Cell division and cell cycle MCQs With Answer

Cell division and cell cycle MCQs With Answer

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Cell division and cell cycle MCQs With Answer

Cell division and the cell cycle are core topics for B.Pharm students, linking cellular biology to pharmacology, toxicology and cancer therapeutics. This set covers mitosis, meiosis, cytokinesis, cell cycle phases (G0, G1, S, G2, M), checkpoints, DNA replication, chromosome segregation, and regulation by cyclins, CDKs, p53, Rb and telomerase. Questions emphasize mechanisms, experimental tools (flow cytometry, BrdU), drug actions (taxanes, vinca alkaloids, topoisomerase inhibitors) and clinical relevance such as cell cycle arrest and targeted CDK inhibitors. Designed to deepen conceptual understanding and exam readiness, the MCQs link molecular events to drug effects and disease. ‘Now let’s test your knowledge with 30 MCQs on this topic.’

Q1. Which phase of the cell cycle is primarily responsible for DNA replication?

  • G1 phase
  • S phase
  • G2 phase
  • M phase

Correct Answer: S phase

Q2. What is the correct sequential order of mitotic phases?

  • Prophase → Metaphase → Anaphase → Telophase
  • Metaphase → Prophase → Anaphase → Telophase
  • Prophase → Anaphase → Metaphase → Telophase
  • Interphase → Prophase → Metaphase → Cytokinesis

Correct Answer: Prophase → Metaphase → Anaphase → Telophase

Q3. Cytokinesis in animal cells is driven mainly by which structure?

  • Mitotic spindle microtubules
  • Contractile ring of actin and myosin
  • Intermediate filament ring
  • Cell wall synthesis

Correct Answer: Contractile ring of actin and myosin

Q4. Which cyclin–CDK complex is most directly associated with progression through the G1 restriction point in mammalian cells?

  • Cyclin A–CDK2
  • Cyclin B–CDK1
  • Cyclin D–CDK4/6
  • Cyclin E–CDK2

Correct Answer: Cyclin D–CDK4/6

Q5. Following DNA damage, p53 primarily promotes G1 arrest by inducing which effector?

  • Cyclin B
  • p21 (CDK inhibitor)
  • Rb phosphorylation
  • Telomerase activation

Correct Answer: p21 (CDK inhibitor)

Q6. Replication origin licensing (loading of MCM helicase) takes place in which cell-cycle window to prevent rereplication?

  • Late G2 phase
  • M phase
  • G1 phase
  • S phase

Correct Answer: G1 phase

Q7. Failure of the spindle assembly checkpoint most commonly leads to which genomic abnormality?

  • Point mutations
  • Aneuploidy
  • Loss of telomeres
  • Mitochondrial DNA depletion

Correct Answer: Aneuploidy

Q8. In meiosis I, which pair separates during anaphase I?

  • Sister chromatids
  • Homologous chromosomes
  • Centromeres only
  • Chromatids and centrioles together

Correct Answer: Homologous chromosomes

Q9. Crossing over (genetic recombination) occurs during which substage of prophase I in meiosis?

  • Leptotene
  • Zygotene
  • Pachytene
  • Diakinesis

Correct Answer: Pachytene

Q10. Telomerase activity in somatic cells is typically low, leading to progressive telomere shortening and eventual:

  • Increased mitochondrial function
  • Replicative senescence
  • Immediate apoptosis after each division
  • Enhanced homologous recombination

Correct Answer: Replicative senescence

Q11. Paclitaxel (taxane) exerts its anticancer effect by:

  • Depolymerizing microtubules
  • Stabilizing microtubules and preventing their disassembly
  • Inhibiting topoisomerase I
  • Blocking CDK4/6 activity

Correct Answer: Stabilizing microtubules and preventing their disassembly

Q12. Vinca alkaloids (e.g., vincristine) primarily act by:

  • Stabilizing DNA double helix
  • Inhibiting DNA polymerase
  • Depolymerizing microtubules and inhibiting spindle formation
  • Activating telomerase

Correct Answer: Depolymerizing microtubules and inhibiting spindle formation

Q13. Etoposide is a chemotherapeutic that targets which enzyme leading to double-strand breaks?

  • Topoisomerase I
  • Topoisomerase II
  • DNA ligase
  • DNA primase

Correct Answer: Topoisomerase II

Q14. Which targeted drug class directly inhibits CDK4/6 to induce G1 arrest in hormone receptor–positive breast cancer?

  • EGFR inhibitors
  • PARP inhibitors
  • CDK4/6 inhibitors (e.g., palbociclib)
  • Topoisomerase inhibitors

Correct Answer: CDK4/6 inhibitors (e.g., palbociclib)

Q15. Flow cytometry measuring DNA content with propidium iodide primarily distinguishes cells in which phases?

  • G1, S and G2/M phases based on DNA content
  • Only mitotic versus non-mitotic cells
  • Apoptotic versus necrotic cells only
  • Metabolic states but not cell-cycle phases

Correct Answer: G1, S and G2/M phases based on DNA content

Q16. Which proteins are central components of the spindle assembly checkpoint that inhibit APC/C when kinetochores are unattached?

  • MAD and BUB family proteins
  • Cyclins A and B
  • Topoisomerases
  • Telomerases

Correct Answer: MAD and BUB family proteins

Q17. Geminin prevents DNA rereplication by inhibiting which licensing factor during S, G2 and M phases?

  • ORC1
  • Cdt1
  • MCM2-7 helicase
  • DNA polymerase delta

Correct Answer: Cdt1

Q18. ATM and ATR kinases differ in their primary activation signals; which is correctly matched?

  • ATM responds to single-stranded DNA; ATR responds to double-strand breaks
  • ATM responds to double-strand breaks; ATR responds to replication stress and single-stranded DNA
  • Both respond only to oxidative stress
  • Both are activated only during mitosis

Correct Answer: ATM responds to double-strand breaks; ATR responds to replication stress and single-stranded DNA

Q19. Centriole duplication occurs once per cycle and is initiated during which phase?

  • G1 phase
  • S phase
  • M phase
  • G0 phase

Correct Answer: S phase

Q20. A syntelic kinetochore attachment is characterized by:

  • Each sister kinetochore attached to opposite spindle poles
  • Both sister kinetochores attached to the same spindle pole
  • No attachment to microtubules
  • Attachment to astral microtubules only

Correct Answer: Both sister kinetochores attached to the same spindle pole

Q21. Which small GTPase is a key regulator of contractile ring formation during cytokinesis?

  • Ras
  • RhoA
  • Rab5
  • Ran

Correct Answer: RhoA

Q22. Hypophosphorylated retinoblastoma protein (pRb) in early G1 primarily exerts cell-cycle control by:

  • Activating cyclin B expression
  • Sequestering E2F transcription factors and preventing S-phase gene expression
  • Directly degrading cyclins
  • Stimulating telomerase

Correct Answer: Sequestering E2F transcription factors and preventing S-phase gene expression

Q23. Which feature distinguishes apoptosis from necrosis?

  • Cell swelling and membrane rupture
  • Energy-independent process
  • Programmed DNA fragmentation and membrane blebbing without inflammation
  • Always results from acute infection

Correct Answer: Programmed DNA fragmentation and membrane blebbing without inflammation

Q24. Homologous recombination repair of double-strand breaks is most active in which cell-cycle phases and why?

  • G1 phase, because chromatin is most condensed
  • S and G2 phases, because a sister chromatid is available as template
  • M phase, due to spindle forces
  • G0 phase, when cells are quiescent

Correct Answer: S and G2 phases, because a sister chromatid is available as template

Q25. Which term describes a cell with an abnormal number of chromosomes not in whole multiples of the haploid set?

  • Polyploidy
  • Aneuploidy
  • Euploidy
  • Diploidy

Correct Answer: Aneuploidy

Q26. Among cell-cycle phases, which is typically the most variable in duration and responsive to extracellular signals?

  • M phase
  • S phase
  • G1 phase
  • G2 phase

Correct Answer: G1 phase

Q27. Antimitotic chemotherapeutics that target microtubules are most active against cells in which phase?

  • G1 phase
  • S phase
  • M phase (mitosis)
  • G0 phase

Correct Answer: M phase (mitosis)

Q28. Camptothecin derivatives inhibit topoisomerase I; the most direct consequence during S phase is:

  • Accumulation of single-strand breaks that convert to double-strand breaks during replication
  • Immediate inhibition of spindle assembly
  • Direct cleavage of centrosomes
  • Activation of telomerase

Correct Answer: Accumulation of single-strand breaks that convert to double-strand breaks during replication

Q29. Failure of cytokinesis can produce tetraploid cells; persistent tetraploidy may contribute to tumorigenesis by promoting:

  • Enhanced DNA repair fidelity
  • Genomic instability and aneuploidy
  • Reduced proliferation capacity only
  • Immediate cell differentiation

Correct Answer: Genomic instability and aneuploidy

Q30. Activation of the spindle assembly checkpoint prevents anaphase onset by inhibiting which E3 ubiquitin ligase complex?

  • SCF complex
  • APC/C (anaphase-promoting complex/cyclosome)
  • Mdm2
  • BRCA1-BARD1 complex

Correct Answer: APC/C (anaphase-promoting complex/cyclosome)

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