CBSE Class 12 Biology Syllabus 2025-26
Official chapter-wise syllabus for CBSE Class 12 Biology — unit-wise marks distribution, list of deleted/reduced topics, and the 2025-26 exam paper pattern. Use this page alongside the Class 12 Biology preparation guide for full exam readiness.
2025-26
Academic Year
70
Theory Marks
30
Practical Marks
16
Total Chapters
Unit-Wise Marks Distribution
70 marks (theory)Unit VI: Reproduction
Reproduction in Organisms · Sexual Reproduction in Flowering Plants · Human Reproduction · Reproductive Health
23% of theory marks
Unit VII: Genetics and Evolution
Principles of Inheritance and Variation · Molecular Basis of Inheritance · Evolution
29% of theory marks
Unit VIII: Biology and Human Welfare
Human Health and Disease · Microbes in Human Welfare
17% of theory marks
Unit IX: Biotechnology
Biotechnology: Principles and Processes · Biotechnology and its Applications
17% of theory marks
Unit X: Ecology
Organisms and Populations · Ecosystem · Biodiversity and Conservation
14% of theory marks
Chapter-Wise Syllabus
16 chapters| # | Chapter | Marks |
|---|---|---|
| 1 | Reproduction in Organisms | 5 |
| 2 | Sexual Reproduction in Flowering Plants | 8 |
| 3 | Human Reproduction | 8 |
| 4 | Reproductive Health | 4 |
| 5 | Principles of Inheritance & Variation | 8 |
| 6 | Molecular Basis of Inheritance | 8 |
| 7 | Evolution | 5 |
| 8 | Human Health and Disease | 6 |
| 9 | Strategies for Enhancement in Food Production | 4 |
| 10 | Microbes in Human Welfare | 4 |
| 11 | Biotechnology: Principles and Processes | 6 |
| 12 | Biotechnology and Its Applications | 4 |
| 13 | Organisms and Populations | 5 |
| 14 | Ecosystem | 5 |
| 15 | Biodiversity and Conservation | 4 |
| 16 | Environmental Issues | 4 |
Deleted / Reduced Topics 2025-26
Note: The following topics have been deleted or reduced from the CBSE Class 12 Biology syllabus. Do not spend time studying these for the 2025-26 board exam. Always verify with the official CBSE syllabus document before your exam.
Reproductive Health
Medical termination of pregnancy — detailed ethical discussion
Evolution
Hardy-Weinberg equilibrium mathematical derivation
Ecosystem
Ecological services — detailed economic valuation
Environmental Issues
Entire chapter removed from board exam
Exam Paper Pattern 2025-26
70 marks total| Section | Marks/Q | Count | Total | |
|---|---|---|---|---|
| Section A | 1 | 16 | 16 | |
| Section B | 2 | 5 | 10 | |
| Section C | 3 | 7 | 21 | |
| Section D | 5 | 3 | 15 | |
| Section E | 4 | 2 | 8 | |
| Total Theory Marks | 70 | |||
Practical / Internal Assessment Marks — assessed throughout the year by your school (projects, lab work, notebooks).
How to Use This Syllabus
Prioritise by marks
Use the unit-wise distribution above. Focus first on units with 20+ marks — they give the best return on study time.
Skip deleted topics
CBSE will not ask deleted topics in the board exam. Don't waste time on them — use that time for NCERT exercises instead.
Know the paper pattern
Section E (Case Study) has new-format questions many students ignore. Practise these separately — they're easy marks.
You know the syllabus. Now practise it.
ClearSteps gives you chapter-wise mock tests aligned to the exact CBSE Class 12 Biology syllabus, with AI evaluation against the official marking scheme.