The Council for the Indian School Certificate Examinations (CISCE) has prescribed the Biology syllabus for ISC Class 12 students for the academic session 2026-27. The syllabus covers five major units, including Reproduction, Genetics and Evolution, Biology and Human Welfare, Biotechnology and its Applications, and Ecology and Environment. These units introduce students to important biological concepts, human health, genetic processes, modern scientific techniques and environmental conservation.
Students preparing for the ISC Class 12 Board Examination 2027 should understand the complete syllabus before starting their preparation. The syllabus also explains the marks distribution for theory, practical examinations, project work and practical files. Here is the complete syllabus explained in simple language, following the topics prescribed by CISCE.
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ISC Class 12 Biology Exam Pattern 2026-27
According to the CISCE syllabus, Biology is divided into theory, practical examination, project work and practical file assessment. The subject carries a total of 100 marks.
| Examination component | Duration | Marks |
|---|---|---|
| Paper I – Theory | 3 hours | 70 |
| Paper II – Practical | 3 hours | 15 |
| Project Work | — | 10 |
| Practical File | — | 5 |
ISC Class 12 Biology Unit-Wise Marks Distribution
The theory syllabus consists of five units. The marks assigned to each unit are given below.
| No. | Units | Marks |
|---|---|---|
| 1 | Reproduction | 16 |
| 2 | Genetics and Evolution | 15 |
| 3 | Biology and Human Welfare | 14 |
| 4 | Biotechnology and its Applications | 10 |
| 5 | Ecology and Environment | 15 |
| Total | 70 |
Reproduction carries the highest weightage of 16 marks, followed by Genetics and Evolution and Ecology and Environment, with 15 marks each. Students should prepare all five units because each contributes to the final theory examination.
ISC Class 12 Biology Complete Syllabus 2026-27: All Units Explained
CISCE has divided the Biology syllabus into five units. Below is the complete topic-wise breakdown in easy language to help students understand what they need to study.
1. Reproduction – 16 Marks
This unit explains how plants and humans reproduce and how new life develops. It covers three major chapters.
| Chapters | Complete topics explained in easy language |
|---|---|
| Sexual Reproduction in Flowering Plants | Structure of flowers; male and female gametophytes; structure and development of pollen grains; microsporogenesis and megasporogenesis; pollination and its types (self-pollination and cross-pollination); pollination through wind, water and insects; outbreeding devices; pollen-pistil interaction; artificial hybridisation, emasculation and bagging; fertilisation and double fertilisation; development of endosperm and embryo; formation of seeds and fruits; monocot and dicot embryos; types of endosperm; true and false fruits; albuminous and non-albuminous seeds; apomixis, parthenocarpy, polyembryony and seed dispersal. |
| Human Reproduction | Male and female reproductive systems and their functions; microscopic structure of testes and ovaries; spermatogenesis and oogenesis; sperm and ovum structure; hormonal control of gamete formation; menstrual cycle and its phases; fertilisation; development of the embryo up to the blastocyst stage; implantation; pregnancy; placenta and its functions; childbirth (parturition); breastfeeding (lactation); menarche and menopause. |
| Reproductive Health | Meaning and importance of reproductive health; family planning and reproductive health programmes; population explosion and its control; sexually transmitted diseases (STDs), their causes, symptoms and prevention; natural and artificial contraceptive methods; birth control devices; medical termination of pregnancy (MTP); amniocentesis; causes of infertility; assisted reproductive technologies such as IVF, IUT, ZIFT, ICSI, GIFT, AI and IUI. |
Students learn how plants produce seeds, how reproduction takes place in humans, and how reproductive health can be maintained.
2. Genetics and Evolution – 15 Marks
This unit explains how characteristics pass from parents to children, how DNA controls inheritance and how living organisms change over generations.
| Chapters | Complete topics explained in easy language |
|---|---|
| Principles of Inheritance and Variation | Heredity and variation; Mendel's experiments and laws of inheritance; monohybrid and dihybrid crosses; test cross and back cross; dominant and recessive genes; genotype and phenotype; incomplete dominance; co-dominance; multiple alleles and ABO blood groups; polygenic inheritance; pleiotropy; chromosomal theory of inheritance; sex determination in humans and other organisms; linkage and crossing over; mutations; sex-linked inheritance; pedigree charts; genetic disorders such as haemophilia, colour blindness, sickle cell anaemia, thalassaemia and phenylketonuria; chromosomal disorders including Down's syndrome, Turner's syndrome and Klinefelter's syndrome. |
| Molecular Basis of Inheritance | DNA and RNA structure; discovery of genetic material; DNA packaging and chromosomes; DNA replication; central dogma; transcription and translation; genetic code and codons; protein synthesis; types of RNA; gene expression and regulation; lac operon; Human Genome Project; DNA fingerprinting and its applications. |
| Evolution | Origin of life; abiogenesis and biogenesis; Oparin-Haldane theory; Miller-Urey experiment; evidence of evolution through fossils, comparative anatomy, embryology and molecular biology; Darwin's theory of natural selection; modern synthetic theory of evolution; mutation and genetic recombination; natural selection; gene flow and genetic drift; Hardy-Weinberg principle; adaptive radiation; geological time scale; human evolution. |
This unit helps students understand why children inherit features from their parents, how genes and DNA work, and how different species have evolved over time.
3. Biology and Human Welfare – 14 Marks
This unit focuses on human health, diseases, immunity and the useful role of microorganisms in everyday life.
| Chapters | Complete topics explained in easy language |
|---|---|
| Human Health and Diseases | Communicable diseases and their causes; viral diseases such as common cold, chikungunya and dengue; bacterial diseases such as typhoid, pneumonia, diphtheria and plague; protozoan diseases such as malaria and amoebiasis; helminthic diseases such as ascariasis and filariasis; fungal diseases such as ringworm; immunity and its types; antibodies and vaccines; allergies; cancer and its diagnosis and treatment; HIV and AIDS; immune system organs; drug and alcohol abuse; effects of smoking and addiction. |
| Microbes in Human Welfare | Use of microorganisms in making curd, bread and cheese; industrial production of alcohol, organic acids, enzymes and antibiotics; penicillin; sewage treatment; biogas production; biocontrol agents; biofertilisers; beneficial microorganisms such as Lactobacillus, Rhizobium and Azotobacter; harmful effects of chemical pesticides. |
Students learn about common diseases, how the body protects itself from infections, and how microorganisms are useful in food production, industries and agriculture.
4. Biotechnology and its Applications – 10 Marks
This unit introduces students to modern biological techniques used in medicine, agriculture and scientific research.
| Chapters | Complete topics explained in easy language |
|---|---|
| Biotechnology – Principles and Processes | Meaning and principles of biotechnology; genetic engineering; recombinant DNA technology; isolation of DNA and desired genes; restriction enzymes and DNA ligase; cloning vectors such as pBR322, BAC and YAC; transfer of recombinant DNA into host cells; selection of recombinant organisms; gene amplification through PCR; bioreactors and their types; downstream processing. |
| Biotechnology and its Applications | Use of biotechnology in agriculture and medicine; genetically modified crops; Bt crops; RNA interference (RNAi); golden rice; micropropagation and somatic hybridisation; production of human insulin and vaccines; stem cell technology; gene therapy; molecular diagnosis through PCR and ELISA; transgenic animals; biosafety; biopiracy; biopatents and ethical issues. |
Students understand how scientists use genes and living cells to develop medicines, improve crops and diagnose diseases.
5. Ecology and Environment – 15 Marks
This unit explains the relationship between living organisms and their surroundings, the functioning of ecosystems and the importance of protecting biodiversity.
| Chapters | Complete topics explained in easy language |
|---|---|
| Organisms and Populations | Meaning of population; population density; birth rate and death rate; immigration and emigration; sex ratio and age distribution; population growth; exponential and logistic growth models; carrying capacity; population interactions such as mutualism, competition, predation, parasitism, commensalism and amensalism; Gause's principle of competitive exclusion. |
| Ecosystem | Meaning and types of ecosystems; biotic and abiotic components; pond ecosystem; productivity; gross and net primary productivity; decomposition; energy flow; food chains and food webs; trophic levels; ecological pyramids of number, biomass and energy; 10% law; standing crop and standing state. |
| Biodiversity and its Conservation | Meaning and types of biodiversity; genetic, species and ecosystem diversity; patterns of biodiversity; importance of biodiversity; causes of biodiversity loss; extinct species; habitat destruction; overexploitation; alien species invasion; co-extinction; biodiversity hotspots; endangered species; Red Data Book; conservation through national parks, wildlife sanctuaries, biosphere reserves, sacred groves, seed banks, botanical gardens and captive breeding; Ramsar sites; Earth Summit and World Summit. |
This unit teaches students how plants, animals and microorganisms interact with their environment, how ecosystems work and why protecting wildlife and natural resources is important.
ISC Class 12 Biology Practical Syllabus 2026-27
Apart from theory, CISCE has prescribed practical work carrying 15 marks. Students must perform experiments, prepare slides, identify specimens and demonstrate their understanding of biological structures.
ISC Class 12 Biology Practical Syllabus 2026-27
According to the CISCE syllabus, the Biology practical examination carries 15 marks. Students are required to perform experiments, prepare slides, identify specimens and demonstrate their knowledge of biological structures and processes.
1. Taxonomy
Study and identify floral characteristics of the following seven plant families:
- Malvaceae
- Leguminosae (Papilionaceae)
- Solanaceae
- Liliaceae or Amaryllidaceae
- Cruciferae
- Compositae (Asteraceae)
- Gramineae (Poaceae)
Students must learn flower dissection, floral formula, floral diagrams and labelled diagrams.
2. Biochemical and Physiological Experiments
- Study the distribution of stomata in monocot and dicot leaves
- Compare soil samples from two locations based on texture, moisture, humus, water-holding capacity and pH
- Study the effect of temperature and pH on amylase or diastase activity in starch
- Isolate DNA from plant materials such as banana, spinach, green peas or papaya
3. Slide Preparation
- Germination of pollen grains in a nutrient medium
- Transverse section (T.S.) of ovary to show marginal or axile placentation
- T.S. of hydrophyte stem
- T.S. of xerophytic leaf (Nerium).
- Longitudinal section (L.S.) of monocot and dicot seeds
4. Spotting
Identification of the following specimens and slides:
- Mammalian ovary and testis
- Germinating pollen grains
- Types of placentation
- Blastula or blastocyst
- Plasmodium sporozoite
- Entamoeba histolytica
- Ascaris
Students must also identify:
- Ecological adaptations
- Flowers pollinated by insects
- Flowers pollinated by water
- Flowers pollinated by wind
ISC Class 12 Biology Practical Marks Distribution
| Component | Marks |
|---|---|
| Practical Examination | 15 |
| Project Work | 10 |
| Practical File | 5 |
| Total (including theory) | 100 |
Some suggested project topics mentioned in the official syllabus include:
- Genetic disorders
- Gene therapy
- Human Genome Project
- DNA fingerprinting
- Biopiracy
- Cancer
- AIDS and Hepatitis
- Drug addiction and its effects on society
- Role of microorganisms in industries
- Human population
- Mendelian inheritance
- Environmental resistance
- Traditional and modern methods of pest control
- Role of agrochemicals in increasing food production
The project should include an introduction, relevant information, presentation through diagrams, graphs, tables or photographs, a conclusion and a bibliography. Original handwritten investigatory projects are preferred. The practical file must contain date-wise records of experiments checked and signed by the teacher.
Important Instructions for ISC Class 12 Biology Students
- Students should prepare all five theory units according to the prescribed syllabus
- Internal and external structures mentioned in the syllabus must be studied with diagrams
- Students should practise labelled biological diagrams and understand the experiments rather than memorising only their names
- Numerical topics, particularly population growth and the Hardy-Weinberg principle, should be practised with examples
- Students should also prepare the prescribed list of scientists and their contributions and the list of Biology abbreviations given in the official syllabus
ISC Class 12 Biology Syllabus PDF Download
Students can download the complete ISC Class 12 Biology Syllabus 2026-27 PDF from the link given below. The official document contains the prescribed syllabus and examination scheme for the academic session 2026-27.
| Subject | Official Syllabus PDF |
|---|---|
| ISC Class 12 Biology Syllabus 2026-27 | Download PDF |