NCERT Solutions for CBSE Class 12 Biology

CBSE Class 12 Biology NCERT Solution All Chapters

NCERT Solutions for Class 12 Biology : Biology may seem to be easy but sometimes it might get tough. The national council of education and training (NCERT) has set a curriculum for schools which follow the central board of secondary education (CBSE). NCERT solutions have been provided below to aid the students with answering the questions correctly, using a logical approach and methodology. The solutions provide ample material to enable students to form a good base with the fundamentals of the subject.

NCERT textbooks are prescribed by CBSE as the best books for preparation of the school as well as board examinations. The textbooks are deemed as more than enough, without any aid from other refreshers. The solutions are designed keeping in mind the language and the simplicity of the explanations that are given in the NCERT textbooks. Not just the board and school examinations, NCERT textbooks are known to play a very important role in JEE and NEET.

NCERT Solutions for Class 12 Biology

Several important concepts like Reproduction, Inheritance, Evolution, Food Production, Biotechnology, Ecosystem, biodiversity, etc are explained precisely in the NCERT class 12 biology textbook with good diagrams for better understanding of teachers as well as students so that their basics are clear from the very beginning and thus helps them in scoring good marks in boards exam.Class 12 Biology NCERT solutions will help in the following manner:

  • Authentic Homework Guide
  • The base for the preparation of competitive exams like JEE and NEET
  • Strengthening basic concepts of subjects
  • Error-free solutions
  • Extra problems to build upon the basic concepts

Class 12 Biology Chapter 1 Reproduction in Organisms

In this chapter, we will learn about types, modes and the process of reproduction in different organisms.The subtopics covered in this chapter include asexual reproduction, sexual reproduction, pre-fertilization events, fertilization, and post-fertilization events. Well illustrated diagrams are also present which makes the learning easy for the students and helps them understand the topic thoroughly.

Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants

This chapter is a combination of four chapters and holds a weightage of fourteen marks in 12 board examination.In this chapter, we will learn about the structure, morphology, and process of sexual reproduction in flowering plants. Also, the subtopics covered in this chapter include pre-fertilization events, double fertilization, post fertilization events and the knowledge about apomixis and polyembryony.

Class 12 Biology Chapter 3 Human Reproduction

In this chapter, we will learn about the human male and female reproductive system. Diagrams, illustrations, flowcharts, and easy language makes this chapter comprehensive and easy to learn. Moreover, the sequential progress of the topics helps us retain and grasp better.
The sub topics covered in this chapter are-

  • Reproductive structures,
  • Male reproductive systems,
  • Female reproductive systems,
  • The role of sex hormones,
  • Gametogenesis,
  • Spermatogenesis and more introductory topics of human reproduction.

Class 12 Biology Chapter 4 Reproductive Health

This chapter focusses on the issues of the significance of reproductive health and the methods to achieve it.This chapter also focusses on maternal health and the health of the child during pre-pregnancy, pregnancy and post-pregnancy periods.Infant mortality maternal mortality and amniocentesis are other topics covered here.
The subtopics covered in this chapter are:

  • Reproductive Health – Problems and Strategies
  • Population Explosion and Birth Control
  • Medical Termination of Pregnancy
  • Sexually Transmitted Diseases
  • Infertility.

Class 12 Biology Chapter 5 Principles of Inheritance and Variation

It basically revolves around Genetics and Evolution.Similarity and variation between the parents and offsprings are discussed in this chapter.Mendel”s law of inheritance, the inheritance of one gene, the inheritance of two genes, sex determination, mutations, and genetic disorders are main topics discussed here.

Diagrams, illustrations, flowcharts, and easy language makes this chapter comprehensive and easy to learn. Moreover, the sequential progress of the topics helps us retain and grasp better.

Class 12 Biology Chapter 6 Molecular Basis of Inheritance

In this chapter, very simplified diagrams are given to understand all the structures of DNA,RNA, the process of replication, etc.
The topics covered in this chapter are:

  • The DNA: Structure of polynucleotide chain, Packaging of DNA helix.
  • The search for genetic material: The genetic material is DNA, Properties of genetic material.
  • RNA world.
  • Replication: The experimental proof, the machinery, and enzymes.
  • Transcription: The transcription unit, Transcription unit and the gene, Types of RNA and the process of transcription.
  • Genetic code: Mutations and genetic code, t RNA. Translation. Regulation of gene expression.
  • The Lac Operon.
  • Human genome project: Salient

Class 12 Biology Chapter 7 Evolution

Evolution biology is the study of history of life forms on earth.This chapter deals with the origin of life and the evolution of life forms or biodiversity on planet earth in the context of evolution of earth and against the background of evolution of universe itself. Diagrams, illustrations, flowcharts, and easy language makes this chapter comprehensive and easy to learn. Moreover, the sequential progress of the topics helps us retain and grasp better.

Class 12 Biology Chapter 8 Health and Diseases

Health, maintenance of optimum health, diseases, types, treatment and prevention, immunity, and its types and address to some diseases such as AIDS, cancer, and adolescent issues constitute this chapter.
Subtopics covered in this chapter are:

  • Common Diseases in Humans
  • Immunity
  • AIDS
  • Cancer
  • Drugs and Alcohol Abuse.

Class 12 Biology Chapter 9 Strategies for Enhancement in Food Production

This chapter deals with biological principles applied to animal husbandry and plant breeding that have a major role in to increase food production. Several new techniques like embryo transfer technology and tissue culture techniques that play a pivotal role in further enhancing food production are discussed in this chapter.

Class 12 Biology Chapter 10 Microbes in Human Welfare

Microbes are also referred to as micro-organisms or microscopic organisms as they can only be seen under a microscope. They are tiny living creatures, invisible to the naked eye and are present all around us, in air, water, soil and so on. They played a key role in the evolution of the planet earth. Few microbes cause severe infections and disease that even result in death and others are the beneficial ones and harmless to our lives. Disease-causing microbes are called as pathogens. Influenza, tuberculosis, polio, cholera, HIV are some of the best examples of disease caused by these microbes. The most common microbes include Bacteria, protozoa viroid, some algae, Fungi, and Viruses.

Class 12 Biology Chapter 11 Biotechnology Principles and Processes

The european federation of biotechnology has defined biotechnology as” the integration of natural science and organisms, cells, parts thereof, and molecular analogs for products and services”.This chapter, deals in depth study of principles and processes involved in biotechnology.
Among many techniques, modern biotechnology is the result of the following two core techniques. They are-

  • Genetic engineering
  • Manufacturing of Antibiotics, Drugs and other Vaccines

Class 12 Biology Chapter 12 Biotechnology and its Application

In this chapter, students will learn that how human beings have used biotechnology to improve the quality of human life, especially in the field of food production and health. Biotechnology has given humans several useful products by using microbes, plants, animals, and their metabolic machinery.

Class 12 Biology Chapter 13 Organisms and Populations

In this chapter, students shall explore ecology at organismic and population level. This chapter deals with topics such as organisms and its environment, niche, major abiotic factors affecting the organisms and its environment such as temperature, water, light, soil, responses to abiotic factors such as regulation , conformation, migration and suspension.

Diagrams, illustrations, flowcharts, and easy language makes this chapter comprehensive and easy to learn. Moreover, the sequential progress of the topics helps us retain and grasp better.

Class 12 Biology Chapter 14 Ecosystem

An ecosystem can be visualized as a functional unit of nature, where living organisms interact among themselves and also with the surrounding physical environment.In this chapter student will first learn about structure of ecosystem,in order to appreciate the input (productivity), transfer of energy (food chain) and the output.

Class 12 Biology Chapter 15 Biodiversity and its Conservation

In this chapter students will learn about importance and significance of biodiversity, its types, patterns, evolution, degradation, and conservation.
Genetic diversity, species diversity, latitudinal gradients, species area relationship, causes of biodiversity losses, in-situ conservation and ex-situ conservation are few topics covered in this chapter.

Class 12 Biology Chapter 16 Environmental Issues

This chapter deals with the problems that are posing a threat to the ecological balance in nature such as pollution, global warming, deforestation, etc. and measures taken to control such kind of pollution. This chapter also covers the effects of pollution on the human life and how it is affecting the peoples day to day life.

The solutions are guaranteed to be error-free and easily comprehensible. The students are advised to refer to these authentic solutions against the multiple refresher books. The NCERT textbooks are prescribed by CBSE, and hence form the most authentic source of knowledge in the school syllabus.

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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