Important Questions Class 11 Biology Chapter 10 Cell Cycle and Cell Division With Answers

Cell division is the process by which one parent cell forms new daughter cells. Mitosis maintains chromosome number, while meiosis reduces chromosome number for sexual reproduction.

Growth, repair, reproduction, and genetic continuity depend on accurate cell division. Important Questions Class 11 Biology Chapter 10 help students prepare Cell Cycle and Cell Division for CBSE 2026-27 school exams, NEET foundation practice, and NCERT-based state board tests. The chapter carries diagram-based, sequence-based, reasoning, and comparison questions from interphase, G₁ phase, S phase, G₂ phase, M phase, mitosis, cytokinesis, meiosis I, meiosis II, crossing over, synapsis, bivalents, chiasmata, and chromosome number changes.

Key Takeaways

• Cell Cycle Duration: A typical human cell in culture divides once in about 24 hours.
• Interphase Share: Interphase takes more than 95 percent of the cell cycle duration.
• Mitosis Result: Mitosis produces two genetically identical daughter cells.
• Meiosis Result: Meiosis produces four haploid daughter cells after two nuclear divisions.

Important Questions Class 11 Biology Chapter 10 Structure 2026

Important Questions Class 11 Biology Chapter 10 for CBSE 2026-27

Cells divide with strict order because DNA replication, chromosome movement, and cytoplasm division must stay coordinated. In CBSE 2026-27, this chapter commonly appears through stage identification, differences, and event-sequence questions.

1. What is cell division?

Cell division is the process by which a parent cell divides to form daughter cells. It supports growth, repair, and reproduction.

1. One parent cell divides.
2. Daughter cells form from the parent cell.
3. New cells can grow and divide again.
4. Cell division maintains life processes.

Final answer: Cell division produces new cells from pre-existing cells.

2. What is cell cycle Class 11 Biology?

Cell cycle is the sequence of events by which a cell duplicates its genome and divides into daughter cells.

1. The cell grows.
2. DNA replication occurs.
3. Cell components form.
4. The cell divides into two daughter cells.

Final answer: Cell cycle includes growth, DNA replication, and cell division.

3. Why must DNA replication and cell division remain coordinated?

DNA replication and cell division must remain coordinated to form daughter cells with intact genomes.

1. DNA must copy before division.
2. Chromosomes must distribute equally.
3. Cell growth must support division.
4. Genetic control maintains order.

Final fact: Incorrect coordination can disturb chromosome distribution.

4. What is the average cell cycle span for a mammalian cell?

The average cell cycle span for a mammalian cell is about 24 hours.

1. Human cells in culture show this duration.
2. Cell cycle duration varies by organism.
3. Cell cycle duration varies by cell type.
4. Yeast can complete it in about 90 minutes.

Final answer: A typical mammalian cell cycle lasts about 24 hours.

Cell Cycle Class 11 Biology Questions on Interphase and M Phase

Interphase prepares the cell, while M phase divides it. Students should remember that interphase is active, even though it was once called the resting phase.

5. What are the two basic phases of the cell cycle?

The two basic phases of the cell cycle are interphase and M phase.

1. Interphase occurs between two successive M phases.
2. M phase represents actual cell division.
3. Interphase lasts more than 95 percent of the cycle.
4. M phase lasts about one hour in a 24-hour cycle.

Final answer: Cell cycle has interphase and M phase.

6. What is interphase Class 11 Biology?

Interphase is the phase between two successive M phases. The cell grows and prepares for division.

1. The cell remains metabolically active.
2. DNA replication occurs in S phase.
3. Proteins and organelles prepare for division.
4. It occupies most of the cell cycle.

Final fact: Interphase is a preparation phase, not an inactive phase.

7. What are the three stages of interphase?

The three stages of interphase are G₁ phase, S phase, and G₂ phase.

1. G₁ phase occurs before DNA replication.
2. S phase marks DNA synthesis.
3. G₂ phase prepares the cell for mitosis.

Final answer: Interphase consists of G₁, S, and G₂ phases.

8. What is M phase in cell cycle?

M phase is the phase of actual cell division. It includes nuclear division and usually cytoplasmic division.

1. Nuclear division is called karyokinesis.
2. Cytoplasmic division is called cytokinesis.
3. Daughter chromosomes separate during M phase.
4. Two daughter cells form after cytokinesis.

Final answer: M phase includes mitosis and cytokinesis.

Interphase Class 11 Biology Questions With Answers

Interphase decides whether division will be accurate. The cell grows in G₁, replicates DNA in S phase, and prepares for mitosis in G₂.

9. What happens during G₁ phase?

G₁ phase is the interval between mitosis and DNA replication.

1. The cell grows continuously.
2. The cell remains metabolically active.
3. DNA replication does not occur.
4. Normal cell metabolism continues.

Final fact: G₁ phase prepares the cell before DNA synthesis.

10. What happens during S phase?

S phase is the period of DNA synthesis or DNA replication.

1. DNA amount doubles from 2C to 4C.
2. Chromosome number remains unchanged.
3. A 2n cell remains 2n after S phase.
4. Centriole duplicates in animal cells.

Final answer: S phase doubles DNA content, not chromosome number.

11. What happens during G₂ phase?

G₂ phase prepares the cell for mitosis after DNA replication.

1. Cell growth continues.
2. Proteins required for mitosis form.
3. The cell checks readiness for division.
4. M phase follows G₂ phase.

Final fact: G₂ phase supports mitotic preparation.

12. If DNA content is 2C in G₁, what is DNA content after S phase?

DNA content becomes 4C after S phase.

Given Data:

1. DNA content in G₁ = 2C.
2. S phase causes DNA replication.

Calculation:
2C × 2 = 4C

Final Result: DNA content after S phase = 4C.

13. If a diploid cell has 2n chromosomes in G₁, what is chromosome number after S phase?

The chromosome number remains 2n after S phase.

1. DNA replicates during S phase.
2. Sister chromatids form.
3. Chromosome number does not double.
4. Each chromosome has two chromatids.

Final answer: Chromosome number remains 2n after S phase.

14. What is G₀ phase Class 11 Biology?

G₀ phase is a quiescent stage where cells remain metabolically active but do not divide.

1. Some cells exit G₁ phase.
2. They stop proliferation.
3. They remain metabolically active.
4. They may divide again if required.

Final fact: Heart cells are common examples of non-dividing adult cells.

Mitosis Class 11 Biology Questions for CBSE 2026

Mitosis keeps chromosome number constant. It becomes easier when students track chromosome condensation, metaphase alignment, chromatid separation, and daughter nuclei formation.

15. What is mitosis?

Mitosis is equational division that produces daughter cells with the same chromosome number as the parent cell.

1. It usually occurs in diploid somatic cells.
2. It forms two daughter cells.
3. Daughter cells have identical genetic complement.
4. Plants can show mitosis in haploid and diploid cells.

Final answer: Mitosis maintains chromosome number.

16. Why is mitosis called equational division?

Mitosis is called equational division because parent and daughter cells have the same chromosome number.

1. Chromosomes duplicate before mitosis.
2. Sister chromatids separate during anaphase.
3. Each daughter nucleus receives equal chromosomes.
4. Genetic complement remains identical.

Final fact: Mitosis conserves chromosome number.

17. Name the four stages of karyokinesis in mitosis.

The four stages are prophase, metaphase, anaphase, and telophase.

1. Prophase starts chromosome condensation.
2. Metaphase aligns chromosomes.
3. Anaphase separates chromatids.
4. Telophase forms daughter nuclei.

Final answer: Mitotic karyokinesis has prophase, metaphase, anaphase, and telophase.

18. What happens during prophase of mitosis?

Prophase begins chromosome condensation and spindle apparatus formation.

1. Chromatin condenses into compact chromosomes.
2. Each chromosome has two chromatids.
3. Chromatids attach at the centromere.
4. Centrosomes move towards opposite poles.
5. Asters and spindle fibres form mitotic apparatus.

Final fact: Nuclear envelope and nucleolus disappear by late prophase.

19. What happens during metaphase of mitosis?

Metaphase aligns chromosomes at the equator of the cell.

1. Nuclear envelope disintegrates completely.
2. Chromosomes spread through cytoplasm.
3. Spindle fibres attach to kinetochores.
4. Chromosomes align on the metaphase plate.

Final answer: Metaphase is best for studying chromosome morphology.

20. What is metaphase plate?

Metaphase plate is the plane of chromosome alignment at the equator during metaphase.

1. Chromosomes lie at the spindle equator.
2. Sister chromatids face opposite poles.
3. Kinetochores attach to spindle fibres.

Final fact: Metaphase plate forms during metaphase.

21. What are kinetochores?

Kinetochores are small disc-shaped structures on centromeres.

1. They occur on chromosome centromeres.
2. Spindle fibres attach to them.
3. They help move chromosomes.

Final fact: Kinetochores connect chromosomes with spindle fibres.

22. What happens during anaphase of mitosis?

Anaphase separates sister chromatids into daughter chromosomes.

1. Centromeres split simultaneously.
2. Sister chromatids separate.
3. Daughter chromosomes move to opposite poles.
4. Centromeres lead chromosome movement.

Final answer: Anaphase separates chromatids.

23. What happens during telophase of mitosis?

Telophase forms two daughter nuclei from separated chromosome sets.

1. Chromosomes reach opposite poles.
2. Chromosomes decondense.
3. Nuclear envelope reforms.
4. Nucleolus reappears.
5. Golgi complex and ER reform.

Final fact: Telophase reverses many prophase events.

24. Which mitotic stage shows centromere splitting?

Anaphase shows centromere splitting.

1. Chromosomes align before anaphase.
2. Centromeres split at anaphase onset.
3. Sister chromatids separate.
4. Chromatids move to opposite poles.

Final answer: Centromeres split during anaphase.

Cytokinesis Class 11 Biology and Karyokinesis Questions

Karyokinesis divides the nucleus, while cytokinesis divides the cytoplasm. Their difference is a common NCERT exercise question.

25. What is karyokinesis?

Karyokinesis is the division of the nucleus during cell division.

1. It separates duplicated chromosomes.
2. It forms daughter nuclei.
3. It includes prophase, metaphase, anaphase, and telophase.

Final answer: Karyokinesis means nuclear division.

26. What is cytokinesis?

Cytokinesis is the division of cytoplasm after nuclear division.

1. It completes cell division.
2. It separates daughter cells.
3. It distributes organelles between daughter cells.

Final answer: Cytokinesis means cytoplasmic division.

27. Distinguish cytokinesis from karyokinesis.

Karyokinesis divides the nucleus, while cytokinesis divides the cytoplasm.

Final fact: Cell division completes after cytokinesis.

28. How does cytokinesis occur in animal cells?

Animal cells undergo cytokinesis by furrow formation in the plasma membrane.

1. A furrow appears in the membrane.
2. The furrow gradually deepens.
3. It joins at the centre.
4. Cytoplasm divides into two parts.

Final answer: Animal cytokinesis occurs by cleavage furrow.

29. How does cytokinesis occur in plant cells?

Plant cells undergo cytokinesis by cell plate formation.

1. Wall formation starts at the centre.
2. Cell plate grows outward.
3. It meets existing lateral walls.
4. It forms the middle lamella.

Final answer: Plant cytokinesis occurs through cell plate formation.

30. What is syncytium?

Syncytium is a multinucleate condition formed when karyokinesis occurs without cytokinesis.

1. Nuclei divide.
2. Cytoplasm does not divide.
3. Many nuclei remain in one cytoplasmic mass.

Example:
Liquid endosperm in coconut

Final fact: Syncytium forms due to absence of cytokinesis.

Significance of Mitosis Class 11 Biology Questions

Mitosis matters because it builds bodies, repairs tissues, and maintains chromosome number. In plants, it also supports continuous growth through meristems.

31. What is the significance of mitosis?

Mitosis supports growth, repair, replacement, and genetic stability.

1. It produces identical daughter cells.
2. It supports growth in multicellular organisms.
3. It restores nucleo-cytoplasmic ratio.
4. It repairs damaged tissues.
5. It replaces worn-out cells.

Final fact: Mitosis maintains genetic continuity in somatic cells.

32. How does mitosis help growth?

Mitosis increases cell number in multicellular organisms.

1. A zygote divides repeatedly.
2. More cells form through mitosis.
3. Tissues and organs grow.
4. Body size increases.

Final answer: Growth in multicellular organisms depends on mitosis.

33. How does mitosis help cell repair?

Mitosis replaces damaged or lost cells in tissues.

1. Epidermal cells get replaced.
2. Gut lining cells get replaced.
3. Blood cells get replaced.
4. Damaged tissues recover through new cells.

Final fact: Cell repair needs mitotic division.

34. Why do plants continue to grow throughout life?

Plants continue to grow because meristematic tissues divide by mitosis.

1. Apical meristem supports length growth.
2. Lateral cambium supports girth growth.
3. Meristematic cells keep dividing.

Final fact: Plant growth continues through mitosis in meristems.

Meiosis Class 11 Biology Questions With Answers

Meiosis reduces chromosome number and creates genetic variation. It happens during gametogenesis in sexually reproducing organisms.

35. What is meiosis?

Meiosis is reduction division that forms haploid daughter cells from specialised diploid cells.

1. Chromosome number reduces by half.
2. Gametes form through meiosis.
3. Meiosis has two divisions.
4. Four haploid cells form at the end.

Final answer: Meiosis produces haploid cells for sexual reproduction.

36. Why is meiosis called reduction division?

Meiosis is called reduction division because it reduces chromosome number from diploid to haploid.

1. Diploid cells have 2n chromosomes.
2. Meiosis I separates homologous chromosomes.
3. Haploid cells form.
4. Fertilisation restores diploid number.

Final fact: Meiosis maintains chromosome number across generations.

37. What are the key features of meiosis?

Meiosis has two nuclear divisions but only one DNA replication.

1. Meiosis I and meiosis II occur sequentially.
2. DNA replicates before meiosis I.
3. Homologous chromosomes pair.
4. Crossing over occurs.
5. Four haploid cells form after meiosis II.

Final answer: Meiosis combines reduction and recombination.

38. Name the stages of meiosis I and meiosis II.

Meiosis I and meiosis II each have prophase, metaphase, anaphase, and telophase.

Meiosis I:

1. Prophase I.
2. Metaphase I.
3. Anaphase I.
4. Telophase I.

Meiosis II:

1. Prophase II.
2. Metaphase II.
3. Anaphase II.
4. Telophase II.

Final fact: Meiosis has two sequential divisions.

Prophase I Class 11 Biology Questions

Prophase I is the longest and most complex meiotic phase. It contains the key events that create variation through synapsis and crossing over.

39. Name the five stages of prophase I.

The five stages are leptotene, zygotene, pachytene, diplotene, and diakinesis.

1. Leptotene shows visible chromosomes.
2. Zygotene shows synapsis.
3. Pachytene shows crossing over.
4. Diplotene shows chiasmata.
5. Diakinesis shows terminalisation.

Final answer: Prophase I has five sub-stages.

40. What happens during leptotene?

Leptotene is the stage where chromosomes become gradually visible under the light microscope.

1. Chromosomes start compacting.
2. Chromatin condensation begins.
3. Compaction continues through leptotene.

Final fact: Leptotene begins visible chromosome organisation.

41. What happens during zygotene?

Zygotene is the stage where homologous chromosomes start pairing.

1. Pairing is called synapsis.
2. Homologous chromosomes come together.
3. Synaptonemal complex forms.
4. Paired chromosomes form bivalents.

Final fact: Synapsis occurs during zygotene.

42. What is synapsis?

Synapsis is the pairing of homologous chromosomes during zygotene of prophase I.

1. Homologous chromosomes associate.
2. Synaptonemal complex supports pairing.
3. It prepares chromosomes for crossing over.

Final answer: Synapsis means pairing of homologous chromosomes.

43. What is a bivalent?

A bivalent is a pair of synapsed homologous chromosomes.

1. It forms during zygotene.
2. It becomes clearer in pachytene.
3. Each bivalent contains four chromatids.

Final fact: A bivalent is also called a tetrad.

44. What happens during pachytene?

Pachytene is the stage where crossing over occurs between non-sister chromatids.

1. Tetrads become clearly visible.
2. Recombination nodules appear.
3. Crossing over occurs at these sites.
4. Recombinase helps the process.

Final answer: Crossing over occurs during pachytene.

45. What is crossing over Class 11 Biology?

Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes.

1. It occurs during pachytene.
2. Recombination nodules mark its sites.
3. Recombinase enzyme helps the process.
4. It creates genetic recombination.

Final fact: Crossing over increases genetic variation.

46. What happens during diplotene?

Diplotene begins when synaptonemal complex dissolves and homologous chromosomes start separating.

1. Recombined homologues separate partly.
2. They remain attached at crossover sites.
3. X-shaped chiasmata become visible.

Final answer: Diplotene shows chiasmata.

47. What are chiasmata?

Chiasmata are X-shaped structures where recombined homologous chromosomes remain attached.

1. They appear during diplotene.
2. They mark crossover sites.
3. They hold homologues temporarily.

Final fact: Chiasmata show evidence of crossing over.

48. What happens during diakinesis?

Diakinesis shows terminalisation of chiasmata and full chromosome condensation.

1. Chromosomes become fully condensed.
2. Meiotic spindle forms.
3. Nucleolus disappears.
4. Nuclear envelope breaks down.

Final answer: Diakinesis prepares chromosomes for metaphase I.

Meiosis I and Meiosis II Class 11 Biology Questions

Meiosis I separates homologous chromosomes, while meiosis II separates sister chromatids. This difference explains reduction division clearly.

49. What happens during metaphase I?

Bivalent chromosomes align on the equatorial plate during metaphase I.

1. Homologous chromosomes remain paired.
2. Bivalents arrange at the equator.
3. Spindle microtubules attach to kinetochores.

Final fact: Metaphase I aligns bivalents, not single chromosomes.

50. What happens during anaphase I?

Homologous chromosomes separate during anaphase I.

1. Sister chromatids remain attached.
2. Homologous chromosomes move to opposite poles.
3. Chromosome number reduces.

Final answer: Anaphase I separates homologous chromosomes.

51. What happens during telophase I?

Telophase I forms a dyad of cells after homologous chromosomes separate.

1. Nuclear membrane reappears.
2. Nucleolus reappears.
3. Cytokinesis follows.
4. Two haploid cells form.

Final fact: Telophase I produces a dyad.

52. What is interkinesis?

Interkinesis is the short stage between meiosis I and meiosis II.

1. It occurs after telophase I.
2. It is usually short-lived.
3. DNA replication does not occur.
4. Prophase II follows interkinesis.

Final answer: Interkinesis has no DNA replication.

53. What happens during prophase II?

Prophase II begins after cytokinesis and resembles a simpler mitotic prophase.

1. Chromosomes become compact again.
2. Nuclear membrane disappears.
3. Spindle formation begins.

Final fact: Prophase II is simpler than prophase I.

54. What happens during metaphase II?

Chromosomes align at the equator during metaphase II.

1. Chromosomes arrange at the equator.
2. Spindle fibres attach to kinetochores.
3. Sister chromatids face opposite poles.

Final answer: Metaphase II resembles mitotic metaphase.

55. What happens during anaphase II?

Sister chromatids separate during anaphase II.

1. Centromeres split simultaneously.
2. Sister chromatids separate.
3. Chromatids move towards opposite poles.

Final fact: Anaphase II resembles mitotic anaphase.

56. What happens during telophase II?

Telophase II forms four haploid daughter cells after cytokinesis.

1. Chromosome groups receive nuclear envelopes.
2. Cytokinesis follows.
3. Four haploid cells form.

Final answer: Meiosis ends with a tetrad of haploid cells.

Mitosis and Meiosis Difference Class 11 Biology

Mitosis supports growth and repair, while meiosis supports sexual reproduction. Their clearest difference lies in chromosome number and genetic variation.

57. Distinguish between mitosis and meiosis.

Mitosis forms two identical cells, while meiosis forms four haploid cells with variation.

Final fact: Mitosis is equational, while meiosis is reductional.

58. Distinguish anaphase of mitosis from anaphase I of meiosis.

Mitotic anaphase separates sister chromatids, while anaphase I separates homologous chromosomes.

Final fact: Anaphase I reduces chromosome number.

59. Can there be mitosis without DNA replication in S phase?

No, normal mitosis cannot occur without DNA replication in S phase.

1. DNA must replicate before mitosis.
2. Sister chromatids must form.
3. Chromosomes must distribute to daughter cells.
4. Missing replication would produce incomplete genomes.

Final answer: Mitosis requires prior DNA replication.

60. Can there be DNA replication without cell division?

Yes, DNA replication can occur without immediate cell division in some cells.

1. DNA replication belongs to S phase.
2. Cell division occurs later in M phase.
3. Some cells may replicate DNA and delay division.

Final fact: DNA replication and cell division are linked but distinct events.

Significance of Meiosis Class 11 Biology Questions

Meiosis protects species chromosome number across generations. It also produces variation, which supports evolution.

61. What is the significance of meiosis?

Meiosis maintains chromosome number across generations and increases genetic variation.

1. It produces haploid gametes.
2. Fertilisation restores diploid number.
3. Crossing over creates new combinations.
4. Variation supports evolution.

Final answer: Meiosis supports sexual reproduction and evolution.

62. How does meiosis maintain chromosome number?

Meiosis halves chromosome number before fertilisation.

1. Diploid cells undergo meiosis.
2. Haploid gametes form.
3. Two gametes fuse during fertilisation.
4. Diploid chromosome number returns.

Final fact: Meiosis and fertilisation balance chromosome number.

63. How does meiosis increase genetic variation?

Meiosis increases genetic variation through crossing over and recombination.

1. Homologous chromosomes pair.
2. Non-sister chromatids exchange segments.
3. New allele combinations form.
4. Gametes become genetically different.

Final answer: Meiosis creates variation through recombination.

Class 11 Biology Cell Cycle and Cell Division Questions With Answers for Board Practice

NCERT exercise questions often ask direct stage-event matching. Stage names, chromosome behaviour, and DNA content changes decide the correct answer.

64. Name the stage where chromosomes move to the spindle equator.

Metaphase is the stage where chromosomes move to the spindle equator.

1. Spindle fibres attach to kinetochores.
2. Chromosomes move to the centre.
3. They align along the metaphase plate.

Final answer: Chromosomes move to the spindle equator during metaphase.

65. Name the stage where centromeres split and chromatids separate.

Anaphase is the stage where centromeres split and chromatids separate in mitosis.

1. Chromosomes split at centromeres.
2. Sister chromatids separate.
3. Daughter chromosomes move to opposite poles.

Final answer: Centromeres split during anaphase.

66. Name the stage where homologous chromosomes pair.

Zygotene is the stage where homologous chromosomes pair.

1. Pairing is called synapsis.
2. Homologous chromosomes form bivalents.
3. Synaptonemal complex appears.

Final fact: Synapsis occurs during zygotene.

67. Name the stage where crossing over occurs.

Pachytene is the stage where crossing over occurs.

1. Tetrads become visible.
2. Recombination nodules appear.
3. Non-sister chromatids exchange genetic material.

Final answer: Crossing over occurs during pachytene.

68. In onion root tip cells, chromosome number is 16. What will be the number after S phase?

The chromosome number remains 16 after S phase.

Given Data:

1. Onion root tip chromosome number = 16.
2. S phase causes DNA replication.

Reason:
Chromosome number remains same, but DNA content doubles.

Final Result: Chromosome number after S phase = 16.

69. If DNA content after M phase is 2C, what is DNA content in G₁, after S, and in G₂?

DNA content is 2C in G₁, 4C after S phase, and 4C in G₂.

Given Data:
DNA content after M phase = 2C

Calculation:

1. G₁ = 2C
2. After S phase = 4C
3. G₂ = 4C

Final Result: G₁ = 2C, S = 4C, G₂ = 4C.

Class 11 Biology Important Links