SyllabusCBSE class 12 Biology syllabus, 2026-27
Units, chapters and marks for Biology, from the CBSE curriculum for the session 2026-27.
- Board and class
- CBSE, class 12
- Theory paper
- 70 marks, 3 hours
- Practical
- 30 marks
- Total
- 100 marks
- Official file
- Open the CBSE file (PDF)
- Read on
- 12 November 2026
About this syllabus
The Board numbers the class 12 units VI to X, continuing from the five units of class 11. There are thirteen chapters. Genetics and Evolution is the heaviest unit at 20 marks, followed by Reproduction at 16. The practical examination is 30 marks and includes spotting, slide preparation and an investigatory project.
Marks by unit
| Unit | Marks | Share of the paper |
|---|---|---|
| Reproduction | 16 | 23% |
| Genetics and Evolution | 20 | 29% |
| Biology and Human Welfare | 12 | 17% |
| Biotechnology and its Applications | 12 | 17% |
| Ecology and Environment | 10 | 14% |
| Total, theory | 70 | 100% |
Units and chapters
- Reproduction
- Sexual Reproduction in Flowering Plants
- Human Reproduction
- Reproductive Health
- Genetics and Evolution
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Biology and Human Welfare
- Human Health and Diseases
- Microbes in Human Welfare
- Biotechnology and its Applications
- Biotechnology: Principles and Processes
- Biotechnology and its Applications
- Ecology and Environment
- Organisms and Populations
- Ecosystem
- Biodiversity and its Conservation
Where the marks are
The theory paper is 70 marks in 3 hours. The largest share goes to Genetics and Evolution with 20 marks, which is 29% of the paper. The smallest is Ecology and Environment with 10 marks. The two largest entries in the table together carry 36 marks, 51% of the paper. With 13 chapters in all, an average chapter is worth about 5.4 marks, but the table shows how unevenly they are spread.
The other marks
| Part | Marks | How it is split |
|---|---|---|
| Practical | 30 | Experiments, slide preparation, spotting, practical record with viva, and an investigatory project with its record and viva; the split is given in the official file |
Using this to plan
- Genetics and Evolution with Reproduction is 36 of 70 marks: more than half the theory paper from six chapters.
- Diagrams are part of the answer in biology. Practise the labelled diagrams of each chapter.
- Biotechnology is two chapters for 12 marks, a good return for the time it takes.
Make a study plan from these marks Official file
Questions people ask
How many marks is the CBSE class 12 Biology theory paper?
The theory paper is 70 marks. With practical (30) it makes a total of 100.
Which unit carries the most marks in class 12 Biology?
Genetics and Evolution, with 20 of the 70 marks, according to the CBSE curriculum for 2026-27.
Where is the official syllabus?
On CBSE's academic website, cbseacademic.nic.in, under Curriculum. This page links to the exact file for Biology.
Always check the official file. This page is a summary of the CBSE curriculum for 2026-27, made from the subject file on cbseacademic.nic.in, which we read on 12 November 2026. CBSE can revise a syllabus by circular during the year. Before an examination, download the current file from the official site. This is an independent site, not connected with CBSE.