On July 5, 2021, CBSE had announced that the Syllabus for Class 12 Board Exams will be reduced as per a Term-based Examination System and on July 22, 2021, they finalised the reduced syllabus as well by providing updated PDFs

Units Unit Names Marks
Term I
VI Reproduction - Chapter 2, 3 and 4 15
VII Genetics and Evolution - Chapter 5 and 6 20
Practical Work 15
Term II
VIII Biology and Human Welfare - Chapter 8 and 10 14
IX Biotechnology and its Applications - Chapter 11 and 12 11
X Ecology and Environment - Chapter 13 and 15 10
Practical Work 15

Unit VI Reproduction

Chapter 1: Reproduction in Organisms

Reproduction, a characteristic feature of all organisms for continuation of species; modes of reproduction – asexual and sexual reproduction; asexual reproduction – binary fission, sporulation, budding, gemmule formation, fragmentation; vegetative propagation in plants; events in sexual reproduction.

Chapter 2: Sexual Reproduction in Flowering Plants

Flower structure; development of male and female gametophytes; pollination – types, agencies and examples; outbreeding devices; pollen-pistil interaction; 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.

Chapter 3: Human Reproduction

Male and female reproductive systems; microscopic anatomy of testis and ovary; gametogenesis – spermatogenesis and oogenesis; menstrual cycle; fertilisation, embryo development upto blastocyst formation, implantation; pregnancy and placenta formation (elementary idea); parturition (elementary idea); lactation (elementary idea).

Chapter 4: Reproductive Health

Need for reproductive health and prevention of Sexually Transmitted Diseases (STDs); birth control – need and methods; medical termination of pregnancy (MTP); amniocentesis; infertility and assisted reproductive technologies – IVF, ZIFT, GIFT, AI (elementary idea for general awareness)

Unit VII Genetics and Evolution

Chapter 5: Principles of Inheritance and Variation

Heredity and variation, Mendelian inheritance; deviations from Mendelism – incomplete dominance, codominance, multiple alleles and inheritance of blood groups, pleiotropy; elementary idea of polygenic inheritance; chromosome theory of inheritance; chromosomes and genes; linkage and crossing over; Sex determination – in human being, birds, grasshopper and honey bee; Mutation, Pedigree analysis, sex linked inheritance – haemophilia, colour blindness; Mendelian disorders in humans sickle cell anaemia, Phenylketonuria,

thalassemia; chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes.

Chapter 6: Molecular Basis of Inheritance

Structure of DNA and RNA; DNA packaging; Search for genetic material and DNA as genetic material; DNA replication; Central Dogma; transcription, genetic code, translation; gene expression and regulation – lac operon; Human genome project; DNA fingerprinting.

Chapter 7: Evolution

Origin of life; biological evolution and evidences for biological evolution (paleontology, comparative anatomy, embryology and molecular evidences); adaptive radiation; Biological evolution: Lamarck’s theory of use and disuse of organs, Darwin’s theory of evolution; mechanism of evolution – variation (mutation and recombination) and natural selection with examples, types of natural selection; Gene flow and genetic drift; Hardy – Weinberg’s principle; brief account of evolution; human evolution.

Unit VIII Biology and Human Welfare

Chapter 8: Human Health and Diseases

Pathogens; parasites causing human diseases (malaria, dengue, chikungunya, filariasis, ascariasis, typhoid, pneumonia, common cold, amoebiasis, ringworm) and their control; Basic concepts of immunology – vaccines; cancer, HIV and AIDS; Adolescence – drug and alcohol abuse.

Chapter 9: Strategies for Enhancement in Food Production

Animal husbandry, Plant breeding, tissue culture, single cell protein.

Chapter 10: Microbes in Human Welfare

Microbes in food processing, industrial production, Antibiotics; production and judicious use, sewage treatment, energy generation and microbes as biocontrol agents and bio-fertilizers.

Unit IX Biotechnology and its Applications

Chapter 11: Biotechnology – Principles and Processes

Genetic Engineering (Recombinant DNA Technology).

Chapter 12: Biotechnology and its Application

Application of biotechnology in health and agriculture: genetically modified organisms – Bt crops; RNA interference, Human insulin, gene therapy; molecular diagnosis; transgenic animals; biosafety issues, biopiracy and patents.

Unit X Ecology and Environment

Chapter-13: Organisms and Populations

Organisms and environment: Habitat and niche, abiotic factors, ecological adaptations; population interactions – mutualism, competition, predation, parasitism, commensalism; population attributes – growth, birth rate and death rate, age distribution.

Chapter 14: Ecosystem

Ecosystem: structure and function; productivity and decomposition; energy flow; pyramids of number, biomass, energy; nutrient cycles (carbon and phosphorous); ecological succession; ecological services – carbon fixation, pollination, seed dispersal, oxygen release (in brief).

Chapter 15: Biodiversity and Conservation

Biodiversity – Concept, levels, patterns, importance; loss of biodiversity; biodiversity conservation; hotspots, endangered organisms, extinction, Red Data Book, Sacred Groves, biosphere reserves, national parks, wildlife, sanctuaries and Ramsar sites.

Chapter 16: Environmental Issues

Air pollution and its control; water pollution and its control; agrochemicals and their effects; solid waste management; radioactive waste management; greenhouse effect and climate change impact and mitigation; ozone layer depletion; deforestation; case study exemplifying success stories addressing environmental issue(s).

Practical Evaluation Scheme

Experiments Term I Term II Marks
Part A
One Major Experiment Experiment 1 Experiment 3 04
One Minor Experiment Experiment 2 Experiment 4, 5 03
Part B
Spotting (3 Spots for 1 mark each) 1, 3, 4, 5, 7 9, 10, 11 03
Practical Record + Investigatory Project & Record + Viva Voce 05

List of Practicals

Term I

  1. Isolate DNA from available plant material such as spinach, green pea seeds, papaya, etc.
  2. Prepare a temporary mount of onion root tip to study mitosis.

Term II

  1. Prepare a temporary mount to observe pollen germination.
  2. Collect water from two different water bodies around you and study them for pH, clarity and presence of any living organism.
  3. Collect and study soil from at least two different sites and study them for texture, moisture content, pH and water holding capacity. Correlate with the kinds of plants found in them.
  4. Study the presence of suspended particulate matter in air at two widely different sites.
  5. Study the plant population density by quadrat method.
  6. Study the plant population frequency by quadrat method.
  7. Prepare a temporary mount of onion root tip to study mitosis.

Study the effect of different temperatures and three different pH on the activity of salivary amylase on starch.


Term I


    1. Flowers adapted to pollination by different agencies (wind, insects, birds).
    2. Pollen germination on stigma through a permanent slide or scanning electron micrograph.
    3. Identification of stages of gamete development, i.e., T.S. of testis and T.S. of ovary through permanent slides (from grasshopper/mice).
    4. Meiosis in onion bud cells or grasshopper testis through permanent slides.
    5. T.S. of blastula through permanent slides (Mammalian).
    6. Mendelian inheritance using seeds of different colour/sizes of any plant.
    7. Prepared pedigree charts of any one of the genetic traits such as rolling of tongue, blood groups, ear lobes, widow’s peak and color blindness.

Term II

  1. Controlled pollination – emasculation, tagging and bagging.
  2. Common disease causing organisms like Ascaris, Entamoeba, Plasmodium, any fungus causing ringworm through permanent slides, models or virtual images. Comment on symptoms of diseases that they cause.
  3. Two plants and two animals (models/virtual images) found in xeric conditions. Comment upon their morphological adaptations.
  4. Two plants and two animals (models/virtual images) found in aquatic conditions. Comment upon their morphological adaptations.