Chapter 10 — Cell Cycle and Cell Division

Chapter 10 of the Class 11 Biology NCERT textbook, "Cell Cycle and Cell Division", explains this topic. It covers how cells divide through mitosis and meiosis: mitosis produces identical diploid daughter cells for growth and repair, while meiosis creates four haploid gametes for sexual reproduction.

• The cell cycle as a prepared sequence — The chapter presents division as the climax of a cycle: a long interphase (G1, S, G2) in which the cell grows and replicates its DNA prepares it for the brief M phase where division actually happens.
• Mitosis conserves, meiosis reduces — It contrasts the two divisions in purpose—mitosis is an equational division keeping chromosome number constant for growth and repair, while meiosis is a reduction division that halves chromosomes to make gametes.
• Meiosis and genetic variability — The chapter explains why meiosis matters beyond counting chromosomes: synapsis and crossing over between homologous chromosomes shuffle genes, so the four haploid products carry new combinations that fuel variation.

1. 01Cell cycle consists of interphase (95% of duration) and M phase, with DNA replication occurring only during the S phase
2. 02Mitosis is equational division conserving chromosome number; includes prophase, metaphase, anaphase, telophase, and cytokinesis
3. 03Significance of mitosis: growth of multicellular organisms, cell repair, and continuous plant growth via meristematic tissues
4. 04Meiosis is reduction division halving chromosome number through two sequential divisions with crossing over and genetic recombination
5. 05Meiosis I features synapsis of homologous chromosomes, bivalent formation, and crossing over between non-sister chromatids
6. 06Four haploid daughter cells result from meiosis II; meiosis maintains species chromosome number and increases genetic variability