NCERT Books Class 12 Biology: Official PDF Chapters
Looking for the official NCERT Class 12 Biology textbook? This page links the exact, verified edition prescribed by CBSE for the 2026-27 session. All 13 chapter PDFs have been checked on ncert.nic.in (last verified 11 July 2026, HTTP 200 confirmed). Using an outdated PDF risks missing rationalised topics or hitting renumbered chapters—verify your download against the page counts listed here.
About the NCERT Books Class 12 Biology Textbook
The official NCERT Biology textbook for Class 12 is a single, unified book containing 13 chapters across five broad units. Unlike Physics and Chemistry, which are split into Part 1 and Part 2, Biology is one complete volume. This English-medium edition is prescribed by CBSE for all boards following the national curriculum. The textbook aligns with the 2026-27 syllabus and covers reproduction, genetics, evolution, health, biotechnology, and ecology.
Chapter-wise PDFs: What Each Section Covers
| Ch. | Chapter | Pages | Official PDF |
|---|---|---|---|
| 1 | SEXUAL REPRODUCTION IN FLOWERING PLANTS | 25 | |
| 2 | HUMAN REPRODUCTION | 15 | |
| 3 | REPRODUCTIVE HEALTH | 10 | |
| 4 | PRINCIPLES OF INHERITANCE AND VARIATION | 28 | |
| 5 | MOLECULAR BASIS OF INHERITANCE | 31 | |
| 6 | EVOLUTION | 17 | |
| 7 | HUMAN HEALTH AND DISEASE | 22 | |
| 8 | MICROBES IN HUMAN WELFARE | 12 | |
| 9 | BIOTECHNOLOGY : PRINCIPLES AND PROCESSES | 16 | |
| 10 | BIOTECHNOLOGY AND ITS APPLICATIONS | 11 | |
| 11 | ORGANISMS AND POPULATIONS | 17 | |
| 12 | ECOSYSTEM | 11 | |
| 13 | BIODIVERSITY AND CONSERVATION | 13 |
- Chapter 1: Sexual Reproduction in Flowering Plants (25 pages) — explores pollination mechanisms, double fertilisation, and the development of seeds and fruits.
- Chapter 2: Human Reproduction (15 pages) — describes the male and female reproductive systems, spermatogenesis, and oogenesis.
- Chapter 3: Reproductive Health (10 pages) — covers contraception methods, sexually transmitted infections, and assisted reproductive technologies.
- Chapter 4: Principles of Inheritance and Variation (28 pages) — examines Mendelian inheritance patterns, pedigree analysis, and chromosomal disorders.
- Chapter 5: Molecular Basis of Inheritance (31 pages) — details DNA replication, transcription, translation, and the genetic code.
- Chapter 6: Evolution (17 pages) — traces origin of life, natural selection, and Hardy–Weinberg equilibrium.
- Chapter 7: Human Health and Disease (22 pages) — discusses pathogens, immunity, AIDS, and cancer biology.
- Chapter 8: Microbes in Human Welfare (12 pages) — explores fermentation, biogas production, and biofertilisers.
- Chapter 9: Biotechnology: Principles and Processes (16 pages) — introduces recombinant DNA technology, restriction enzymes, and cloning vectors.
- Chapter 10: Biotechnology and its Applications (11 pages) — covers genetically modified crops, gene therapy, and molecular diagnosis.
- Chapter 11: Organisms and Populations (17 pages) — examines population interactions, competition, and population growth curves.
- Chapter 12: Ecosystem (11 pages) — analyzes energy flow, biogeochemical cycles, and ecological pyramids.
- Chapter 13: Biodiversity and Conservation (13 pages) — addresses species richness, conservation strategies, and biodiversity hotspots.
CBSE Marks Weightage for Class 12 Biology
The 70-mark theory exam is divided into five units, each carrying a fixed number of marks. Knowing the weightage helps you prioritise your study time on high-scoring chapters.
| Unit | Chapters | Marks |
|---|---|---|
| Unit VI: Reproduction | 1, 2, 3 | 16 |
| Unit VII: Genetics and Evolution | 4, 5, 6 | 20 |
| Unit VIII: Biology and Human Welfare | 7, 8 | 12 |
| Unit IX: Biotechnology and its Applications | 9, 10 | 12 |
| Unit X: Ecology and Environment | 11, 12, 13 | 10 |
Total theory: 70 marks (plus 30 marks for internal assessment and practicals). Source: CBSE Curriculum 2026-27, Senior Secondary Biology (verified 12 July 2026).
How to Use This Book for Board Exam Preparation
Reading the textbook in chapter order is useful for building a foundation, but exam success comes from prioritising high-weightage units first. Follow this strategy:
- Start with Unit VII: Genetics and Evolution (Chapters 4–6, 20 marks) — This is the heaviest-weighted unit and builds on concepts from earlier classes. Master Mendelian inheritance, molecular genetics, and evolutionary mechanisms first so you score in this section with confidence.
- Then tackle Unit VI: Reproduction (Chapters 1–3, 16 marks) — These chapters are descriptive and diagram-heavy; allocate time for labelling and understanding gametogenesis, fertilisation, and health-related topics.
- Next, cover Unit VIII and IX (Chapters 7–10, 24 marks combined) — These include immune systems, disease, and biotechnology. They often feature direct textbook questions, so read carefully and annotate key pathways.
- Finish with Unit X: Ecology and Environment (Chapters 11–13, 10 marks) — Though lower-weighted, these chapters test conceptual understanding of population dynamics and conservation; they integrate multiple smaller concepts.
Common mistake: Downloading an outdated NCERT PDF can leave you unprepared. If you download from a third-party source, verify the file has the same page counts listed in this article—for example, Chapter 4 must be 28 pages. If your PDF shows different chapter numbers or lengths, it is from an older edition and may contain deleted or rearranged topics.
Edge case note: Some students search for “NCERT Biology Part 2 Class 12” expecting a second volume, as they are familiar with Physics and Chemistry being split into two parts. Biology is not split. There is no Part 2. All 13 chapters fit into one book, and the official download consists of 13 individual PDFs corresponding to these chapters.
Related NCERT Resources for Class 12 Students
As you study Biology, you may benefit from related textbooks and resource hubs. Visit the Class 12 NCERT Books hub to access official editions of Chemistry and Physics alongside Biology. If you need to revisit foundational cell biology or genetics concepts, the Class 11 Biology textbook provides essential background, especially for Unit VII topics. For a quick overview of all Class 12 subjects and their official books, browse the CBSE Notes hub.
FAQs: NCERT Books Class 12 Biology
Is the NCERT Class 12 Biology textbook split into Part 1 and Part 2 like Physics and Chemistry?
No. The Class 12 Biology textbook is a single, unified book containing all 13 chapters. Physics and Chemistry are each split into two parts, but Biology is not. You do not need to search for a second volume.
How many chapters are in the NCERT Class 12 Biology book for the 2026-27 session?
There are 13 chapters in the official 2026-27 edition. All PDFs are listed and verified on this page.
Which NCERT Biology chapters carry the most marks in the CBSE Class 12 exam?
Unit VII (Genetics and Evolution, Chapters 4–6) carries the highest weightage at 20 marks. Unit VI (Reproduction) follows with 16 marks. Together, these two units account for 36 out of 70 theory marks.
Are any Class 12 Biology chapters removed under the rationalised NCERT syllabus?
The 2026-27 CBSE syllabus includes all 13 Biology chapters without deletion. However, some sections within chapters may have been shortened or reordered. Always download the official PDF verified on ncert.nic.in to ensure you are studying the current syllabus.
Where can I check if my NCERT Biology PDF is the latest official edition?
Visit ncert.nic.in/textbook.php, the official NCERT portal, to download directly or verify edition details. You can also check the page count of each chapter against the numbers shown in the chapter list on this page—if the counts match, your PDF is the current edition.
Reference: NCERT Class 12 Biology textbook, official edition on ncert.nic.in.