Class 11 Biology - WEST-BENGAL
Cell Cycle and Cell Division
The chapter 'Cell Cycle and Cell Division' in Class 11 Biology under the West Bengal Board (WBBSE) explores how a single cell grows, replicates its genetic material, and divides to form daughter cells. It covers the sequential phases of the cell cycle—Interphase and M-phase—along with detailed mechanisms of Mitosis and Meiosis. Understanding this chapter is crucial for board exams as it forms the fundamental basis of genetics, growth, tissue repair, and reproduction, frequently appearing in both short and descriptive question formats.
Start Learning FreeKey Concepts
Cell Cycle
The ordered series of events involving cell growth and division that generates two daughter cells from a single parent cell, consisting of Interphase and M-phase.
Interphase
The preparatory phase of the cell cycle divided into G1, S (DNA synthesis), and G2 phases, where the cell grows and duplicates its DNA before division.
Mitosis
Equational division occurring in somatic cells where the chromosome number remains constant, divided into prophase, metaphase, anaphase, and telophase.
Meiosis
Reductional division occurring in germ cells that halves the chromosome number and introduces genetic variation through crossing over, producing four haploid cells.
Crossing Over
The exchange of genetic material between non-sister chromatids of homologous chromosomes during pachytene of meiotic prophase I, leading to genetic recombination.
Important Formulas
Board Exam Info
In the West Bengal (WBBSE) Class 11 Biology annual examination, this chapter typically carries around 6 to 8 marks. Questions frequently include short-answer questions (SAQ), multiple-choice questions (MCQ), and 3-5 mark descriptive questions requiring the comparison between mitosis and meiosis or detailed diagrams of mitotic phases.
Frequently Asked Questions
Why is meiosis called reductional division?
Meiosis is called reductional division because the chromosome number is reduced to half in the daughter cells compared to the parent cell.
What is the significance of the S phase in the cell cycle?
The S phase (Synthesis phase) is crucial because DNA replication takes place, ensuring that each daughter cell receives an identical copy of the genetic material.
At which stage does crossing over occur?
Crossing over occurs during the pachytene stage of Prophase I in Meiosis.
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