Cell Cycle and Cell Division Mock Test – Class 11 Biology

1. Assertion: Meiosis II is a reductional division since DNA content per cell decreases from to .
Reason: Chromosome-set number remains while sister chromatids separate during meiosis II.

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

3. 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?

4. Evaluate the following statements about crossing over and chiasmata.
I. Crossing over occurs during pachytene.
II. Chiasmata become clearly evident during diplotene.
III. A visible chiasma corresponds to a site associated with an earlier crossover.
IV. Chiasmata arise through exchange between sister chromatids.

5. A treatment selectively prevents mitosis in both shoot apical meristems and lateral cambium while leaving mature cells temporarily functional. The most likely long-term effect is:

6. An ordered cell-cycle diagram contains three consecutive interphase regions P, Q and R. P begins when mitosis ends and finishes when nuclear DNA synthesis starts. Q contains DNA replication, and R lies immediately before M phase. Region P is:

7. Assertion: Meiosis II is an equational division.
Reason: It separates sister chromatids without causing a further reduction in chromosome-set number.

8. Assertion: Meiosis is essential for maintaining a species-specific chromosome number across sexual generations.
Reason: It halves chromosome number before fertilisation, allowing when gametes fuse.

9. Four diploid cells, each with DNA, show the following features.

Which identification is correct?

10. Use the arrangement described below. Numerous nuclei lie within one continuous mass of cytoplasm, and no internal cellular boundaries separate them. The condition arose through repeated nuclear divisions without corresponding cytoplasmic divisions. This organisation is:

11. A species has . Compare one metaphase-I cell with the complete pair of metaphase-II cells derived from it after normal meiosis I. Which relation is correct?

12. A diploid cell with has entered mitotic anaphase, but cytokinesis has not begun. All centromeres have divided. The complete undivided cell now contains:

13. Cells are prevented from entering M phase but remain in interphase. Measurements show continued oxygen consumption, protein synthesis and increase in cell mass. The observations most strongly support the inference that:

14. Arrange the following events in one normal proliferative cell cycle.
P. Cellular growth occurs before DNA replication.
Q. DNA amount increases from to .
R. Replicated chromosomes attach to the spindle and align.
S. Sister chromatids separate and daughter nuclei form.
T. Cytokinesis produces two daughter cells.

15. 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:

16. Evaluate the following comparisons between mitosis and meiosis.
I. Both are normally preceded by DNA replication.
II. Mitosis usually contains one nuclear division and produces two daughter cells.
III. Meiosis contains two nuclear divisions and ordinarily produces four haploid cells.
IV. DNA replication normally occurs before both meiosis I and meiosis II.

17. Four cells were examined immediately before or during mitosis.

Which cell most closely represents the beginning of prophase?

18. A meiotic cell contains fully condensed bivalents and terminalised chiasmata. Its spindle is assembling, while the nucleolus and nuclear envelope are disappearing. This combination identifies:

19. One diploid somatic cell and one diploid meiocyte have each completed DNA replication and contain DNA. The somatic cell completes normal mitosis, while the meiocyte completes normal meiosis. Which final summary is correct?

20. During one substage of prophase I, corresponding maternal and paternal chromosomes begin pairing along their lengths. This association is called:

21. A species has . Counts refer to one complete cell or one daughter nucleus, as stated.

Which record is biologically inconsistent?

22. 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:

23. A cell contains centromeres. Every centromere joins two sister chromatids, and no centromere has divided. The cell contains:

24. Evaluate these statements about .
I. Cells may enter it by leaving .
II. Cells in it can remain metabolically active.
III. Some cells may return from it to the proliferative cycle when required.
IV. Cells in it must continuously duplicate nuclear DNA.

25. Four meiotic conditions are compared below.

Which pair of rows contains biologically defensible expectations?

26. A species has . In one undivided anaphase-II cell, all centromeres have split and the daughter chromosomes are moving normally. Which count is expected?

27. An unknown cell changes according to the relation , while every chromosome in the product still contains two chromatids. The transition most directly represents:

28. 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:

29. 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:

30. Cells are exposed successively to two treatments. Treatment P prevents nuclear DNA from increasing above . After P is removed, the cells reach , condense chromosomes and align them normally. Treatment Q is then applied; centromeres fail to divide and poleward chromosome separation does not begin. The correct interpretation is:

31. A record begins immediately after one cell division and ends when the same cell completes its next division. Which order best represents the major events during this interval?

32. In an average human cell cycle lasting , M phase occupies approximately . The approximate duration and percentage of interphase are:

33. Assertion: Assuming no DNA loss, the four final products of one meiosis together contain the same total DNA as the original meiocyte immediately after premeiotic S phase.
Reason: The decreases from to and then are per-cell changes caused by partitioning DNA among two and then four products.

34. A meiocyte completes synapsis and later segregates homologous chromosomes normally, but crossing over is experimentally prevented. The most reasonable final outcome is:

35. Recombination is completed normally, but a treatment prevents dissolution of the synaptonemal complex as the cell should enter diplotene. The most direct expected effect is:

36. Four dividing cells show the following arrangements.

Which cell is specifically in metaphase I?

37. A cell is one of the two products of a completed reductional division. No DNA replication has occurred since that division. Its individual replicated chromosomes align at the equator, after which centromeres split and daughter chromosomes move apart. The separating stage is:

38. Control cells form a compact metaphase plate. In treated cells, kinetochores remain attached to spindle fibres, but the fibres cannot generate effective movement, and chromosomes stay scattered. The strongest inference is that:

39. Consider the following statements integrating the cell cycle and cell division.
I. S phase can double DNA amount without changing chromosome number.
II. Centromere division can increase chromosome count within an undivided anaphase cell.
III. Cytokinesis is required to convert daughter nuclear regions into separate cells.
IV. Meiosis II causes a second reduction from haploidy to half-haploidy.

40. Evaluate the following statements.
I. Meiosis I separates homologous chromosomes and reduces ploidy.
II. Meiosis II separates sister chromatids without further reducing ploidy.
III. A separate S phase normally precedes each meiotic division.
IV. Meiosis II does not restore the diploid chromosome complement.

41. A cell grows, synthesises many proteins and duplicates its genome, but it never undergoes nuclear or cytoplasmic division. Has it completed a cell cycle?

42. Four possible division outcomes are listed below.

Which outcome represents completion of normal meiosis II and cytokinesis?

43. 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:

44. A treatment permits chromosome condensation and meiotic-spindle assembly but prevents chiasmata from moving towards chromosome ends. The most direct observation during diakinesis would be:

45. In an adult animal, heart cells continue performing their specialised functions but ordinarily do not divide. Another cell population begins dividing when neighbouring cells die and require replacement. This comparison shows that:

46. A graph plots two variables against progression through prophase I. Curve P, representing active segment exchange between homologous chromosomes, rises during pachytene and falls to nearly zero before diplotene. Curve Q, representing clearly visible X-shaped connections between partly separated homologues, is low during pachytene and rises during diplotene. The graph supports the conclusion that:

47. Consider the following statements about the metaphase plate.
I. It represents the equatorial alignment of replicated chromosomes.
II. It is produced through chromosome interactions with the spindle.
III. It is a permanent membrane separating the future daughter cells.
IV. Sister chromatids remain joined while chromosomes occupy it.

48. A graph plots chromosome condensation and nuclear-envelope integrity against progression through a division. Condensation rises as envelope integrity falls, remains high during equatorial alignment and segregation, then falls as envelope integrity rises again. Which interpretation best fits the paired curves?

49. Match each cellular context with its correct description. Each Column II entry is used once.

50. Replicated chromosomes align normally in metaphase II, and their sister kinetochores attach to opposite poles. A treatment then prevents every centromere from dividing. The most immediate outcome will be: