11 Bio Chapter Summary

Cell Division

Chapter Summary

  • The phase between subsequent cell divisions is called the interphase. The interphase lasts for more than 95% of the cell cycle.
  • The actual cell division takes place in the M phase. The M phase lasts for less than 5% of the cell cycle.
  • Cells which do not divide further, exit G1 phase to enter an inactive stage. This stage is called quiescent stage (G0) of the cell cycle.
  • The cell division after which two daughter cells are formed and number of chromosomes remains the same as in mother cell is called mitosis. Mitosis is divided into four stages, viz. Prophase, Metaphase, Anaphase and Telophase
  • Division of cytoplasm is achieved by cytokinesis.



  • Mitosis results in the formation of new cells which are required for growth and repair.
  • The cell division after which four daughter cells are formed and number of chromosomes becomes half compared to in mother cell is called meiosis.
  • Meiosis involves two sequential cycles of nuclear and cell division, but only a single cycle of DNA replication. Meiosis is divided into meiosis I and meiosis II.
  • Prophase in meiosis I is typically longer and more complex than the prophase in meiosis II. Prophase I is subdivided into five phases, viz. Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.
  • Conservation of specific chromosome number of each species is achieved across successive generations in sexually reproducing organisms through meiosis.
  • Meiosis helps in increasing the genetic variations in the population of organisms from one generation to the next.