Are you searching for the CBSE Class 12 Biology Syllabus 2026-27? You are on the right page. This guide covers the complete CBSE Biology syllabus with all units, chapters and topics, marks distribution, exam pattern, important dates, expert study tips and common mistakes. Whether you are a student or educator, bookmark this page for the most detailed and updated resource.

CBSE Class 12 Biology 2026-27 — Quick Overview

CBSE Class 12 Biology Exam Structure 2026-27

The CBSE Class 12 Biology paper consists of a theory component of 70 marks and a practical component of 30 marks. Understanding the question paper design helps you allocate time efficiently during the exam.

Theory Paper Design

CBSE Class 12 Biology Marks Distribution 2026-27 — Unit-Wise

The unit-wise marks weightage is essential for strategic preparation. Units like Genetics and Evolution and Reproduction carry the highest marks and must be prioritised.

CBSE Class 12 Biology Complete Syllabus 2026-27 — All Units, Chapters & Topics

The following is the complete and official CBSE Class 12 Biology syllabus for 2026-27, with every chapter and sub-topic listed. Use this as your ultimate checklist for board exam preparation.

Unit VI: Reproduction

Chapter 1: Reproduction in Organisms

•        Modes of reproduction — asexual and sexual reproduction

•        Asexual reproduction — binary fission, budding, sporulation, fragmentation, vegetative propagation

•        Sexual reproduction — pre-fertilisation events, fertilisation, post-fertilisation events

•        Life span of organisms and relationship with reproduction

Chapter 2: Sexual Reproduction in Flowering Plants

•        Flower structure — parts and their functions

•        Development of male and female gametophytes

•        Pollination — types (autogamy, geitonogamy, xenogamy), agents (wind, water, insects)

•        Outbreeding devices — self-incompatibility, dicliny, dichogamy

•        Pollen-pistil interaction, double fertilisation

•        Post-fertilisation events — endosperm development, embryogenesis

•        Seed and fruit development, apomixis, polyembryony

Chapter 3: Human Reproduction

•        Male reproductive system — testes, accessory ducts, glands

•        Female reproductive system — ovaries, fallopian tubes, uterus

•        Gametogenesis — spermatogenesis and oogenesis (with diagrams)

•        Menstrual cycle — phases and hormonal regulation (very important for long answer)

•        Fertilisation, implantation, embryonic development

•        Parturition and lactation

Chapter 4: Reproductive Health

•        Reproductive health — definition, significance, government programmes

•        Population explosion and birth control — need and methods

•        Contraception — barrier, IUDs, oral pills, surgical methods

•        Medical Termination of Pregnancy (MTP) — legality and concerns

•        Sexually Transmitted Infections (STIs) — types, prevention

•        Infertility — causes and Assisted Reproductive Technologies (ART)

•        IVF, ZIFT, GIFT, IUI — definitions and applications

Unit VII: Genetics and Evolution

Chapter 5: Principles of Inheritance and Variation

•        Mendelian Inheritance — Law of Dominance, Law of Segregation, Law of Independent Assortment

•        Deviations from Mendelism — incomplete dominance, co-dominance, multiple alleles, pleiotropy

•        Chromosomal Theory of Inheritance — Morgan's experiments, linkage

•        Crossing over, recombination

•        Sex Determination — XX-XY mechanism (humans, Drosophila), ZW-ZZ (birds)

•        Mutation — chromosomal and gene mutations

•        Genetic Disorders — Down's syndrome, Turner's syndrome, Klinefelter's syndrome

•        Mendelian disorders — haemophilia, colour blindness, phenylketonuria, sickle cell anaemia

Chapter 6: Molecular Basis of Inheritance

•        DNA as Genetic Material — Griffith's experiment, Hershey-Chase experiment

•        Structure of DNA — Watson and Crick model, Chargaff's rules

•        Packaging of DNA — nucleosome, chromatin, chromosomes

•        DNA Replication — semi-conservative method, Meselson-Stahl experiment

•        Transcription — template strand, coding strand, process in prokaryotes and eukaryotes

•        Genetic Code — codons, wobble hypothesis, characteristics

•        Translation — ribosomes, tRNA, process of protein synthesis

•        Regulation of Gene Expression — lac operon (inducible system)

•        Human Genome Project — goals, findings, applications

•        DNA Fingerprinting — VNTR, process, applications

Chapter 7: Evolution

•        Origin of Life — chemical evolution, Miller-Urey experiment

•        Theories of Evolution — Lamarckism, Darwinism, Neo-Darwinism

•        Evidence of Evolution — palaeontology, comparative anatomy, embryology, molecular biology

•        Natural Selection — types (stabilising, directional, disruptive)

•        Genetic Drift — founder effect, bottleneck effect

•        Gene flow, mutation as mechanisms of evolution

•        Hardy-Weinberg Principle — conditions, significance

•        Speciation — allopatric and sympatric

•        Human Evolution — Homo habilis to Homo sapiens

Unit VIII: Biology and Human Welfare

Chapter 8: Human Health and Disease

•        Concept of health, disease, pathogens

•        Common Diseases — typhoid, pneumonia, common cold, amoebiasis, malaria (lifecycle of Plasmodium)

•        Immune System — innate and acquired immunity

•        Active and Passive Immunity — vaccines, antigen-antibody reaction

•        Lymphoid organs — thymus, spleen, MALT

•        AIDS — HIV, transmission, diagnosis, prevention

•        Cancer — types, causes, detection, treatment

•        Drugs and Alcohol Abuse — effects, addiction, prevention

Chapter 9: Microbes in Human Welfare

•        Microbes in Food Production — curd, cheese, bread, idli, dosa

•        Industrial uses — production of ethanol, antibiotics (penicillin), statins

•        Microbes in Sewage Treatment — primary and secondary treatment, activated sludge

•        Biogas — production, composition, biogas plants

•        Biocontrol Agents — Bacillus thuringiensis, Trichoderma, baculoviruses

•        Biofertilisers — Rhizobium, Azospirillum, Azolla, mycorrhiza

Unit IX: Biotechnology and Its Applications

Chapter 10: Biotechnology — Principles and Processes

•        Basic Concepts — genetic engineering, recombinant DNA technology

•        Restriction enzymes — types, nomenclature, sticky ends, blunt ends

•        Tools of Recombinant DNA Technology — restriction enzymes, cloning vectors, host organism

•        Cloning Vectors — plasmids (pBR322), bacteriophage, cosmids, BAC, YAC

•        Process of Recombinant DNA Technology — isolation, ligation, transformation, selection

•        PCR — Polymerase Chain Reaction — steps, applications

•        Gel Electrophoresis — principle and applications

Chapter 11: Biotechnology and Its Applications

•        Applications in Agriculture — Bt cotton, Bt brinjal, golden rice, pest-resistant plants

•        Applications in Medicine — insulin production, gene therapy, molecular diagnosis

•        Transgenic Animals — uses in research, pharming

•        Ethical Issues — biopiracy, GMO concerns, GEAC

•        Human Insulin — recombinant insulin production (Eli Lilly process)

•        RNAi — RNA interference mechanism, applications

Unit X: Ecology and Environment

Chapter 12: Organisms and Populations

•        Ecology — definition, levels of organisation

•        Abiotic factors — temperature, water, light, soil

•        Adaptations — terrestrial, aquatic, temperature adaptation

•        Population Attributes — birth rate, death rate, age distribution, sex ratio

•        Population Growth — exponential and logistic growth models, carrying capacity (K)

•        Population interactions — mutualism, commensalism, predation, competition, parasitism, amensalism

Chapter 13: Ecosystem

•        Ecosystem Structure — biotic and abiotic components

•        Productivity — primary and secondary productivity, GPP, NPP

•        Food Chains and Food Webs — grazing food chain, detritus food chain

•        Ecological Pyramids — pyramid of number, biomass, energy

•        Energy Flow — 10% law (Lindemann), trophic levels

•        Nutrient Cycling — carbon cycle, phosphorus cycle (diagrams are important)

•        Ecosystem Services — provisioning, regulating, cultural, supporting

Chapter 14: Biodiversity and Conservation

•        Biodiversity — genetic, species, ecological diversity

•        Patterns of Biodiversity — latitudinal gradient, species-area relationship

•        Loss of Biodiversity — causes (habitat loss, overexploitation, alien species, co-extinctions)

•        Hotspots of Biodiversity — definition, 34 global hotspots, India's hotspots

•        Conservation strategies — in situ conservation (national parks, biosphere reserves, wildlife sanctuaries)

•        Ex situ conservation — seed banks, zoological parks, botanical gardens, in vitro fertilisation

•        Sacred groves, biodiversity treaties — CBD, CITES

Chapter 15: Environmental Issues

•        Air Pollution — sources, pollutants, effects, control measures

•        Water Pollution — eutrophication, BOD, biomagnification

•        Solid Waste Management — e-waste, radioactive waste

•        Deforestation — causes, effects, reforestation

•        Global Warming — greenhouse effect, greenhouse gases, effects on climate

•        Ozone Layer Depletion — CFCs, UV radiation, effects

•        Case Studies — Chipko movement, Joint Forest Management

CBSE Class 12 Biology Practical Syllabus 2026-27 (30 Marks)

Biology practicals are one of the easiest 30 marks you can score if you prepare systematically. Focus on observations, diagrams, and viva questions.

Key Practicals Students Must Prepare

•        Study of pollen germination on a slide

•        Preparing temporary mount of onion root tip to study mitosis

•        Identification of common disease-causing organisms from slides/photographs

•        Study of yeast, Agaricus, Rhizopus under microscope

•        Preparation of T.S. of testis and ovary — identification of stages

•        Isolation of DNA from onion/spinach

•        Study of insects, earthworm, birds for ecological adaptations

•        Spotting specimens — seeds, flowers, animal specimens

CBSE Class 12 Biology 2026-27 — Important Dates

Plan your preparation using the CBSE 2026-27 academic calendar. Knowing key dates helps you avoid last-minute panic.

⚠️ Note: All dates are indicative and subject to official CBSE announcements. Verify on cbse.gov.in and cbseacademic.nic.in.

Chapter-Wise Priority & Expected Marks — CBSE Class 12 Biology

Based on 10 years of CBSE previous year paper analysis, here is how you should prioritise chapters:

Expert Study Tips for CBSE Class 12 Biology 2026-27

These proven strategies are used by students who consistently score 90+ marks in CBSE Biology:

1. NCERT Is Your Bible — Read It Cover to Cover

•        Over 80% of CBSE Biology questions are directly or indirectly from NCERT

•        Read every paragraph, caption, and footnote — CBSE often picks questions from NCERT boxes and examples

•        Do not skip diagrams — label every diagram in NCERT and redraw them in your notes

2. Master Diagrams — They Carry Direct Marks

•        10–15 marks in the board exam are diagram-based

•        Practice daily: T.S. of testis and ovary, double fertilisation, replication fork, lac operon, ecosystem pyramid

•        Always label diagrams neatly with correct terminology

3. Solve Previous Year Papers Religiously

•        Solve last 10 years' CBSE papers — many questions repeat in slightly different forms

•        Identify frequently repeated questions and prepare model answers for them

•        Time yourself — attempt full papers in 3 hours 15 minutes to build stamina

4. Use Mnemonics and Flowcharts for Complex Processes

•        Create flowcharts for DNA replication, transcription, translation — step-by-step processes

•        Use mnemonics to remember Mendelian laws, linkage groups, genetic disorders

•        Prepare comparison tables — e.g., DNA vs RNA, mitosis vs meiosis, grazing vs detritus food chain

5. Prioritise Genetics and Molecular Biology

•        Units VII accounts for 20 marks — do not neglect even a single topic

•        Practice numerical genetics problems — monohybrid, dihybrid, sex-linked crosses

•        Memorise all codons and key experiments (Hershey-Chase, Meselson-Stahl, Griffith)

Top Scoring Tips for CBSE Class 12 Biology Board Exam

Want to score 95+ in Biology? These exam-time strategies make the difference between good and great:

•        Attempt all questions — CBSE has no negative marking. Never leave any question blank

•        Write point-wise answers with sub-headings for long answer questions — easier to read and mark

•        Draw labelled diagrams wherever possible — they add visual impact and fetch extra marks

•        For 1-mark MCQs, do not overthink — trust your first instinct based on NCERT reading

•        In Assertion-Reason questions, read both A and R carefully — the logic of the connection matters

•        Use biological terms correctly — scientific terminology impresses examiners

•        For case-based questions, read the passage twice before answering — the answer is embedded in the case

•        Begin long answers with a definition or key statement — it signals clarity to the examiner

•        Maintain neat, legible handwriting with clear margins — presentation affects evaluation

•        Revise the entire NCERT twice before the board exam — once for understanding, once for memorisation

Common Mistakes to Avoid in CBSE Class 12 Biology

Avoid these costly mistakes that cause students to lose marks unnecessarily:

•        Skipping diagrams — students lose 10–15 easy marks by not drawing or mislabelling diagrams

•        Confusing similar terms — e.g., mitosis vs meiosis, GPP vs NPP, spermatogenesis vs oogenesis

•        Not practising genetics problems — numerical crosses fetch 4–5 marks and are fully predictable

•        Writing long, unstructured answers — use bullet points and subheadings for better readability

•        Ignoring Environmental Issues chapter — it is easy and consistently fetches 5–7 marks

•        Not reading NCERT examples and inset boxes — these are frequently the source of 1-mark questions

•        Mugging up without understanding — conceptual questions in case studies cannot be answered by rote

•        Poor revision of Reproductive Health — it is smaller but often directly questions appear from it

•        Neglecting practical preparation — 30 marks is too important to ignore

•        Starting board exam prep late — begin comprehensive revision from November at the latest

Best Books and Resources for CBSE Class 12 Biology 2026-27

Must-Have Official Resources

•        NCERT Biology Textbook Class 12 — most critical resource, no substitute

•        NCERT Exemplar Problems — Class 12 Biology (for application-based and MCQ practice)

•        CBSE Sample Papers 2026-27 — released officially on cbseacademic.nic.in

•        CBSE Question Bank (Chapter-wise) — for structured practice

Recommended Reference Books

•        Trueman's Elementary Biology Vol. 2 — comprehensive explanations for board and entrance

•        Pradeep's Biology Class 12 — detailed coverage with diagrams

•        MTG Objective Biology — for MCQ and objective practice

•        Previous Year CBSE Papers (10 years)

Frequently Asked Questions — CBSE Class 12 Biology Syllabus 2026-27

Q1. Is the CBSE Class 12 Biology syllabus reduced for 2026-27?

No. CBSE has restored the full syllabus for 2026-27. There are no reductions from the standard curriculum. Students must prepare all 5 units comprising 15 chapters.

Q2. Which unit has the highest marks in CBSE Class 12 Biology?

Unit VII — Genetics and Evolution carries the highest weightage with 20 marks, followed by Unit VI — Reproduction with 16 marks.

Q3. How many diagrams should I prepare for the board exam?

You should prepare at least 20–25 key diagrams including T.S. testis and ovary, gametogenesis, embryo development, DNA replication, lac operon, ecosystem pyramids, food chains, and Bt cotton mechanism.

Q4. Is NCERT enough for scoring 95+ in Biology?

Yes, if you read NCERT thoroughly including examples, captions and inset boxes. Complement it with NCERT Exemplar and previous year papers for application-based questions.

Q5. How should I prepare for Assertion-Reason questions in Biology?

First determine if the Assertion (A) is true or false independently, then check if the Reason (R) is true or false, and finally judge whether R is the correct explanation of A. Practice with CBSE sample papers to build accuracy.

Disclaimer

This content is prepared based on the official CBSE Biology curriculum and is intended for educational reference only. For the most accurate, updated information, always refer to the official CBSE website: cbse.gov.in and cbseacademic.nic.in. Syllabus and exam details are subject to change by CBSE at any time.