Class 11 Biology - TAMILNADU
Cell Cycle and Cell Division
The chapter 'Cell Cycle and Cell Division' in Tamil Nadu Class 11 Biology explores how a single cell divides to form new cells, which is fundamental for growth, repair, and reproduction in living organisms. Students will learn about the phases of the cell cycle including Interphase and M-phase, and deeply understand the two types of nuclear division: Mitosis, which maintains chromosome number in somatic cells, and Meiosis, which reduces the chromosome number by half to form gametes. Mastery of this chapter is vital for board exams as it forms the basis of genetics and cellular biology.
Start Learning FreeKey Concepts
Cell Cycle
The orderly sequence of events by which a cell duplicates its genome, synthesizes other cell constituents, and divides into two daughter cells.
Interphase
The preparatory phase of the cell cycle consisting of G1, S, and G2 phases, where the cell grows and replicates its DNA before division.
Mitosis
Equational division occurring in somatic cells where the chromosome number remains the same in the parent and daughter cells.
Meiosis
Reductional division occurring in germ cells that reduces the chromosome number by half, producing four genetically different haploid cells.
Crossing Over
The exchange of genetic material between non-sister chromatids of homologous chromosomes during pachytene of meiosis I, leading to genetic variation.
Important Formulas
Board Exam Info
In the Tamil Nadu (Samacheer Kalvi) Class 11 Biology board examination, this chapter typically carries around 6 to 8 marks. Questions frequently include direct 1-mark objective questions, 2-mark definitions, 3-mark phase comparisons (like Mitosis vs. Meiosis), and 5-mark detailed essay questions explaining the stages of Meiosis I.
Frequently Asked Questions
Why is interphase called the resting phase?
Interphase is historically called the resting phase because there is no visible division taking place, but metabolically, it is the most active phase where DNA replication and cell growth occur.
What is the main difference between cytokinesis in plant and animal cells?
In animal cells, cytokinesis occurs by furrowing or cleavage of the plasma membrane, whereas in plant cells, it occurs by the formation of a cell plate from the center outwards.
Why is meiosis important for sexual reproduction?
Meiosis reduces the chromosome number by half to form gametes and introduces genetic variation through crossing over, ensuring constancy of chromosome number across generations.
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