CBSE Class 12 Biology Chapter-Wise Weightage
CBSE Class 12 Biology chapter-wise weightage tells about the distribution of marks for each chapter in the Class 12 Biology syllabus. It shows how many questions or marks come from each topic. Understanding the chapter-wise weightage of Biology class 12 is very important because it helps you know which chapters are more important and need more focus while studying.
Class 12 is a very important year for students, as board exam marks play an important role in future courses, especially if you're aiming for a career in medicine, pharmacy, or dentistry. Biology is considered a scoring subject because most of its questions are from theory. So, by knowing the Biology class 12 weightage, you can plan your study time smartly, focus on chapters that carry more marks, and increase your chances of scoring high marks in the final board exams.
Check Out: CBSE Class 12 Books
Biology Class 12 Weightage
Understanding the Biology Class 12 weightage helps you prepare smartly for the upcoming board exam. The exam tests theory, with a greater focus on concepts, diagrams, and application-based questions, and practical skills, including experiments, record work, and viva. Check the biology weightage class 12 here:
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Biology Weightage Class 12 |
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Particulars |
Marks |
Overview |
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Theory Exam |
70 |
Covers all Biology units with a focus on concepts, diagrams, and application-based questions |
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Practical Exam |
30 |
Includes experiments, record work, project, and viva |
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Total |
100 |
Balanced assessment of theory and practical understanding |
Knowing this biology weightage class 12 helps you divide your time smartly between theory and practicals and makes sure of better preparation for scoring high marks in the board exams.
Read More: Toughest and Easiest Chapters in CBSE Class 12 Biology
Class 12 Biology Syllabus
Before learning about the weightage of chapters in Biology Class 12, it is important to know the detailed syllabus. Understanding the syllabus helps you plan your study schedule and cover all topics without missing anything. Check out the detailed Class 12 Biology syllabus here:
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Class 12 Biology Syllabus |
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Unit |
Chapter |
Topics Covered |
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Unit VI: Reproduction |
Chapter 1: Sexual Reproduction in Flowering Plants |
Flower structure; male & female gametophyte development; pollination types and agencies; outbreeding devices; pollen-pistil interaction; double fertilization; post-fertilization events (endosperm, embryo, seed, fruit); special modes (apomixis, parthenocarpy, polyembryony); significance of seed dispersal and fruit formation |
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Chapter 2: Human Reproduction |
Male & female reproductive systems; microscopic anatomy of testis & ovary; spermatogenesis & oogenesis; menstrual cycle; fertilization; embryo development up to blastocyst; implantation; pregnancy & placenta formation (basic idea); parturition & lactation (basic idea) |
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Chapter 3: Reproductive Health |
Need for reproductive health; prevention of STDs; birth control methods; contraception & medical termination of pregnancy; amniocentesis; infertility & assisted reproductive technologies (IVF, ZIFT, GIFT – basic idea) |
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Unit VII: Genetics and Evolution |
Chapter 4: Principles of Inheritance and Variation |
Mendelian inheritance; deviations (incomplete dominance, co-dominance, multiple alleles, blood groups, pleiotropy); polygenic inheritance (basic); chromosome theory; sex determination (humans, birds, honey bee); linkage & crossing over; sex-linked inheritance (haemophilia, color blindness); Mendelian & chromosomal disorders (thalassemia, Down’s, Turner’s, Klinefelter’s) |
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Chapter 5: Molecular Basis of Inheritance |
Search for genetic material; DNA as genetic material; DNA & RNA structure; DNA packaging & replication; Central Dogma; transcription, genetic code, translation; gene expression & regulation (lac operon); genome projects (human & rice); DNA fingerprinting |
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Chapter 6: Evolution |
Origin of life; biological evolution & evidences (paleontology, comparative anatomy, embryology, molecular); Darwin’s contribution; modern synthetic theory; mechanisms (mutation, recombination, natural selection, types); gene flow & genetic drift; Hardy-Weinberg principle; adaptive radiation; human evolution |
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Unit VIII: Biology and Human Welfare |
Chapter 7: Human Health and Diseases |
Pathogens & parasites causing human diseases (malaria, dengue, chikungunya, filariasis, ascariasis, typhoid, pneumonia, common cold, amoebiasis, ringworm) & their control; basic immunology & vaccines; cancer, HIV & AIDS; adolescence issues – drug & alcohol abuse |
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Chapter 8: Microbes in Human Welfare |
Microbes in food processing, industry, sewage treatment, energy generation; microbes as bio-control agents & bio-fertilizers; antibiotics – production & use |
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Unit IX: Biotechnology and its Applications |
Chapter 9: Biotechnology – Principles and Processes |
Genetic engineering (Recombinant DNA Technology) |
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Chapter 10: Biotechnology and its Applications |
Applications in health & agriculture (human insulin & vaccines, stem cell technology, gene therapy); GMOs (Bt crops, transgenic animals); biosafety, biopiracy, patents |
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Unit X: Ecology and Environment |
Chapter 11: Organisms and Populations |
Population interactions (mutualism, competition, predation, parasitism); population attributes – growth, birth & death rates, age distribution |
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Chapter 12: Ecosystem |
Ecosystem patterns & components; productivity & decomposition; energy flow; pyramids of number, biomass, energy |
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Chapter 13: Biodiversity and Its Conservation |
Concept, patterns & importance of biodiversity; loss & conservation; hotspots, endangered organisms, extinction, Red Data Book; Sacred Groves, biosphere reserves, national parks, wildlife sanctuaries, Ramsar sites |
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Now that you know the complete Class 12 Biology syllabus, let’s check the CBSE Class 12 Biology chapter-wise weightage to understand the marks distribution.
Check Out: Class 12 Sample Papers
Chapter-Wise Weightage of Biology Class 12
By checking the chapter-wise weightage of biology class 12, you focus on each unit according to its marks. This makes your board exam preparation more organised and effective. Here is the CBSE Class 12 Biology Chapter-Wise Weightage for the theory exam:
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CBSE Class 12 Biology Chapter-Wise Weightage |
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Unit |
Chapter |
Weightage (Marks) |
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Unit VI: Reproduction |
Sexual Reproduction in Flowering Plants |
7 |
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Human Reproduction |
6 |
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Reproductive Health |
3 |
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Total |
16 |
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Unit VII: Genetics and Evolution |
Principles of Inheritance and Variation |
8 |
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Molecular Basis of Inheritance |
8 |
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Evolution |
4 |
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Total |
20 |
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Unit VIII: Biology and Human Welfare |
Human Health and Diseases |
9 |
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Microbes in Human Welfare |
3 |
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Total |
12 |
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Unit IX: Biotechnology and Its Applications |
Biotechnology – Principles and Processes |
6 |
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Biotechnology and Its Applications |
6 |
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Total |
12 |
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Unit X: Ecology and Environment |
Organisms and Populations |
5 |
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Ecosystem |
3 |
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Biodiversity and Its Conservation |
2 |
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Total |
10 |
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The weightage of chapters in biology class 12 shows that units like Genetics and Evolution and Reproduction carry more marks, so you should give them proper time while also preparing for other chapters under Ecology, Biotechnology, and Human Welfare.
Check Out: Class 12 Question Banks
How to Prepare for Class 12 Biology Exam To Score 90+ Marks
Scoring 90+ marks in Class 12 Biology is possible if you study smartly and focus on the high-scoring chapters. Biology is mostly a theoretical subject, so understanding concepts and remembering important points is key. Here are some tips on how to prepare to score 90+ marks in the Class 12 Biology exam:
Understand the Syllabus and Biology Chapter Weightage Class 12:
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First, go through the complete Class 12 Biology syllabus carefully. Knowing all units and chapters helps you plan your study and ensures no topic is left out.
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After that, check the biology chapter weightage class 12 to identify the chapters like Genetics and Evolution, Reproduction, and Human Physiology, which carry more marks.
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Solve chapter-wise and topic-wise questions by using PW CBSE Question for Biology, which helps you practice all important concepts, diagrams, and application-based questions in a proper way.
Use Class 12 Biology NCERT Thoroughly:
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Many questions in the board exam come directly from the NCERT textbook. Read this chapter deeply, practice diagrams, and learn definitions and examples properly.
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Focus on NCERT exercise solutions and in-between chapter questions because they are very important and often asked in exams.
Solve Class 12 Biology Previous Year Questions:
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Solving Class 12 Biology Previous Year Questions helps you understand the type of questions asked, the weightage of chapters, and how to write answers correctly.
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It also improves speed and accuracy, which is important during exams.
Make Notes and Revision Charts:
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Prepare short notes, diagrams, and flowcharts for each chapter.
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These help in quick revision before the exam and make remembering key points easier.
Practice Answer Writing With Class 12 Biology Sample Papers:
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Write answers to different types of questions given in the Class 12 Biology Sample Papers within the exam time limit.
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This helps you get used to managing time and answering questions properly. You can also identify weak areas and revise them before the exam.
Use Reliable Biology Books by PW:
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For better practice and understanding, you can refer to additional biology books by PW.
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These PW Class 12th Books provide extra questions, solved examples, and practice exercises, which strengthen your preparation for final board examinations.
Also Read: Mnemonics for Class 12 CBSE Biology, Download PDF
CBSE Class 12 Biology Chapter-Wise Weightage FAQs
Q.1. What is CBSE Class 12 Biology Chapter-Wise Weightage?
Ans. CBSE Class 12 Biology chapter-wise weightage shows the marks distribution of all chapters in biology. It helps you understand which chapters carry more marks and how to plan your study for the board exam.
Q.2. Which chapters carry the highest marks in Class 12 Biology?
Ans. As per the Biology class 12 weightage, chapters like Principles of Inheritance and Variation, Molecular Basis of Inheritance, Human Health and Diseases, Sexual Reproduction in Flowering Plants, and Human Reproduction carry the higher weightage of marks.
Q.3. Is biology a tough subject in Class 12 board exams?
Ans. Biology is not very tough if you study smartly. It is mostly a theoretical subject, so understanding concepts, learning diagrams, and practicing chapter-wise questions can help you score high marks.
Q.4. How can I prepare for the Biology Class 12 boards in just 3 months?
Ans. Focus on NCERT thoroughly, solve previous year questions and sample papers, revise diagrams, and practice chapter-wise questions. Make short notes and flowcharts for quick revision.
