WBCHSE Class 12 Biology Syllabus 2020-21

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Unitwise Marks Distribution

Unit NameMarks
Unit I: Reproduction Organisms14
Unit II: Genetics and Evolution*18
Unit III: Biology and Human Welfare14
Unit V: Ecology and Environment*14

*Few topics or chapters have been reduced from the unit mentioned above.


  1. Reproduction in Organisms

1.1 Introduction: Reproduction a characteristic features of all organism froms, continuation of species.

1.2 Modes of reproduction: Asexual and sexual

1.3 Asexual reproduction: definition, characteristics

1.4 Modes of asexual reproduction: General discussion of the following types in brief with common examples & diagram of each type:

a) Binary fission

b) Sporulation

c) Budding

d) Gemmule

e) Fragmentation

f) Regeneration

1.5 Vegetative propagation in plants:

a) Natural: (general discussion in brief, Mention common example and give figures)

b) Artificial: (brief description of method, example and diagram)- cutting grafting layering and gootee.

  1. Sexual Reproduction In flowering Plants

2.1 Flower structure: Typical structure of a complete regular flower with diagram.

2.2 Pollination: Definition, types-Self pollination ( autogamy and geitonogamy) and cross pollination. (allogamy and xenogamy); agents of pollinationwind, water, animals, insects and birdsbrief description with example, significance.

2.3 Development of male gametophyte

2.4 Development of female gametophyte

2.5 Outbreeding devices

2.6 Pollen- pistil interaction

2.7 Double fertization

2.8 Post fertilisation events – development of endosperm and embryo (details not required).

2.9 Formation of fruit and development of seed (elementary)

2.10 Special modes – apomixes, parthenogenesis, Parthenocarpy and Polyembryony (brief account)

2.11 Significance of seed and fruit formation

  1. Human Reproduction

3.1 Introduction

3.2 Male Reproductive system (outline with diagram)

3.3 Female Reproductive system (outline with diagram)

3.4 Microscopic anatomy of testis and ovary

3.5 Gametogenesis- Definition and type

3.6 Spermatogenesis (brief account)

3.7 Oogenesis (brief account)

3.8 Menstrual cycle

3.9 Fertilization and development of embryo upto blastocyst formation and implantation.

3.10 Pregnancy and Placenta formation (elementary idea)

3.11 Parturition (elementary idea)

3.12 Lactation (elementary idea)

  1. Reproductive Health

4.1 Introduction: what is reproductive health?

4.2 Need for reproductive health

4.3 Sexually Transmitted diseases (STD) And its prevention

4.4 Birth control- Needs and Methods:

  1. i) Contraception
  2. ii) Medial termination of pregnancy (MTP)

4.5 Amniocentesis: What it is and it’s Significance

4.6 Infertility and assisted reproductive Technologies – IVF (in vitro fertilization), ZIFT (Zygote intrafallopian transfer), GIFT (Gamete intrafallopian transfer), Elementary idea for general awareness.


From the above unit, the topic Mechanism of evolution have been discarded from 2020-21 syllabus.

  1. Heredity and Variation

5.1 Introduction

5.2 Mendelian Inheritance (laws only)

5.3 Deviations from Mendelism

i) Incomplete dominance

ii) Co-dominance

iii) Multiple alleles and Inheritance of Blood groups (ABO & Rh)

iv) Pleiotroph

5.4 Polygenic inheritance (elementary)

5.5 Chromosome theory of inheritance

5.6 Chromosomes and genes

5.7 Sex determination in – human, bird and honey bee

5.8 Linkage and crossing over

5.9 Sex- linked inheritance – Haemophilia and colour blindness

5.10 Mendelian disorder in human:

Chromosomal disorders:

i) Autosomal – thalassemia

ii) Sex-linked – Down’s Syndrome,

iii) Turner’s Syndrome and Klinefelter’s Syndrome (cause & symptoms only, process of inheritance is not required)

  1. Molecular Basis of Inheritance

6.1 Search for genetic material

6.2 DNA as genetic material: (experiments on Bacterial transformation by F. Griffith; Avery, McLeod and Harshey & Chase)

6.3 Structure of DNA

6.4 Structure of RNA

6.5 Types of RNA – mRNA; rRNA & tRNA

6.6 DNA Packaging

6.7 Central dogma (elementary), DNA replication, transcription, genetic code and translation.

6.8 Regulation of Gene expression (elementary) Lac Operon

6.9 Genome and Human genome project

6.10 DNA finger printing

  1. Evolution

7.1 Introduction

7.2 Origin of life – Origin of earththeories on the origin of life on earth:

i) Special creation

ii) Spontaneous generation

iii) Extra-terrestrial or cosmic origin (all with brief statement)

iv) Abiogenic origin or chemical origin of life – Oparin-Haldane Hypothesis supported by Miller’s experiment, conclusion

7.3 Biological Evolution

a) What is biological Evolution?

b) Evidence for Biological Evolution

i) Paleonotological

ii) From comparative anatomy

iii) Embryological

iv) Molecular

7.4 Theories of organic evolution

Introduction – Drawin’s contribution- Modern Synthetic Theory- Hardy Weinberg’s Principle

  1. Mechanism of Evolution

8.1 Variation- Sources of variation

8.2 Mutation as a sources of variation (types not needed, mention only Hugo de V ries experiment)

8.3 Recombination as a source of Variation (process is not needed)

8.4 Natural selection with examples:

Types of Natural selection

8.5 Gene Flow and genetic drift; Hardy-Weinberg’s Principle

8.6 Adaptive radiation

Human evolution (with diagram)


  1. Health and Diseases

9.1 Basic concept of immunology – vaccines

Introduction-immune system- Antigen, Antibody, Antigen-Antibody reaction-Types of immunity-vaccines and vaccination

9.2 Pathogens, parasites causing human diseases- Malaria, Filariasis, Ascariasis, Typhoid, Psneumonia,common cold, Amoebiosis and ring worm. (symptoms of Disease, name of causative agent, mode of Transmission, preventive measures)

9.3 Cancer, HIV and AIDS – Symptoms of disease, causative agent, mode of transmission, preventive measures

9.4 Adolescence : drug and alcohol abuse

10.Improvement in Food Production

10.1 Plant breeding

10.2 Tissue culture

10.3 Single cell protein (SCP)

10.4 Biofortification

10.5 Animal husbandary (poultry and diary, farm management, animal breeding, beekeeping and fisheries)

  1. Microbes In Human Welfare

11.1 In household food processing

11.2 Industrial production

11.3 Sewage treatment

11.4 Energy generation

11.5 Bio control agents and bio fertilizers

Unit- IV BIOTECHNOLOGY ITS APPLICATION  (This chapter has been discarded from 2020-21 syllabus)

  1. Biotechnology and its Application

12.1 Introduction

12.2 Principle

12.3 Process – Genetic Engineering (Recombinant DNA technology)

12.4 Application of Biotechnology in health and agriculture – introduction

12.5 Human insulin and vaccine productiongene therapy

12.6 Genetically modified organisms- BT crops (What is G.M.O.? example- cotton), Transgenic animals.

12.7 Bio safety issues

12.8 Bio piracy and patents


From the above unit, the topic Ecosystem have been discarded from 2020-21 syllabus.

  1. Ecology Environment & Population

13.1 Meaning of ecology, environment, habitat and niche

13.2 Organisms and environment

i) Introduction- biome concept and distribution

ii) Major abdiotic factors- water, light, temperature and soil

iii) Responses to abiotic factors

iv) Adaptations

13.3 Population and ecological adaptations

i) Population interactions – mutualism, competition, predation,parasitism

ii) Population attributes – growth, birth rate and death rate, age distribution


14.1 What is ecosystem and its pattern

14.2 Components of ecosystem

14.3 Energy flow

14.4 Nutrient cycling (carbon and phosphorus)

14.5 Productivity and Decomposition

14.6 Pyramids of number, biomass and energy

14.7 Ecological Succession

14.8 Ecological service: Carbon fixation, Pollination and Oxygen release

  1. Biodiversity And Conservation

15.1 What is biodiversity

15.2 Levels of biodiversity (genetic, species and Ecological) Patterns of biodiversity, Importance and loss of Biodiversity

15.3 Threats to need for biodiversity conservation

15.4 Hotspots, endangered organisms, extinction, Red Data book

15.5 Biodiversity conservation –

a) Biosphere reserve

b) National parks and sanctuaries

16.Environment Issues

16.1 Introduction

16.2 Air Pollution and its control

16.3 Water Pollution and its control

16.4 Agro-Chemicals and their effects

16.5 Solid waste management

16.6 Radioactive waste management

16.7 Green House effect and global warming

16.8 Ozone depletion

16.9 Deforestation

16.10 Three success stories addressing environmental issues – Chipko movement, Dasholi Gram Swarajya Mandal (DGSM) movement; Silent valley or Amrita Devi – Bishnoi (Jaipur) movements

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