Cell Cycle and Cell Division covers the phases of the cell cycle (G₁, S, G₂, M), the events of mitosis (with each phase), and meiosis — with particular focus on Prophase I substages and the significance of crossing over. NEET sets 2–4 MCQs from this chapter every year. The five substages of Prophase I, the mitosis vs meiosis comparison table, and the timing of crossing over are the highest-yield topics.
The cell cycle is the sequence of events from one cell division to the next. It has two major stages:
Mitosis produces two daughter cells genetically identical to the parent. It is the basis of growth, repair, and asexual reproduction. Mitosis has four stages plus cytokinesis:
| Phase | Key events |
|---|---|
| Prophase | Chromatin condenses into chromosomes; spindle fibres begin to form; nucleolus disappears; nuclear envelope starts to break down. |
| Metaphase | Chromosomes align at the metaphase plate (equatorial plane); spindle fibres attach to centromeres. Best stage to count chromosomes. |
| Anaphase | Centromeres split; sister chromatids pulled to opposite poles by spindle. Number of chromosomes doubles transiently. |
| Telophase | Nuclear envelope reforms around each set; chromosomes decondense; nucleolus reappears. |
| Cytokinesis | Animal cells: cleavage furrow (actin ring). Plant cells: cell plate formed by Golgi vesicles. |
Meiosis produces four haploid daughter cells from one diploid parent cell. It occurs in reproductive organs during gamete formation. Meiosis has two sequential divisions:
Significance:
Prophase I is the longest and most complex phase of meiosis. It is divided into five substages (LZPDDIA):
| Substage | Key events |
|---|---|
| Leptotene | Chromosomes begin to condense; become visible as thin threads. |
| Zygotene | Synapsis — homologous chromosomes pair up; synaptonemal complex forms; the paired structure = bivalent (tetrad). |
| Pachytene | Crossing over — exchange of segments between non-sister chromatids of homologous chromosomes at chiasmata; recombination nodules visible. |
| Diplotene | Synaptonemal complex dissolves; homologs remain attached at chiasmata; terminalisation of chiasmata begins. |
| Diakinesis | Chromosomes maximally condensed; nuclear envelope breaks; spindle forms; chiasmata move to chromosome ends. |
| Feature | Mitosis | Meiosis |
|---|---|---|
| Where occurs | Somatic cells | Germline cells (gonads) |
| Divisions | One | Two |
| Daughter cells | 2, diploid (2n) | 4, haploid (n) |
| Chromosome pairing | No synapsis | Synapsis in Meiosis I |
| Crossing over | No | Yes (Pachytene) |
| Genetic outcome | Identical | Varied (recombination) |
| Purpose | Growth, repair, asexual repro. | Sexual reproduction, gametes |
Use this section after the first reading. It connects facts into mechanisms, comparisons, and NEET-style decision rules.
G1 is growth and decision-making, S is DNA synthesis, G2 is preparation for mitosis, and M phase is actual division. G0 is a quiescent exit from active cycling. A cell should not enter mitosis unless DNA replication and repair are complete.
NEET cue: DNA amount doubles in S phase, but chromosome number does not double until sister chromatids separate.
Leptotene condenses chromosomes. Zygotene pairs homologues by synapsis. Pachytene performs crossing over. Diplotene shows chiasmata. Diakinesis completes terminalisation and prepares for metaphase I.
The single most tested confusion: crossing over happens in pachytene, while chiasmata are clearly seen in diplotene.
Use this process after reading the notes. It turns NCERT lines into exam-ready recall, diagrams, and MCQ decisions.
Memory mistake: make a two-column comparison table.
Diagram mistake: redraw the labelled structure from memory.
Process mistake: rewrite the sequence with arrows.
Assertion-reason mistake: check truth of each statement first, then relation.
Practice these before starting MCQs. They are designed to lock core concepts with minimum theory load.
S phase of interphase.
Metaphase.
Pachytene.
Diplotene.
Reductional, because homologous chromosomes separate and chromosome number halves.
Chapter note placement for Cell Cycle and Cell Division.
Test your understanding of Cell Cycle and Cell Division with focused sectional tests and a full-length NEET-style module test. Each chapter now runs 5 practice tests of 25 questions each, and every question has a 90-second timer — matching real NEET exam pacing.
5 focused sessions: cell cycle phases, mitosis events, meiosis overview, Prophase I substages, and mitosis vs meiosis comparison — 25 NEET-style MCQs each.
Open Session TestsNEET-style 125-question module test on Cell Cycle and Cell Division with timer, palette, answer review, and subtopic accuracy breakdown.
Open Full MockInline banner shown in the practice section — high-intent placement for test-prep and coaching campaigns.
Open any of these 105 quality-checked NEET questions to review all four options, the correct answer, and the worked explanation.
Move straight from chapter-wise questions into a subject test, then loop back into weaker areas instead of ending the session here.