Class 12 Prelims: Environment 11 h reading
Biology
Chapters 5, 7–13: genes, health, microbes, biotechnology, ecology, biodiversity; skim chapters 2 and 6.
Why read it
It answers more Environment and Science questions than any other NCERT book (21 questions since 2016), most from Microbes in Human Welfare (ch 8). Download it chapter by chapter: the full book is a large file.
Read chapters 5, 7–13 only
Skim or skip: Skim chapters 2 (Human Reproduction) and 6 (Evolution).
Chapters (open on phones)
- Ch 1 Sexual Reproduction in Flowering Plants optional 25 pages · 37 MB
- Ch 2 Human Reproduction optional 15 pages · 65 MB
- Ch 3 Reproductive Health optional 10 pages · 1.3 MB
- Ch 4 Principles of Inheritance and Variation optional 28 pages · 19 MB
- Ch 5 Molecular Basis of Inheritance 31 pages · 4.1 MB 3 Prelims questions · Test yourself →
- Ch 6 Evolution optional 17 pages · 13 MB
- Ch 7 Human Health and Disease 22 pages · 4.5 MB 4 Prelims questions · Test yourself →
- Ch 8 Microbes in Human Welfare 12 pages · 13 MB 6 Prelims questions · Test yourself →
- Ch 9 Biotechnology: Principles and Processes 16 pages · 3.1 MB 2 Prelims questions · Test yourself →
- Ch 10 Biotechnology and its Applications 11 pages · 1.5 MB 4 Prelims questions · Test yourself →
- Ch 11 Organisms and Populations 17 pages · 1.6 MB 3 Prelims questions · Test yourself →
- Ch 12 Ecosystem 11 pages · 2.4 MB 1 Prelims question · Test yourself →
- Ch 13 Biodiversity and Conservation 13 pages · 2.3 MB 2 Prelims questions · Test yourself →
NCERT's original ZIP (file names in code) · 161 MB · Saves as lebo1dd.zip Large file (168 MB). On mobile data, download chapter by chapter.
What's inside the ZIP
NCERT names its files by code, not by chapter. Match each file to what it contains:
| lebo1ps.pdf | Opening pages: title, foreword, contents |
| lebo101.pdf | Ch 1 · Sexual Reproduction in Flowering Plants |
| lebo102.pdf | Ch 2 · Human Reproduction |
| lebo103.pdf | Ch 3 · Reproductive Health |
| lebo104.pdf | Ch 4 · Principles of Inheritance and Variation |
| lebo105.pdf | Ch 5 · Molecular Basis of Inheritance |
| lebo106.pdf | Ch 6 · Evolution |
| lebo107.pdf | Ch 7 · Human Health and Disease |
| lebo108.pdf | Ch 8 · Microbes in Human Welfare |
| lebo109.pdf | Ch 9 · Biotechnology: Principles and Processes |
| lebo110.pdf | Ch 10 · Biotechnology and its Applications |
| lebo111.pdf | Ch 11 · Organisms and Populations |
| lebo112.pdf | Ch 12 · Ecosystem |
| lebo113.pdf | Ch 13 · Biodiversity and Conservation |
UPSC Prelims 2016–2026
21 Environment and Science questions could be answered from this book
2026 answers follow UPSC's provisional answer key.
Test yourself (21 questions) →Where it helps
- Prelims: Environmental ecology, Bio-diversity and Climate Change
- Prelims: General Science
- GS III: Conservation, environmental pollution and degradation
- GS III: bio-technology
Edition: First published 2006; trimmed by NCERT 2022; this print 2026-27