NCERT Solutions and Notes for CBSE Class 12 Biology

CBSE Class 12 Biology Study Materials All Chapters

CBSE Syllabus 2020-21: Check Deleted Topics From 12th Biology Syllabus 2020-21

Learn about the deleted topics of CBSE Class 12th Biology Syllabus 2020-21. In this article, you will also find links to access revised CBSE 12th Biology Syllabus 2020-21.

Check deleted portion of CBSE 12th Biology Syllabus 2020-21. The board has reduced CBSE 12th Biology Syllabus 2020-21 by 30%. In this article, we have provided the details of the topics which have been deleted by the Central Board of Secondary Education. Links to access other important articles and the latest CBSE Syllabus are also available here. 

Deleted Topics from CBSE 12th Biology Syllabus 2020-21: 

Unit-VI Reproduction

o Chapter-1: Reproduction in Organism

• 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.

Under Unit-VII Genetics and Evolution

o Chapter-7: Evolution

• Origin   of  life;  biological   evolution   and   evidences   for  biological   evolution (paleontology, comparative anatomy, embryology and molecular evidences); Darwin’s  contribution,  modern  synthetic  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; adaptive radiation; human evolution.

Unit-VIII Biology and Human Welfare

o Chapter 9: Strategies for Enhancement in Food Production

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

Unit-X Ecology and Environment

o Chapter-14: Ecosystem

• Ecosystems:  Patterns,  components;  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).

o 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;  exemplifying  case study as a success story addressing environmental issue(s).


A: List of Experiments

1.   Study the presence of suspended particulate matter in air at two widely different sites.

2.   Study the plant population density by quadrat method.

3.   Study the plant population frequency by quadrat method.

B. Study/Observer of the following (spotting)

1.   Pollen   germination   on   stigma   through   a   permanent   slide   or   scanning   electron micrograph.

2.   Mendelian inheritance using seeds of different colour/sizes of any plant.

3.   Controlled pollination – emasculation, tagging and bagging.

CBSE Class 12 Biology Syllabus (Revised): 2020-21 

Revised CBSE 12th Biology Syllabus 2020-21 PDF and prepare for CBSE 12th Biology board exam 2020-21. This NCERT based CBSE 12th Biology Syllabus (Theory & Practical) is important for preparation. Links to other important articles for preparation of CBSE 12th Biology board exam 2020-21 are also available here.

CBSE Class 12 Biology Syllabus 2020-21 (Revised & Reduced): 








Genetics and Evolution



Biology and Human Welfare



Biotechnology and its Applications



Ecology and Environment





Unit-VI 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, contraception and medical termination of pregnancy (MTP); amniocentesis; infertility and assisted reproductive technologies – IVF, ZIFT, GIFT (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, co-dominance, multiple alleles and inheritance of blood groups, pleiotropy; elementary idea of polygenic inheritance; chromosome theory of inheritance; chromosomes and genes; Sex determination – in human being, birds and honey bee; linkage and crossing over; sex linked inheritance – haemophilia, colour blindness; Mendelian disorders in humans -thalassemia; chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes. 

Chapter-6: Molecular Basis of Inheritance

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

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, ring worm) and their control; Basic concepts of immunology – vaccines; cancer, HIV and AIDS; Adolescence – drug and alcohol abuse.  

Chapter-10: Microbes in Human Welfare

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

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: Human insulin and vaccine production, stem cell technology, gene therapy; genetically modified organisms – Bt crops; transgenic animals; biosafety issues, biopiracy and patents. 

Unit-X Ecology and Environment

Chapter-13: Organisms and Populations

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

Chapter-15: Biodiversity and its Conservation

Biodiversity – Concept, 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. 

CBSE Class 12 Biology Practical Syllabus 2021 (Revised) 


Time allowed: 3 Hours, Max. Marks: 30  

Evaluation Scheme


One Major Experiment    5, 6


One Minor Experiment   2, 3


Slide Preparation             1, 4




Practical Record + Viva Voce


Credit to the students’ work over the academic session may be given


Investigatory Project and its

Project and its Record + Viva Voce





A.  List of Experiments

1. Prepare a temporary mount to observe pollen germination.

2. 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.

3. Collect water from two different water bodies around you and study them for pH, clarity and presence of any living organism.

4. Prepare a temporary mount of onion root tip to study mitosis.

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

6. Isolate DNA from available plant material such as spinach, green pea seeds, papaya, etc.

 B.  Study/observation of the following (Spotting)

1. Flowers adapted to pollination by different agencies (wind, insects, birds).

2. Identification of stages of gamete development, i.e., T.S. of testis and T.S. of ovary through permanent slides (from grasshopper/mice).

3. Meiosis in onion bud cell or grasshopper testis through permanent slides.

4. T.S. of blastula through permanent slides (Mammalian).

5. Prepared pedigree charts of any one of the genetic traits such as rolling of tongue, blood groups, ear lobes, widow’s peak and colour blindness.

6. 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.

7. Two plants and two animals (models/virtual images) found in xeric conditions. Comment upon their morphological adaptations.

8. Two plants and two animals (models/virtual images) found in aquatic conditions. Comment upon their morphological adaptations.

Prescribed Books (For CBSE Class 12 Biology Board Exam 2021 Preparation):

1. Biology, Class-XII, Published by NCERT

2. Other related books and manuals brought out by NCERT (including multimedia)

3. Biology Supplementary Material (Revised). Available on CBSE website.

Which book is best for CBSE 12 Class Biology?

It is a well-known fact that NCERT books are the best for CBSE Class 12th Board exam preparation. But then again, simply mugging the NCERT books is also not enough. Students should be thorough with NCERT books at least 5 months before their boards. This will give them ample time for using other reference books for CBSE Class 12 Biology.

Best Reference Books for Class 12 CBSE Biology

Below given are some of the good reference books for preparation of class 12 Biology exam.

  1. CBSE Biology Chapterwise Solved Papers class 12th by Arihant Expert
  2. NCERT class 12 Biology Textbook
  3. Pradeep’s A Text Book of Biology class 12 by P.S. Dhami
  4. S.Chand’s Biology for class XII by B.P. Pandey
  5. Trueman’s Elementary Biology for Class 12 and NEET by K.N. Bhatia and M.P. Tyagi
  6. Together with Biology by S.Chand
  7. Biology by Campbell and Reece
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