NCERT Class 12 Biology Textbook PDF: What’s Inside All 13 Chapters

The class 12 biology textbook pdf you are looking for is the official NCERT book: 13 chapters across 228 printed pages, from Sexual Reproduction in Flowering Plants to Biodiversity and Conservation. Every chapter’s official PDF is linked below, hosted on ncert.nic.in.

What the PDF alone does not show is what each chapter actually contains. From the book’s own text we have counted every chapter’s named sections, numbered figures and end-of-chapter questions, so you can see where the content and the question load sit before you open a single file.

Download the official Class 12 Biology textbook PDF

All 13 files below are NCERT’s own PDFs, hosted on the official portal at ncert.nic.in — open the chapter you need and what you study will match the printed book.

Class 12 Biology at a glance: 13 chapters, 228 pages (old NCERT PDF vs new edition)

• 13 chapters across 228 printed pages
• 13 verified official chapter PDFs, linked above
• 139 named sections
• 109 verified numbered figures indexed from the textbook
• 179 exercise questions

As the unit table shows, the question load does not track page count. Unit 2 (Genetics and Evolution) spans 76 pages but sets only 40 questions, while the 50-page reproduction unit sets 51; Unit 3 packs 32 questions into 34 pages, the densest stretch in the book. Unit 4 (Biotechnology) is the lightest on figures, with just 10 indexed figures across 27 pages.

This page indexes the current English edition. If you came looking for an old NCERT Biology Class 12 PDF, NCERT’s official rationalisation notice on ncert.nic.in is the authority on what changed between editions.

What the Class 12 Biology chapters PDF contains: sections, figures and questions

The directory below is the evidence core of this page — every count in it is read from the textbook itself.

What the columns count: a ‘section’ is one of NCERT’s own numbered headings, a ‘figure’ is a numbered figure indexed from the book, and a ‘question’ is an end-of-chapter exercise. No chapter in this book prints activities, so that column is all zeros.

Chapter 1: Sexual Reproduction in Flowering Plants (pp. 1-25)

Flowers are the seat of sexual reproduction in angiosperms. The androecium (stamens) forms the male organs and the gynoecium (pistils) the female organs, so the chapter is built around how these structures meet and fuse.

1. 1.1 Flower – a Fascinating Organ of Angiosperms (p. 3)
2. 1.2 Pre-Fertilisation: Structures and Events (p. 4)
3. 1.3 Double Fertilisation (p. 18)
4. 1.4 Post-Fertilisation: Structures and Events (p. 18)
5. 1.5 Apomixis and Polyembryony (p. 22)

With 11 named sections, 15 indexed figures and 18 questions, it opens the reproduction unit as its diagram-heavy first chapter.

Chapter 2: Human Reproduction (pp. 26-40)

Humans are sexually reproducing and viviparous. The male reproductive system comprises a pair of testes, sex accessory ducts, accessory glands and external genitalia, and the chapter follows the same organs-to-events order for the female system.

1. 2.1 The Male Reproductive System (p. 26)
2. 2.2 The Female Reproductive System (p. 28)
3. 2.3 Gametogenesis (p. 31)
4. 2.4 Menstrual Cycle (p. 33)
5. 2.5 Fertilisation and Implantation (p. 35)
6. 2.6 Pregnancy and Embryonic Development (p. 37)
7. 2.7 Parturition and Lactation (p. 38)

Its 12 figures and 21 questions (34 parts) make it the heaviest exercise load in the book.

Chapter 3: Reproductive Health (pp. 41-50)

Reproductive health means total well-being in all aspects of reproduction — physical, emotional, behavioural and social — and the chapter notes that India was the first nation to launch national action plans for it.

1. 3.1 Reproductive Health – Problems and Strategies (p. 41)
2. 3.2 Population Stabilisation and Birth Control (p. 43)
3. 3.3 Medical Termination of Pregnancy (p. 46)
4. 3.4 Sexually Transmitted Infections (p. 47)
5. 3.5 Infertility (p. 47)

At 10 pages, 4 figures and 12 questions it is the lightest chapter of the reproduction unit; all four figures (condom, Copper T, implants, vasectomy) sit in the birth-control section (pp. 44-45).

Chapter 4: Principles of Inheritance and Variation (pp. 51-78)

This is the genetics core of the book. It runs from Mendel’s laws of inheritance through one-gene and two-gene inheritance to polygenic inheritance, pleiotropy, sex determination, mutation and genetic disorders.

1. 4.1 Mendel’s Laws of Inheritance (p. 54)
2. 4.2 Inheritance of One Gene (p. 55)
3. 4.3 Inheritance of Two Genes (p. 62)
4. 4.4 Polygenic Inheritance (p. 69)
5. 4.5 Pleiotropy (p. 69)
6. 4.6 Sex Determination (p. 69)
7. 4.7 Mutation (p. 72)
8. 4.8 Genetic Disorders (p. 72)

With 18 named sections and 16 indexed figures — the most in the book — it anchors the genetics unit, closing on 16 questions across 28 pages.

Chapter 5: Molecular Basis of Inheritance (pp. 79-109)

Nucleic acids are long polymers of nucleotides. DNA stores genetic information while RNA mostly helps transfer and express it; both can act as genetic material, but DNA is the more stable store.

1. 5.1 The DNA (p. 80)
2. 5.2 The Search for Genetic Material (p. 84)
3. 5.3 RNA World (p. 88)
4. 5.4 Replication (p. 88)
5. 5.5 Transcription (p. 91)
6. 5.6 Genetic Code (p. 95)
7. 5.7 Translation (p. 98)
8. 5.8 Regulation of Gene Expression (p. 99)
9. 5.9 Human Genome Project (p. 102)
10. 5.10 DNA Fingerprinting (p. 105)

At 31 pages and 24 named sections it is the longest and most fragmented chapter in the book, yet it sets only 14 questions.

Chapter 6: Evolution (pp. 110-126)

The origin of life is understood against the origin of the universe, and most scientists believe chemical evolution — the formation of biomolecules — preceded the first life forms.

1. 6.1 Origin of Life (p. 110)
2. 6.2 Evolution of Life Forms – a Theory (p. 112)
3. 6.3 What Are the Evidences for Evolution? (p. 113)
4. 6.4 What is Adaptive Radiation? (p. 116)
5. 6.5 Biological Evolution (p. 118)
6. 6.6 Mechanism of Evolution (p. 119)
7. 6.7 Hardy-Weinberg Principle (p. 120)
8. 6.8 A Brief Account of Evolution (p. 121)
9. 6.9 Origin and Evolution of Man (p. 124)

Its 17 pages carry 10 figures and 10 questions; the Hardy-Weinberg section (p. 120) is the chapter’s one quantitative idea.

Chapter 7: Human Health and Disease (pp. 127-148)

Health is not just the absence of disease but a state of complete physical, mental, social and psychological well-being. The chapter works through common diseases such as typhoid, cholera, pneumonia, fungal skin infections and malaria before turning to immunity, AIDS, cancer and substance abuse.

1. 7.1 Common Diseases in Humans (p. 130)
2. 7.2 Immunity (p. 134)
3. 7.3 AIDS (p. 138)
4. 7.4 Cancer (p. 140)
5. 7.5 Drugs and Alcohol Abuse (p. 142)

With 16 named sections, 10 figures and 17 questions, it is the second-heaviest question load in the book; the immunity section (7.2) alone has seven sub-sections across pp. 134-137.

Chapter 8: Microbes in Human Welfare (pp. 149-160)

Microbes are a vital component of life on earth, and not all are pathogenic. Many are useful, and the chapter collects the ones we use in households, industry, sewage treatment, biogas, biocontrol and biofertilisers.

1. 8.1 Microbes in Household Products (p. 151)
2. 8.2 Microbes in Industrial Products (p. 151)
3. 8.3 Microbes in Sewage Treatment (p. 153)
4. 8.4 Microbes in Production of Biogas (p. 155)
5. 8.5 Microbes as Biocontrol Agents (p. 156)
6. 8.6 Microbes as Biofertilisers (p. 157)

Across 12 pages it sets 8 figures and 15 questions — a short chapter with a high question-per-page ratio.

Chapter 9: Biotechnology — Principles and Processes (pp. 161-176)

Biotechnology deals with large-scale production and marketing of products using live organisms, cells or enzymes. Modern biotechnology with genetically modified organisms became possible only when humans learned to alter DNA directly.

1. 9.1 Principles of Biotechnology (p. 163)
2. 9.2 Tools of Recombinant DNA Technology (p. 165)
3. 9.3 Processes of Recombinant DNA Technology (p. 171)

Its 16 pages carry 12 sections, 7 figures and 12 questions; the key diagrams — restriction enzymes, cloning vectors and PCR — all sit in the tools section (9.2).

Chapter 10: Biotechnology and its Applications (pp. 177-187)

Biotechnology has given humans useful products by harnessing microbes, plants, animals and their metabolic machinery, and tissue culture and somatic hybridisation offer vast potential for manipulating plants.

1. 10.1 Biotechnological Applications in Agriculture (p. 177)
2. 10.2 Biotechnological Applications in Medicine (p. 181)
3. 10.3 Transgenic Animals (p. 183)
4. 10.4 Ethical Issues (p. 184)

Only 3 figures but 13 questions over 11 pages — read it after Chapter 9, because it applies Chapter 9’s tools.

Chapter 11: Organisms and Populations (pp. 188-204)

Ecology is the study of the relationships of living organisms with the abiotic and biotic components of their environment, at four levels of organisation; this chapter narrows the focus to populations.

1. 11.1 Populations (p. 190)
2. Population Attributes (p. 191)
3. Population Growth (p. 192)
4. Life History Variation (p. 196)
5. Population Interactions (p. 196)

Across 17 pages it sets 6 named sections, 4 figures and 10 questions; the population-growth curve (Fig. 11.3, p. 194) carries the chapter’s central idea.

Chapter 12: Ecosystem (pp. 205-215)

An ecosystem is a structural and functional unit of nature comprising abiotic components (air, water and soil) and biotic components (producers, consumers and decomposers).

1. 12.1 Ecosystem – Structure and Function (p. 206)
2. 12.2 Productivity (p. 206)
3. 12.3 Decomposition (p. 207)
4. 12.4 Energy Flow (p. 209)
5. 12.5 Ecological Pyramids (p. 211)

Its 11 pages hold 4 figures and 11 questions — but 32 question parts, the highest parts-to-questions ratio in the book; the decomposition and energy-flow figures (12.1, p. 208; 12.2, p. 210) anchor the chapter.

Chapter 13: Biodiversity and Conservation (pp. 216-228)

Life originated on earth nearly 3.8 billion years ago and has diversified enormously since; biodiversity is the sum total of that diversity at all levels of biological organisation.

1. 13.1 Biodiversity (p. 216)
2. How Many Species are there on Earth and How Many in India? (p. 217)
3. Patterns of Biodiversity (p. 219)
4. The Importance of Species Diversity to the Ecosystem (p. 220)
5. Loss of Biodiversity (p. 221)
6. 13.2 Biodiversity Conservation (p. 223)
7. Why Should We Conserve Biodiversity? (p. 223)
8. How do we conserve Biodiversity? (p. 224)

Across 13 pages it prints just 2 indexed figures — the lightest figure load in the book — and 10 questions; the species-area relationship figure (13.2, p. 220) is the diagram students are most often asked to interpret.

Chapter study pages: find your 12th Biology chapter by name

If you want more than the PDF — chapter-wise notes and revision help — each chapter below has a dedicated study page on this site.

How to use the NCERT Class 12 Biology book for revision

• The printed order is the right order for the first half. Chapters 1-3 trace reproduction from flower to population, then Chapters 4-5-6 build inheritance, the molecular basis of inheritance and evolution.
• Keep Chapters 9 and 10 in order. Chapter 9 teaches the tools of recombinant DNA technology; Chapter 10 applies them.
• For a last-minute pass, start at the SUMMARY. Every chapter closes with a printed SUMMARY, and the ecology run (Chapters 11-13) is the shortest stretch at 17 + 11 + 13 pages.
• For diagram practice, use Chapters 1, 2 and 4. They hold 43 of the book’s 109 indexed figures.
• For question practice, Chapter 2 (21 questions) and Chapter 7 (17 questions) carry the heaviest loads; Chapter 5 sets only 14 questions despite being the longest chapter at 31 pages.
• Studying in Hindi? NCERT publishes Hindi and other language editions of this book on ncert.nic.in; the download table above indexes the English edition.
• One caveat: textbook contents and the examinable syllabus are not always identical — check the current official CBSE syllabus.

Related resources

This listing is maintained for the 2026-27 academic session using the NCERT textbook information available to us. NCERT remains the authority for confirming the latest edition.

For the complete set of official textbooks, browse the NCERT books directory. To move between Class 12 subjects, use the Class 12 hub, which collects this site’s Class 12 book pages.

Sources and data verification

• The counts and captions on this page come from the NCERT Class 12 Biology textbook editions this directory indexes — the chapter PDFs lebo101 to lebo113 on ncert.nic.in.
• The dataset covers chapter titles, NCERT section headings, indexed figures and end-of-chapter exercise counts. It does not cover every illustration in the book, and it is not the CBSE syllabus.
• This listing is maintained for the current academic session using the NCERT information available to us.
• NCERT settles textbook editions and PDFs; CBSE settles curriculum, syllabus and examinations.

Reference: NCERT Class 12 Biology textbook, official edition on ncert.nic.in. Figure captions and section titles quoted from the textbook; page references are to the official PDF.

Frequently asked questions

How many chapters are in the Class 12 Biology NCERT textbook?

Thirteen. The book runs from Chapter 1, Sexual Reproduction in Flowering Plants, to Chapter 13, Biodiversity and Conservation, across 228 printed pages. The chapters group into five units: reproduction, genetics and evolution, biology in human welfare, biotechnology, and ecology.

Is the Class 12 Biology textbook PDF free and official?

Yes. NCERT publishes the chapter PDFs free on ncert.nic.in, and the 13 links above are those official files. The printed book’s price is set by NCERT and printed on the book itself; the PDF costs nothing.

Which chapters cover genetics and inheritance?

Chapter 4 (Principles of Inheritance and Variation), Chapter 5 (Molecular Basis of Inheritance) and Chapter 6 (Evolution) form Unit 2, Genetics and Evolution, on pp. 51-126. Chapter 4 carries the book’s largest figure load, with 16 indexed diagrams.

Where can I find the answers to the exercises in this book?

The exercises print at the end of each chapter in the official PDFs above, and the directory on this page counts them chapter by chapter. For worked answers, follow your teacher’s guidance and NCERT’s official material on ncert.nic.in.

Is there a Hindi edition of the Class 12 Biology NCERT book?

Yes. NCERT publishes Hindi and other language editions on ncert.nic.in. This page indexes the current English edition (13 chapters); for what changed from older editions, NCERT’s official rationalisation notice is the authority.