ISC Class 12 Biology Syllabus




Described Syllabus For Theory Exam:

There will be two papers in the subject.

Paper I: Theory: 3 hours ………. 70 marks

Paper II: Practical: 3 hours ..… 20 marks

                  Project Work …………. 7 marks

                  Practical File ………….. 3 marks


PAPER I –THEORY – 70 Marks

There will be one paper of 3 hours duration divided into two parts.

Part I (20 marks) will consist of compulsory short answer questions, testing knowledge, application and skills relating to elementary/fundamental aspects of the entire syllabus.

Part II (50 marks) will be divided into three Sections A, B and C. Candidates will be required to answer two out of three questions from Section A (each carrying 5 marks), two out of three questions from Section B (each carrying 10 marks) and two out of three questions from Section C (each carrying 10 marks). Therefore a total of six questions are to be answered in Part II.

All structures (internal and external) are required to be taught along with diagrams.


1. Origin and Evolution of Life

(i) Origin of life: living and nonliving; chemical evolution; organic evolution – Oparin ideas, Miller-Urey experiments; interrelationship among organisms and evidences of evolution: morphological evidences – homology and analogy, vestigial organs, atavism; embryological, palaeontological (fossils) and biogeographical evidences. Origin of life. Important views on the origin of life, modern concept of origin of life, Oparin Haldane theory, coacervates, Miller and Urey experiment, evidences of evolution: vestigial organs, atavism, homologous and analogous organs (two examples each from plants and animals), embryological evidences – theory of recapitulation, palaeontological evidence – definition and example of Archaeopteryx, biogeographical evidence – Darwin’s finches.

(ii) Theories of evolution: Lamarckism: evidences in favour of Lamarckism (giraffe’s neck), criticism of Lamarckism; Darwinism: basic postulates of Darwinism, drawbacks of Darwinism, Neo-Darwinism; Hardy Weinberg’s principle; variations: causes of variation, mutation, selected examples and types of natural selection (DDT resistance in mosquito, sickle-cell anaemia); artificial selection; adaptations. Human evolution: Dryopithecus, Australopithecus, Homo erectus, Homo neanderthalensis, Cromagnon man and Homo sapiens; differences between apes and man.

Brief idea of Lamarck’s theory to be given for better understanding of evolution; salient features of Darwinism; causes of variation, mutation – definition and its role in evolution (frameshift and substitution), examples of natural selection – resistance of mosquitoes to DDT, sickle cell anaemia, difference between natural and artificial selection, types of natural selection (directional, disruptive and stabilising) mechanism of speciation, definition of gene pool, gene flow, genetic drift and Hardy Weinberg’s principle; evolution of man – brief idea of ancestors leading to man of today; comparison and homology in chromosomes of apes and man.



2. Multicellularity

A. Plants

(i) Tissues: types of plant tissues: Meristematic: Classification of Meristematic tissue. Permanent Tissues: Structure and function of simple tissues (parenchyma, collenchyma and sclerenchyma) and complex tissues (xylem and phloem), types of vascular bundles, T. S of young dicot and monocot stem, T. S of young dicot and monocot root and V. S. of dicot and monocot leaf. Secondary growth in stem: brief idea of formation of secondary xylem and secondary phloem by cambium ring formation, annual rings.

Characteristics of meristematic tissue; classification of meristems based on origin and location; characteristics of permanent tissues; simple and complex tissues; types of vascular bundles to be taught with the help of diagrams; anatomical differences between dicot and monocot root, stem and leaf must be taught for better understanding.

Basic idea of how secondary growth takes place in stems and formation of annual rings.

(ii) Absorption and movement of water in plants: diffusion, imbibition, osmosis, osmotic pressure, turgor pressure/ pressure potential wall pressure, water potential, diffusion pressure deficit. Types of soil water, mechanism of water absorption (active and passive absorption), root pressure, transpiration, transpiration pull theory for ascent of sap, mechanism of opening and closing of stomata (active potassium theory), guttation.

Characteristics of imbibition; factors affecting imbibition; importance of imbibition, characteristics and significance of diffusion; osmosis – endosmosis and exosmosis; significance of osmosis, plasmolysis, importance of water, soil water (gravitational, capillary, hygroscopic and combined water – only definitions); active and passive absorption of water; apoplastic and symplastic movements, definition of water potential. Explanation and definition of transpiration to give students a clear idea; differences between transpiration and guttation; significance of transpiration. Stomatal mechanism – K+ transport mechanism. Mechanism of ascent of sap by cohesion – tension and transpiration pull theory.

(iii) Photosynthesis: ultra structure of chloroplast, photochemical and biosynthetic phases, absorption and action spectra, factors affecting photosynthesis, photophosphorylation; photorespiration, transport of solutes.

Photosynthesis and photorespiration.

Brief idea of photosynthetic pigments, photochemical phase – pigment systems, cyclic and non-cyclic photophosphorylation; bi
osynthetic phase- C3 and C4 cycles; photorespiration pathway in brief – explanation of how RuBP carboxylase acts as RuBP oxygenase. Kranz anatomy. Blackman’s Law of limiting factors, factors affecting Photosynthesis.

Transport of solutes and water; Evidences which indicate that downward movement of organic solutes takes place in phloem; mechanism of translocation; mass flow hypothesis with diagram.

(iv) Reproduction and development in angiosperms: vegetative reproduction, sexual reproduction: development of male and female gametophytes, placentation, pollination, fertilisation (Amphimixis) and formation of endosperm, embryo, seed and fruits (broadly classified). Apomixes, Polyembryony, Parthenocarpy. Significance of seed and fruit formation.

Natural and artificial vegetative propagation, advantages and disadvantages of vegetative reproduction. Advantages of self and cross-pollination and events leading to fertilization should be discussed. Fruits to be classified into simple (dry and fleshy), aggregate and multiple. Apomixes, Polyembryony, Parthenocarpy to be explained briefly. Significance of seed and fruit formation.

(v) Differentiation and organ formation.

Embryo formation (monocot and dicot); endosperm formation; changes in the ovule and ovary for seed and fruit formation.

B. Animals

Reproduction (human): internal structure of human testis and ovary, menstrual cycle, gametogenesis, embryonic development in mammals (up to three germ layers). Medical termination of pregnancy, infertility. Amniocentesis. Assisted reproductive technologies.

Organs of male and female reproductive system and their functions; internal structure of testis and ovary; gametogenesis-spermatogenesis and oogenesis; menstrual cycle – different phases and hormone action, capaciation, fertilisation, physio-chemical events during fertilisation, implantation, embryonic development up to three germ layers, foetal membranes, placenta and its functions. Parturition; lactation – hormonal control and importance; brief knowledge about medical termination of pregnancy and causes of infertility. Amniocentesis – role in detecting genetic defects. Assisted reproductive technologies — IVF, ZIFT, GIFT (Definition and application only).



3. Genetics

(i) Fundamentals of Genetics: concept of alleles: dominant and recessive; phenotype and genotype, homozygous and heterozygous, mono and dihybrid crosses.

Homologous chromosomes, autosomes and sex chromosomes; alleles – dominant and recessive; phenotype; genotype; homozygous; heterozygous, monohybrid and dihybrid crosses; back cross and test cross, definitions to be taught with simple examples.

(ii) Mendel’s experiments with peas; Mendel’s Principles of inheritance, incomplete dominance, co-dominance and multiple alleles.

Explanation of the terms heredity and variation; Mendel’s Principles of inheritance; reasons for Mendel’s success; incomplete dominance and co-dominance, epistasis, multiple alleles – e.g blood groups, polygenic inheritance.

(iii) Genes: packaging of hereditary material in chromosomes. Linkage and crossing over; linkage maps, sex determination and sex linkage, search for DNA as genetic material, central dogma; genetic code, protein synthesis. Human genome project. DNA finger printing.

Chromosomal theory of inheritance; chromosomes in eukaryotic organisms, autosomes and sex chromosomes (sex determination in humans, birds and honey bees), sex-linked inheritance, complete and incomplete linkage and crossing over, chromosomal mapping and its significance; replication of genetic material, functions of genes – expression of genetic information, gene expression in prokaryotes, search for DNA as genetic material – Griffith’s experiment, Hershey and Chase’s experiment; central dogma; Lac Operon; genetic code. Transcription, translation and protein synthesis.

Human genome project: goal, methodologies, salient features and applications. DNA finger printing – technique, application and ethical issues to be discussed briefly.

(iv) Recombinant DNA technology and its applications.

Restriction enzymes, DNA insertion by vectors and other methods, regeneration of recombinants. In human health – production of insulin, vaccines and growth hormones, gene therapy. In industry – production of expensive enzymes, strain improvement to scale up bioprocesses. In agriculture – GM crops by transfer of genes for nitrogen fixation, herbicide-resistance and pestresistance including Bt crops. Brief idea about Transgenics and GMO with special reference to Bt crops. Biosafety issues: biopiracy and patents.


4. Applications of Biology

(i) Crop improvement: methods of crop improvement: selection, hybridisation, plant breeding, plant introduction, tissue culture; single cell protein; biofortification; biopesticides.

A reference to green revolution only. Plant breeding, introduction, selection, and techniques of hybridisation. Polyploidy – origin of wheat must be discussed. Definition of heterosis, protoplast culture and protoplasmic fusion. Applications of tissue culture to be discussed; single cell protein – source and significance; biofortification: meaning and its role in improving food production. Biopesticides: definition, importance and two examples (Bioinsecticides e.g. Bacillus thuringiensis, Bioherbicides e.g. Cochineal insect)

(ii)Biodiversity today: importance of biodiversity, types of biodiversity, genetic conservation, gene banks and cryopreservation. Loss of biodiversity – threatened, endangered and extinct species. Strategies for conservation of biodiversity – in-situ and ex-situ.

Importance of biodiversity, Few examples of each type of biodiversity – species, ecosystem and genetic. A general idea that species share a common gene pool and represent the lowest taxonomic group. Definition of genetic conservation, genetic erosion, gene bank and cryopreservation; factors affecting genetic erosion.

Only a brief understating of the following is required:

Implications of loss of biodive
rsity. Categorizing species in different groups like – threatened, endangered and extinct. Examples of plants and animals. Looking at various in-situ and ex-situ strategies for their efficacy and viability. In-situ – protected areas (biosphere reserves, national parks, wildlife sanctuaries). Hotspots and red data book. Ex-situ – captive breeding, zoo, botanical garden.

(iii) Biofertilisers: green manure, nitrogen fixation – symbiotic and non-symbiotic organisms.

Green manures – definition and types; reasons for preference of biofertilisers over chemical fertilisers should be discussed. Role of bacteria in improving soil fertility.

(iv) Human Diseases: body’s defence mechanisms: (specific and non-specific); immune disorders (SCID and AIDS); allergies, interferons, communicable diseases: causative agent, symptoms and prevention of the following: bacterial diseases (typhoid and pneumonia), viral diseases (common cold, swine flu and dengue), protozoa (malaria, and amoebiasis), helminthes (ascariasis, ringworm, and filariasis); sexually transmitted diseases (STD); non-communicable diseases: cancer (types, causes, diagnosis and treatment); human genetic disorders: (haemophilia, thalassaemia, albinism, Down’s syndrome, Klinefelter’s syndrome, Turner syndrome).

Rh factor incompatibility – during transfusion and pregnancy. Genetic counselling; a brief idea of stem cells, organ transplants and immunosuppression.

Skin, blood vessels, WBC, antibodies to be discussed as non-specific defence mechanisms; Humoral and cell-mediated immune system; antibody and antigen; cells of the immune system; mechanism of action of T cells to antigens; brief idea of SCID and AIDS; sexually transmitted diseases (STD), diseases should be discussed on basis of causative agent, symptoms and prevention; cancer (types, causes, diagnosis and treatment); human genetic disorders: (haemophilia, thalassaemia, albinism, Down’s syndrome, Klinefelter’s syndrome, Turner syndrome). Rh factor incompatibility – role of Rh factor in blood transfusion and pregnancy; brief idea of genetic counselling, role of genetic counsellor and role of immunosuppressants. A brief idea of the role of stem cells in medical treatment.

(v) Adolescent issues: alcoholism and drugs.

Adolescent issues (alcoholism and drugs – reasons for addiction and its effects on health).

(vi) Biomedical Engineering: (only applications) Instruments – ECG, EEG, CT scan, ultrasound, MRI, pacemakers, implants, disposables, external prosthesis.

Students should know one application of each of the instruments mentioned above. Details are not required.

(vii) Human population: population growth curves, causes of increase in population.

Terms biotic potential, environmental resistance and carrying capacity; population: birth rate, death rate, age distribution; types of growth curves; causes and measures to control population (natural and artificial).

(viii) Animal Husbandry: Dairy farm management, poultry farm management, apiculture, pisiculture.

Brief idea of inbreeding, outbreeding, crossbreeding, artificial insemination and measures for farm maintenance.





1) Taxonomy: Study floral characteristics through dissection of flowers, drawing floral formula and diagrams of following families:

(i) Malvaceae: type – China rose / Hollyhock.

(ii) Compositae: type – Sunflower/ Cosmos/ Marigold (with single whorled ray florets)/ Dahlia/ Zinnia.

(iii) Leguminosae: subfamily – Papilionaceae – type – Sweet pea/ Pea/ Bean/ Sesbania/ Clitoria (single flower).

(iv) Solanaceae: type – Petunia / Datura / Brinjal Flower / Solanum nigrum.

(v) Liliaceae: type – Onion or Amarallydaceae –type – Lily/Spider lily/ Tiger lily/ Tube rose/ Gladiolus.

Floral characteristics should be explained by dissection of flowers. Students should be taught how to take vertical section of the flower and draw accordingly labelled diagrams. The technique of drawing floral diagrams with the mother axis in the right position should be taught. Floral formula should be correctly written. Identification of the correct family giving reasons, technique of cutting T.S. and L.S of ovary should be explained and accordingly correct labelled-diagram should be drawn.

Students should be taught the examples of plants (belonging to each family) which are of economic importance. The examples of common names of plants must be supported with correct scientific names as well.

2) Simple biochemical and physiological experiments-

(i) Study of imbibition in raisins/seeds.

(ii) Demonstration of plasmolysis (using rheo leaf and onion bulb).

(iii) Demonstration of osmosis in living plant cells (potato osmoscope).

(iv) Demonstration of unequal transpiration in leaves.

(v) Study of arrangement/distribution of stomata on isobilateral and dorsiventral leaves.

(vi) To demonstrate the effect of different intensities of light on photosynthesis.

(vii) To demonstrate that oxygen is evolved during photosynthesis.

(viii) Effect of different carbon dioxide concentrations on the rate of photosynthesis.

Students should be taught to set up and demonstrate the experiments with correct diagram of the set up and give conclusions. This will give a clear idea of the physiological processes.

3) Slide preparation –

(i) T.S. of dicot root.

(ii) T.S. of monocot root.

(iii) T.S. of dicot stem.

(iv) T.S. of monocot stem.

(v) Germination of pollen grain.

The technique of collecting the material from the correct location, staining and mounting neatly should be explained. Identification of the mount under the microscope should be taught. Students must know the use of low power and high power microscope. They should also know how to make labelled outline drawings.

4) Spotting: (Three minutes to be given for each spot which includes identification, drawing a labelled diagram and writing two characteristics). Spotting must be done on a separate answer sheet during examination, which should be handed over to the Examiner immediately after spotting.

(i) Identify and comment on permanent slides of:

     (a) T.S of monocot and dicot stem.

     (b) T.S. of monocot and dicot root.

     (c) T.S. of monocot and dicot leaf.

     (d) T.S. of ovary of mammal.

     (e) T.S. of testis of mammal.

     (f) Germinating pollen grain.

     (g) T.S. of morula

     (h) T.S. of blastula.

     (i) T.S. of gastrula.

     (j) Plasmodium.

     (k) Entamoeba histolytica.

Students should be taught how to identify, draw, label and give significantly visible characteristics as observed, of each spot, in a given time of three minutes.

(ii) Students should identify, draw and comment on:

(a) Different types of inflorescence – basic racemose, basic cymose and capitulum. Students should be able to identify the type of inflorescence, draw its diagram and write two characteristics of the specimen.

(b) Flowers adapted to pollination by different agencies – insect and wind. Students should be able to identify the type of pollination of the given flower, draw the diagram of the flower and give two reasons for the type of pollination.

(iii)Comment on experimental set up studied in physiology.

(a) Osmosis

(b) Transpiration

(c) Photosynthesis

(d) Transpiration pull.

Students should identify (aim of the experiment), draw the physiological set-up and write a brief description (observation, inference, precautions) of the experiment within the allotted time i.e., 3 minutes.



Project Work – 7 Marks

The project work is to be assessed by a Visiting Examiner appointed locally and approved by the Council.

The candidate is to creatively execute one project/assignment on an aspect of biology. Teachers may assign or students may choose any one project of their choice. Students can choose any other project besides the ones indicated in the list. Following is only a suggestive list of topics:

(i) Diabetes.

(ii) Cancer.

(iii) AIDS/Hepatitis.

(iv) Drug addiction and community.

(v) Endocrine glands.

(vi) Role of micro-organisms in industry.

(vii) Human population.

(viii) Mendelian Inheritance

(ix) Environmental resistance.

(x) Traditional and modern methods: Study of a few traditional methods of pest deterrence vis-a-vis modern methods of pest control – viability of traditional methods in today’s scenario and limitations and dangers of modern methods.

(xi) Role of agrochemicals in increasing food production.


Practical File – 3 Marks

The Visiting Examiner is required to assess students on the basis of the Biology Practical file maintained by them during the academic year

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