CBSE Sample Papers, Worksheets , Revision Notes

CBSE Class 12 Biology Chapter-wise Notes | Question Answers

Weightage of Content/Subject Units

Unit Content Marks
VI  Reproduction 14
VII  Genetics and Evolution 18
VIII  Biology and Human Welfare 14
IX  Biotechnology and its Applications 10
X  Ecology and Environment 14
Total 70

Weightage of Different Form of Questions

S.NO            Form of Questions   Marks for Each     No of Questions  Total Marks
1 Very Short Answer (VSA) 1 5 5
2 Short Answer ( SA I) 2 7 14
3 Short Answer ( SA II) 3 12 36
4 Long Answer ( LA ) 5 3 15
27 70

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.

CBSE Class 12 Biology Revision Notes Chapter 1 With Question Answers


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.

CBSE Class 12 Biology Revision Notes Chapter 2 With Question Answers


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).

CBSE Class 12 Biology Revision Notes Chapter 3 With Question Answers


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).

CBSE Class 12 Biology Revision Notes Chapter 4 With Question Answers


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; Sex determination – in humans, 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.

CBSE Class 12 Biology Revision Notes Chapter 5 With Question Answers


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 and human and rice genome projects; DNA fingerprinting.

CBSE Class 12 Biology Revision Notes Chapter 6 With Question Answers


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.

CBSE Class 12 Biology Revision Notes Chapter 7 With Question Answers


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.

CBSE Class 12 Biology Revision Notes Chapter 8 With Question Answers


Chapter-9: Strategies for Enhancement in Food Production
Improvement in food production: Plant breeding, tissue culture, single cell protein,Biofortification, Apiculture and Animal husbandry.

CBSE Class 12 Biology Revision Notes Chapter 9 With Question Answers


Chapter-10: Microbes in Human Welfare
In household food processing, industrial production, sewage treatment, energy generation and microbes as biocontrol agents and biofertilizers. Antibiotics; production and judicious use.

CBSE Class 12 Biology Revision Notes Chapter 10 With Question Answers


Unit-IX Biotechnology and Its Applications

Chapter-11: Biotechnology – Principles and processes
Genetic Engineering (Recombinant DNA Technology).

CBSE Class 12 Biology Revision Notes Chapter 11 With Question Answers


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,bio piracy and patents.

CBSE Class 12 Biology Revision Notes Chapter 12 With Question Answers


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

CBSE Class 12 Biology Revision Notes Chapter 13 With Question Answers


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).

CBSE Class 12 Biology Revision Notes Chapter 14 With Question Answers


Chapter-15: Biodiversity and its Conservation
Biodiversity-Concept, patterns, importance; loss of biodiversity; biodiversity conservation; hotspots,endangered organisms, extinction, Red Data Book, biosphere reserves, national parks, sanctuaries and Ramsar sites.

CBSE Class 12 Biology Revision Notes Chapter 15 With Question Answers


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; any one case study as success story addressing environmental issue(s)

CBSE Class 12 Biology Revision Notes Chapter 16 With Question Answers


CBSE Sample Papers for Class 12 Biology

CBSE Sample Question Papers for Class 12 Biology With Solutions – 4 ( 2018 )

CBSE Sample Question Papers for Class 12 Biology With Solutions – 3 ( 2018 )

CBSE Sample Question Papers for Class 12 Biology – 9 ( 2018 )

CBSE Sample Question Papers for Class 12 Biology – 8 ( 2018 )

CBSE Sample Question Papers for Class 12 Biology – 7 ( 2018 )

CBSE Sample Question Papers for Class 12 Biology – 10 ( 2018 )

CBSE Sample Question Papers for Class 12 Biology ( 2018 )

CBSE Sample Question Papers for Class 12 Biology (Half Yearly Exam )

CBSE Sample Question Papers for Class 12 Biology – 2 ( Half Yearly Exam )

Class 12 Biology Question Papers ( Periodic test 2 ) – Apeejay school

CBSE Sample Question Papers for Class 12 Biology ( 2015 )

CBSE Sample Question Papers for Class 12 Biology ( Practice paper )

CBSE Sample Question Papers for Class 12 Biology (Model Test Paper 2)

CBSE Sample Question Papers for Class 12 Biology ( Model Test Paper 1 )

CBSE Sample Question Papers for Class 12 Biology ( 2019 )

CBSE Sample Question Papers for Class 12 Biology ( 2017 Jamia )


Important Questions Chapterwise –  Class 12 Biology

CBSE Class 12 Biology Important Questions ( Environmental Issues )

CBSE Class 12 Biology Important Questions (Biodiversity and Conservation )

CBSE Class 12 Biology Important Questions ( Ecosystem )

CBSE Class 12 Biology Important Questions (Organisms and Populations)

CBSE Class 12 Biology Important Questions (Biotechnology and Its Applications)

CBSE Class 12 Biology Important Questions (Biotechnology Principles and Processes)

CBSE Class 12 Biology Important Questions ( Microbes in Human Welfare)

CBSE Class 12 Biology Important Questions (Strategies for Enhancement in Food Production)

CBSE Class 12 Biology Important Questions (Human Health and Disease)

CBSE Class 12 Biology Important Questions ( Bank Evolution )

CBSE Class 12 Biology Important Questions (Molecular Basis Inheritance)

CBSE Class 12 Biology Important Questions  (Principal of Inheritance and Variation)

CBSE Class 12 Biology Important Questions (Productive Health )

CBSE Class 12 Biology Important Questions ( Human Reproduction)

CBSE Class 12 Biology Important Questions (Sexual Reproduction in Flowering Plants )

CBSE Class 12 Biology Important Questions (Reproduction in Organisms)


Tips to avoid Errors/Mistakes committed by students in attemption Biology Paper of Class 12.

  • Don’t start with the most difficult question: Before answering, go through the whole question paper once. Without glancing the question paper, you may start with the most difficult question which could put you under mental stress and you may not impress your examiner by your answers. As you mind is focused to the first difficult question, you may find difficulty in answering other questions also
  • Don’t miss out important Instructions: Read all the instructions written in the front page of question paper and go through he complete paper This will get you time to segregate between easy and difficult problems by ignoring those instructions, you may end up answering those questions which are not required.
  • Don’t forget to answer ail the questions: Most of you effort to attempt easy questions first and leaving some to be attend at the end There can be a situation that you get stuck with difficult questions at last, leaving no time to return to those questions
  • Not reading the question paper: One of the most common mistakes students make is not utilising the 15 minute leading time properly. Students should read the question paper carefully so that they can organise their thoughts and manage their time during the exam.
  • Time mismanagement: Time management is crucial for getting a perfect score in the board exams. It is important to not spend more than the required time on a particular question: otherwise you’ll struggle to complete the paper. While writing the paper, students should stick to the word limit and the time limit they are allocated for attempting questions of different weightage. Plan in advance how much time you will dedicate to each question and category.
  • Not following the hierarchy: (Writing unplanned answer): Generally, students answer the questions without planning the order properly according to the points that need to be covered at first Thus, the students should regularly analyse the content of their answers by keeping in mind the value points given in the marking scheme and compare their answers with model papers. This is how the students will be able to develop the skill of determining the hierarchy of relevance of content and will able to score better marks in boards
  • Copying incorrect data: Sometimes students copy the data given in the question paper incorrectly in the questions Students should take extra care as it might save a couple of marks in the exam.
  • Diagrams: For questions where diagrams are asked for, students should draw and label them properly and preferably, in pencil. Using diagrams can help scoring better marks. • Highlight: While presenting answers underline the headings and highlight the important keywords and phrases. This will help in improving your marks 
  • Answer length: The answer length should be in accordance to the marks provided for the question. A question of 1 mark should not be answered in half a page or a whole page.
  • VBQ: In value based question (Question no. 23), which is of 4 marks, students tend to write only one sentence. This question generally has two parts. One is related with the content of text book and another related with the values. The student ought to write the positive values (aspects/ views) related with the concept of the question in at least 3-4 sentences in order to get full marks.
  • Correct question number: Students should make sure they write the correct question number for the answer they are writing. Any mistake here means they would lose the entire marks even if their answer is correct.
  • Reason based questions must be answered in two points: (i) cause (ii) consequence Though these questions carry one mark each, two key points are expected from students Most of the time students write only one point.
  • Principle involved in a process: Students often write the process or steps involved but do not mention the principle behind the process.
  • Writing full length answers when running out of time: Another common mistake in board exams because of which you can easily lose marks is working hard on answering a question or an essay when your time is running out. In such critical situations quickly write down the bullet points. That way the examiner can see that you’ve thought about the question, and they’ll know what you would have written if you had the time top openly deal with the question.
  • Check your Answer sheet Before Submitting: Most of you may not find this step necessary but by proper checking before submitting helps you notice some errors and if time left, you can attempt those left out questions also
  • Don’t attempt easy questions in the eleventh hour: The questions which you think can be answered easily, do them first. This way you pick up marks upfront’ It you start with difficult questions, you may end up spending a lot of time on them, leaving mistake or no time for the ones from which you could have gained more marks. Leaving the easiest questions until last. Leaving the exam room early
  • # Poor spelling and grammar (Biological terms and scientific names).
  • # Providing irrelevant responses.
  • # Providing multiple answers hoping one answer is correct.
  • # Misinterpreting the key words.
  • # Failing to bring along required stationery or items.
  • # Panicking before or during a paper.
  • # Jumping straight into answering a question without proper planning.