important topics for Chapters 1–4 of Karnataka State Board (2nd PUC/Class 12) Biology, aligned with the 2025–26 syllabus:

 

Confirmation of Syllabus Status for 2025–26

The Karnataka Board has confirmed that the 2nd PUC Biology syllabus for 2025–26 remains unchanged from the previous academic year—students are expected to study the full syllabus with no reductions.

Full Chapter Coverage & Marking Weightage

According to a recent breakdown, the Class 12 Biology syllabus still includes the following chapters with their corresponding marks:

Chapter No.	Chapter Name	Marks
1	Sexual Reproduction in Flowering Plants	11
2	Human Reproduction	10
3	Reproductive Health	6
4	Principles of Inheritance and Variation	13

Chapter-wise Key Topics (Chapters 1–4)

Drawing from detailed syllabus content, here's what you should focus on for each of these chapters:

• Chapter 1: Sexual Reproduction in Flowering Plants

  • Flower structure (male/female reproductive parts), gametophyte development

  • Pollination types and agents, out-breeding devices

  • Pollen–pistil interaction, double fertilization

  • Post-fertilization events: endosperm, embryo, seed, fruit formation

  • Apomixis, parthenocarpy, polyembryony

  • Significance of seed dispersal and fruit formationCollegeSearch

• Chapter 2: Human Reproduction

  • Anatomical details of male and female reproductive systems

  • Gametogenesis (spermatogenesis and oogenesis), menstrual cycle

  • Fertilization, embryo development up to blastocyst stage

  • Implantation, placenta formation, parturition, lactation (basic concepts)CollegeSearch

• Chapter 3: Reproductive Health

  • Importance of reproductive health, birth control methods

  • Medical Termination of Pregnancy (MTP), amniocentesis

  • Prevention of STDs

  • Infertility and assisted reproductive technologies (IVF, ZIFT, GIFT)CollegeSearch

• Chapter 4: Principles of Inheritance and Variation

• Heredity and variation, Mendelian inheritance

• Deviations: incomplete dominance, co-dominance, multiple alleles (e.g., blood groups), pleiotropy, polygenic inheritance

• Chromosome theory of inheritance

• Chromosomal disorders like Down’s, Turner’s, Klinefelter’s syndromeCollegeSearch

Summary: Why These Topics Matter

• These four chapters together account for 40 marks in the theory paper (which is itself 70 marks), making them crucial for exam success.

• Topics are not only foundational for Karnataka PUC exams but also essential for competitive exams like NEET, as the syllabus closely mirrors NCERT content.Careers360 SchoolsAakash Institute

• Many of these topics are concept-heavy and diagram-oriented, and consistently appear in high-mark questions.

Study Recommendations

1. Master Diagrams
   Focus on drawing and labeling structures like floral anatomy, reproductive systems, gametogenesis, embryonic stages, etc.

2. Understand Concepts Deeply
   Don’t just memorize—understand processes like double fertilization, menstrual cycle, gene inheritance patterns, etc.

3. Practice Problems and Sample Papers
   Work on a mix of question types including MCQs, short answers, and long answers.

4. Revise Regularly
   Use chapter-wise notes and model papers (available online) to track your revision.Pucnotes SolutionsDPU Exam

5. Integrate with Later Units
   Although Chapters 5–16 also cover high-yield topics like molecular biology, evolution, biotechnology, human welfare, and ecology, solid mastery of Chapters 1–4 sets a strong foundation.