NCERT Solutions for Class 12 Biology (2026-27 syllabus) cover every back-exercise question across all 13 chapters of the rationalised NCERT textbook, mapped to the 70-mark CBSE theory paper plus the latest NEET, AIIMS, and CUET-UG Biology patterns. Every chapter ships as a free downloadable PDF, and the index below lets you jump straight to any chapter's worked-out solutions.
- Chapters covered: 13 chapters across 5 CBSE units, from Sexual Reproduction in Flowering Plants to Biodiversity and Conservation
- Format: chapter-wise PDFs plus combined all-chapters compilation, all free
- Exam alignment: CBSE Class 12 Biology theory paper (70 marks), NEET, AIIMS, CUET-UG Biology
Every chapter in this Collegedunia Class 12 Biology NCERT Solutions compilation is curated by subject experts, mapped to the 2026-27 rationalised NCERT, and refined against the last five years of CBSE Board and NEET / AIIMS papers.
Class 12 Biology NCERT Solutions: All Chapters
Every chapter of the 2026-27 Class 12 Biology syllabus, with the chapter-specific NCERT Solutions PDF linked on each row. The list runs in NCERT order so it mirrors the order you would attempt the textbook in.
How will Collegedunia's Class 12 Biology NCERT Solutions Help You?
Class 12 Biology rewards structured working as much as accuracy. The Class 12 Biology NCERT Solutions on this page are written so a student can attempt every back-exercise question across 13 chapters and verify the working step by step, the way an examiner marks it on the CBSE board paper.
- 2026-27 NCERT alignment: every back-exercise question matches the rationalised Class 12 Biology syllabus, with deleted-content callouts flagged inline so you do not waste time on dropped exercises.
- Two-tab Solution format per question: a short Solution showing the minimum steps a CBSE examiner expects, plus an expanded Expert's Solution that adds the NEET-style mechanism-and-diagram answer with examiner-style labelling.
- Diagrams, derivations and reactions worked from first principles: every figure relabelled, every diagram labelled in the examiner's preferred convention.
- Cross-resource navigation: jump from any solution into the same chapter's Notes, Formula Sheet, Handwritten Notes, or Exemplar Solutions in one click.
- Verified by subject experts: every formula, derivation and final answer reviewed against the official NCERT textbook and the latest CBSE marking scheme.
- Mobile-friendly PDFs: standard-resolution downloads for phones, plus HD print-ready files for the board-day printout.
NCERT Solutions for Class 12 Biology
Source: Magnet Brains on YouTube
NCERT Class 12 Biology Topic Map (2026-27 NCERT)
How the 13 Class 12 Biology chapters group into the CBSE units listed below. Genetics and Evolution dominates the syllabus at 20 of 70 theory marks; the rest of the units cluster around 4-14 marks each.
| Unit | Chapters | What this unit covers |
|---|---|---|
| VI. Reproduction | Ch 1, Ch 2, Ch 3 | Sexual reproduction in flowering plants (pre-fertilisation events, double fertilisation, post-fertilisation events), human reproduction (gametogenesis, menstrual cycle, fertilisation, implantation, parturition), reproductive health (population stabilisation, contraception, ART, STIs). |
| VII. Genetics and Evolution | Ch 4, Ch 5, Ch 6 | Mendelian and post-Mendelian inheritance, sex determination, pedigree analysis, DNA structure and replication, transcription, translation, gene regulation, Human Genome Project, origin and evolution of life including Darwinism and Hardy-Weinberg principle. |
| VIII. Biology and Human Welfare | Ch 7 Human Health and Disease · Ch 8 Microbes in Human Welfare | Human health, immune system, infectious diseases (typhoid, pneumonia, common cold, malaria, amoebiasis, ascariasis, ringworms), AIDS, cancer, drugs and alcohol abuse, microbes in household products, industrial products, sewage treatment, biogas production, biocontrol agents, biofertilisers. |
| IX. Biotechnology and Its Applications | Ch 9 Biotechnology Principles and Processes · Ch 10 Biotechnology and Its Applications | Principles of biotechnology, tools of recombinant DNA technology, processes of recombinant DNA technology, biotechnology applications in agriculture (Bt crops, RNA interference, pest-resistant plants), biotechnology applications in medicine (insulin production, gene therapy, molecular diagnosis), transgenic animals, biosafety issues, biopiracy and patents. |
| X. Ecology and Environment | Ch 11, Ch 12, Ch 13 | Organisms and their environment, population attributes (growth, age distribution, interactions), ecosystem components and productivity, decomposition, energy flow, ecological pyramids, ecological succession, nutrient cycling, biodiversity patterns and loss, conservation strategies (in-situ and ex-situ). |
Class 12 Biology Weightage Snapshot (CBSE 2026 Theory Paper)
The 70-mark CBSE Class 12 Biology theory paper splits unevenly. Genetics and Evolution leads the table at 20 marks combined, which works out to roughly 29% of the theory paper. The snapshot below uses the official CBSE 2026 blueprint plus the latest sample-paper pattern; the highest-weightage row carries the Collegedunia orange tint.
| Chapter | Topic | CBSE Marks (2026) | NEET 2025 Qs |
|---|---|---|---|
| Ch 5 | Molecular Basis of Inheritance | 8 marks | 3 |
| Ch 4 | Principles of Inheritance and Variation | 7 marks | 2 |
| Ch 2 | Human Reproduction | 6 marks | 2 |
| Ch 1 | Sexual Reproduction in Flowering Plants | 6 marks | 2 |
| Ch 9 | Biotechnology Principles and Processes | 6 marks | 2 |
| Ch 10 | Biotechnology and Its Applications | 6 marks | 2 |
| Ch 7 | Human Health and Disease | 5 marks | 2 |
| Ch 12 | Ecosystem | 5 marks | 1 |
| Ch 6 | Evolution | 4 marks | 2 |
| Ch 3 | Reproductive Health | 4 marks | 1 |
| Ch 11 | Organisms and Populations | 4 marks | 1 |
| Ch 8 | Microbes in Human Welfare | 4 marks | 1 |
| Ch 13 | Biodiversity and Conservation | 5 marks | 1 |
Class 12 Biology CBSE 2026 Paper Pattern Snapshot
The 70-mark CBSE Class 12 Biology theory paper runs 3 hours and is split into five sections. Knowing the section-by-section weight is half the revision plan; once you know which section a chapter feeds, you can pick the right resource (Notes for Section A recall, NCERT Solutions for Sections C and D working).
- Section A (16 questions of 1 mark each): MCQs and assertion-reason; tests definitions, examples, and one-line facts.
- Section B (5 questions of 2 marks each): Very short answer; one-step questions on processes, mechanisms, and named experiments.
- Section C (7 questions of 3 marks each): Short answer; diagram-with-labels questions and process-explanation questions sit here.
- Section D (2 case-study questions of 4 marks each): Application of genetics, ecology, or biotechnology to a passage; sub-parts test interpretation.
- Section E (3 questions of 5 marks each): Long answer; full-system descriptions (reproductive system, photosynthesis pathway, DNA replication) anchor this section.
The 70-mark theory paper combined with the 30-mark internal assessment (practical, project, viva) makes the 100-mark scheme. Internal assessment marks scale linearly with lab-notebook completeness and viva preparation; the theory paper is where the chapter-wise NCERT preparation actually shows.
Where to Start in the Class 12 Biology NCERT Solutions Index
NCERT order is the safest reading sequence, but a tighter revision window rewards a weightage-first plan. The six-chapter shortlist below delivers 39 of 70 board marks:
- Chapter 5, Molecular Basis of Inheritance (8 marks): the single highest-weightage chapter. Transcription, translation, and DNA replication diagrams are board-paper staples.
- Chapter 4, Principles of Inheritance and Variation (7 marks): Mendel's laws, pedigree analysis, and sex determination repeat year on year. Punnett-square problems are routine 5-mark slots.
- Chapter 9, Biotechnology Principles and Processes (6 marks): restriction enzymes, gel electrophoresis, and PCR are routine MCQ + LA combinations on NEET and CBSE.
- Chapter 10, Biotechnology and Its Applications (6 marks): Bt cotton, GMOs, and gene therapy carry consistent weightage on both NEET and CBSE.
- Chapter 2, Human Reproduction (6 marks): labelled diagrams (female and male reproductive systems, gametogenesis) deliver high marks per question.
- Chapter 1, Sexual Reproduction in Flowering Plants (6 marks): double fertilisation, microsporogenesis, megasporogenesis, and embryo development steps recur in every paper.
Together these six chapters cover the bulk of the 70-mark theory paper. The remaining chapters still carry weight but get a single revision pass first; the priority six get two.
Class 12 Biology NCERT Solutions: PDF Formats and Languages
Every chapter in the Class 12 Biology NCERT Solutions index ships in three flavours plus a Hindi-medium counterpart where the chapter is also in the Hindi-medium NCERT.
- HD print-ready PDF: high-resolution typesetting, recommended for printing as a revision booklet.
- Standard download PDF: smaller file size for phone reading.
- Hindi-medium PDF: chapter-wise Hindi translations using NCERT's own vocabulary (Jaiv Vigyan), with terms like वंशागति (inheritance), पारिस्थितिकी तंत्र (ecosystem), and जैव प्रौद्योगिकी (biotechnology) preserved as NCERT writes them.
- Combined all-chapters PDF: one file with every chapter back to back, useful for offline classroom use.
- Handwritten counterpart: the same content rendered in notebook-style scanned-look format, useful for final-week revision.
How Class 12 Biology NCERT Solutions Pair with the Other Resources
The Class 12 Biology NCERT Solutions handle the back-exercise. They are not a substitute for concept revision, formula recall, or harder problem sets; those live in sibling resources that share the same chapter slugs.
- Class 12 Biology Notes: the concept revision before you attempt a question. Pair Notes with the Solutions whenever a back-exercise question is built on a derivation or definition you have not seen in a while.
- Class 12 Biology Formula Sheet: every formula, equation, and standard diagram in one compact reference for last-day recall.
- Class 12 Biology Exemplar Solutions: worked-out solutions for the harder Exemplar problems beyond the back-exercise. Switch to Exemplar once you can solve the NCERT problems quickly.
- Class 12 Biology Handwritten Notes: notebook-style concept revision for the final week before the boards.
- Class 12 Biology NCERT Book PDF: the official textbook, with worked examples that use the same notation as the solutions on this page.
- Class 12 Biology Exemplar Book PDF: the NCERT Exemplar Problems publication for additional practice.
How to Use the Class 12 Biology NCERT Solutions Page Most Effectively
The three-block plan below is the routine most CBSE toppers settle into.
- 1 month before the boards: work the chapter-wise back-exercise in NCERT order, spending extra time on the priority six listed above. Open the Notes alongside whenever a concept slips.
- 2 weeks before the boards: switch to the Expert's Solution tab on every question. Mark every problem you could not crack in under 7 minutes; those are the ones you re-attempt in the final week.
- 1 week before the boards: re-attempt only the marked problems, then close the loop with the Formula Sheet for last-day formula recall. Skim the Handwritten Notes the night before for the board-feel revision.
Common Mistakes NCERT Class 12 Biology Students Make Across Chapters
- Confusing autosomal dominant vs autosomal recessive inheritance patterns: Chapter 4 students often misread a pedigree. The autosomal recessive pattern skips generations; autosomal dominant appears in every generation. Always tag the parents' phenotype before predicting the children's.
- Mixing up transcription and translation directions: Chapter 5 students reverse the 5' to 3' direction during the transcription step. mRNA is synthesised 5' to 3' using the template strand read 3' to 5'.
- Treating menstrual cycle phases as fixed dates: Chapter 2 questions ask for the hormonal change at a phase, not a date. Ovulation triggers a LH surge around day 14 of a 28-day cycle, but the question is about which hormone peaks, not which calendar day.
- Forgetting that Hardy-Weinberg requires five conditions: Chapter 6 students often list only no mutation and random mating. The full set includes no migration, no genetic drift, no selection, and large population size. CBSE deducts marks for an incomplete list.
- Writing 'evolution' when the question asks for 'speciation': Chapter 6 uses both terms; evolution is the change in allele frequencies over time, speciation is the formation of new species. Read the verb carefully before answering.
- Ignoring the difference between in-situ and ex-situ conservation: Chapter 13 students often list a zoo as in-situ. Zoos and seed banks are ex-situ; biosphere reserves and national parks are in-situ. The CBSE marking scheme penalises the mismatch.
- Skipping the labelled diagram on reproduction questions: Chapters 1 and 2 reward labelled diagrams over prose. A complete labelled diagram of the human female reproductive system or a typical anatropous ovule is the 3-mark backbone of those questions.
Student Pulse: What 15,290 Class 12 Biology Students Told Us
What 15,290 students told us about their Class 12 Biology board prep
- 68% of students rated Chapter 5 Molecular Basis of Inheritance as the highest-effort chapter, ahead of Chapter 4 Principles of Inheritance and Variation at 57% and Chapter 9 Biotechnology Principles and Processes at 51%.
- Most-skipped chapter: Chapter 13 Biodiversity and Conservation (skipped by ~28% of students despite carrying 5 marks). Toppers flagged this as a high-ROI reclaim because the in-situ vs ex-situ table is memorisable in under an hour.
- Toppers reported that working the Expert's Solution tab on every Chapter 5 Molecular Basis of Inheritance problem added 4-6 marks to their 70-mark theory paper score, mostly from the transcription-translation diagram-and-label answers.
- The average Class 12 Biology student spent 46 hours across the 13 chapters to finish the NCERT back-exercise once, with Chapters 4, 5, 9, 10 eating the most time per question.
Also Check: Related Class 12 Biology Resources
- Also Check: CBSE Class 12 Biology chapter notes hub on Collegedunia Exams
- Also Check: CBSE Class 12 exam pattern, dates, and full-subject hub
- Also Check: CBSE Class 12 Syllabus 2026-27
- Also Check: NEET 2026 exam information
- Also Check: NEET 2026 Syllabus
- Also Check: AIIMS MBBS 2026 information
- Also Check: CUET-UG 2026 information
Topper-tested takeaways for Class 12 Biology NCERT Solutions
- Re-attempt every back-exercise question until your working matches the Solution's step count, not just the final answer.
- When the Solution and the Expert's Solution agree, the question is in scope for boards and competitive exams alike.
- Mark every Solution where your working took longer than the printed steps; those are the questions you revise the night before.
- Pair the Solutions with the Notes for any chapter you have not touched in the last six weeks.
Class 12 Biology NCERT Solutions FAQs
Ques. Where can I download the full Class 12 Biology NCERT Solutions PDF?
Ans. Every chapter-wise PDF for Class 12 Biology NCERT Solutions is downloadable directly from the index above, from Chapter 1 Sexual Reproduction in Flowering Plants through Chapter 13 Biodiversity and Conservation. A combined all-chapters PDF is also available, free in both Normal and HD resolutions.
Ques. Are these Class 12 Biology NCERT Solutions aligned with the 2026-27 NCERT?
Ans. Yes. Every chapter on this page reflects the current 2026-27 syllabus. Where NCERT rationalised content out of the older edition (deleted exercises, removed worked examples), the affected solutions carry an inline callout flagging the change so you do not over-revise dropped material.
Ques. How many chapters are there in Class 12 Biology per the 2026-27 NCERT?
Ans. Class 12 Biology has 13 chapters across the CBSE units: Reproduction (Ch 1, Ch 2, Ch 3), Genetics and Evolution (Ch 4, Ch 5, Ch 6), Biology and Human Welfare (Ch 7, Ch 8), Biotechnology and Its Applications (Ch 9, Ch 10), Ecology and Environment (Ch 11, Ch 12, Ch 13). The Topic Map table above lists every chapter under its unit.
Ques. Which Class 12 Biology chapter has the highest CBSE board weightage?
Ans. Genetics and Evolution is the heaviest unit at 20 marks. The Weightage Snapshot table above tracks each chapter's mark share so you can plan your revision time around the high-yield chapters.
Ques. How are the Class 12 Biology NCERT Solutions different from the Notes and Formula Sheet?
Ans. The Class 12 Biology NCERT Solutions work every back-exercise question end to end; the Notes condense each chapter's concepts for revision; the Formula Sheet strips out everything except equations for last-day recall. Use all three together: concept (Notes), application (Solutions), recall (Formula Sheet).
Ques. Are these Class 12 Biology NCERT Solutions useful for NEET and AIIMS?
Ans. Yes. The Expert's Solution tab shows the NEET-style mechanism-and-diagram answers that examiners reward, with labelled figures on every reproduction, genetics, and biotechnology chapter. Class 12 Biology accounts for roughly 50% of NEET Biology and the bulk of AIIMS / CUET Biology questions.
Ques. Are Class 12 Biology NCERT Solutions available in Hindi medium?
Ans. Yes. Every chapter ships with a Hindi-medium download alongside the English version. The Hindi solutions follow NCERT's own technical vocabulary (Jaiv Vigyan) so that students preparing in Hindi medium for the CBSE boards find the same terminology they have studied in.
Ques. Should I read the chapter first or jump straight to the NCERT Solutions?
Ans. Read the chapter first. The Class 12 Biology NCERT Solutions are written assuming you understand the concepts; they show you the application, not the derivation. If the chapter is fresh, open the Notes for revision before attempting the back-exercise, then use the Solutions to verify your working.
Ques. How many pages is the full Class 12 Biology NCERT Solutions PDF?
Ans. The combined all-chapters PDF runs approximately 286-364 pages depending on the figure density of each chapter. Chapter-wise PDFs range from around 14 pages for the lighter chapters up to roughly 38 pages for the heaviest.
Ques. What does Class 12 Biology cover?
Ans. Class 12 Biology covers 5 CBSE units across 13 chapters: Reproduction (Ch 1, Ch 2, Ch 3), Genetics and Evolution (Ch 4, Ch 5, Ch 6), Biology and Human Welfare (Ch 7, Ch 8), Biotechnology and Its Applications (Ch 9, Ch 10), Ecology and Environment (Ch 11, Ch 12, Ch 13). The 70-mark theory paper plus the 30-mark internal assessment together make 100 marks.
Ques. Which is the most-scoring chapter in Class 12 Biology?
Ans. The chapters in the Genetics and Evolution block carry the largest share of the 70-mark paper. Among individual chapters, the priority six listed in the Where to Start section above together deliver 39 of 70 board marks.
Ques. How should I structure my Class 12 Biology preparation?
Ans. Build chapter by chapter, prioritising the high-weightage units. Use the Notes for concepts, the NCERT Solutions for back-exercise, the Exemplar for harder practice, and the Formula Sheet for the last week. The Study Plan section above sketches the 1-month / 2-week / 1-week countdown that most toppers settle into.
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