Class 11 Biology - CBSE
Cell Cycle and Cell Division
The chapter 'Cell Cycle and Cell Division' explores how a single cell grows, replicates its DNA, and divides to form two daughter cells. Students learn about the phases of the cell cycle—Interphase and M-phase—along with the intricate details of Mitosis and Meiosis. Understanding this chapter is crucial for mastering genetics, biotechnology, and human physiology in Class 11 and 12. For CBSE board exams, it is a high-weightage chapter frequently tested through diagram-based questions, ploidy calculations, and the fundamental differences between mitotic and meiotic divisions.
Start Learning FreeKey Concepts
Interphase
The preparatory phase of the cell cycle consisting of G1, S, and G2 phases, where the cell grows, synthesizes proteins, and replicates its DNA.
Mitosis
Equational division resulting in two genetically identical daughter cells with the same chromosome number as the parent cell, used for growth and repair.
Meiosis
Reductional division occurring in germ cells, producing four genetically diverse haploid daughter cells and maintaining chromosome number across generations.
Crossing Over
The exchange of genetic material between non-sister chromatids of homologous chromosomes during pachytene of meiosis I, leading to genetic variation.
G0 Phase (Quiescent Stage)
A stage where cells exit the active cell cycle to remain metabolically active without proliferating, unless called upon to divide.
Important Formulas
Board Exam Info
This chapter typically carries around 4 to 6 marks in the CBSE Class 11 Biology theory exam. Common question types include distinguishing between mitosis and meiosis, explaining the sub-stages of prophase I, diagram-based identification of cell division phases, and calculating DNA or chromosome amounts at specific cell cycle checkpoints.
Frequently Asked Questions
What is the main difference between mitosis and meiosis?
Mitosis produces two identical diploid daughter cells for growth and repair, while meiosis produces four genetically diverse haploid cells for sexual reproduction.
Why is meiosis called reductional division?
It is called reductional division because the chromosome number is halved from diploid (2n) to haploid (n) in the daughter cells.
What happens during the S phase of the cell cycle?
DNA replication takes place, meaning the amount of DNA per cell doubles while the chromosome number remains the same.
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