Chapter Overview & Weightage
- Marks in Boards: 10–14 marks (highest in Genetics unit – usually 2–3 questions + diagram/numerical)
- Repeated Topics: DNA structure, replication, transcription, translation, genetic code, lac operon, human genome project, DNA fingerprinting.
- Difficulty: High • Heavy on diagrams (DNA double helix, replication fork, transcription unit, lac operon) + processes & experimental evidence.
- Trend (2021–2025): 1 diagram-based (5 marks) on replication/transcription + 1 long answer (5 marks) on lac operon/genetic code + MCQs on central dogma.
Most Important & Repeated Questions (2021–2025)
- Repeated 5–6 times: Draw a labelled diagram of semi-conservative DNA replication. Explain the process. (5 marks)
- Repeated 5 times: Describe the process of transcription in eukaryotes with diagram. (5 marks)
- Repeated 4–5 times: Explain the lac operon regulation with diagram (inducible system). (5 marks)
- Repeated 4 times: What is genetic code? Give characteristics (degenerate, universal, unambiguous, commaless). (3 marks)
- Repeated 3–4 times: Explain central dogma of molecular biology. (3 marks)
- Repeated 3 times: Describe structure of tRNA with diagram. Role in translation. (3 marks)
- Repeated 3 times: What is DNA fingerprinting? Explain its principle & applications. (5 marks)
- Repeated 2–3 times: Explain human genome project & its findings. (3 marks)
- Assertion-Reason (2023–2025): Assertion: DNA replication is semi-conservative. Reason: Each new DNA has one old and one new strand. (Both true, reason explains – repeated 2x)
Important Keywords & Concepts to Memorize
- DNA, RNA, double helix, Watson-Crick model, semi-conservative replication, replication fork, leading/lagging strand, Okazaki fragments, DNA polymerase, ligase, helicase, topoisomerase, transcription, promoter, terminator, RNA polymerase, mRNA, tRNA, rRNA, genetic code, codon, anticodon, translation, ribosome, initiation, elongation, termination, lac operon, repressor, inducer, operator, regulator gene, human genome project, DNA fingerprinting, VNTR, satellite DNA, polymorphism, Hershey-Chase experiment, Meselson-Stahl experiment.
Exam Strategy for Chapter 6 (2026 Boards)
- Focus: Diagrams (DNA replication fork, transcription unit, lac operon, tRNA) – practice 4 daily
- High-scoring: DNA replication & lac operon (5 marks each) + labelled diagram
- Time: 8–10 minutes per 5-mark question (diagram + explanation)
- Tip: Label 8–10 parts in every diagram – neatness = full marks
- Repeated: Genetic code characteristics (degenerate, universal) – 2–3 marks
This is Chapter 6 complete PYQ analysis.
If you want Chapter 7 or any other chapter, just say the chapter number or name.