Cell Cycle and Cell Division Mock Test – Class 11 Biology

1. Centromeres split prematurely while homologous chromosomes are beginning to segregate in anaphase I. The most immediate consequence would be:

2. Cell loss suddenly increases in a tissue whose resting cells can divide when replacement is required. The most likely response is:

3. An onion root-tip cell has chromosomes in . It completes S phase and later undergoes normal mitosis. Which set of counts is accurate?

4. Assertion: A cell in may contain DNA even though nuclear DNA synthesis is not occurring.
Reason: Nuclear DNA amount normally doubles during .

5. Use the cellular arrangement described here. Two chromosome groups lie at opposite poles. Each chromosome still consists of two sister chromatids. Nuclear envelopes are beginning to surround the groups, and a cytoplasmic partition is forming between them. The stage is:

6. An isolated tissue increases its cell number only when existing cells divide. This observation most directly supports:

7. A haploid male-honey-bee cell has chromosomes in . It completes S phase and reaches mitotic anaphase, where all centromeres have divided but cytokinesis has not begun. Which count is correct?

8. Four meiotic samples show the following features.

In which sample is crossing over actively associated with its characteristic nodular sites rather than merely represented by later visible chiasmata?

9. A meiocyte is observed at three successive times.

The stage sequence is:

10. Assertion: Each chromosome reaching a pole in normal anaphase I still consists of two sister chromatids.
Reason: Centromeres do not divide during anaphase I, so the two sister chromatids of each chromosome move together towards the same pole.

11. Use the arrangement described below. A haploid cell contains replicated chromosomes whose centromeres have just divided. The two former sister chromatids of each chromosome are moving towards opposite poles. This arrangement represents:

12. Assertion: Named mitotic stages remain useful even though mitosis proceeds through continuous transitions.
Reason: Each stage is recognised by a dominant combination of chromosome organisation, centromere state, spindle relation and nuclear-envelope condition rather than by an instantaneous switch.

13. Evaluate the following comparisons.
I. Mitosis usually preserves chromosome number in daughter cells.
II. Meiosis I separates homologous chromosomes.
III. Mitosis and meiosis II both involve sister-chromatid separation.
IV. Crossing over is a normal feature of mitotic prophase.

14. A meiotic preparation shows the following arrangement. Two replicated homologous chromosomes are fully paired. Their four chromatids are clearly visible, and small nodular structures occur where one chromatid of each homologue approaches the other. The arrangement most directly represents:

15. A dividing diploid cell has completed one DNA-replication phase. Homologous chromosomes pair and exchange segments, two nuclear divisions follow, and four cellular products form. A second diploid cell also completes one replication but shows no homologue pairing and produces two cells after one division. The cells are undergoing:

16. Four cell cultures show the following events during one attempted division.

Which culture is most likely to produce two separate daughter cells, each receiving an intact duplicated genome?

17. Two daughter nuclei have formed inside one animal cell. A furrow then appears at the cell surface, deepens towards the centre and finally separates the cytoplasm into two compartments. The final process described is:

18. A diploid meiocyte has . After premeiotic DNA replication and normal completion of meiosis I, each of the two daughter cells contains:

19. A plant cell completes normal chromosome segregation and forms two daughter nuclei. Cytokinesis also occurs, but nearly all plastids remain in only one daughter-cell region before separation is completed. The most direct consequence is that:

20. A graph follows one diploid cell from through S phase, metaphase and early anaphase. Curve P rises during S phase and then remains constant. Curve Q remains constant through metaphase and rises only when anaphase begins. The curves most reasonably represent:

21. Four proposed comparisons of animal- and plant-cell cytokinesis are shown below.

Which comparison correctly relates the mechanisms and their directions?

22. In a metaphase-I bivalent, both homologous chromosomes become attached to spindle fibres leading towards the same pole, while sister centromeres remain intact. If this arrangement persists, the most direct risk is:

23. Assertion: Division of centromeres marks the initiation of mitotic anaphase.
Reason: Centromere division immediately reduces the chromosome number of the undivided cell to half.

24. Control cells form spindle fibres that attach to chromosomes and produce a clear metaphase plate. Treated cells form an apparently bipolar spindle, but their chromosomes remain scattered and show no stable spindle attachment. The treatment most directly affected:

25. Four chromosome groups lie at the poles of two dividing haploid cells. Each chromosome consists of one chromatid, and nuclear envelopes are forming around all four groups. The cells are in:

26. Two cells both have DNA and intact sister-centromere associations. Cell P is preparing for ordinary mitosis, while Cell Q is entering meiosis I. Which observation would identify Cell Q?

27. A fluorescent marker is placed at the centromere of each chromosome, while a second marker labels the chromosome ends. During time-lapse imaging, the centromere markers remain closer to the approaching poles than the end markers. The observation supports the inference that:

28. Match each interval with its defining chromosome event. Each Column II entry is used once.

29. A haploid somatic cell of a male honey bee has chromosomes in . After completing S phase, it reaches mitotic metaphase. Which description is correct?

30. Control animal cells form two asters at opposite poles and align chromosomes at the equator. Treated cells condense chromosomes normally but retain both asters close together and rarely achieve equatorial alignment. The observations most strongly indicate that the treatment disrupted:

31. The observations below were recorded for normal mitotic divisions.

Which conclusion is best supported by the complete data?

32. A species has . Compare two cells:

Why does the equal chromosome count not imply equal ploidy?

33. The features of four cells are summarised below.

Which cell most closely represents telophase?

34. Control cells entering late prophase show condensed chromosomes, separated centrosomal regions and loss of visible distinction of the nuclear envelope, nucleolus, Golgi complexes and endoplasmic reticulum. Treated cells show chromosome condensation and centrosomal separation, but all four cellular structures remain visibly distinct. The treatment most directly disrupted:

35. Consider the following statements about telophase.
I. Nuclear envelopes form around the daughter chromosome sets.
II. Nucleoli become visible again.
III. Chromosomes become maximally condensed for morphology study.
IV. Golgi complexes and endoplasmic reticulum re-form.

36. Cell P is a haploid plant cell that has completed S phase and will undergo mitosis. Cell Q is an product of meiosis I entering meiosis II. Which comparison is correct?

37. A cell has completed DNA replication and synthesised proteins needed for chromosome segregation. It has not yet begun nuclear division. The cell is still in interphase mainly since:

38. Three diploid meiocytes, each with , complete normal meiosis independently. Assuming all cytokinetic divisions are completed, the result is:

39. A diploid meiocyte produces two cells. Each cell has one chromosome from every homologous pair, but every chromosome still contains two sister chromatids. Nuclear membranes are present, and the chromosomes remain partly condensed. These cells are:

40. A graph compares two systems receiving equal nutrient input. In both, total cellular material rises steadily. In System P, cell number rises stepwise after each division. In System Q, cell number remains at one while mean cell size rises continuously. Which interpretation is most appropriate?

41. One founding cell produces two lineages. In lineage P, four rounds of mitosis and cytokinesis are completed normally. In lineage Q, the first three rounds are normal, but during the fourth round every cell completes karyokinesis without cytokinesis. The final numbers of cellular compartments are:

42. A treatment prevents nuclear-envelope breakdown but allows chromosome condensation. Treated cells fail to achieve normal spindle attachment and equatorial alignment, whereas control cells proceed into metaphase. The strongest conclusion is that:

43. Assertion: Mitosis in animals cannot be described as occurring exclusively in diploid cells.
Reason: Cells of a haploid male honey bee can undergo mitotic division.

44. Consider the following statements about meiosis in plants and animals.
I. It begins in specialised diploid cells.
II. It contributes to the formation of cells belonging to the haploid phase.
III. It ordinarily preserves the diploid chromosome number in every final product.
IV. It occurs in association with gamete formation.

45. Two cell populations pass through , S, and M phase in the same order. One population completes the cycle in , while the other requires . The strongest inference is that:

46. Under otherwise unchanged conditions, the duration of a proliferating cell’s cycle becomes longer while the observation period remains fixed. The most reasonable prediction is:

47. During a typical proliferative cell cycle, cellular growth may continue through much of interphase, whereas nuclear DNA synthesis is:

48. Assertion: Every metabolically active cell that enters is permanently incapable of returning to the cell cycle.
Reason: Some cells can re-enter and proliferate when replacement or organismal requirements provide an appropriate signal.

49. Control meiocytes show close pairing of homologous chromosomes followed by recombination between selected chromatids. Treated meiocytes compact their chromosomes normally, but homologous chromosomes fail to pair. The most direct expected effect is:

50. Use the meiotic arrangement described here. Two replicated homologous chromosomes lie closely paired along their lengths. A continuous structure extends between them and maintains their organised association before they begin separating. The structure and the substage in which its formation accompanies pairing are: