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NCERT Class 12 Biology textbooks are designed to build a strong understanding of life processes, genetics, evolution, and modern biology concepts like biotechnology and ecology. This book focuses on conceptual clarity of biological concepts helping students prepare effectively for board exams and competitive exams.
This textbook is fully aligned with the latest CBSE syllabus and follows the vision of NEP 2020, ensuring a balance between theoretical knowledge and practical understanding.
Download Class 12 NCERT Biology Book PDF
NCERT Biology Book Class 12: Overview
The Class 12 Biology NCERT helps students not just with what is in the syllabus but connects them to real-life through case-studies. It develops skills like experimental understanding and application of detailed complex biological processes which are useful for exams like NEET and related exams.
Points to Notice for Class 12 NCERT Biology
- Based on the latest CBSE syllabus for 2026-27
- Covers core units like Reproduction, Genetics, Evolution, Biotechnology, and Ecology
- Includes labelled diagrams, case studies, and experimental concepts
- Strong focus on conceptual clarity and application-based learning
- Supports board and competitive exam preparation (like NEET)
- Includes NCERT-based questions, assertion-reason, and case-based questions
NCERT Biology Textbook for Class 12
The NCERT Biology Class 12 book is structured to cover the entire syllabus prescribed by CBSE. Here is a detailed breakdown of the Units:
Unit VI - Reproduction
- Chapter 1: Sexual Reproduction in Flowering Plans - Explains structure, pollination, fertilisation, and seed formation in plants.
- Chapter 2: Human Reproduction - Covers reproductive systems, gamete formation, fertilisation, and development.
- Chapter 3: Reproductive Health - Focuses on population control, contraception, and reproductive well-being.
Unit VII - Genetics and Evolution
- Chapter 4: Principles of Inheritance and Variation - Explains Mendelian genetics and patterns of inheritance.
- Chapter 5: Molecular Basis of Inheritance - Covers DNA structure, replication, and gene expression.
- Chapter 6: Evolution - Discusses origin of life and theories explaining evolution of species.
Unit VIII - Biology in Human Welfare
- Chapter 7: Human Health and Disease - Explains pathogens, immunity, and common diseases.
- Chapter 8: Microbes in Human Welfare - Highlights useful roles of microbes in industry and environment.
Unit IX - Biotechnology
- Chapter 9: Biotechnology: Principles and Processes - Covers genetic engineering tools and techniques.
- Chapter 10: Biotechnology and its Applications - Explains use of biotechnology in medicine, agriculture, and industry.
Unit X - Ecology
- Chapter 11: Organisms and Populations - Discusses interactions between organisms and their environment.
- Chapter 12: Ecosystems - Explains structure, function, and energy flow in ecosystems.
- Chapter 13: Biodiversity and Conservation - Focuses on importance and conservation of biological diversity.
Biology NCERT Class 12 Study Material
The study material offered by NCERT for Class 12 Biology is enough to score good marks in the CBSE board exams. The NCERT textbook is easily accessible to everyone and offers the best understanding of the subject.
Deleted Chapters from Class 12 Biology Textbook
As per the new guidelines by NCERT for the syllabus, there are no deletions or alterations in the Biology syllabus for Class 12 and the similar books shall be used throughout the academic session 2026-27.
Most Important Questions from Class 12 NCERT Biology
For Class 12 Biology, there are a few questions which are asked more frequently than others and the related chapters are more important comparatively. Some of those important questions are answered below.
Chapter 3: Reproductive Health
Q1. What do you think is the significance of reproductive health in society?
Ans. Healthy reproductive organs with normal functions are referred to as reproductive health.
Physical, emotional, behavioral, and social elements of reproduction are all included. It aids in the prevention of sexually transmitted illnesses such as syphilis, AIDS, and others.
Educating people about birth control options, prenatal care, postnatal care for the mother and child, the importance of breastfeeding, and equal opportunities for male and female children, among other topics, would address the importance of raising socially conscious, healthy families of the desired size. It also aids in the reduction of social ills such as sex abuse and sex-related crimes. This will contribute to the development of a socially responsible and healthy society.
Q2. Suggest some methods to assist infertile couples to have children.
Ans. The following are some strategies for assisting infertile couples in having children:
(i) Baby-in-a-tube program: The ova from the wife/donor (female) and the sperms from the husband/donor (male) are collected and induced to form a zygote in the laboratory under simulated conditions. The zygote created is subsequently put into a typical female's fallopian tube.
(ii) Gamete Intra Fallopian Transfer (GIFT): The transfer of an ovum from a donor into the fallopian tube of another female who cannot produce eggs but can offer a fertile environment.
(iii) Intracytoplasmic sperm injection (ICSI): A sperm is injected directly into the ovum.
(iv) Artificial insemination (AI): Semen is obtained from the husband or a healthy donor and
artificially implanted into the female's vaginal or uterine cavity.
Chapter 4: Principles of Inheritance and Variation
Q1. Explain the Law of Dominance using a monohybrid cross.
Ans. Mendel’s Law of Dominance states that characters are controlled by discrete units that occur in pairs, called as factors. In a dissimilar pair of factors, one factor dominates over the other. Therefore, when two parents (P) of contrasting traits are crossed, the progeny (F1) will express only one of the traits and not the other. The trait expressed in the progeny will “dominate” over the trait and is called the dominant trait whereas the alternate trait is called the recessive trait.
The recessive trait reappears in the next generation (F2) when the F1 generation is selfed. This means that the recessive trait did not completely vanish but its expression was suppressed by the presence of the dominant allele. It can be explained as follows using a monohybrid cross. Monohybrid cross is a cross between two parents homozygous for contrasting traits of the only one character. e.g., cross between tall (TT) and short (tt) This shows that the dominant trait expresses itself in both homozygous and heterozygous condition whereas the recessive trait expresses itself only in the homozygous condition on the absence of the dominant trait.
Q2. Briefly mention the contribution of T.H. Morgan in genetics.
Ans. T.H. Morgan contributed immensely to the field of genetics through his studies on the fruit fly, Drosophila melanogaster. Some of his major contributions to the field of genetics are as follows:
1. He experimentally proved the Chromosomal Theory of Inheritance. This theory states that the genes are located on chromosomes and that chromosomes are inherited by daughter cells
2. He proved the existence of linked genes. Linked genes are genes located on the same chromosome. The theory of linkage says that genes that are located on the same chromosome are inherited together and are less likely to form recombinants.
3. He demonstrated that the distance between the genes in the chromosome affects their recombination rate. The more closely two genes are linked together the more likely that they will be inherited together. The more apart two genes are located in a chromosome the
more likely that they will form recombinants.
4. He demonstrated crossing over in chromosomes during meiosis.
5. He demonstrated the X-linked inheritance in the fruit fly Drosophila melanogaster Due to his contribution many theories of genetics could be proved experimentally and for this reason he is
called as the “Father of Experimental Genetics”
Chapter 7: Human Health and Disease
Q1. Differentiate the following and give examples of each:
(a) Innate and acquired immunity
(b) Active and passive immunity
Ans. (a) Innate and acquired immunity
(b) Active and passive immunity
Chapter 8: Microbes in Human Welfare
Q1. Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes under a microscope, which sample would you carry and why?
Ans. A sample, Curd, can be used for the study of microbes. Numerous lactic acid bacteria (LAB) or Lactobacillus are present in Curd. Acids are produced by these bacteria that coagulate and digest milk proteins.
In the research laboratory, a tiny low drop of curd is carried because it contains multitudes of bacteria, which might be easily observed under a microscope which are of varied shapes and sizes.
Q2. Do you think microbes can also be used as a source of energy? If yes, how?
Ans. Yes, microbes can be used as an energy source. Bacteria like Methane bacterium are employed for the generation of gobar gas or biogas.
(i) In a biogas plant, the generation of biogas is an anaerobic process which consists of a concrete tank (10-15 feet deep) with sufficient outlets and inlets.
(ii) Slurry is formed by the mixture of dung and water and is further thrown into the tank.
The digester of the tank contains numerous anaerobic methane-producing bacteria, which produce biogas from the slurry.
(iii) Biogas can be used as a source of energy after removal through the pipe, while the spent slurry is removed from the outlet and is used as a fertilizer.
Chapter 10: Biotechnology and Its Applications
Q1. Consult the internet and find out how to make orally active & protein pharmaceutical. What is the major problem to be encountered?
Ans. To make orally active and protein pharmaceuticals, the drugs must be undergone coating with the help of a film that is protein degrading enzyme resistant.
The problem associated with the pharmaceutical drugs which can be consumed orally is that those drugs, if made without proper coating or film, can be easily degraded by the enzymes such as proteases that are present in our alimentary canal.
Q2. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Ans. Gene therapy is a technique that believes in utilizing genes to treat or prevent diseases. However, it can either replace a mutated gene that can cause disease or it is also capable of inactivating a mutated gene that fails to function normally.
Gene therapy is described below using the example of adenosine deaminase deficiency:
- Due to adenosine deaminase deficiency, production of severe immunodeficiency as well as functions of T, B and natural killer cells impairment can be seen.
- These complications can be resolved with the help of gene therapy which contains enriched cells subjected to transduction with a retroviral vector and the immune reconstitution can be done.
Chapter 13: Biodiversity and Conservation
Q1. How is biodiversity important for ecosystem functioning?
Ans. An ecosystem with high species diversity is far more stable than an ecosystem with low species diversity. In terms of productivity and more resistance towards disturbances like alien species invasions and floods, the ecosystem becomes more stable. The ecological balance would not get hampered if an ecosystem is rich in biodiversity.
In an ecosystem, all the trophic levels are connected via food chains. If any organism or all organisms of any one trophic level is killed, then the entire food chain will be disturbed.
For example, if all plants are killed in a food chain, then all deer will die due to the lack of food. Soon the tigers will also die if the death of deer occurs. Thus, other food alternatives would be there at each trophic level which might not allow an organism to die because of the absence of their food resource if an ecosystem is rich in species.
Hence, a crucial role is played by biodiversity in maintaining the health and ecological balance of an ecosystem.
Q2. The species diversity of plants (22 per cent) is much less than that of animals (72 per
cent). What could be the explanations for how animals achieved greater diversification?
Ans. On the Earth, it is recorded that more than 70 percent of species are animals and only 22 percent of species are planted. A large difference is seen in their percentage. As in comparison to plants, animals have adapted themselves to ensure their survival in changing environments. In the case of insects and other animals.
A complex nervous system is being developed by them to control and coordinate their body structure. Also, Insects are made versatile by their repeated body segments with paired appendages and external cuticles, and as compared to other life forms, they have been given the ability to survive in various habitats.
Effective Prep Tips Using NCERT Class 12 Biology Book
Preparing through Class 12 NCERT textbook for Class 12 can be structured in a proper manner by following these tips given below.
- Stick to NCERT line-by-line
Most board and NEET questions are directly framed from NCERT text, diagrams, and examples.
- Prioritise diagrams and labelling
Biology is highly visual—practice neat, labelled diagrams regularly to score full marks.
- Revise consistently, not randomly
Biology requires multiple revisions. Plan at least 3-4 complete revisions before exams.
- Use flowcharts and tables for retention
Convert lengthy processes (like replication, cycles, pathways) into short visual formats.
- Practice NCERT back questions and exemplar
These questions often repeat directly or in modified forms in exams.
FAQs
Q1. Are NCERT books enough for Class 12 Biology board exams?
Ans. Yes, NCERT is the most important resource. Most board questions are directly or indirectly based on NCERT concepts, diagrams, and examples.
Q2. Is NCERT Biology enough for NEET preparation?
Ans. NCERT forms the base for NEET. Around 80-85% of questions are directly from NCERT, but additional practice is recommended.
Q3. Which unit has the highest weightage in Class 12 Biology?
Ans. Genetics & Evolution and Ecology usually carry higher weightage.
Q4. How important are NCERT diagrams in board exams?
Ans. Extremely important. Questions are frequently based on diagrams, and drawing them correctly can fetch easy marks.
Q5. How should I write answers to score full marks in Biology?
Ans. Write in points, use proper terminology, add diagrams wherever possible, and avoid unnecessary explanations.
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