glands and their interrelationships

1.17 Comparative anatomy of vertebrates

• Integument and derivatives
• Endoskeleton
• Locomotory organs
• Digestive and respiratory systems
• Heart and aortic arches
• Urinogenital system
• Brain and sense organs

2. Ecology

2.1 Biosphere and community ecology

• Biomes
• Biogeochemical cycles
• Greenhouse effect
• Ecological succession
• Ecotones
• Community ecology

2.2 Ecosystem

• Structure and function
• Types of ecosystem
• Ecological adaptation

2.3 Population ecology

• Characteristics
• Population dynamics
• Population stabilization

2.4 Biodiversity and conservation

• Biodiversity
• Conservation of natural resources

2.5 Wildlife of India

2.6 Remote sensing for sustainable development

2.7 Pollution and biodegradation

• Environmental biodegradation
• Pollution and its impact
• Prevention

3. Ethology

3.1 Behaviour and learning

• Sensory filtering, responsiveness, sign stimuli
• Learning and memory
• Instinct, habituation, conditioning, imprinting

3.2 Hormones, pheromones and social behaviour

• Hormones in drive
• Pheromones
• Crypsis, predator detection and tactics
• Social hierarchies in primates
• Social organization in insects

3.3 Orientation and biological rhythms

• Orientation, navigation, homing
• Biological clock
• Tidal, seasonal and circadian rhythms

3.4 Methods and evolution of behaviour

• Methods of studying behaviour
• Sexual conflict
• Selfishness, kinship and altruism

4. Economic Zoology

4.1 Animal culture

• Apiculture
• Sericulture
• Lac culture
• Carp, pearl and prawn culture
• Vermiculture

4.2 Human infectious diseases

• Malaria, filaria, tuberculosis, cholera and AIDS
• Vectors, pathogens and prevention

4.3 Livestock diseases

• Helminth pathogens
• Vectors (ticks, mites, Tabanus, Stomoxys)

4.4 Crop pests

• Pyrilla perpusilla
• Achaea janata
• Sitophilus oryzae

4.5 Transgenic animals

4.6 Medical biotechnology

• Human genetic disease and genetic counselling
• Gene therapy

4.7 Forensic biotechnology

5. Biostatistics

5.1 Experimental design and hypothesis testing

• Designing of experiments
• Null hypothesis
• Chi square, Student’s t-test, F-test

5.2 Descriptive statistics, correlation and regression

• Measures of central tendency
• Distribution
• Correlation
• Regression

6. Instrumentation methods

6.1 Spectrophotometry, microscopy and tracers

• Spectrophotometer
• Phase contrast and fluorescence microscopy
• Radioactive tracer
• Ultracentrifuge

6.2 Molecular techniques

• Gel electrophoresis
• PCR
• ELISA
• FISH and chromosome painting

6.3 Electron microscopy

• TEM
• SEM

Paper II

1. Cell Biology

1.1 Cell organelles

• Nucleus, plasma membrane, mitochondria, Golgi bodies, ER, ribosomes, lysosomes

1.2 Cell division and cell cycle

• Mitosis and meiosis
• Mitotic spindle and apparatus
• Chromosome movement
• Cell cycle regulation

1.3 Chromosomes and chromatin

• Polytene and lampbrush chromosomes
• Organization of chromatin
• Heterochromatin

1.4 Nucleic acids and DNA replication

• Nucleic acid topology
• DNA motif
• DNA replication

1.5 Transcription and translation

• Transcription
• RNA processing
• Translation
• Protein folding and transport

2. Genetics

2.1 Concept of gene and genetic code

• Modern concept of gene
• Split gene
• Genetic code

2.2 Sex chromosomes and sex determination

• Evolution of sex chromosomes
• Sex determination in Drosophila and human

2.3 Mendelian genetics and linkage

• Mendel’s laws
• Recombination and linkage
• Multiple alleles
• Blood groups
• Pedigree analysis
• Hereditary diseases

2.4 Mutations and mutagenesis

2.5 Recombinant DNA technology

• Plasmid, cosmid, artificial chromosomes
• Transgenics
• DNA cloning
• Whole animal cloning

2.6 Gene regulation and expression

• Prokaryotes
• Eukaryotes

2.7 Signal molecules and cell death

• Signalling pathways and their defects
• Cell death

2.8 Molecular markers and genomics

• RFLP, RAPD, AFLP
• DNA fingerprinting
• Ribozyme technologies
• Human genome project
• Genomics and proteomics

3. Evolution

3.1 Origin of life

3.2 Theories of evolution and speciation

• Natural selection
• Mutation in evolution
• Evolutionary patterns
• Molecular drive
• Mimicry
• Variation, isolation and speciation

3.3 Evolution of horse, elephant and human

3.4 Hardy-Weinberg law

3.5 Continental drift and animal distribution

4. Systematics

4.1 Systematics

• Zoological nomenclature and international code
• Cladistics
• Molecular taxonomy
• Biodiversity

5. Biochemistry

5.1 Biomolecules and bioenergetics

• Carbohydrates, fats, fatty acids, cholesterol
• Proteins and amino acids
• Nucleic acids
• Bioenergetics

5.2 Metabolism and ATP

• Glycolysis and Krebs cycle
• Oxidative phosphorylation
• ATP
• Cyclic AMP

5.3 Hormones

• Classification
• Steroid and peptide hormones
• Biosynthesis and functions

5.4 Enzymes

• Types
• Mechanisms of action

5.5 Vitamins and co-enzymes

5.6 Immunoglobulins and immunity

6. Physiology (with special reference to mammals)

6.1 Blood

• Composition
• Blood groups and Rh factor
• Coagulation and anticoagulants
• Iron metabolism
• Acid-base balance
• Thermoregulation

6.2 Haemoglobin and respiratory gases

• Composition and types
• Transport of oxygen and carbon dioxide

6.3 Digestion and absorption

• Salivary glands
• Liver
• Pancreas
• Intestinal glands

6.4 Excretion and osmoregulation

• Nephron and urine formation
• Osmoregulation
• Excretory products

6.5 Muscles

• Types
• Mechanism of contraction
• Effects of exercise

6.6 Neuron and synapse

• Nerve impulse
• Synaptic transmission
• Neurotransmitters

6.7 Vision, hearing and olfaction

6.8 Reproductive physiology

• Puberty and menopause in human

7. Developmental Biology

7.1 Gametogenesis and fertilization

• Spermatogenesis, semen, capacitation
• Oogenesis
• Totipotency
• Fertilization

7.2 Early development and morphogenesis

• Morphogenesis and morphogen
• Blastogenesis
• Body axes
• Fate map
• Gastrulation in frog and chick

7.3 Developmental genes and organogenesis

• Genes in chick development
• Homeotic genes
• Development of eye and heart
• Placenta in mammals
• Developmental genes in human

7.4 Cell interactions, teratogenesis and metamorphosis

• Cell lineage
• Cell-to-cell interaction
• Teratogenesis
• Thyroxine and amphibian metamorphosis
• Paedogenesis and neoteny
• Cell death and aging

7.5 IVF, cloning and stem cells

• In vitro fertilization and embryo transfer
• Cloning
• Stem cells: sources, types and uses

7.6 Biogenetic law

Total: 79 numbered topics across 13 units.

Last updated: 31 October 2026