🔬 Cell Cycle and Cell Division – MCQs

Part 1 (Q1–Q25)

Q1. The series of events by which a cell duplicates its genome and divides is called

A) Mitosis
B) Meiosis
C) Cell cycle ✅
D) Cytokinesis

Explanation: The cell cycle includes genome duplication, growth, and division.

Q2. The longest phase of the cell cycle is

A) Prophase
B) Interphase ✅
C) Anaphase
D) Metaphase

Explanation: Interphase (~90% of cell cycle) is longest, for growth and DNA replication.

Q3. Interphase consists of

A) G₁, S, G₂ phases ✅
B) Prophase, metaphase, anaphase
C) G₁, G₂ only
D) Cytokinesis

Explanation: Interphase = G₁ (growth), S (DNA synthesis), G₂ (growth + preparation).

Q4. DNA replication occurs during

A) G₁ phase
B) S phase ✅
C) G₂ phase
D) M phase

Explanation: The S (synthesis) phase is where DNA replication occurs.

Q5. Protein synthesis mainly occurs in

A) G₁ and G₂ phases ✅
B) S phase
C) M phase
D) Cytokinesis

Explanation: Growth and protein synthesis occur during G₁ and G₂.

Q6. Chromosomes condense and become visible during

A) Interphase
B) Prophase ✅
C) Metaphase
D) Anaphase

Explanation: Prophase is marked by chromatin condensation into chromosomes.

Q7. Spindle fibres attach to chromosomes at

A) Telomeres
B) Centromere (kinetochore) ✅
C) Nucleolus
D) Chromatid arms

Explanation: Spindle fibres attach to kinetochore at centromere.

Q8. The alignment of chromosomes at the equator occurs in

A) Prophase
B) Metaphase ✅
C) Anaphase
D) Telophase

Explanation: In metaphase, chromosomes align at the cell equatorial plate.

Q9. Separation of sister chromatids occurs in

A) Prophase
B) Metaphase
C) Anaphase ✅
D) Telophase

Explanation: During anaphase, centromeres split and sister chromatids separate.

Q10. Nuclear membrane reappears in

A) Prophase
B) Metaphase
C) Anaphase
D) Telophase ✅

Explanation: Telophase restores nuclear envelope and nucleolus.

Q11. Cytokinesis in plant cells occurs by

A) Furrow method
B) Cell plate formation ✅
C) Binary fission
D) Cleavage

Explanation: Plant cells form cell plate during cytokinesis.

Q12. Cytokinesis in animal cells occurs by

A) Cell plate formation
B) Furrow formation ✅
C) Budding
D) Fragmentation

Explanation: Animal cells form a cleavage furrow by actin-myosin contraction.

Q13. Mitosis is also called

A) Reduction division
B) Equational division ✅
C) Meiotic division
D) Amitosis

Explanation: Mitosis maintains chromosome number, hence equational division.

Q14. Meiosis is also called

A) Reduction division ✅
B) Equational division
C) Amitosis
D) Binary fission

Explanation: Meiosis halves chromosome number, hence reduction division.

Q15. Synapsis (pairing of homologous chromosomes) occurs in

A) Prophase I of meiosis ✅
B) Metaphase I
C) Anaphase II
D) Prophase of mitosis

Explanation: Synapsis occurs during zygotene of prophase I in meiosis.

Q16. Crossing over occurs in

A) Pachytene of meiosis I ✅
B) Zygotene
C) Diplotene
D) Anaphase I

Explanation: Crossing over = exchange of segments in pachytene of prophase I.

Q17. Chiasmata appear in

A) Zygotene
B) Pachytene
C) Diplotene ✅
D) Diakinesis

Explanation: Chiasmata (cross-over sites) become visible during diplotene.

Q18. The separation of homologous chromosomes occurs in

A) Anaphase I of meiosis ✅
B) Anaphase II
C) Mitosis anaphase
D) Pachytene

Explanation: Anaphase I separates homologous chromosomes, reducing chromosome number.

Q19. The separation of sister chromatids occurs in

A) Anaphase I
B) Anaphase II ✅
C) Metaphase I
D) Zygotene

Explanation: Sister chromatids separate during anaphase II (like mitosis).

Q20. The number of daughter cells after meiosis is

A) 1
B) 2
C) 4 ✅
D) 8

Explanation: Meiosis produces 4 haploid daughter cells.

Q21. The number of daughter cells after mitosis is

A) 1
B) 2 ✅
C) 4
D) 8

Explanation: Mitosis produces 2 diploid identical cells.

Q22. The diploid chromosome number in humans is

A) 23
B) 46 ✅
C) 92
D) 44

Explanation: Humans have 46 (2n = 46) chromosomes.

Q23. The haploid chromosome number in humans is

A) 23 ✅
B) 46
C) 44
D) 92

Explanation: Gametes are haploid (n=23).

Q24. The mitotic spindle is composed of

A) Actin filaments
B) Microtubules ✅
C) Collagen
D) Intermediate filaments

Explanation: Spindle fibres are made of microtubules.

Q25. Which is true about mitosis?

A) Occurs in germ cells only
B) Maintains chromosome number ✅
C) Produces variation
D) Results in haploids

Explanation: Mitosis is equational and maintains chromosome number in somatic cells.

🔬 Cell Structure and Function — Cell Cycle and Cell Division

Part 2 (Q26–Q50)

Q26. The phase between two successive mitotic divisions is

A) Interphase ✅
B) Prophase
C) Anaphase
D) Cytokinesis

Explanation: Interphase is the interval between two successive mitoses, allowing growth and DNA synthesis.

Q27. G₀ phase is a

A) Resting, non-dividing phase ✅
B) DNA replication phase
C) Chromosome separation phase
D) Cytokinesis phase

Explanation: G₀ phase is a quiescent stage where cells exit the cycle and stop dividing.

Q28. The cell cycle checkpoints ensure

A) Faster division
B) Proper DNA replication and repair ✅
C) Chromosome loss
D) Nuclear breakdown

Explanation: Checkpoints (G₁, G₂, spindle) prevent errors in cell cycle.

Q29. Which is not a stage of prophase I of meiosis?

A) Leptotene
B) Pachytene
C) Diplotene
D) Anaphase ✅

Explanation: Anaphase belongs to later stages, not prophase I.

Q30. Chromosomes are most condensed and visible during

A) Prophase
B) Metaphase ✅
C) Anaphase
D) Telophase

Explanation: Metaphase chromosomes are most condensed → used for karyotyping.

Q31. The first phase of prophase I is

A) Leptotene ✅
B) Zygotene
C) Pachytene
D) Diplotene

Explanation: Leptotene = thin thread-like chromosomes first appear.

Q32. Homologous chromosomes pair during

A) Zygotene ✅
B) Leptotene
C) Pachytene
D) Anaphase I

Explanation: Synapsis of homologs occurs in zygotene with synaptonemal complex.

Q33. Crossing over is significant for

A) Replication
B) Genetic variation ✅
C) Mutation repair
D) Cytokinesis

Explanation: Crossing over (pachytene) introduces variation in gametes.

Q34. Terminalization of chiasmata occurs in

A) Diplotene
B) Diakinesis ✅
C) Pachytene
D) Metaphase I

Explanation: In diakinesis, chiasmata move to chromosome ends (terminalization).

Q35. Independent assortment of chromosomes occurs during

A) Prophase I
B) Metaphase I ✅
C) Anaphase II
D) Cytokinesis

Explanation: Random arrangement of homologous pairs in metaphase I → independent assortment.

Q36. Centromeres do not divide during

A) Anaphase I ✅
B) Anaphase II
C) Mitosis
D) Prophase

Explanation: In anaphase I, homologous chromosomes separate but centromeres remain intact.

Q37. Centromeres divide during

A) Anaphase I
B) Anaphase II ✅
C) Zygotene
D) Pachytene

Explanation: In anaphase II, centromeres split and sister chromatids move apart.

Q38. The reduction in chromosome number occurs during

A) Anaphase I ✅
B) Anaphase II
C) Prophase I
D) Metaphase II

Explanation: In anaphase I, homologs separate → diploid → haploid.

Q39. The number of chromatids in metaphase I of meiosis in humans is

A) 46
B) 92 ✅
C) 23
D) 69

Explanation: Each of 46 chromosomes has 2 chromatids → 92 chromatids.

Q40. The number of chromatids in metaphase II in humans is

A) 92
B) 46 ✅
C) 23
D) 69

Explanation: Haploid cells (23 chromosomes × 2 chromatids) → 46 chromatids.

Q41. The mitotic spindle is formed from

A) Intermediate filaments
B) Microtubules ✅
C) Actin filaments
D) Keratin

Explanation: Spindle fibres are microtubules from centrosomes/centrioles.

Q42. Checkpoint between G₁ and S ensures

A) Proper spindle formation
B) DNA damage repair ✅
C) Chromatid separation
D) Cytokinesis

Explanation: The G₁/S checkpoint ensures DNA integrity before replication.

Q43. Checkpoint between G₂ and M ensures

A) Proper chromosome alignment
B) DNA replication completion ✅
C) Crossing over
D) Cell plate formation

Explanation: G₂/M checkpoint checks if DNA is fully replicated and undamaged.

Q44. Which phase is absent in meiosis II but present in mitosis?

A) Interphase ✅
B) Prophase
C) Metaphase
D) Anaphase

Explanation: No DNA replication (S-phase) occurs between meiosis I and II.

Q45. Meiosis occurs in

A) Somatic cells
B) Germ cells ✅
C) Liver cells
D) Muscle cells

Explanation: Meiosis occurs in germ cells to produce gametes.

Q46. Which type of division restores diploid number after fertilization?

A) Meiosis
B) Amitosis
C) Mitosis ✅
D) Binary fission

Explanation: Mitosis maintains diploid state in zygote after fertilization.

Q47. If a cell has 20 chromosomes, how many will its gametes have?

A) 10 ✅
B) 20
C) 40
D) 5

Explanation: Meiosis halves chromosome number → gametes = n = 10.

Q48. The number of chromosomes after mitosis remains

A) Same ✅
B) Halved
C) Doubled
D) Tripled

Explanation: Mitosis is equational, chromosome number remains unchanged.

Q49. Which enzyme is crucial in spindle fiber microtubule dynamics?

A) Helicase
B) Tubulin ✅
C) Ligase
D) RNA polymerase

Explanation: Tubulin proteins polymerize/depolymerize to form spindle fibers.

Q50. The cells produced after meiosis are genetically

A) Identical
B) Variable ✅
C) Polyploid
D) Mutant

Explanation: Crossing over + independent assortment → genetic variability in gametes.

🔬 Cell Structure and Function — Cell Cycle and Cell Division

Part 3 (Q51–Q75)

Q51. The mitotic index is

A) Ratio of dividing cells to total cells ✅
B) Total number of chromosomes
C) Ratio of DNA to RNA
D) Length of cell cycle

Explanation: Mitotic index = % of cells in mitosis, used for growth studies.

Q52. Duration of S phase in human cell cycle is about

A) 2 hours
B) 6–8 hours ✅
C) 20 hours
D) 30 minutes

Explanation: S phase (DNA replication) takes about 6–8 hours in humans.

Q53. Duration of M phase in human cells is about

A) 1 hour ✅
B) 10 hours
C) 6 hours
D) 24 hours

Explanation: M phase is short, lasting about 1 hour.

Q54. The shortest stage of mitosis is

A) Prophase
B) Metaphase
C) Anaphase ✅
D) Telophase

Explanation: Anaphase is shortest, where chromatids quickly separate.

Q55. The longest stage of mitosis is

A) Prophase ✅
B) Metaphase
C) Anaphase
D) Telophase

Explanation: Prophase is the longest mitotic stage, involving chromosome condensation.

Q56. The phase of meiosis responsible for genetic variation is

A) Prophase I ✅
B) Metaphase II
C) Anaphase II
D) Telophase I

Explanation: Crossing over (pachytene) and independent assortment occur in prophase I.

Q57. G₂ phase prepares the cell for

A) DNA replication
B) Mitosis ✅
C) Crossing over
D) Cytokinesis

Explanation: G₂ phase ensures proteins and organelles are ready for mitosis.

Q58. Kinetochores are made of

A) RNA
B) DNA
C) Proteins ✅
D) Lipids

Explanation: Kinetochores are protein structures at centromeres where spindle attaches.

Q59. The spindle checkpoint ensures

A) DNA replication is complete
B) Chromosomes are aligned at metaphase plate ✅
C) Cytokinesis occurs
D) Chromosomes condense

Explanation: Spindle checkpoint prevents anaphase until all kinetochores are attached.

Q60. The number of DNA molecules in G₂ phase of human somatic cell is

A) 46
B) 92 ✅
C) 23
D) 69

Explanation: After S phase, each of 46 chromosomes has 2 chromatids → 92 DNA molecules.

Q61. The term synaptonemal complex is related to

A) Prophase of mitosis
B) Prophase I of meiosis ✅
C) Anaphase II
D) Cytokinesis

Explanation: Synaptonemal complex forms between homologous chromosomes during zygotene.

Q62. In diplotene stage of meiosis,

A) Synapsis occurs
B) Crossing over occurs
C) Chiasmata are visible ✅
D) Chromosomes disappear

Explanation: Diplotene shows chiasmata as homologs start to repel.

Q63. Bivalents are formed in

A) Mitosis
B) Meiosis I ✅
C) Meiosis II
D) Cytokinesis

Explanation: Bivalents (tetrads) form during synapsis in prophase I.

Q64. Number of bivalents in human meiosis I is

A) 23 ✅
B) 46
C) 92
D) 69

Explanation: In humans (2n=46), meiosis I forms 23 bivalents.

Q65. Reduction division occurs in

A) Mitosis
B) Meiosis I ✅
C) Meiosis II
D) Binary fission

Explanation: Meiosis I reduces chromosome number → haploid cells.

Q66. Equational division occurs in

A) Meiosis I
B) Meiosis II ✅
C) Prophase I
D) G₁ phase

Explanation: Meiosis II resembles mitosis, separating sister chromatids.

Q67. In which stage of meiosis does crossing over occur?

A) Pachytene ✅
B) Zygotene
C) Diplotene
D) Metaphase I

Explanation: Pachytene stage is where exchange of genetic material occurs.

Q68. In which stage of meiosis does synapsis occur?

A) Leptotene
B) Zygotene ✅
C) Diplotene
D) Diakinesis

Explanation: Zygotene = pairing (synapsis) of homologs.

Q69. The term “crossing over” was coined by

A) Morgan
B) Sutton
C) Morgan and Bridges
D) Morgan’s student A.H. Sturtevant ✅

Explanation: Sturtevant used crossing over to create first genetic maps.

Q70. At the end of meiosis I, daughter cells are

A) Haploid ✅
B) Diploid
C) Polyploid
D) Tetraploid

Explanation: Meiosis I reduces chromosome number → haploid cells.

Q71. At the end of meiosis II, daughter cells are

A) Diploid
B) Haploid ✅
C) Polyploid
D) Identical to parent

Explanation: Meiosis II produces 4 haploid gametes.

Q72. Which stage of cell division ensures each daughter cell receives identical chromosomes?

A) Anaphase of mitosis ✅
B) Prophase I
C) Metaphase II
D) Zygotene

Explanation: Anaphase (mitosis) separates sister chromatids equally to both poles.

Q73. A cell with 10 chromosomes undergoes mitosis. How many chromosomes in each daughter cell?

A) 5
B) 10 ✅
C) 20
D) 15

Explanation: Mitosis maintains chromosome number → each daughter gets 10.

Q74. A cell with 10 chromosomes undergoes meiosis. How many chromosomes in each gamete?

A) 5 ✅
B) 10
C) 20
D) 15

Explanation: Meiosis halves chromosome number → gametes have 5.

Q75. The key difference between mitosis and meiosis is

A) Mitosis reduces chromosomes
B) Meiosis produces variation ✅
C) Both are reductional
D) Mitosis produces gametes

Explanation: Meiosis introduces variation (crossing over, assortment), unlike mitosis.

🔬 Cell Structure and Function — Cell Cycle and Cell Division

Part 4 (Q76–Q100)

Q76. The spindle fibers are made up of

A) Actin filaments
B) Microtubules ✅
C) Myosin
D) Collagen

Explanation: Spindle fibres are microtubules made of tubulin proteins.

Q77. Karyokinesis refers to

A) Division of nucleus ✅
B) Division of cytoplasm
C) DNA replication
D) Organelle duplication

Explanation: Karyokinesis = nuclear division; cytokinesis = cytoplasmic division.

Q78. The first cell division in meiosis is

A) Equational
B) Reductional ✅
C) Amitosis
D) Binary

Explanation: Meiosis I reduces chromosome number → reductional division.

Q79. The second cell division in meiosis is

A) Reductional
B) Equational ✅
C) Amitosis
D) Binary

Explanation: Meiosis II separates sister chromatids → equational division.

Q80. Which is not a feature of mitosis?

A) Crossing over ✅
B) Chromatid separation
C) Cytokinesis
D) Chromosome condensation

Explanation: Crossing over occurs in meiosis I, not in mitosis.

Q81. Which event is unique to meiosis?

A) DNA replication
B) Synapsis and crossing over ✅
C) Cytokinesis
D) Spindle formation

Explanation: Synapsis and crossing over are exclusive to meiosis I.

Q82. The centrioles duplicate during

A) G₁
B) S phase ✅
C) G₂
D) M phase

Explanation: Centriole duplication occurs in S phase, along with DNA replication.

Q83. The M phase includes

A) G₁, S, G₂
B) Prophase, metaphase, anaphase, telophase ✅
C) DNA replication
D) Cytoplasmic growth

Explanation: M phase = mitosis stages (PMAT) and cytokinesis.

Q84. Chiasmata are points of

A) Mutation
B) Crossing over ✅
C) DNA replication
D) Nucleolus formation

Explanation: Chiasmata mark sites of genetic exchange between homologs.

Q85. The first stage of mitosis is

A) Metaphase
B) Prophase ✅
C) Anaphase
D) Telophase

Explanation: Prophase begins mitosis with chromatin condensation.

Q86. The last stage of mitosis is

A) Anaphase
B) Metaphase
C) Telophase ✅
D) Prophase

Explanation: Telophase completes mitosis, restoring nuclear membrane.

Q87. Which of the following is a haploid structure?

A) Somatic cell
B) Gamete ✅
C) Liver cell
D) Zygote

Explanation: Gametes (sperm/egg) are haploid (n).

Q88. Diploid organisms produce haploid gametes by

A) Mitosis
B) Meiosis ✅
C) Amitosis
D) Binary fission

Explanation: Meiosis halves chromosome number in gametes.

Q89. The phase in which spindle fibers shorten and pull chromatids is

A) Prophase
B) Metaphase
C) Anaphase ✅
D) Telophase

Explanation: Anaphase = spindle fibres pull chromatids to poles.

Q90. Which organelle is involved in spindle formation in animal cells?

A) Nucleolus
B) Centrosome ✅
C) Ribosome
D) Lysosome

Explanation: Centrosomes organize spindle microtubules.

Q91. The nucleolus disappears during

A) Prophase ✅
B) Metaphase
C) Anaphase
D) Telophase

Explanation: Nucleolus disappears in prophase and reappears in telophase.

Q92. The DNA content of a cell doubles during

A) G₁
B) S phase ✅
C) G₂
D) M phase

Explanation: DNA replication occurs only in S phase.

Q93. At which stage of meiosis does the law of segregation operate?

A) Metaphase I
B) Anaphase I ✅
C) Metaphase II
D) Anaphase II

Explanation: Law of segregation = homologs separate in anaphase I.

Q94. At which stage of meiosis does the law of independent assortment operate?

A) Metaphase I ✅
B) Prophase I
C) Anaphase II
D) Telophase I

Explanation: Independent assortment occurs due to random orientation at metaphase I.

Q95. In mitosis, if a cell has 16 chromosomes, how many will be in each daughter cell?

A) 8
B) 16 ✅
C) 32
D) 4

Explanation: Mitosis maintains chromosome number.

Q96. In meiosis, if a cell has 16 chromosomes, how many will be in each gamete?

A) 8 ✅
B) 16
C) 32
D) 4

Explanation: Meiosis halves chromosome number.

Q97. Colchicine arrests mitosis at

A) Prophase
B) Metaphase ✅
C) Anaphase
D) Telophase

Explanation: Colchicine inhibits spindle fibre formation, arresting cells in metaphase.

Q98. Which division is called the “reductional division”?

A) Meiosis I ✅
B) Meiosis II
C) Mitosis
D) Amitosis

Explanation: Meiosis I reduces diploid → haploid.

Q99. Which division is called the “equational division”?

A) Mitosis ✅
B) Meiosis I
C) Meiosis II ✅
D) Amitosis

Correct Answer: Both Mitosis and Meiosis II

Explanation: Both maintain chromosome number → equational.

Q100. Significance of mitosis is

A) Variation
B) Growth and repair ✅
C) Gamete formation
D) Chromosome reduction

Explanation: Mitosis helps in growth, repair, and asexual reproduction.

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