Last Updated: April 2026
Cell division in NEET 2026 is a high-yield chapter — expect 2–4 questions directly from this topic every year. Cell Division (Chapter 10, NCERT Class 11 Biology) covers the cell cycle, mitosis, and meiosis. Understanding the differences between these processes, their phases, and biological significance is essential for scoring in both Botany and Zoology sections of NEET-UG.
Cell Cycle: Overview
The cell cycle is the ordered sequence of events a cell undergoes from its formation to its division into two daughter cells. Duration: varies by cell type (a typical human cell divides in ~24 hours).
| Phase | Sub-phase | Key Events | Duration (typical) |
|---|---|---|---|
| Interphase (90% of cycle) | G1 (Gap 1) | Cell growth, protein synthesis, preparation for DNA replication | ~11 hours |
| S (Synthesis) | DNA replication — DNA content doubles (2N → 4N DNA) | ~7–8 hours | |
| G2 (Gap 2) | Further growth, synthesis of proteins needed for division | ~4 hours | |
| M Phase (Mitotic) | Mitosis + Cytokinesis | Nuclear and cytoplasmic division | ~1 hour |
G0 Phase: Some cells exit the cell cycle and enter a non-dividing state called G0 (quiescence). Neurons and muscle cells remain in G0 permanently. Liver cells can re-enter the cycle when needed.
Mitosis: Cell Division for Growth and Repair
Mitosis produces two genetically identical daughter cells with the same chromosome number as the parent cell. Occurs in somatic (body) cells for growth, repair, and asexual reproduction.
Phases of Mitosis
| Phase | Key Events | NEET Markers |
|---|---|---|
| Prophase | Chromatin condenses into chromosomes; centrioles move to poles; spindle forms; nucleolus disappears | First visible chromosomes; spindle formation begins |
| Metaphase | Chromosomes align at metaphase plate (equatorial plate); spindle fibres attach to centromeres | Chromosomes MOST VISIBLE — best stage for karyotyping |
| Anaphase | Centromeres split; sister chromatids separate and move to opposite poles; cell elongates | V, J, L shaped chromosomes; “anaphase lag” leads to aneuploidy |
| Telophase | Chromosomes reach poles; nuclear envelope reforms; nucleolus reappears; chromosomes decondense | Reverse of prophase |
| Cytokinesis | Cytoplasm divides; cell plate forms in plant cells (inside out); cleavage furrow in animal cells (outside in) | Cell plate — unique to plants; furrow — animal cells |
Meiosis: Cell Division for Sexual Reproduction
Meiosis produces four genetically diverse haploid daughter cells. Occurs in reproductive organs (gonads in animals, anthers and ovules in plants). Two divisions: Meiosis I (reductional) and Meiosis II (equational).
Meiosis I — Reductional Division (Chromosome number halved)
| Sub-phase | Key Events | NEET Tips |
|---|---|---|
| Leptotene | Chromosomes become visible; bead-like chromomeres appear | Earliest visible condensation |
| Zygotene | Homologous chromosomes pair (synapsis); synaptonemal complex forms | Synapsis begins; bivalents form |
| Pachytene | Crossing over occurs; chiasmata visible; genetic recombination | MOST IMPORTANT phase — crossing over = genetic diversity |
| Diplotene | Synaptonemal complex dissolves; chiasmata visible; chromosomes start to repel | Chiasmata visible here; dictyotene in oocytes (arrest) |
| Diakinesis | Terminal chiasmata; nuclear envelope breaks; spindle forms | Transition to Metaphase I |
| Metaphase I | Bivalents align at equatorial plate; spindle attaches to centromeres | Whole bivalent aligns (unlike mitotic metaphase) |
| Anaphase I | Homologous chromosomes separate; centromeres do NOT split | Centromeres do NOT split in Anaphase I — key difference from mitosis |
| Telophase I + Cytokinesis | Two haploid cells (n chromosomes, 2c DNA) formed | DNA halved to n but each chromosome still has 2 chromatids |
Meiosis II — Equational Division
Meiosis II is similar to mitosis. Centromeres split, sister chromatids separate. Results in 4 haploid cells with n chromosomes and 1c DNA each.
Mitosis vs Meiosis: Key Differences (NEET Comparison Table)
| Feature | Mitosis | Meiosis |
|---|---|---|
| Occurs in | Somatic cells | Reproductive cells (gonads) |
| Number of divisions | 1 | 2 |
| Daughter cells produced | 2 | 4 |
| Ploidy of daughter cells | Diploid (2n) | Haploid (n) |
| Genetic identity | Identical to parent | Genetically diverse |
| Crossing over | Absent | Occurs in Pachytene of Prophase I |
| Synaptonemal complex | Absent | Present (Zygotene to Pachytene) |
| Centromere split | Anaphase (splits) | Anaphase II only (not in Anaphase I) |
| Biological purpose | Growth, repair, asexual reproduction | Gamete formation, genetic diversity |
High-Yield NEET Facts on Cell Division
- Colchicine inhibits spindle formation — arrests cells in metaphase (used for karyotyping)
- Tetrads = bivalents = pairs of homologous chromosomes in Meiosis I
- Dictyotene: arrested state of oocytes in Diplotene — human eggs stay here for years
- Spermatogenesis produces 4 functional sperms; Oogenesis produces 1 egg + 3 polar bodies
- Amitosis (direct division) occurs in prokaryotes and some eukaryotic cells (RBCs in some organisms)
- In plants: Meiosis in pollen mother cells → microspores (male gametes); in ovule → megaspores
Frequently Asked Questions: Cell Division NEET 2026
In which phase of meiosis does crossing over occur?
Crossing over (exchange of segments between non-sister chromatids of homologous chromosomes) occurs during Pachytene of Prophase I of Meiosis I. The physical points of exchange are called chiasmata, which become visible in Diplotene.
What is the significance of meiosis for NEET?
Meiosis maintains the chromosome number constant across generations (halves it in gametes so fertilisation restores 2n). It also generates genetic diversity through crossing over and independent assortment — crucial for evolution and adaptation. NEET typically asks 1–2 MCQs specifically on meiosis phases and their significance.
What is the difference between mitosis and meiosis centromere behaviour?
In mitosis: centromeres split during Anaphase, separating sister chromatids. In Meiosis I: centromeres do NOT split — whole chromosomes (homologs) separate. In Meiosis II: centromeres DO split (like mitosis), separating sister chromatids. This is a classic NEET trap question.
NEET 2026 Biology Practice Quiz — Cell Division
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