Quiz: Cell Cycle and Cell Division — 18 questions

1. Which sequence best describes the cell cycle?

A. Cell enlargement, organelle removal, and migration to a different tissue

B. Nuclear division followed by permanent cellular inactivity and cell death

C. Protein synthesis, chromosome destruction, and fusion with another cell

D. Genome duplication, synthesis of cellular constituents, and division into two daughter cells

Answer: (D)

Explanation

The cell cycle includes genome duplication, synthesis of other cellular constituents, and division into two daughter cells.

2. Which statement correctly distinguishes interphase from M phase?

A. Interphase separates chromatids, whereas M phase synthesizes proteins for future growth

B. Interphase prepares the cell for division, whereas M phase includes mitosis and usually cytokinesis

C. Interphase includes cytokinesis, whereas M phase is limited to cellular metabolism

D. Interphase performs mitosis, whereas M phase duplicates the genome before division

Answer: (B)

Explanation

Interphase prepares the cell for division, while M phase is the division phase that includes mitosis and usually cytokinesis.

3. A cell has completed DNA replication and is synthesizing proteins needed for mitosis. Which phase is it in?

A. S phase

B. G2 phase

C. G1 phase

D. G0 phase

Answer: (B)

Explanation

During G2, the cell continues growing and synthesizes proteins required for mitosis. DNA replication occurs earlier, during S phase.

4. What happens to DNA content and chromosome number during S phase in a diploid cell?

A. DNA content remains unchanged, while chromosome number doubles

B. Both DNA content and chromosome number remain unchanged

C. Both DNA content and chromosome number double

D. DNA content doubles, while chromosome number remains unchanged

Answer: (D)

Explanation

S phase increases DNA content from 2C to 4C, but the chromosome number remains the same, such as 2n before and after replication.

5. Which event characterizes anaphase of mitosis?

A. Chromosomes condense and become visible

B. Daughter nuclei re-form around separated chromosomes

C. Sister chromatids separate and move toward opposite poles

D. Chromosomes align at the cell equator

Answer: (C)

Explanation

Anaphase is the stage in which sister chromatids separate. Equatorial alignment occurs during metaphase, while nuclear re-formation occurs during telophase.

6. At metaphase, what is the role of kinetochores?

A. They hold sister chromatids together throughout cell division

B. They form the nuclear envelope around each daughter nucleus

C. They attach spindle fibres to chromosomes from opposite poles

D. They duplicate the cell's DNA before chromosome alignment

Answer: (C)

Explanation

At metaphase, spindle fibres attach to chromosome kinetochores, with sister chromatids connected to fibres from opposite poles. Centromeres, rather than kinetochores, hold sister chromatids together.

7. How does cytokinesis differ between animal and plant cells?

A. Animals form an inward-cleaving furrow, whereas plants form a centrally growing cell plate

B. Both animals and plants form an inward-cleaving plasma-membrane furrow

C. Animals form a cell plate, whereas plants form an inward-cleaving furrow

D. Both animals and plants form a centrally initiated cell plate

Answer: (A)

Explanation

Animal cytokinesis occurs through an inward-cleaving plasma-membrane furrow. Plant cytokinesis occurs through a cell plate that forms centrally and expands toward the lateral walls.

8. What can result when nuclear division is not followed by cytokinesis?

A. A haploid daughter cell

B. A chromosome-free cytoplasm

C. A multinucleate syncytium

D. A cell plate without nuclei

Answer: (C)

Explanation

If karyokinesis occurs without cytokinesis, the nuclei divide but the cytoplasm does not separate, producing a multinucleate syncytium such as the liquid endosperm of coconut.

9. Why is mitosis described as equational division?

A. It creates daughter cells with different chromosome numbers

B. It reduces the parent cell’s chromosome number by half

C. It preserves the parent cell’s chromosome number in the daughter cells

D. It doubles the chromosome number before daughter-cell formation

Answer: (C)

Explanation

Mitosis is equational because the chromosome number of the parent cell is conserved in each daughter cell. Reduction of chromosome number is characteristic of meiosis.

10. Which biological process is directly supported by the production of genetically identical cells through mitosis?

A. Reduction of chromosome number before fertilisation

B. Creation of genetic variation through homologous recombination

C. Repair of damaged tissue and replacement of worn-out cells

D. Generation of haploid cells for sexual reproduction

Answer: (C)

Explanation

Mitosis produces genetically identical daughter cells that support growth, tissue repair, and replacement of cells such as epidermal, gut-lining, and blood cells.

11. What is the primary outcome of meiosis in a diploid cell?

A. Restoration of the diploid chromosome number before fertilisation

B. Production of genetically identical diploid daughter cells

C. Production of haploid daughter cells for sexual reproduction

D. Production of multinucleate cells without cytoplasmic division

Answer: (C)

Explanation

Meiosis reduces the chromosome number of diploid cells by half, producing haploid daughter cells used in sexual reproduction. Fertilisation, rather than meiosis, restores the diploid number.

12. Which sequence correctly describes DNA replication and nuclear divisions in meiosis?

A. One DNA replication occurring between meiosis I and meiosis II

B. One DNA replication followed by meiosis I and meiosis II

C. Two DNA replications followed by meiosis I and meiosis II

D. Two DNA replications, each followed by one meiotic division

Answer: (B)

Explanation

Meiosis includes two successive divisions, meiosis I and meiosis II, but is preceded by only one cycle of DNA replication.

13. During which stage of prophase I do homologous chromosomes undergo synapsis and crossing over?

A. Pachytene

B. Leptotene

C. Diakinesis

D. Diplotene

Answer: (A)

Explanation

Synapsis is established during zygotene, and crossing over occurs during pachytene. Pachytene is therefore the prophase I stage associated with crossing over.

14. What is exchanged during crossing over, and between which chromatids does it occur?

A. Entire chromosomes between sister chromatids of one chromosome

B. DNA between daughter cells after meiosis II

C. Genetic material between non-sister chromatids of homologous chromosomes

D. Centromeres between non-homologous chromosomes

Answer: (C)

Explanation

Crossing over is an enzyme-mediated exchange of genetic material between non-sister chromatids of homologous chromosomes during pachytene, producing recombination.

15. What separates during anaphase II of meiosis?

A. Homologous chromosomes while centromeres remain intact

B. Entire chromosomes without separation of chromatids

C. Sister chromatids after their centromeres split

D. Paired homologous chromosomes after DNA replication

Answer: (C)

Explanation

During anaphase II, the centromeres split and sister chromatids move to opposite poles. In contrast, homologous chromosomes separate during anaphase I while sister chromatids remain joined.

16. What is the immediate cellular outcome of telophase II and cytokinesis in meiosis?

A. Four diploid cells with duplicated chromosomes

B. Four haploid daughter cells forming a tetrad

C. Two diploid cells that are genetically identical

D. One haploid cell with four chromosome sets

Answer: (B)

Explanation

Meiosis concludes with telophase II and cytokinesis, producing a tetrad of four haploid daughter cells. This differs from the usual outcome of mitosis, which is two genetically identical cells.

17. How does meiosis help maintain a species-specific chromosome number across sexual generations?

A. It prevents chromosome reduction during gamete formation

B. It doubles chromosomes before every fertilisation event

C. It preserves the diploid number in every gamete

D. It produces haploid gametes, and fertilisation restores diploidy

Answer: (D)

Explanation

Meiosis reduces the chromosome number to produce haploid gametes, while fertilisation restores the diploid phase. Together, these processes maintain the species-specific chromosome number.

18. Why is meiosis important for evolutionary change?

A. It increases genetic variability between generations

B. It maintains the same genetic complement as mitosis

C. It produces genetically identical cells that preserve existing traits

D. It prevents variation in sexually reproducing populations

Answer: (A)

Explanation

Meiosis increases genetic variability between generations, and this variation provides material for evolution. Mitosis more typically preserves the genetic complement of the parent cell.