Question Bank — Cell Cycle and Cell Division

NCERT Class 11 Biology · Chapter 10 · CBSE Board Pattern

Class 11 Biology Chapter 10 Question Bank CBSE Board Pattern

Section A — MCQs (10 questions, 1 mark each)

1. The average duration of the cell cycle in a typical human cell in culture is:
(a) 90 minutes
(b) 24 hours
(c) 1 hour
(d) 12 hours

2. In which phase of the cell cycle does the amount of DNA per cell double while the chromosome number remains unchanged?
(a) G1 phase
(b) S phase
(c) G2 phase
(d) M phase

3. Assertion (A): Interphase is called the resting phase of the cell cycle.
Reason (R): During interphase, the cell prepares for division by undergoing cell growth and DNA replication.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

4. The stage of mitosis at which chromosomes are most clearly visible and their morphology can be easily studied is:
(a) Prophase
(b) Metaphase
(c) Anaphase
(d) Telophase

5. Assertion (A): Mitosis is called equational division.
Reason (R): The chromosome number in the parent and progeny cells remains the same after mitosis.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

6. During which stage of prophase I of meiosis does crossing over occur between non-sister chromatids?
(a) Leptotene
(b) Zygotene
(c) Pachytene
(d) Diplotene

7. In animal cells, cytokinesis is achieved by:
(a) Formation of a cell plate
(b) Appearance of a furrow in the plasma membrane
(c) Formation of a synaptonemal complex
(d) Terminalisation of chiasmata

8. The quiescent stage (G0) of the cell cycle is characterised by:
(a) Active DNA replication
(b) Cells remaining metabolically active but not proliferating
(c) Formation of bivalents
(d) Splitting of centromeres

9. The key event that marks the beginning of anaphase in mitosis is:
(a) Condensation of chromosomes
(b) Alignment of chromosomes at the metaphase plate
(c) Splitting of centromeres and separation of chromatids
(d) Reformation of the nuclear envelope

10. Meiosis results in:
(a) Two diploid daughter cells
(b) Four haploid daughter cells
(c) Two haploid daughter cells
(d) Four diploid daughter cells

Section B — Very Short Answer (6 questions, 2 marks each)

1. Distinguish between karyokinesis and cytokinesis.
2. What is the G0 (quiescent) phase of the cell cycle?
3. Why is mitosis called equational division?
4. Name the stage of the cell cycle at which: (i) chromosomes move to the spindle equator, (ii) centromeres split and chromatids separate.
5. Define synapsis and bivalent.
6. How does cytokinesis in plant cells differ from that in animal cells?

Section C — Short Answer (5 questions, 3 marks each)

1. Describe the events occurring during the G1, S and G2 phases of interphase.
2. Explain the key events of prophase of mitosis.
3. Describe the events of anaphase and telophase of mitosis.
4. What is the significance of mitosis in the life of an organism?
5. List the key features of meiosis that distinguish it from mitosis.

Section D — Long Answer (3 questions, 5 marks each)

1. Describe the various stages of mitosis with the help of a labelled diagram.
2. Describe the substages of prophase I of meiosis in detail.
3. Explain the significance of mitosis and meiosis in the life cycle of organisms.

Section E — Case/Source-Based (2 questions, 4 marks each)

Case 1: In a typical human cell, the cell cycle lasts about 24 hours. Cell division proper occurs for only about an hour, while interphase occupies more than 95% of the cycle. DNA replication occurs only in one specific stage, and some adult cells (e.g., heart cells) exit the cycle to enter a quiescent stage.
(i) Identify the phase that lasts more than 95% of the cell cycle.
(ii) Name the phase during which DNA synthesis occurs and state what happens to DNA content.
(iii) What is the quiescent stage and why do some cells enter it?
(iv) Why must cell growth, DNA replication and division occur in a coordinated manner?

Case 2: Meiosis occurs in diploid cells destined to form gametes. It involves two sequential nuclear divisions but only one round of DNA replication, resulting in four haploid cells. Homologous chromosomes pair and undergo crossing over.
(i) Why is meiosis called reduction division?
(ii) Name the two sequential divisions and state how many DNA replications occur.
(iii) What is the role of crossing over in meiosis?
(iv) How does meiosis contribute to genetic variability and conservation of chromosome number across generations?

▶ Answer Key Attempt all questions first,
then tap to reveal

Section A

  1. (b) — 1 mark
  2. (b) — DNA doubles (2C to 4C), chromosome number remains 2n — 1 mark
  3. (a) — Both true, R explains why interphase is preparatory not truly resting — 1 mark
  4. (b) — 1 mark
  5. (a) — Both true, R directly explains equational nature — 1 mark
  6. (c) — 1 mark
  7. (b) — 1 mark
  8. (b) — 1 mark
  9. (c) — 1 mark
  10. (b) — 1 mark

Section B

  1. Karyokinesis = nuclear division (1 mark); Cytokinesis = cytoplasmic division (1 mark)
  2. G0: cells exit G1, remain metabolically active but do not proliferate (2 marks)
  3. Chromosome number remains same in parent and daughter cells (2 marks)
  4. (i) Metaphase (1 mark); (ii) Anaphase (1 mark)
  5. Synapsis = pairing of homologous chromosomes (1 mark); Bivalent = paired homologous chromosomes (1 mark)
  6. Plant: cell plate formation (1 mark); Animal: furrow in plasma membrane (1 mark)

Section C

  1. G1: cell growth, metabolically active, no DNA replication (1 mark); S: DNA replication, DNA content doubles (1 mark); G2: protein synthesis, cell growth continues (1 mark)
  2. Chromosome condensation, centrosome movement to poles, formation of asters and spindle, disappearance of Golgi, ER, nucleolus and nuclear envelope (any 3 points — 3 marks)
  3. Anaphase: centromeres split, chromatids move to opposite poles (1½ marks); Telophase: chromosomes decondense, nuclear envelope and nucleolus reform (1½ marks)
  4. Growth of multicellular organisms, restoration of nucleo-cytoplasmic ratio, cell repair, continuous growth in plants via meristems (any 3 — 3 marks)
  5. Two divisions, one DNA replication; pairing of homologues and crossing over; produces haploid cells (3 marks)

Section D

  1. Prophase, metaphase, anaphase, telophase + cytokinesis with labelled diagram description (stages — 3 marks, diagram labels — 2 marks)
  2. Leptotene to diakinesis (condensation, synapsis, tetrad formation, crossing over, chiasmata, terminalisation) — 5 marks
  3. Mitosis: growth, repair, equational division (2½ marks); Meiosis: reduction division, genetic variability, maintenance of chromosome number (2½ marks)

Section E

Case 1: (i) Interphase (1 mark); (ii) S phase, DNA content 2C → 4C (1 mark); (iii) G0, cells stop dividing unless stimulated (1 mark); (iv) Ensures intact genome in daughter cells (1 mark)
Case 2: (i) Reduces chromosome number by half (1 mark); (ii) Meiosis I and II, single DNA replication (1 mark); (iii) Produces genetic recombination (1 mark); (iv) Maintains species chromosome number, generates variation for evolution (1 mark)

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All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.