Quiz: Cell Cycle and Cell Division — 20 questions

1. Which sequence best describes the overall purpose of the cell cycle?

A. The cell degrades its genome, stops protein synthesis, and fuses with another cell

B. The cell duplicates its membrane, eliminates its nucleus, and becomes permanently quiescent

C. The cell produces two nuclei, prevents DNA replication, and enlarges without dividing

D. The cell duplicates its genome, produces cellular constituents, and divides 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 produces daughter cells, whereas M phase maintains the cell in a nondividing state

B. Interphase separates sister chromatids, whereas M phase increases the cell’s DNA content

C. Interphase carries out nuclear division, whereas M phase prepares the cell by replicating its DNA

D. Interphase prepares the cell for division, whereas M phase carries out nuclear division and usually cytokinesis

Answer: (D)

Explanation

Interphase prepares the cell for division, while M phase includes mitosis and usually cytokinesis. The other choices reverse or misidentify their functions.

3. Which sequence correctly lists the stages of interphase and their general activities?

A. G1 growth, S DNA replication, and G2 protein synthesis and preparation for mitosis

B. G1 chromosome separation, S nuclear-envelope formation, and G2 cytokinesis

C. G1 quiescence, S spindle formation, and G2 homologous-chromosome pairing

D. G1 DNA replication, S chromosome condensation, and G2 daughter-cell separation

Answer: (A)

Explanation

Interphase consists of G1, S, and G2, involving growth, DNA replication, and synthesis of proteins needed for mitosis.

4. A diploid cell enters S phase. What happens to its DNA content and chromosome number?

A. DNA content remains 2C, while the chromosome number rises from 2n to 4n

B. DNA content falls from 4C to 2C, while the chromosome number remains 2n

C. Both DNA content and chromosome number rise from 2C and 2n to 4C and 4n

D. DNA content rises from 2C to 4C, while the chromosome number remains 2n

Answer: (D)

Explanation

DNA replication doubles the DNA content from 2C to 4C, but each chromosome remains counted as one chromosome, so the diploid number stays 2n.

5. What is the principal outcome of mitosis?

A. Duplicated chromosomes are segregated into two daughter nuclei

B. The cell replicates its DNA without separating its nucleus

C. The cytoplasm divides before chromosomes are duplicated

D. Homologous chromosomes pair and exchange genetic material

Answer: (A)

Explanation

Mitosis proceeds through prophase, metaphase, anaphase, and telophase to distribute duplicated chromosomes into two daughter nuclei.

6. Which event is characteristic of prophase in mitosis?

A. Chromosomes decondense and nuclear envelopes form around the chromosome groups

B. Centromeres split and sister chromatids migrate toward opposite poles

C. Chromatin condenses, centrosomes move toward opposite poles, and the mitotic spindle forms

D. Chromosomes align at the equator while spindle fibres attach to kinetochores

Answer: (C)

Explanation

In prophase, chromatin condenses into chromosomes with sister chromatids, centrosomes move apart, and the mitotic spindle forms.

7. A cell is observed with spindle fibres attached to kinetochores and chromosomes arranged across the cell’s equator. Which stage is it in?

A. Metaphase

B. Telophase

C. Anaphase

D. Prophase

Answer: (A)

Explanation

Metaphase is defined by kinetochore attachment and alignment of chromosomes on the metaphase plate. In anaphase, sister chromatids instead move toward opposite poles.

8. What occurs when a mitotic cell enters anaphase?

A. Centromeres split, and sister chromatids migrate to opposite poles as daughter chromosomes

B. Spindle fibres attach to kinetochores, and chromosomes align at the equator

C. Chromatin condenses, and centrosomes begin moving toward opposite poles

D. Chromosomes decondense, and nuclear envelopes form around each chromosome group

Answer: (A)

Explanation

During anaphase, centromeres split and sister chromatids separate and move to opposite poles, where they are regarded as daughter chromosomes.

9. Which process specifically divides the cytoplasm to complete cell division?

A. Cytokinesis

B. DNA replication

C. Karyokinesis

D. Chromosome condensation

Answer: (A)

Explanation

Cytokinesis is the division of the cytoplasm, whereas karyokinesis is the division of the nucleus.

10. How does cytokinesis typically differ between animal and plant cells?

A. Both animal and plant cells form a central cell plate

B. Both animal and plant cells form a cleavage furrow

C. Animal cells form a cleavage furrow, whereas plant cells form a central cell plate

D. Animal cells form a cell plate, whereas plant cells form a cleavage furrow

Answer: (C)

Explanation

Animal cytokinesis occurs through an inward-cleaving plasma-membrane furrow, while plant cytokinesis begins with a central cell plate that grows outward.

11. What is the usual genetic and chromosome-number outcome of mitosis?

A. Diploid daughter cells with newly recombined chromosomes

B. Diploid daughter cells genetically identical to the parent

C. Haploid daughter cells with half the parent’s chromosomes

D. Haploid daughter cells genetically identical to the parent

Answer: (B)

Explanation

Mitosis usually preserves the chromosome number and produces diploid daughter cells genetically identical to the parent cell.

12. Which biological process is directly supported by mitosis?

A. Pairing of homologous chromosomes

B. Growth and repair of multicellular tissues

C. Production of gametes with half the chromosome number

D. Restoration of diploidy during fertilisation

Answer: (B)

Explanation

Mitosis supports organismal growth, tissue repair, and replacement of cells such as epidermal, gut-lining, and blood cells.

13. Why is mitosis described as an equational division?

A. It doubles the chromosome number in daughter cells

B. It reduces the chromosome number by half

C. It conserves the chromosome number in daughter cells

D. It combines chromosomes from two parent cells

Answer: (C)

Explanation

Mitosis is equational because the chromosome number is conserved in the daughter cells; halving the number characterizes reduction division.

14. What is the defining chromosome-number outcome of meiosis?

A. It produces diploid daughter cells for tissue growth

B. It produces haploid daughter cells for sexual reproduction

C. It doubles the chromosome number before fertilisation

D. It preserves the diploid number in every daughter cell

Answer: (B)

Explanation

Meiosis is a specialized division that halves the chromosome number and produces haploid cells used in sexual reproduction.

15. Which combination correctly describes DNA replication and nuclear divisions in meiosis?

A. One DNA replication followed by one division

B. Two DNA replications followed by one division

C. Two DNA replications followed by two divisions

D. One DNA replication followed by two successive divisions

Answer: (D)

Explanation

Meiosis consists of meiosis I and meiosis II, two successive divisions that follow a single cycle of DNA replication.

16. What occurs during prophase I of meiosis?

A. Homologous chromosomes pair and exchange material between non-sister chromatids

B. Homologous chromosomes move to opposite poles without pairing

C. Sister chromatids separate before homologous chromosomes pair

D. Chromosomes replicate twice without exchanging genetic material

Answer: (A)

Explanation

During prophase I, homologous chromosomes pair by synapsis, form bivalents, and exchange genetic material by crossing over between non-sister chromatids.

17. Which event characterizes anaphase I of meiosis?

A. Homologous chromosomes separate while sister chromatids remain joined

B. Sister chromatids separate while homologues remain paired

C. Non-sister chromatids exchange material at chiasmata

D. DNA replication occurs before chromosome movement

Answer: (A)

Explanation

In anaphase I, homologous chromosomes move to opposite poles, while sister chromatids remain joined at their centromeres.

18. Which event characterizes meiosis II rather than meiosis I?

A. Separation of sister chromatids after centromere splitting

B. Replication of DNA before chromosome alignment

C. Separation of homologous chromosome pairs

D. Pairing of homologous chromosomes during synapsis

Answer: (A)

Explanation

In meiosis II, chromosomes align at the equator and sister chromatids separate after their centromeres split. Meiosis I separates homologous chromosomes instead.

19. What is produced by cytokinesis at the end of meiosis II?

A. Four diploid daughter cells

B. Four haploid daughter cells

C. Two diploid cells

D. Two genetically identical haploid cells

Answer: (B)

Explanation

Cytokinesis after meiosis II produces a tetrad consisting of four haploid daughter cells. This differs from typical mitosis, which usually produces two genetically identical cells.

20. How does meiosis help preserve the species-specific chromosome number across sexual generations?

A. It prevents chromosomes from separating during the two meiotic divisions

B. It produces diploid gametes that combine to maintain chromosome number

C. It doubles the chromosome number before fertilisation

D. It produces haploid gametes, and fertilisation restores the diploid number

Answer: (D)

Explanation

Meiosis reduces the chromosome number to the haploid state in gametes, while fertilisation restores the diploid phase when gametes fuse. This maintains the species-specific chromosome number across generations.