CBSE Class 12 Biology Syllabus & Exam Pattern (2025-26)

Overview of CBSE Class 12 Biology

CBSE Class 12 Biology is a comprehensive subject that builds a strong foundation in human physiology, genetics, ecology, reproduction, and biotechnology. It is a core subject for students preparing for NEET and for careers in medicine, dentistry, biotechnology, environmental science, and life sciences.

The syllabus, prescribed by the Central Board of Secondary Education, is organised into 5 units covering 16 chapters, with 70 marks for theory and 30 marks for practicals. Learning focuses on diagrams, biological processes, applications, and case-based questions, ensuring students develop both conceptual clarity and exam readiness. Broadly, the syllabus balances 40% human physiology, 30% genetics and biotechnology, and 30% ecology and reproduction.

Syllabus Highlights & Exam Pattern

The CBSE Class 12 Biology theory examination is a 3-hour paper carrying 70 marks, designed to test understanding, application, and clarity of presentation.

Key highlights of the exam pattern:

• Theory paper structure: 20% MCQs and assertion-reason questions, 20% case-based and competency-focused questions, 60% short and long answers with compulsory diagrams
• Practical examination (30 marks): Spotting and identification, slide preparation, project/investigatory work, viva voce
• Topic emphasis in theory: Human physiology (~20 marks), Genetics & evolution (~16 marks), Ecology & environment (~12 marks)

The syllabus has been rationalised for 2025-26, removing overly complex content while retaining core concepts relevant for board exams and NEET.

Unit-wise Syllabus Breakdown

The Class 12 Biology curriculum progresses from fundamental concepts to advanced applications in modern biology.

Class 12 Biology – Unit-wise Syllabus (Official Format)

UNIT	CHAPTERS	MARKS
Unit–VI	Reproduction Chapter–1: Sexual Reproduction in Flowering Plants Chapter–2: Human Reproduction Chapter–3: Reproductive Health	16
Unit–VII	Genetics and Evolution Chapter–4: Principles of Inheritance and Variation Chapter–5: Molecular Basis of Inheritance Chapter–6: Evolution	20
Unit–VIII	Biology and Human Welfare Chapter–7: Human Health and Diseases Chapter–8: Microbes in Human Welfare	12
Unit–IX	Biotechnology and its Applications Chapter–9: Biotechnology – Principles and Processes Chapter–10: Biotechnology and its Applications	12
Unit–X	Ecology and Environment Chapter–11: Organisms and Populations Chapter–12: Ecosystem Chapter–13: Biodiversity and its Conservation	10
Total (Theory)		70

Students are advised to follow the NCERT textbook sequence and practise 50+ labelled diagrams to ensure alignment with board and NEET questions.

Chapter-wise Weightage (High-Level)

Unit	Marks	Key Focus	Question Types
Genetics & Evolution	20	DNA replication, mutations	Long answers, diagrams
Reproduction	16	Human reproductive system	Diagrams, processes
Human Welfare	12	Immunity, diseases	Short notes, applications
Biotechnology	12	Recombinant DNA technology	Processes, applications
Ecology	10	Ecosystems, biodiversity	Case studies, conservation

High-weightage areas:

Genetics & Evolution alone contribute nearly 29% of the theory paper, making molecular biology concepts and diagrams especially important.

Practical & Lab Components

The Biology practical examination carries 30 marks and is compulsory.

• Spotting (15 marks): Identification of permanent slides (TS/LS), specimens, charts, and models
• Slide preparation (5 marks): Temporary mounts, such as onion root tip (mitosis) or squash preparations
• Project / investigatory work (5 marks): Topics like local biodiversity studies, pollution analysis, or the effects of plant hormones
• Viva voce & practical file (5 marks): Assessment of procedures, observations, and record maintenance

Regular practice of 20+ spotting specimens and neat, well-labelled records significantly improves practical scores.

Evaluation Scheme for Examination (Practical)

Component	Details	Marks
One Major Experiment	Experiment No. 5	5
One Minor Experiment	Experiment No. 2 or 3	4
Slide Preparation	Experiment No. 1 or 4	5
Spotting		7
Practical Record + Viva Voce	Credit may be given for work done during the academic session	4
Investigatory Project + Project Record + Viva Voce		5
Total		30

How to Study CBSE Class 12 Biology Effectively

• Practise NCERT diagrams daily (50+ labelled diagrams across chapters)
• Create flowcharts for key processes such as DNA replication, transcription, translation, and photosynthesis
• Memorise disease-causing agents, symptoms, and prevention methods for Human Welfare chapters
• Solve last 10 years' board papers and NCERT Exemplar questions to understand trends
• NEET focus: Units VI and VII (Reproduction & Genetics) account for nearly 60% of entrance questions
• Weekly revision combining diagrams + NCERT line-by-line reading

Download Biology Syllabus & Study Resources

Access essential Biology preparation resources:

• CBSE Class 12 Biology Syllabus PDF (2025-26)
• Diagram practice charts (50+ labelled diagrams)
• NEET chapter-wise weightage guide
• Spotting specimen identification sheets
• Download Biology Syllabus PDF Free