Cell Division
Level 1: Recognition (MCQ + Matching + True/False with Justification)
Time limit: 20 minutes Total marks: 30
Section A — Multiple Choice (1 mark each) [10 marks]
Choose the single best answer.
Q1. During which phase of the cell cycle does DNA replication occur? a) G1 b) S c) G2 d) M
Q2. A chromosome that has been replicated consists of two identical strands joined at the: a) chiasma b) spindle c) centromere d) cell plate
Q3. In which stage of mitosis do chromosomes align at the equator (metaphase plate)? a) Prophase b) Metaphase c) Anaphase d) Telophase
Q4. Cytokinesis in a plant cell is completed by the formation of a: a) cleavage furrow b) cell plate c) contractile ring d) chiasma
Q5. A human somatic (body) cell is described as diploid because it contains: a) one set of chromosomes b) two sets of chromosomes c) four sets of chromosomes d) no chromosomes
Q6. The proteins that combine with CDKs to drive the cell through cycle phases are called: a) cyclins b) histones c) tubulins d) kinetochores
Q7. Crossing over between homologous chromosomes occurs during: a) prophase I of meiosis b) anaphase of mitosis c) telophase II d) S phase
Q8. Uncontrolled cell division that ignores checkpoint signals can lead to: a) apoptosis b) cancer c) haploidy d) cytokinesis
Q9. How many daughter cells are produced at the end of meiosis (I and II)? a) 1 b) 2 c) 4 d) 8
Q10. The failure of chromosomes to separate correctly during cell division is called: a) crossing over b) independent assortment c) nondisjunction d) replication
Section B — Matching (1 mark each) [8 marks]
Match each term in Column X to its correct description in Column Y. Write the letter.
| Column X | Column Y | |
|---|---|---|
| Q11. G1 phase | A. Point where sister chromatids are joined | |
| Q12. Centromere | B. Cell grows and carries out normal functions before DNA synthesis | |
| Q13. Chiasma | C. Site of crossing over where homologues are connected | |
| Q14. Anaphase | D. Sister chromatids are pulled to opposite poles | |
| Q15. Homologous chromosomes | E. Pair of chromosomes with the same genes, one from each parent | |
| Q16. G2 checkpoint | F. Checks DNA replication is complete before mitosis | |
| Q17. Haploid cell | G. Contains a single set of chromosomes | |
| Q18. Cyclin–CDK complex | H. Molecular switch that triggers progression through the cycle |
Section C — True/False WITH Justification (2 marks each: 1 for T/F, 1 for justification) [12 marks]
Q19. Mitosis produces two genetically identical daughter cells.
Q20. Meiosis produces cells with the same chromosome number as the parent cell.
Q21. Independent assortment of homologous chromosomes increases genetic variation.
Q22. The cleavage furrow forms in dividing plant cells to split the cytoplasm.
Q23. DNA is replicated during both interphase of mitosis and between meiosis I and meiosis II.
Q24. A checkpoint stops the cell cycle if damaged DNA is detected.
Answer keyMark scheme & solutions
Section A — MCQ (1 mark each)
Q1. b) S — S (synthesis) phase is when DNA is replicated. (1) Q2. c) centromere — Two sister chromatids are joined at the centromere. (1) Q3. b) Metaphase — Chromosomes line up on the metaphase plate. (1) Q4. b) cell plate — Plants form a cell plate; a rigid wall prevents furrowing. (1) Q5. b) two sets of chromosomes — Diploid (2n) = two complete sets. (1) Q6. a) cyclins — Cyclins bind CDKs to activate them. (1) Q7. a) prophase I of meiosis — Homologues pair and cross over in prophase I. (1) Q8. b) cancer — Loss of checkpoint control → tumour/cancer. (1) Q9. c) 4 — Meiosis I + II yield four haploid cells. (1) Q10. c) nondisjunction — Failure of chromosome separation. (1)
Section B — Matching (1 mark each)
Q11 → B (G1 = growth before DNA synthesis) (1) Q12 → A (centromere joins sister chromatids) (1) Q13 → C (chiasma = crossing-over connection) (1) Q14 → D (anaphase separates chromatids to poles) (1) Q15 → E (homologues = same genes, one from each parent) (1) Q16 → F (G2 checkpoint verifies replication) (1) Q17 → G (haploid = single chromosome set) (1) Q18 → H (cyclin–CDK = molecular switch) (1)
Section C — True/False with Justification (2 marks each)
Q19. TRUE (1) — Mitosis conserves chromosome number and DNA is copied exactly, so daughter cells are genetically identical clones of the parent. (1)
Q20. FALSE (1) — Meiosis is a reduction division; daughter cells are haploid (half the parental chromosome number). (1)
Q21. TRUE (1) — The random orientation of homologous pairs at metaphase I produces many combinations of maternal/paternal chromosomes, increasing variation. (1)
Q22. FALSE (1) — Plant cells form a cell plate (not a cleavage furrow) because their rigid cell wall cannot pinch inward; the cleavage furrow occurs in animal cells. (1)
Q23. FALSE (1) — DNA is replicated only once (during interphase before meiosis I). There is no S phase between meiosis I and II. (1)
Q24. TRUE (1) — Checkpoints (e.g., G1/G2) halt the cycle when DNA damage is detected, allowing repair or triggering apoptosis. (1)
Mark distribution check
- Section A: 10 × 1 = 10
- Section B: 8 × 1 = 8
- Section C: 6 × 2 = 12
- Total = 30 marks
[
{"claim":"Meiosis produces 4 daughter cells","code":"cells_after_meiosis1 = 2\ncells_after_meiosis2 = cells_after_meiosis1 * 2\nresult = (cells_after_meiosis2 == 4)"},
{"claim":"Section total marks equal 30","code":"secA = 10*1\nsecB = 8*1\nsecC = 6*2\nresult = (secA + secB + secC == 30)"},
{"claim":"Diploid means two sets; haploid means one set (half)","code":"diploid = 2\nhaploid = diploid/2\nresult = (haploid == 1)"},
{"claim":"DNA replicated once produces 2 chromatids per chromosome after one S phase","code":"chromatids = 1\nafter_S = chromatids*2\nresult = (after_S == 2)"}
]