NEET Biology Syllabus 2026: Complete Chapter-Wise Topics

Biology is the most important and highest-scoring subject in the NEET UG examination, contributing 90 questions and 360 marks to the total score of 720. This represents exactly half of the total NEET marks, making Biology preparation the single most consequential factor in determining a student's final NEET rank. The NEET 2026 Biology syllabus is drawn from the Class 11 and Class 12 NCERT Biology textbooks as prescribed by the National Medical Commission (NMC).

The Biology section is divided into two equal halves within the NEET question paper: Botany (Plant Sciences) and Zoology (Animal Sciences), each contributing 45 questions and 180 marks. This division reflects the two major domains of biological study and ensures that students develop comprehensive knowledge of both plant and animal systems. The syllabus spans 38 chapters across Class 11 and Class 12, covering every major branch of biology from cell and molecular biology to ecology and environmental science.

Unlike Physics and Chemistry, where numerical calculations and reaction mechanisms form the core of preparation, Biology in NEET is primarily a conceptual and application-based subject. The NCERT textbooks contain the complete syllabus for approximately 95 percent of NEET Biology questions, making thorough NCERT reading and diagram-based study the most effective preparation strategy. This page provides the complete NEET 2026 Biology syllabus with all 38 chapters broken down into key topics, chapter-wise weightage analysis, high-priority areas, important diagrams, and a comprehensive FAQ section.

NEET Biology 2026: Quick Facts

Biology in NEET: Botany vs Zoology Breakdown

The NEET Biology section is administered as two separate sub-sections within the question paper: Botany and Zoology. Each sub-section has its own Section A (35 questions) and Section B (15 questions, attempt any 10). Understanding which chapters fall under Botany and which under Zoology is essential for targeted preparation.

NEET Biology Class 11 Syllabus: All 22 Chapters and Topics

Class 11 Biology covers five major units: Diversity in the Living World, Structural Organisation in Plants and Animals, Cell Structure and Function, Plant Physiology, and Human Physiology. Together these 22 chapters provide the foundational knowledge for all Class 12 Biology concepts and contribute approximately 40 to 45 percent of the total NEET Biology questions.

Chapter 1: The Living World

This introductory chapter establishes the vocabulary and framework of biological study. Biodiversity and taxonomic hierarchy questions appear occasionally in NEET.

•        What is living? Defining life; characteristics of living organisms

•        Diversity in the living world; biodiversity: concept and importance

•        Nomenclature: binomial nomenclature (Linnaeus); rules; ICBN and ICZN

•        Taxonomic categories and hierarchy: species, genus, family, order, class, phylum/division, kingdom

•        Taxonomic aids: herbarium, botanical gardens, biological museums, zoological parks

•        Keys: dichotomous keys; monographs, flora, manuals, catalogues

Chapter 2: Biological Classification

Biological Classification is tested regularly with questions on kingdom characteristics, especially Monera, Protista, Fungi, and Viruses.

•        Two kingdom classification; limitations; five kingdom classification (Whittaker)

•        Monera: archaebacteria (halophiles, thermoacidophiles, methanogens) and eubacteria

•        Bacteria: morphology (coccus, bacillus, vibrio, spirillum); Gram-positive vs Gram-negative

•        Mycoplasma; cyanobacteria (blue-green algae); actinomycetes

•        Protista: chrysophytes, dinoflagellates (bioluminescence), euglenoids, slime moulds, protozoans (Amoeba, Paramecium, Plasmodium, Trypanosoma, Leishmania)

•        Fungi: general characteristics; Phycomycetes, Ascomycetes, Basidiomycetes, Deuteromycetes

•        Fungi reproduction; economic importance (Penicillium, Aspergillus, Agaricus, Neurospora)

•        Lichens: mutualistic association of fungus and cyanobacteria/alga; ecological significance

•        Viruses: structure (capsid, nucleic acid); types (DNA virus, RNA virus, bacteriophage); AIDS virus, TMV

•        Viroids and prions (brief introduction)

Chapter 3: Plant Kingdom

Plant Kingdom is a medium-to-high weightage chapter. Life cycles (alternation of generations), distinguishing features of major groups, and economic importance are frequently tested.

•        Algae: Chlorophyceae (Chlamydomonas, Spirogyra, Ulothrix, Cladophora, Chara), Phaeophyceae (Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus), Rhodophyceae (Porphyra, Polysiphonia, Gracilaria)

•        Bryophytes: liverworts (Marchantia) and mosses (Funaria, Sphagnum, Polytrichum); dominant gametophyte; amphibians of plant kingdom

•        Pteridophytes: horsetails (Equisetum), ferns (Dryopteris), Selaginella, Salvinia; first plants with vascular tissue

•        Gymnosperms: Cycas, Pinus, Gnetum; heterosporous; naked seeds; male and female cones

•        Angiosperms: monocots vs dicots; dominant plant group on Earth

•        Alternation of generations: gametophytic vs sporophytic generation; haplontic, diplontic, haplo-diplontic life cycles

•        Plant fossils; evolution of plants: algae to angiosperms

Chapter 4: Animal Kingdom

Animal Kingdom is a high-weightage chapter that contributes two to four questions annually. Classification criteria, phylum characteristics, and examples of organisms are the most tested aspects.

•        Basis of classification: symmetry (radial, bilateral, asymmetrical), coelom (acoelomate, pseudocoelomate, coelomate), segmentation, notochord

•        Phylum Porifera: canal system (ascon, sycon, leucon); choanocytes; Sycon, Spongilla, Euspongia

•        Phylum Coelenterata/Cnidaria: nematocysts; polyp and medusa forms; Physalia, Adamsia, Pennatula, Gorgonia, Meandrina

•        Phylum Ctenophora: comb plates; bioluminescence; Pleurobrachia, Ctenoplana

•        Phylum Platyhelminthes: flatworms; flame cells; Taenia (tapeworm), Fasciola (liver fluke), Planaria

•        Phylum Aschelminthes (Nematoda): pseudocoelomate; Ascaris, Wuchereria, Ancylostoma

•        Phylum Annelida: metameric segmentation; setae; closed circulatory system; Nereis, Pheretima (earthworm), Hirudinaria (leech)

•        Phylum Arthropoda: largest phylum; exoskeleton; jointed appendages; open circulatory system; Locusta, Apis, Bombyx, Laccifer, Anopheles, Limulus

•        Phylum Mollusca: mantle, shell, radula; Pila, Pinctada, Sepia, Loligo, Octopus, Aplysia, Dentalium

•        Phylum Echinodermata: water vascular system; spiny skin; Asterias, Echinus, Antedon, Cucumaria, Ophiura

•        Phylum Hemichordata: notochord-like stomochord; Balanoglossus, Saccoglossus

•        Phylum Chordata: notochord, dorsal hollow nerve cord, pharyngeal gill slits; Urochordata, Cephalochordata, Vertebrata

•        Vertebrate classes: Cyclostomata, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, Mammalia — key features and examples

Chapter 5: Morphology of Flowering Plants

Morphology of Flowering Plants tests knowledge of plant parts, their modifications, and floral formulae. Diagrams of root types, leaf venation, and flower structure are important.

•        Root: regions, types (tap root, fibrous root, adventitious); modifications (storage, support, assimilation, respiratory)

•        Stem: characteristics; modifications (underground: rhizome, corm, bulb, tuber; aerial: tendril, thorn, phylloclade, bulbil)

•        Leaf: structure; simple vs compound (pinnately and palmately); venation (parallel, reticulate); phyllotaxy; modifications (tendrils, spine, scale, bladder, pitcher)

•        Inflorescence: racemose, cymose; types: raceme, spike, catkin, panicle, corymb, umbel, head/capitulum, cyme, thyrsus

•        Flower: parts (calyx, corolla, androecium, gynoecium); symmetry; sexuality; positions of ovary (hypogynous, perigynous, epigynous)

•        Fruit: true fruit vs false fruit; types (drupe, berry, pome, capsule, legume, caryopsis)

•        Seed: structure of dicot (Phaseolus) and monocot (maize) seed

•        Family: Fabaceae (Leguminosae), Solanaceae, Liliaceae — floral formula, floral diagram, economic importance

Chapter 6: Anatomy of Flowering Plants

Anatomy is tested with diagram-based questions on tissue types and root, stem, and leaf sections. Differences between dicot and monocot anatomy are essential.

•        Tissues: meristematic (apical, intercalary, lateral) and permanent tissues (simple: parenchyma, collenchyma, sclerenchyma; complex: xylem, phloem)

•        Tissue systems: epidermal, ground, vascular

•        Anatomy of root (dicot and monocot): endodermis, pericycle, casparian strips

•        Anatomy of stem (dicot and monocot): arrangement of vascular bundles

•        Anatomy of leaf (dicot and monocot): mesophyll, venation

•        Secondary growth: vascular cambium; cork cambium; heartwood and sapwood; annual rings

Chapter 7: Structural Organisation in Animals

This chapter covers animal tissues and the anatomy of earthworm, cockroach, and frog. These three organisms are classic NEET question sources.

•        Animal tissues: epithelial (simple and compound), connective (loose, dense, cartilage, bone, blood), muscular (skeletal, smooth, cardiac), neural

•        Earthworm (Pheretima posthuma): morphology; anatomy (alimentary canal, circulatory system, excretory system, nervous system, reproductive system)

•        Cockroach (Periplaneta americana): morphology; anatomy (digestive, circulatory, respiratory — tracheal system, excretory, nervous, reproductive)

•        Frog (Rana tigrina): morphology; digestive, respiratory (cutaneous, pulmonary, buccal), circulatory (three-chambered heart), excretory, nervous, reproductive systems

Chapter 8: Cell: The Unit of Life

Cell structure is a very high-weightage chapter. Ultra-structure of organelles, differences between prokaryotic and eukaryotic cells, and cell membrane models are heavily tested.

•        Cell theory; prokaryotic vs eukaryotic cells

•        Cell membrane: fluid mosaic model (Singer and Nicolson); phospholipid bilayer; membrane proteins (integral and peripheral)

•        Cell wall: composition in plants (cellulose) and bacteria (peptidoglycan); middle lamella; plasmodesmata

•        Endomembrane system: endoplasmic reticulum (smooth and rough ER), Golgi apparatus (cis and trans face), lysosomes, vacuoles

•        Mitochondria: double membrane; cristae; F0-F1 particles; semi-autonomous; 70S ribosomes; own DNA

•        Plastids: chloroplast (thylakoid, granum, stroma, 70S ribosomes), chromoplasts, leucoplasts (amyloplasts, elaioplasts, aleuroplasts)

•        Ribosomes: 70S (prokaryotes: 50S + 30S) and 80S (eukaryotes: 60S + 40S)

•        Cytoskeleton: microtubules, microfilaments, intermediate filaments

•        Cilia and flagella: 9+2 arrangement of microtubules; axoneme

•        Centrosome and centrioles: role in cell division

•        Nucleus: nuclear envelope, nuclear pores, nucleoplasm, chromatin (euchromatin, heterochromatin), nucleolus

Chapter 9: Biomolecules

Biomolecules overlaps significantly with Chemistry Chapter 14 and is tested with two to four questions. Enzyme kinetics, nucleic acid structure, and protein levels of organisation are the most tested aspects.

•        Chemical composition of living cells: inorganic and organic compounds

•        Carbohydrates: monosaccharides (glucose, fructose, ribose, deoxyribose), disaccharides (maltose, sucrose, lactose), polysaccharides (starch, cellulose, glycogen, chitin, inulin)

•        Lipids: fats, oils, phospholipids, waxes, steroids; structure and function

•        Proteins: amino acids; peptide bond; primary, secondary (alpha helix and beta sheet), tertiary, quaternary structure

•        Nucleic acids: nucleotide structure; DNA double helix (Watson-Crick model); RNA types (mRNA, tRNA, rRNA)

•        Enzymes: chemical nature (protein); properties; enzyme-substrate complex; induced fit and lock-and-key models

•        Enzyme kinetics: Michaelis-Menten equation; km; Vmax; enzyme inhibition (competitive, non-competitive)

•        Factors affecting enzyme activity: temperature, pH, substrate concentration, inhibitors

•        Cofactors: inorganic cofactors; organic cofactors (coenzymes, prosthetic groups); apoenzyme + cofactor = holoenzyme

Chapter 10: Cell Cycle and Cell Division

Cell Cycle and Cell Division is a very high-weightage chapter tested with three to five questions. Stages of mitosis and meiosis, significance of each, and key checkpoints are all tested.

•        Cell cycle: interphase (G1, S, G2) and M phase; duration and significance of each phase

•        DNA replication occurs in S phase; cell grows in G1 and G2

•        Mitosis: prophase, metaphase, anaphase, telophase and cytokinesis; karyokinesis

•        Significance of mitosis: growth, repair, asexual reproduction, regeneration

•        Meiosis: two divisions — Meiosis I (reductive) and Meiosis II (equational)

•        Meiosis I stages: prophase I (leptotene, zygotene, pachytene, diplotene, diakinesis), metaphase I, anaphase I, telophase I

•        Synapsis, bivalent, tetrad, chiasma, crossing over — all occur in prophase I

•        Meiosis II: similar to mitosis; produces four haploid cells

•        Significance of meiosis: maintains chromosome number, genetic variation via crossing over

Chapter 11: Transport in Plants

Transport in Plants tests understanding of passive and active transport, water movement, and translocation in phloem.

•        Diffusion; osmosis; water potential (psi = psi_s + psi_p); turgor pressure; plasmolysis

•        Facilitated diffusion: aquaporins; carrier proteins; channel proteins

•        Active transport: energy-dependent; ion pumps; comparison with passive transport

•        Absorption of water: apoplast and symplast pathways; root pressure; guttation

•        Transpiration: stomatal, lenticular, cuticular; stomatal mechanism; factors affecting

•        Cohesion-tension theory (transpiration pull) for water movement; Dixon and Jolly

•        Translocation of organic solutes: phloem; source-to-sink; pressure flow hypothesis (Munch)

•        Mineral uptake: active and passive; electrochemical gradient; mineral distribution

Chapter 12: Mineral Nutrition

Mineral Nutrition is a medium-weightage chapter. Essential elements, deficiency symptoms, and nitrogen fixation are the most tested topics.

•        Essential mineral elements: criteria for essentiality (17 essential elements)

•        Macronutrients: N, P, K, Ca, Mg, S — roles and deficiency symptoms

•        Micronutrients: Fe, Mn, Zn, Cu, Mo, B, Cl, Ni — roles and deficiency symptoms

•        Beneficial elements vs non-essential elements

•        Deficiency symptoms: necrosis, chlorosis, inhibition of cell division, interveinal chlorosis

•        Toxicity of micronutrients: manganese toxicity

•        Nitrogen metabolism: nitrogen cycle; nitrogen fixation (biological: Rhizobium, Azotobacter, Nostoc, Anabaena; industrial: Haber process)

•        Symbiotic nitrogen fixation: root nodules; leghaemoglobin; nitrogenase enzyme

•        Nitrogen assimilation: nitrate reductase, glutamine synthetase; amination, transamination

Chapter 13: Photosynthesis in Higher Plants

Photosynthesis is one of the highest-weightage Plant Physiology chapters, contributing three to five questions. The light reaction, Calvin cycle, C4 pathway, and photorespiration are tested every year.

•        Site of photosynthesis: chloroplast; chlorophyll types (a, b, c, d); absorption spectra; action spectrum

•        Light reaction: photosystem I (P700) and photosystem II (P680); antenna molecules; reaction centre

•        Electron transport chain: Z-scheme; plastoquinone, cytochrome b6f, plastocyanin, ferredoxin

•        Photophosphorylation: cyclic (PS I only; ATP only) and non-cyclic (both PS I and PS II; ATP + NADPH + O2)

•        Photolysis of water: 2H2O → 4H+ + 4e- + O2; Hill reaction

•        Calvin cycle (C3 pathway): CO2 fixation by RuBisCO; 3-PGA; G3P; RuBP regeneration; 3 turns produce 1 G3P

•        C4 pathway (Hatch-Slack): Kranz anatomy; PEPC; oxaloacetate; bundle sheath cells; Saccharum, Zea mays, Sorghum

•        Photorespiration: RuBisCO oxygenase activity; O2 consumption in chloroplast; glycolate pathway; wasteful in C3 plants

•        Factors affecting photosynthesis: light, CO2, temperature, water; law of limiting factors (Blackman)

Chapter 14: Respiration in Plants

Respiration in Plants covers glycolysis, Krebs cycle, and oxidative phosphorylation. The chapter overlaps with Human Physiology and yields reliable marks.

•        Cellular respiration: aerobic and anaerobic; glucose as respiratory substrate

•        Glycolysis (EMP pathway): 10 steps; glucose to 2 pyruvate; net 2 ATP + 2 NADH; cytoplasm

•        Fermentation: alcoholic (pyruvate → ethanol + CO2; yeast) and lactic acid (pyruvate → lactate; RBCs, muscles)

•        Aerobic respiration: pyruvate oxidation to acetyl-CoA; acetyl-CoA + CoA + NAD+ → acetyl-CoA + CO2 + NADH

•        Krebs cycle (TCA cycle): 8 steps; 2 acetyl-CoA → 4 CO2 + 6 NADH + 2 FADH2 + 2 ATP (GTP)

•        Oxidative phosphorylation: electron transport chain (Complex I-IV); chemiosmosis; ATP synthase (F0-F1)

•        P/O ratio: NADH → 2.5 ATP; FADH2 → 1.5 ATP; total ATP from 1 glucose ≈ 30-32

•        Respiratory quotient (RQ): 1 for carbohydrates; 0.7 for fats; >1 for organic acids

•        Amphibolic nature of respiratory pathways; interconnection with anabolism

Chapter 15: Plant Growth and Development

Plant Growth and Development tests understanding of plant hormones and their roles, seed dormancy, and photoperiodism.

•        Plant growth: characteristics; arithmetic and geometric growth; growth rate; absolute and relative growth rate

•        Differentiation, dedifferentiation, redifferentiation

•        Plant growth regulators: overview; classification (auxins, gibberellins, cytokinins, ABA, ethylene)

•        Auxins (IAA): discovery (Darwin, Went); apical dominance; phototropism; gravitropism; cell elongation

•        Gibberellins (GA3): bolting; stem elongation; seed germination; fruit development without fertilisation

•        Cytokinins (Kinetin, Zeatin): cell division; delay of senescence; Richmond-Lang effect; apical dominance (ratio with auxin)

•        Abscisic acid (ABA): stress hormone; stomatal closure; dormancy; seed dormancy; antagonist to gibberellins

•        Ethylene: gaseous hormone; ripening; epinasty; senescence; abscission; triple response

•        Photoperiodism: short-day plants (SDPs), long-day plants (LDPs), day-neutral plants

•        Critical day length; dark period; phytochrome (Pfr and Pr forms); red/far-red reversibility

•        Vernalisation: low temperature requirement for flowering; devernalisation

Chapter 16: Digestion and Absorption

Digestion and Absorption is a high-weightage Zoology chapter. Enzyme actions, peristalsis, and absorption mechanisms in the intestine are tested regularly.

•        Alimentary canal: mouth, oesophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (caecum, colon, rectum, anal canal)

•        Salivary glands: parotid, submaxillary, sublingual; salivary amylase (ptyalin); pH 6.8

•        Gastric glands: oxyntic (parietal) cells — HCl; chief (peptic) cells — pepsinogen; mucus cells

•        Gastric secretions: HCl activates pepsinogen → pepsin; rennin (in infants); gastric lipase

•        Liver: bile; bile pigments (bilirubin, biliverdin); bile salts; emulsification of fats

•        Pancreatic enzymes: trypsinogen, chymotrypsinogen, procarboxypeptidase (activated by enterokinase), pancreatic amylase, lipase, DNase, RNase

•        Intestinal enzymes: maltase, lactase, sucrase, peptidases (aminopeptidase, dipeptidase)

•        Absorption: microvilli; facilitated diffusion (fructose); active transport (glucose, amino acids); fatty acid transport via lacteal (lymph)

•        Egestion: large intestine absorbs water and electrolytes; defaecation reflex

Chapter 17: Breathing and Exchange of Gases

Breathing and Exchange of Gases tests the mechanics of breathing, oxygen transport, and respiratory disorders. Very high-weightage chapter.

•        Respiratory organs: nasal passage, pharynx, larynx, trachea, bronchi, bronchioles, alveoli

•        Lungs: lobes; pleural membranes; pleural fluid; alveolar surface area ~75 m2

•        Breathing mechanism: inspiration (diaphragm contracts, rib cage expands — Boyle's law) and expiration (passive)

•        Lung volumes: tidal volume (500 mL), inspiratory reserve (2500 mL), expiratory reserve (1100 mL), residual volume (1100 mL)

•        Lung capacities: inspiratory (3500 mL), functional residual (2200 mL), vital (3600 mL), total lung (4700 mL)

•        Exchange of gases: partial pressure gradients (pO2 and pCO2); Fick's law; alveoli to blood; blood to tissues

•        Oxygen transport: 97% as oxyhaemoglobin (HbO2); 3% dissolved in plasma; oxyhaemoglobin dissociation curve; Bohr effect (pH, CO2, temperature)

•        Carbon dioxide transport: 70% as bicarbonate (HCO3-); chloride shift (Hamburger's phenomenon); 23% as carbaminohaemoglobin; 7% dissolved

•        Regulation of respiration: respiratory rhythm centre in medulla oblongata; pneumotaxic centre (pons)

•        Respiratory disorders: asthma, emphysema, occupational lung diseases (silicosis, asbestosis); hypercapnia; hypoxia

Chapter 18: Body Fluids and Circulation

Body Fluids and Circulation is the highest-weightage Human Physiology chapter, contributing four to six questions consistently. Heart structure, cardiac cycle, ECG, and blood composition are all tested.

•        Blood composition: plasma (55%) — water, proteins (albumin, globulin, fibrinogen), metabolites; formed elements (45%)

•        Erythrocytes (RBCs): biconcave; no nucleus; 4-5 million/mm3; lifespan 120 days; haemoglobin (Hb); ESR

•        Leucocytes (WBCs): 6000-8000/mm3; granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes)

•        Thrombocytes (platelets): 1.5-3.5 lakh/mm3; role in clotting; lifespan 10 days

•        Blood groups: ABO system (A, B, AB, O); Rh factor; universal donor (O-) and universal recipient (AB+); erythroblastosis foetalis

•        Coagulation: prothrombin → thrombin; fibrinogen → fibrin; role of platelets, Ca2+, vitamin K

•        Lymph: composition; lymphatic system; role of lymph nodes; role in fat absorption and immunity

•        Human heart: double circulation; four chambers; valves (tricuspid, bicuspid/mitral, pulmonary semilunar, aortic semilunar)

•        Cardiac conduction: SA node (pacemaker) → AV node → Bundle of His → Purkinje fibres

•        Cardiac cycle: 0.8 s; systole and diastole; cardiac output = SV x HR = 70 mL x 72 = ~5 L/min

•        ECG: P wave (atrial depolarisation), QRS complex (ventricular depolarisation), T wave (ventricular repolarisation)

•        Blood pressure: systolic (120 mmHg) and diastolic (80 mmHg); Korotkoff sounds; sphygmomanometer

•        Disorders: hypertension, coronary artery disease (atherosclerosis), angina, heart failure

Chapter 19: Excretory Products and their Elimination

Excretion tests nephron structure, urine formation, and osmoregulation. This is a reliable four to five question chapter every year.

•        Modes of excretion: ammonotelism (aquatic), ureotelism (mammals), uricotelism (reptiles, birds)

•        Human excretory system: kidneys (cortex, medulla, pelvis), ureters, urinary bladder, urethra

•        Nephron structure: Bowman's capsule, glomerulus (Malpighian body), PCT, loop of Henle (descending and ascending), DCT, collecting duct

•        Urine formation: glomerular filtration (GFR = 125 mL/min; 180 L/day); selective reabsorption; tubular secretion

•        Reabsorption in PCT: glucose, amino acids, 70-80% Na+, water (obligatory); HCO3-

•        Loop of Henle: countercurrent multiplier; descending limb (water permeable); ascending limb (ion pump)

•        DCT and collecting duct: facultative water reabsorption; ADH (vasopressin) action; aldosterone action (Na+ reabsorption)

•        Countercurrent mechanism: maintains medullary osmotic gradient (300-1200 mOsm/kg)

•        Regulation: ADH (antidiuretic hormone); renin-angiotensin-aldosterone system (RAAS); ANF (atrial natriuretic factor)

•        Micturition reflex; urine composition: water, urea, uric acid, creatinine, electrolytes

•        Disorders: uraemia, renal calculi, glomerulonephritis; dialysis; renal transplant

•        Other excretory organs: skin (sweat), lungs (CO2, H2O), liver (bile pigments)

Chapter 20: Locomotion and Movement

Locomotion and Movement tests muscle types, the structure of a sarcomere, and joint types. The sliding filament theory is a classic NEET question.

•        Types of movement: amoeboid, ciliary, muscular

•        Muscle types: skeletal (striated), smooth (non-striated), cardiac — structural and functional differences

•        Structure of skeletal muscle: muscle fascicle, muscle fibre, myofibril, sarcomere

•        Sarcomere structure: A band (myosin), I band (actin), H zone, M line, Z line; thin (actin) and thick (myosin) filaments

•        Sliding filament theory of muscle contraction: role of Ca2+, troponin, tropomyosin, cross-bridge formation, power stroke

•        Neuromuscular junction; role of ACh; motor unit

•        Skeletal system: functions; axial skeleton (skull, vertebral column, ribs, sternum) and appendicular skeleton (pectoral girdle, pelvic girdle, limb bones)

•        Types of joints: fibrous (sutures), cartilaginous (symphysis), synovial (ball-and-socket, hinge, pivot, gliding)

•        Disorders: myasthenia gravis, muscular dystrophy, tetany, arthritis, gout, osteoporosis

Chapter 21: Neural Control and Coordination

Neural Control is a very high-weightage chapter contributing four to six questions. Reflex arcs, synaptic transmission, special senses (eye and ear), and neurotransmitters are all tested.

•        Neuron structure: cell body (soma), dendrites, axon, myelin sheath, nodes of Ranvier, axon terminals

•        Types of neurons: sensory (afferent), motor (efferent), interneurons (association)

•        Resting membrane potential: -70 mV; maintained by Na+/K+ ATPase pump (3 Na+ out, 2 K+ in)

•        Action potential: depolarisation (Na+ influx), repolarisation (K+ efflux), hyperpolarisation, refractory period; all-or-none law

•        Synaptic transmission: presynaptic membrane; synaptic vesicles; neurotransmitters; postsynaptic receptors; EPSP and IPSP

•        Neurotransmitters: ACh, noradrenaline, dopamine, serotonin, GABA, glycine, glutamate

•        Central nervous system (CNS): brain and spinal cord

•        Brain: forebrain (cerebrum — sulci, gyri, cerebral cortex; thalamus; hypothalamus), midbrain, hindbrain (pons, cerebellum, medulla oblongata)

•        Spinal cord: grey matter (H-shaped); white matter; central canal; spinal nerves

•        Reflex action and reflex arc: receptor, afferent neuron, nerve centre, efferent neuron, effector

•        Eye: structure (sclera, choroid, retina, lens, cornea, iris, pupil, vitreous humour, aqueous humour)

•        Retina: photoreceptors — rods (rhodopsin; scotopic vision) and cones (iodopsin; colour vision; fovea)

•        Phototransduction: bleaching of rhodopsin; optic nerve; optic chiasma; visual cortex

•        Ear: external ear (pinna, ear canal, tympanic membrane), middle ear (ossicles: malleus, incus, stapes; Eustachian tube), inner ear (cochlea, semicircular canals, utricle, saccule)

•        Mechanism of hearing: sound waves → basilar membrane vibration → hair cells → auditory nerve

•        Equilibrium: semicircular canals (dynamic equilibrium); otolith organs — utricle and saccule (static equilibrium)

Chapter 22: Chemical Coordination and Integration

Chemical Coordination (Endocrinology) is a high-weightage chapter tested with three to five questions. Hormones of all major endocrine glands, their functions, and disorders are tested directly from NCERT.

•        Endocrine glands: pituitary, pineal, thyroid, parathyroid, adrenal, pancreas, gonads, thymus, hypothalamus

•        Pituitary gland (hypophysis): pars distalis (GH, TSH, ACTH, FSH, LH, prolactin), pars intermedia (MSH), neurohypophysis (ADH/vasopressin, oxytocin)

•        Hypothalamic hormones: releasing hormones (GHRH, TRH, CRH, GnRH) and inhibiting hormones (somatostatin, PIF) — portal circulation

•        Thyroid hormones: T3 (triiodothyronine) and T4 (thyroxine); calcitonin; role in BMR; iodine deficiency → goitre, cretinism; hyperthyroidism → exophthalmic goitre

•        Parathyroid: PTH (parathormone); increases blood Ca2+; hypercalcaemia; hypoparathyroidism → tetany

•        Adrenal gland: cortex (mineralocorticoids: aldosterone — Na+ reabsorption; glucocorticoids: cortisol — anti-inflammatory; sex corticoids) and medulla (adrenaline/epinephrine, noradrenaline — fight or flight)

•        Pancreatic hormones: insulin (beta cells — lowers blood glucose; GLUT4); glucagon (alpha cells — raises blood glucose); diabetes mellitus (Type 1 and Type 2)

•        Gonadal hormones: testosterone (Leydig cells), oestrogen and progesterone (follicle, corpus luteum)

•        Thymus: thymosin; T-lymphocyte maturation

•        Pineal gland: melatonin; circadian rhythm; anti-ageing

•        Atrial natriuretic factor (ANF): from heart; reduces blood pressure

•        Erythropoietin (EPO): from kidney; stimulates RBC production

NEET Biology Class 12 Syllabus: All 16 Chapters and Topics

Class 12 Biology contributes approximately 55 to 60 percent of the total NEET Biology question count and covers Reproduction, Genetics and Evolution, Biology in Human Welfare, Biotechnology, and Ecology. Genetics and Molecular Biology are consistently the highest-weightage Class 12 units, followed by Ecology and Reproduction. These chapters reward students who combine thorough NCERT reading with diagrammatic understanding and regular MCQ practice.

Chapter 1: Reproduction in Organisms

This foundational chapter introduces modes of reproduction with examples from diverse organisms. Questions focus on types of asexual reproduction and terminology.

•        Asexual reproduction: binary fission (Amoeba, bacteria), budding (Hydra, yeast), fragmentation (Spirogyra), regeneration (Planaria, Hydra), sporulation (bread mould), vegetative propagation

•        Types of vegetative propagation: natural (runners, rhizomes, suckers, tubers, bulbs, corms) and artificial (cutting, layering, grafting, micropropagation/tissue culture)

•        Phases of life cycle: juvenile, reproductive, senescent

•        Sexual reproduction: events — pre-fertilisation (gametogenesis, gamete transfer), fertilisation, post-fertilisation (zygote, embryogenesis)

•        Oestrous cycle vs menstrual cycle; seasonal and continuous breeders

Chapter 2: Sexual Reproduction in Flowering Plants

Sexual Reproduction in Flowering Plants is a very high-weightage chapter with four to six questions per NEET paper. Microsporogenesis, megasporogenesis, double fertilisation, and fruit and seed development are essential.

•        Flower structure: stamen (anther + filament), pistil (stigma, style, ovary)

•        Microsporogenesis: PMC (2n) → meiosis → microspore tetrad → pollen grains; pollen wall (exine/sporopollenin; intine)

•        Pollen grain (male gametophyte): generative cell and vegetative (tube) cell; germination; pollen tube

•        Megasporogenesis: MMC (2n) → meiosis → 4 megaspores → 3 degenerate; functional megaspore → female gametophyte (embryo sac)

•        Embryo sac development: 8-nucleate, 7-celled; egg cell, 2 synergids, 3 antipodal cells, central cell (2 polar nuclei)

•        Pollination: types (autogamy, geitonogamy, xenogamy); agents (wind/anemophily, water/hydrophily, insects/entomophily, birds/ornithophily)

•        Pollen-pistil interaction: recognition (stigma, exudate); self-incompatibility (SI); pollen tube growth through style

•        Double fertilisation: tube nucleus guides pollen tube; syngamy (n + n → 2n zygote); triple fusion (n + 2n → 3n primary endosperm nucleus (PEN))

•        Post-fertilisation: zygote → embryo; PEN → endosperm (nuclear, cellular, helobial types)

•        Embryo development (embryogeny): pro-embryo → globular → heart-shaped → torpedo → mature embryo

•        Dicot embryo structure: epicotyl, hypocotyl, radicle, two cotyledons (seed leaves); plumule

•        Monocot embryo: coleoptile, scutellum, coleorhiza; endosperm persists (albuminous seed)

•        Apomixis: seed formation without fertilisation (agamospermy, vegetative apomixis); polyembryony (mango, citrus)

Chapter 3: Human Reproduction

Human Reproduction is a high-weightage chapter tested with three to five questions. Gametogenesis, the menstrual cycle, fertilisation, and embryo implantation are all heavily tested topics.

•        Male reproductive system: testes (seminiferous tubules + Leydig cells + Sertoli cells), epididymis, vas deferens, seminal vesicle, prostate gland, bulbourethral gland, penis

•        Spermatogenesis: spermatogonia → primary spermatocyte → secondary spermatocyte → spermatids → spermatozoa (spermiogenesis); spermiation

•        Sperm structure: head (acrosome + nucleus), middle piece (mitochondria), tail (flagellum)

•        Female reproductive system: ovaries (follicles + corpus luteum), fallopian tubes (fimbriae → ampulla → isthmus), uterus (fundus, body, cervix), vagina

•        Oogenesis: oogonia → primary oocyte (arrested at prophase I at birth) → meiosis resumes at puberty → secondary oocyte → ovum + polar bodies

•        Folliculogenesis: primordial → primary → secondary → antral → Graafian follicle; LH surge → ovulation

•        Menstrual cycle: ~28 days; menstrual phase (1-5), follicular/proliferative phase (6-13), ovulatory (14), luteal/secretory phase (15-28)

•        Hormonal regulation: FSH → follicle growth; oestrogen → proliferation + LH surge; LH → ovulation + corpus luteum; progesterone → secretory phase + implantation

•        Fertilisation: in ampullary region of fallopian tube; acrosome reaction; cortical reaction (block to polyspermy); zygote formation

•        Embryo development: zygote → cleavage → morula (16-cell solid ball) → blastocyst (ICM + trophoblast); implantation in endometrium

•        Placenta: structure and functions (nutrition, excretion, respiration, endocrine — hCG, oestrogen, progesterone)

•        Foetal development: major milestones (heart beat at 1 month, limbs at 2 months, organ systems at 3 months, movement at 5 months, eyelashes at 6 months); parturition

Chapter 4: Reproductive Health

Reproductive Health is a low-to-medium weightage chapter. Questions focus on STDs, contraceptive methods, and MTP regulations.

•        Reproductive health: WHO definition; problems; national programmes (RCHA, MTP Act 1971)

•        Population stabilisation: importance; Total Fertility Rate (TFR)

•        Contraceptive methods: natural (periodic abstinence, coitus interruptus, lactational amenorrhoea)

•        Barrier methods: condom (male and female), diaphragm, cervical cap, vaults; spermicidal creams/jellies

•        IUDs: non-medicated (Lippes loop), copper releasing (Cu-T, Cu-7, Multiload-375), hormone releasing (Progestasert, LNG-20); mechanism

•        Oral contraceptives: combined pills (oestrogen + progesterone); mini-pills (progestin only); emergency contraception

•        Surgical methods: vasectomy (male), tubectomy (female); permanent; irreversible

•        Medical termination of pregnancy (MTP): legal up to 20 weeks; reasons

•        Sexually transmitted diseases (STDs): gonorrhoea, syphilis, herpes, hepatitis-B, chlamydiasis, genital warts; AIDS (HIV)

•        Infertility: causes; ART (Assisted Reproductive Technologies): IVF (test tube baby), ZIFT, GIFT, ICSI, ET, IUI

Chapter 5: Principles of Inheritance and Variation

Principles of Inheritance is the highest-weightage chapter in all of NEET Biology, consistently contributing five to eight questions per paper. Mendel's laws, incomplete dominance, codominance, sex-linked inheritance, and chromosomal disorders are all tested.

•        Mendel's experiments: garden pea (Pisum sativum); 7 contrasting characters; reasons for success

•        Law of Dominance; Law of Segregation (Purity of Gametes): monohybrid cross; 3:1 phenotypic ratio; 1:2:1 genotypic ratio

•        Law of Independent Assortment: dihybrid cross; 9:3:3:1 phenotypic ratio; chi-square test

•        Test cross and back cross; incomplete dominance (4 O'clock plant — Mirabilis jalapa); codominance (ABO blood groups)

•        Multiple alleles: ABO blood group system (IA, IB, i); genetics of blood groups

•        Pleiotropy: one gene affects multiple phenotypes; Marfan syndrome; sickle cell anaemia

•        Polygenic inheritance: continuous variation; multiple genes for one trait; skin colour in humans

•        Chromosomal theory of inheritance: Sutton and Boveri; Morgan's experiments with Drosophila

•        Linkage and recombination: linked genes; crossing over; recombination frequency; chromosome mapping

•        Sex determination: XX-XY (humans, Drosophila), XX-XO (grasshoppers), ZW-ZZ (birds, butterflies)

•        Sex-linked inheritance: haemophilia (X-linked recessive); colour blindness; criss-cross inheritance

•        Mutation: chromosomal aberrations (deletion, duplication, inversion, translocation); point mutations (transition, transversion)

•        Pedigree analysis: symbols; autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive patterns

•        Mendelian disorders: albinism, phenylketonuria, sickle-cell anaemia, thalassaemia, haemophilia, colour blindness

•        Chromosomal disorders: Down syndrome (trisomy 21); Turner syndrome (45, XO); Klinefelter syndrome (47, XXY); Patau syndrome; Edwards syndrome

Chapter 6: Molecular Basis of Inheritance

Molecular Basis of Inheritance is equally high-weightage as Chapter 5. DNA structure, replication, transcription, translation, and gene regulation are the core tested areas.

•        DNA as genetic material: Griffith's experiment (transformation); Avery-MacLeod-McCarty experiment; Hershey-Chase experiment (T2 bacteriophage)

•        DNA structure: nucleotide structure; Watson-Crick double helix model; Chargaff's rules (A=T, G=C); 3.4 nm pitch; 0.34 nm per base pair; 2 nm diameter; anti-parallel strands; major and minor grooves

•        Packaging of DNA: histones (H1, H2A, H2B, H3, H4); nucleosome core (146 bp around histone octamer); 30 nm fibre; chromatin

•        DNA replication: semi-conservative (Meselson-Stahl experiment with N15 label)

•        Enzymes of replication: helicase (unwinds), topoisomerase (relieves tension), primase (RNA primer), DNA polymerase III (elongation 5'→3'), DNA polymerase I (removes primer), DNA ligase

•        Leading strand (continuous) and lagging strand (Okazaki fragments); replication fork

•        Transcription in prokaryotes: RNA polymerase; promoter; sigma factor; template strand (3'→5'); RNA is 5'→3'; termination

•        Types of RNA: mRNA (message), tRNA (adaptor — anticodon loop, CCA-3' amino acid attachment; cloverleaf structure), rRNA (ribozyme activity in peptidyl transferase)

•        Transcription in eukaryotes: three RNA polymerases (I, II, III); pre-mRNA processing: 5' capping (7-methylguanosine), 3' polyadenylation, splicing (removal of introns); hnRNA → mRNA

•        Genetic code: triplet codon; degenerate (64 codons for 20 amino acids); unambiguous; universal (except mitochondria); non-overlapping; commaless; AUG (start — methionine/fMet); UAA, UAG, UGA (stop)

•        Translation: ribosomes (A site, P site, E site); aminoacyl-tRNA synthetase; initiation, elongation (translocation, peptide bond — peptidyl transferase), termination; polyribosomes

•        Regulation of gene expression: lac operon (Jacob-Monod model); structural genes (z, y, a); operator; promoter; regulatory gene (i); inducer (allolactose); repressor; catabolite repression

•        Human Genome Project (HGP): goals; methods (BAC/YAC cloning, STS, Sanger sequencing, shotgun); findings (3164.7 million bp; 30,000 genes; 45% repetitive sequences)

•        DNA fingerprinting: VNTR; Southern blotting; hybridisation; applications (forensics, paternity, evolution)

Chapter 7: Evolution

Evolution is tested with two to four questions focusing on theories, evidences, and speciation mechanisms.

•        Origin of life: Oparin-Haldane hypothesis (primordial soup; prebiotic synthesis); Urey-Miller experiment (amino acids from CH4, H2O, H2, NH3)

•        Evidence for evolution: palaeontology (fossils; geological time scale); comparative anatomy (homologous organs — divergent evolution; analogous organs — convergent evolution; vestigial organs)

•        Embryological evidence; molecular evidence (DNA homology); biogeography

•        Lamarckism: inheritance of acquired characters; use and disuse; disproved

•        Darwinism: natural selection; variation; struggle for existence; survival of the fittest; Theory of Natural Selection (On the Origin of Species, 1859)

•        Neo-Darwinism (Modern Synthesis): Darwin + Mendel + population genetics; gene pool; allele frequency

•        Hardy-Weinberg principle: p2 + 2pq + q2 = 1; equilibrium conditions; factors disturbing equilibrium (mutation, gene flow, genetic drift, selection, non-random mating)

•        Types of natural selection: stabilising, directional, disruptive

•        Speciation: allopatric (geographic isolation → reproductive isolation) and sympatric; reproductive isolating mechanisms

•        Adaptive radiation: Darwin's finches; Australian marsupials; convergent evolution (wings of bat and bird)

•        Brief account of human evolution: Dryopithecus → Ramapithecus → Australopithecus → Homo habilis → Homo erectus → Homo sapiens neanderthalensis → Homo sapiens sapiens

Chapter 8: Human Health and Disease

Human Health and Disease is a high-weightage chapter tested with three to five questions. Pathogens, immunity, drugs, and cancer biology are all important NEET areas.

•        Health: WHO definition; lifestyle diseases; components of good health

•        Common diseases: typhoid (Salmonella typhi), pneumonia (Streptococcus, Haemophilus), common cold (rhinovirus), malaria (Plasmodium; P. vivax — benign tertian; P. falciparum — malignant tertian), amoebiasis (Entamoeba histolytica), ascariasis (Ascaris), elephantiasis/filariasis (Wuchereria)

•        Immunity: innate (non-specific: barriers, inflammation, phagocytosis, NK cells, fever, interferon) and adaptive/acquired (specific)

•        Adaptive immunity: humoral immunity (B cells → plasma cells → antibodies — IgG, IgA, IgM, IgE, IgD) and cell-mediated immunity (T cells: T helper, T cytotoxic, T suppressor, T memory)

•        Antibody structure: 4 polypeptides (2H + 2L chains); variable and constant regions; 5 classes

•        Primary and secondary immune response; memory cells; active and passive immunity

•        Vaccination and immunisation: principle; types of vaccines (live attenuated, killed, subunit, toxoid, recombinant)

•        Allergies: allergens; IgE; mast cells; histamine; anaphylaxis

•        Autoimmunity: examples (rheumatoid arthritis, multiple sclerosis, systemic lupus)

•        AIDS: HIV (retrovirus); structure; transmission; replication (reverse transcription); targets T helper cells (CD4+); AIDS progression; ELISA test; antiretroviral therapy

•        Cancer: benign vs malignant tumours; carcinogens; oncogenes and tumour suppressor genes; metastasis; diagnosis (biopsy, radiography, CT, MRI); treatment (surgery, radiation, chemotherapy, immunotherapy)

•        Drugs and alcohol abuse: opioids (morphine, heroin), cannabinoids (marijuana, hashish), cocaine; depressants, stimulants, hallucinogens; addiction, dependence, withdrawal

Chapter 9: Strategies for Enhancement in Food Production

This chapter provides two to three reliable marks with focused preparation on plant breeding, tissue culture, and animal husbandry.

•        Animal husbandry: management of livestock (cattle, poultry, fisheries)

•        Cattle farming: dairy and draught animals; breeds; animal nutrition; disease management (foot and mouth, rinderpest, pox)

•        Poultry farming: egg and meat production; breeds (Leghorn, Rhode Island Red, White Rock, Plymouth Rock)

•        Fish production: aquaculture; capture fishing; mariculture (Sargassum, Gracilaria; mussels, oysters, prawns)

•        Bee-keeping (apiculture): Apis cerana indica, A. mellifera; products (honey, beeswax)

•        Plant breeding: objectives; methods (selection, hybridisation, polyploidy, mutation breeding)

•        Steps in hybridisation programme: collection of variability → evaluation → selection → testing → release and commercialisation

•        Classical plant breeding achievements: semi-dwarf wheat (Norman Borlaug; Sonalika, Kalyan Sona), semi-dwarf rice (IR-8, Jaya, Ratna), Pusa Komal (cowpea), Pusa Sawani (okra — aphid resistant)

•        Tissue culture: totipotency; explant; callus; somatic embryogenesis; somaclonal variation; artificial seeds; micropropagation

•        Somatic hybridisation: protoplast fusion; cybrid; somatic hybrids

•        Single cell protein (SCP): Spirulina; protein source

Chapter 10: Microbes in Human Welfare

Microbes in Human Welfare is tested with two to three questions, focusing on fermentation, antibiotics, and biogas production.

•        Microbes in household products: curd (Lactobacillus); bread (Saccharomyces cerevisiae); idli-dosa (Leuconostoc); cheese (Lactobacillus; Propionibacterium; Penicillium camemberti); toddy (palm sap); vinegar (Acetobacter)

•        Microbes in industry: fermentation; beer, wine (Saccharomyces); whisky, brandy, rum; distilled beverages

•        Industrial products: antibiotics — penicillin (Penicillium notatum; Alexander Fleming); statins (Monascus purpureus — blood cholesterol lowering); cyclosporin A (Trichoderma polysporum — immunosuppressant)

•        Biogas production: biogas plant; methanogens (Methanobacterium); inputs; slurry; energy source

•        Sewage treatment: primary treatment (physical removal of large particles); secondary treatment (biological — BOD reduction by microbes; activated sludge; anaerobic digestion in sludge digesters)

•        Microbes in biocontrol: Bacillus thuringiensis (Bt) toxin; cry genes; biopesticides; Trichoderma for plant pathogens; Baculovirus (Nucleopolyhedrovirus) as biocontrol agent

•        Microbes as biofertilisers: Rhizobium, Azospirillum, Azotobacter (free-living N-fixers); Nostoc, Anabaena, Tolypothrix (cyanobacteria); mycorrhiza (Glomus — phosphorus solubilisation)

Chapter 11: Biotechnology: Principles and Processes

Biotechnology Principles is a very high-weightage chapter with three to five questions per NEET paper. Restriction enzymes, vectors, PCR, and recombinant DNA technology are the core tested topics.

•        Biotechnology: definition; principles — genetic engineering and bioprocess engineering

•        Restriction enzymes (REases): endonucleases; recognition sequences (palindromic); sticky ends vs blunt ends; EcoRI (G↓AATTC); HindIII; BamHI; specific examples

•        Cloning vectors: plasmids (pBR322: ampR, tetR, ori; features of good vector); bacteriophages (λ phage, M13); cosmids; BAC; YAC

•        Selectable markers: antibiotic resistance genes; insertional inactivation (blue-white selection with lacZ gene)

•        Gel electrophoresis: separation by size; agarose gel; ethidium bromide; UV transilluminator; restriction mapping

•        Recombinant DNA technology steps: isolation of DNA → cutting with REase → gel electrophoresis → ligation (DNA ligase) → transformation → selection and screening

•        Competent cells: CaCl2 treatment for E. coli; heat shock; transformation; electroporation

•        PCR (Polymerase Chain Reaction): Kary Mullis; thermostable DNA polymerase (Taq polymerase); denaturation (94°C), annealing (55°C), extension (72°C); exponential amplification

•        Bioreactors: stirred-tank reactor; sparger; impeller; pH and temperature control; scale-up; downstream processing (separation, purification)

•        Expression systems: E. coli, yeast (Saccharomyces), plant cells, animal cells; protein folding; inclusion bodies

Chapter 12: Biotechnology and its Applications

Biotechnology Applications is tested with two to four questions on GM crops, insulin production, gene therapy, and ethical considerations.

•        Genetically modified (GM) organisms: transgenic plants, animals, microbes

•        GM crops: Bt cotton (cry1Ac and cry2Ab against bollworm); Bt brinjal (cry1Ab); Bt corn; herbicide-tolerant crops (Roundup Ready — EPSPS gene)

•        Golden rice: beta-carotene (pro-vitamin A) synthesising genes from daffodil and Erwinia; humanitarian use

•        Concerns: biosafety; Bt toxin allergy; ethics; terminator technology; gene escape to wild relatives; loss of biodiversity

•        Recombinant insulin (Humulin): A and B chains in E. coli; pro-insulin; C peptide removal; Eli Lilly (1983)

•        Gene therapy: somatic gene therapy (ADA deficiency — first clinical gene therapy); viral vectors (retroviruses); ex vivo and in vivo approaches

•        Molecular diagnosis: PCR for early detection of pathogens (HIV, TB); ELISA (HIV, hepatitis); recombinant DNA probes

•        Transgenic animals: Rosie the cow (human protein-enriched milk); knock-out mice; disease models

•        GEAC (Genetic Engineering Approval Committee): India's regulatory body

•        IPR and patents: biopiracy; neem (W.R. Grace), turmeric (wound healing), basmati rice; India's legal challenges

Chapter 13: Organisms and Populations

Organisms and Populations introduces ecological concepts, adaptations, and population growth models that are heavily tested with three to four questions.

•        Ecology: definition; levels of organisation (organism, population, community, ecosystem, biome, biosphere)

•        Abiotic factors: temperature, water, light, soil; limiting factors; Shelford's law of tolerance

•        Adaptations: terrestrial (xeric, mesic, hydric); aquatic; thermoregulation; conformers vs regulators

•        Population attributes: birth rate, death rate, age distribution (pyramid), sex ratio, density

•        Population growth: exponential growth: dN/dt = rN; N(t) = N0 e(rt); r = intrinsic rate of natural increase

•        Logistic growth: dN/dt = rN[(K-N)/K]; sigmoid curve (S-shaped); carrying capacity K; J-curve vs S-curve

•        Population interactions: mutualism (+/+), commensalism (+/0), parasitism (+/-), predation (+/-), competition (-/-), amensalism (-/0)

•        Predation: Lotka-Volterra equations; prey-predator cycles; keystone predators (starfish and Pisaster); coevolution

•        Competition: interspecific (resource partitioning, competitive exclusion — Gause's law) and intraspecific

•        Mutualism: mycorrhiza; fig-wasp mutualism; cleaner fish; ants and Acacia

•        Commensalism: barnacles on whales; orchids on mango trees; cattle egret and cattle

Chapter 14: Ecosystem

Ecosystem is tested with three to four questions on energy flow, productivity, ecological pyramids, and nutrient cycles.

•        Ecosystem: components — biotic (producers, consumers, decomposers) and abiotic; types

•        Productivity: GPP (Gross Primary Productivity) and NPP (Net Primary Productivity = GPP - R); secondary productivity

•        Decomposition: detritivory; fragmentation; catabolism; humification; mineralisation

•        Energy flow: 10% law (Lindeman's efficiency); unidirectional; food chains and food webs

•        Ecological pyramids: pyramids of number, biomass, and energy; inverted pyramids (biomass in aquatic ecosystem); always erect pyramid of energy

•        Ecosystem services: provisioning, regulating, cultural, supporting services; economic value

•        Nutrient cycling: biogeochemical cycles

•        Carbon cycle: atmosphere-biosphere exchange; photosynthesis, respiration, combustion, decomposition

•        Phosphorus cycle: lithosphere reservoir; weathering; absorption; decomposition; no atmospheric phase

•        Nitrogen cycle: fixation, ammonification, nitrification (Nitrosomonas, Nitrobacter), denitrification (Pseudomonas)

•        Ecosystem stability; succession: primary (bare rock → soil → climax community) and secondary (disturbed area); pioneer community; climax community

Chapter 15: Biodiversity and Conservation

Biodiversity and Conservation is tested with two to four questions. Hotspots, extinction threats, and in situ vs ex situ conservation are directly tested from NCERT.

•        Biodiversity: genetic, species, ecological; distribution — latitudinal gradient (species richness highest near tropics)

•        Species-area relationship: log S = log C + Z log A; Z = 0.1-0.2 (small areas); Z = 0.6-1.2 (large areas/islands)

•        Global biodiversity: estimated 7 million species; only ~1.5 million described; IUCN Red List

•        Importance: rivet popper hypothesis (Paul Ehrlich); HIPPO (Habitat destruction, Invasive species, Pollution, Population explosion, Overhunting)

•        Mass extinctions: 5 major events; Holocene extinction (sixth mass extinction)

•        Biodiversity hotspots: 34 worldwide; criteria (>1500 endemic plants; <30% original natural vegetation); Western Ghats + Sri Lanka; Indo-Burma; Himalaya; Sundaland

•        IUCN categories: extinct, extinct in the wild, critically endangered, endangered, vulnerable, near threatened, least concern

•        In situ conservation: national parks, wildlife sanctuaries, biosphere reserves, sacred groves and forests

•        Ex situ conservation: seed banks, botanical gardens, zoological parks, tissue culture, cryopreservation, gene banks

•        International conventions: CITES, CBD (Convention on Biological Diversity), Ramsar Convention (wetlands)

Chapter 16: Environmental Issues

Environmental Issues is a low-to-medium weightage chapter providing two to three factual marks on pollution control, deforestation, and global warming.

•        Air pollution: particulates, SO2, NOx, CO, CFCs, hydrocarbons; effects; control

•        Electrostatic precipitators: removal of particulates; scrubbers for SO2 and other gases

•        Catalytic converters in automobiles: Pt/Pd/Rh catalysts; CO and NO to CO2 and N2

•        Vehicular pollution: CNG (compressed natural gas) as cleaner fuel; unleaded petrol

•        Water pollution: BOD; sewage treatment; industrial effluents; detergents; heavy metals (Hg — Minamata disease, Cd — Itai-Itai disease)

•        Eutrophication: excess nutrients → algal bloom → oxygen depletion → fish death; cultural vs natural

•        Biomagnification: DDT; persistent organic pollutants; highest concentration in top predators

•        Solid waste: municipal solid waste; biodegradable vs non-biodegradable; e-waste; radioactive waste

•        Deforestation: causes (agriculture, cattle ranching, logging, mining); effects (soil erosion, loss of biodiversity, climate change)

•        Reforestation: Chipko movement; Joint Forest Management (JFM)

•        Global warming and climate change: greenhouse gases (CO2, CH4, N2O, CFCs); greenhouse effect; IPCC; effects (sea level rise, extreme weather events, species migration)

•        Ozone depletion: stratospheric ozone; CFCs (chlorofluorocarbons); Montreal Protocol

•        Radioactive waste: low-level and high-level waste; underground storage; nuclear accidents (Chernobyl, Fukushima)

NEET Biology Chapter-Wise Overview Table

The table below summarises all 38 chapters of the NEET 2026 Biology syllabus with their class, unit, approximate weightage, and priority level. Botany and Zoology chapters are identified for reference.

How to Prepare NEET Biology 2026: Unit-Wise Strategy

Biology preparation for NEET is fundamentally different from Chemistry and Physics. The most effective method is NCERT-based, diagram-anchored, and MCQ-validated reading. Students who read each NCERT chapter three times — first for understanding, second for important lines and diagrams, third for revision — and simultaneously practice 20 to 30 Biology MCQs daily consistently achieve 320 or above out of 360 in NEET Biology.

Genetics and Molecular Biology (Chapters 27-28): Non-Negotiable Priority

The two Genetics chapters together contribute ten to thirteen questions in a single NEET Biology paper, making this the single highest-yielding unit in all of NEET. Mendel's laws, genetic crosses, chromosomal disorders, DNA replication, transcription, translation, and the lac operon must be mastered with absolute precision. Pedigree analysis practice (at least 30 problems) and Punnet square exercises for all types of inheritance are essential. These chapters reward students who invest time in them with extraordinarily predictable and reliable marks.

Human Physiology (Chapters 16-22): Seven Chapters, Very High Reward

The seven Human Physiology chapters together contribute 18 to 25 questions per NEET Biology paper. Body Fluids and Circulation (ECG, blood groups, cardiac cycle), Neural Coordination (eye, ear, action potential, reflex), and Chemical Coordination (hormones and disorders) are the three highest-priority chapters within this unit. For each chapter, prepare a consolidated table of all hormones, enzymes, or structures with their properties — NEET frequently tests comparative knowledge within a single chapter.

Reproduction (Chapters 24-25): High Yield, Diagram-Driven

Sexual Reproduction in Flowering Plants and Human Reproduction together contribute seven to nine questions. These chapters require diagram mastery: the T.S. of anther, embryo sac, and stages of spermatogenesis and oogenesis must be drawn and annotated repeatedly until the details are automatic. Double fertilisation and the development of the embryo from zygote to mature stage are among the most reliably tested topics in NEET Biology.

Photosynthesis, Cell Biology, and Animal Kingdom: Core Science Topics

Photosynthesis (Chapter 13), Cell Structure (Chapter 8), Cell Division (Chapter 10), and Animal Kingdom (Chapter 4) together contribute twelve to eighteen questions. Photosynthesis questions frequently test the distinction between the light reaction and the Calvin cycle, or between C3 and C4 plants. Cell structure questions test organelle function and ultrastructure details. Mitosis and meiosis stages must be memorised with chromosome movements for each stage. Animal Kingdom questions test phylum characteristics and example organisms — prepare a comparison table for all phyla from Porifera to Mammalia.

Ecology (Chapters 35-37) and Biotechnology (Chapters 33-34): Rewarding but Specific

The four Ecology and Biotechnology chapters together contribute ten to fourteen questions. Ecology questions are largely conceptual and frequently test the 10% energy law, ecological pyramids, succession sequences, and biodiversity hotspot facts. Biotechnology questions are highly specific and NCERT-bound: restriction enzyme names and cut sequences, PCR conditions, recombinant insulin production steps, and Bt toxin gene names (cry1Ac, cry2Ab) must be memorised precisely. These chapters repay careful NCERT reading with very high-confidence answers.

Frequently Asked Questions: NEET Biology Syllabus 2026

How many chapters are in the NEET 2026 Biology syllabus?

The NEET 2026 Biology syllabus comprises 38 chapters in total: 22 chapters from Class 11 Biology and 16 chapters from Class 12 Biology. These chapters are divided between Botany (plant sciences) and Zoology (animal sciences) within the NEET question paper.

What is the highest-weightage chapter in NEET Biology?

Principles of Inheritance and Variation (Chapter 27 / Class 12 Chapter 5) and Molecular Basis of Inheritance (Chapter 28 / Class 12 Chapter 6) are jointly the highest-weightage chapters, together contributing ten to thirteen questions per NEET Biology section. Other very high-weightage chapters include Neural Control and Coordination, Chemical Coordination, Body Fluids and Circulation, Sexual Reproduction in Flowering Plants, and Photosynthesis.

How is Biology split between Botany and Zoology in NEET?

The NEET Biology section is divided into two equal sub-sections of 45 questions each: Botany (90 Marks effective attempt) and Zoology (90 marks effective attempt). Botany covers plant kingdom, plant structure, plant physiology, and plant reproduction. Zoology covers animal kingdom, human physiology (digestion, breathing, circulation, excretion, locomotion, neural, endocrine), animal reproduction, health, and ecology. Several chapters (Genetics, Cell Biology, Ecology, Biotechnology) contribute questions to both sub-sections.

Is NCERT enough for NEET Biology?

Yes, NCERT is sufficient for approximately 95 percent of NEET Biology questions. Unlike Physics and Chemistry where supplementary resources are recommended, Biology preparation almost exclusively requires NCERT Class 11 and Class 12 textbooks. Students should read every line, every box, every table, every figure, and every figure caption in the NCERT Biology books. NEET frequently asks questions directly from NCERT figures and diagram labels. Additional books like Trueman's Biology or MTG Objective NCERT are useful only for MCQ practice, not for content beyond NCERT.

How many marks should I target in NEET Biology?

Students targeting MBBS in government medical colleges should aim for 300 to 340 marks out of 360 in Biology (83 to 94 percent accuracy on attempted questions). Students targeting top government medical colleges typically need 340 or above. Since Biology contributes 50 percent of the total NEET score, maximising Biology performance is the most efficient route to a high NEET rank. A score of 340 in Biology combined with 130 in Physics and 150 in Chemistry gives a competitive total of 620 for most government medical college cutoffs.

Which Biology unit requires the most preparation time?

Genetics and Evolution (Chapters 27-29) requires the most focused preparation time due to its consistently high question count and the precision required in applying Mendel's laws, solving genetics problems, and understanding molecular biology mechanisms. Human Physiology (Chapters 16-22) requires the most total preparation time due to its seven-chapter scope, but individual chapters within it can be prepared more quickly than Genetics chapters. Students should allocate at least 25 to 30 percent of their Biology preparation time exclusively to the Genetics unit.

Are diagrams important in NEET Biology?

Yes, diagrams are extremely important in NEET Biology. A significant proportion of Biology questions are diagram-based, showing unlabelled or partially labelled biological structures and asking students to identify components, describe functions, or distinguish between similar structures. The most important diagrams to master include: T.S. of anther and ovule, embryo sac, cardiac cycle (ECG), nephron structure, neuron and synapse, DNA double helix, lac operon, sarcomere, mitosis and meiosis stages, and phylogenetic trees for kingdoms and phyla.