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The ISC Class 12 Biology Syllabus 2026–27, set by the Council for the Indian School Certificate Examinations, is designed to strengthen students’ grasp of biological principles and their practical relevance.
It supports preparation for board examinations and competitive exams like NEET by combining theoretical knowledge with hands-on practical learning.
Download PDF: ISC Class 12 Biology Syllabus (2026-27)
ISC Class 12 Biology Syllabus 2027 Overview
The syllabus covers key areas such as Genetics, Ecology, Human Physiology, and Biotechnology, with equal emphasis on conceptual clarity and practical skills.
It follows a structured evaluation pattern, including theory and internal assessment, helping students develop analytical and scientific reasoning abilities.
ISC Class 12 Biology 2026-27 Syllabus: Major Key Points
These are the main highlights for ISC Class 12 Biology syllabus 2026-27:
- Strong focus on conceptual biology and application-based questions
- 70 marks theory + 30 marks practical work
- Practical examination includes experiments, spotting and slide identification
- Project work is compulsory and assessed by an external examiner
- Diagrams and labelled biological illustrations carry significant marks
- Analytical and reasoning-based questions are increasingly common
ISC Class 12 Biology Unit-Wise Marks Distribution
The table below shows the unit-wise marks distribution of theory and practical paper of Biology syllabus for Class 12 with the proper weightage shown with respect to the chapters.
ISC Biology Class 12 Chapter Sub Unit Bifurcation
The complete bifurcation of the Biology syllabus is given below for a better understanding of the syllabus in detail.
Paper I - Theory (70 Marks)
1. Reproduction
(i) Sexual reproduction in flowering plants
- Flower structure
- Development of male and female gametophytes
- Pollination - types, agencies and examples
- Outbreeding devices
- Pollen-pistil interaction
- Artificial hybridisation
- Double fertilization
- Post-fertilization events - development of endosperm and embryo
- Development of seed and formation of fruit
- Special modes - apomixis, parthenocarpy, polyembryony
- Significance of seed dispersal and fruit formation
(ii) Human Reproduction
- Male and female reproductive systems
- Microscopic anatomy of testis and ovary
- Gametogenesis - spermatogenesis and oogenesis
- Menstrual cycle
- Fertilisation, embryo development up to blastocyst formation, implantation
- Pregnancy and placenta formation (elementary idea)
- Parturition (elementary idea)
- Lactation (elementary idea)
(iii) Reproductive Health
- Need for reproductive health and prevention of Sexually Transmitted Diseases (STDs)
- Birth control - need and methods
- Contraception and Medical Termination of Pregnancy (MTP)
- Amniocentesis
- Infertility and assisted reproductive technologies (elementary idea for general awareness)
2. Genetics and Evolution
(i) Principles of inheritance and variation
- Heredity and variation
- Mendelian inheritance
- Deviations from Mendelism - incomplete dominance, co-dominance, multiple alleles, inheritance of blood groups, pleiotropy
- Elementary idea of polygenic inheritance
- Chromosomal theory of inheritance
- Sex determination
- Linkage and crossing over
- Mutation
- Sex-linked inheritance
- Mendelian disorders and chromosomal disorders in humans
(ii) Molecular basis of Inheritance
- Search for genetic material
- Structure of DNA and RNA
- DNA packaging
- DNA replication
- Central dogma
- Transcription, genetic code, translation
- Regulation of gene expression - lac operon
- Human Genome Project
- DNA fingerprinting
(iii) Evolution
- Origin of life
- Biological evolution and evidences for biological evolution (palaeontology, comparative anatomy, embryology and molecular evidences)
- Darwin’s contribution
- Modern synthetic theory of evolution
- Mechanism of evolution - variation and natural selection with examples, types of natural selection
- Gene flow and genetic drift
- Hardy-Weinberg’s principle
- Adaptive radiation
- Human evolution
3. Biology and Human Welfare
(i) Human Health and Diseases
- Pathogens; parasites causing human diseases (viruses, bacteria, protozoans, helminths, and fungi)
- Basic concepts of immunology - vaccines
- Cancer, HIV and AIDS
- Adolescence - drug and alcohol abuse
(ii) Microbes in Human Welfare
- In household food processing, industrial production, sewage treatment, energy generation and microbes as biocontrol agents and biofertilisers
- Antibiotics
4. Biotechnology and its Applications
(i) Biotechnology - Principles and processes
Genetic Engineering (recombinant DNA technology)
(ii) Biotechnology and its applications
- Applications of biotechnology in health and agriculture: human insulin and vaccine production, stem cell technology, gene therapy
- Genetically modified organisms - Bt crops
- Transgenic animals
- Biosafety issues, biopiracy and biopatents
5. Ecology and Environment
(i) Organisms and Populations
Population; population interactions - population attributes - growth, birth rate and death rate, age distribution
(ii) Ecosystem
Ecosystems: patterns, components; productivity and decomposition; energy flow; pyramids of number, biomass, energy
(iii) Biodiversity and its Conservation
Concept of biodiversity; patterns of biodiversity; importance of biodiversity; loss of biodiversity; biodiversity conservation; hotspots, endangered organisms, extinction, Red Data Book, biosphere reserves, national parks, sanctuaries and Ramsar sites
Paper II - Practical Work (15 Marks)
Candidates are required to complete the following experiments:
- Taxonomy - Study floral characteristics of 7 prescribed families (Malvaceae, Papilionaceae, Solanaceae, Liliaceae/Amaryllidaceae, Cruciferae, Compositae, Gramineae).
- Simple biochemical and physiological experiments (food tests, effect of temperature/pH on enzyme, chromatography, plasmolysis, osmosis, etc.).
- Morphology - Modification of roots, stems, leaves.
- Cytology - Temporary slides of onion peel, mitosis, T.S. of dicot/monocot stem/root.
- Spotting - 13 prescribed spots (meiosis stages, blood cells, bacteria, plant/animal specimens, ecological adaptations, etc.).
Project Work & Practical File (15 Marks)
- Project Work (10 Marks) - One creative investigatory project (handwritten preferred).
- Practical File (5 Marks) - Assessment based on all experiments recorded during the year.
Class 12 ISC Biology Deleted Chapters (2026-27)
ISC Biology Syllabus Class 12 recently released by CISCE, has no alterations as compared to the previous year 2025-26. There are no chapters deleted or added in the updated syllabus for the year 2026-27.
How to Best Prepare for ISC Class 12 Biology Exams
To prepare for ISC Class 12 Biology exam 2027, these preparation tips can surely be helpful.
- Understand the syllabus and weightage first
Start by identifying high-weightage units like Reproduction, Genetics, and Ecology to prioritise your preparation.
- Focus on concepts, not memorisation
Biology in ISC requires understanding processes (like reproduction, evolution, biotechnology) rather than rote learning.
- Practice diagrams regularly
Neat, well-labelled diagrams can help you score better, especially in questions from Human Physiology and Ecology.
- Revise NCERT thoroughly
Many questions, especially for NEET-level prep, are directly based on NCERT concepts and lines.
- Make concise notes for revision
Summarise important terms, cycles, and processes for quick last-minute revision.
- Prepare practicals and spotting seriously
Practice slide identification, specimens, and experiments as they are crucial for scoring in internal assessment.
- Solve previous years’ papers
This helps you understand frequently asked topics and improves answer-writing skills.
- Focus on keywords in answers
Use scientific terms and proper terminology to match ISC marking expectations.
FAQs
Q1. How are diagrams evaluated in the ISC Biology exam?
Ans. Diagrams carry dedicated marks. Neat, well-labelled, and relevant diagrams can help improve overall scores even if the answer is partially correct.
Q2. What type of questions are asked in ISC Class 12 Biology exams?
Ans. The exam includes a mix of direct theory, application-based questions, diagram-based questions, and reasoning-type questions.
Q3. Why is Genetics considered the most scoring yet tricky unit?
Ans. Genetics is logic based and so it is scoring yet tricky at the same time.
Q4. Is the ISC syllabus for Class 12 Biology 2026-27 released?
Ans. Yes, the syllabus for Class 12 Biology for the academic year 2026-27 has been officially released on the CISCE website.
Q5. Can I skip any chapter in ISC Class 12 Biology and still score well?
Ans. ISC papers are well-balanced and skipping a chapter completely can cost marks.
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