What is the cell cycle?
The sequence of events where a cell duplicates its genome, synthesizes constituents, and divides.
How long does a typical human cell take to complete one cell cycle?
Approximately 24 hours.
How long does yeast take to complete one cell cycle?
About 90 minutes.
What are the two basic phases of the cell cycle?
Interphase and M phase.
What happens during interphase?
The cell prepares for division.
What occurs during M phase?
Mitosis and usually cytokinesis occur.
Which phases make up interphase in the cell cycle?
G1, S, and G2 phases.
What happens to DNA during interphase?
It replicates in preparation for mitosis.
What cellular activities occur during interphase?
The cell grows and synthesises proteins.
How does DNA content change during S phase?
It increases from 2C to 4C.
Does chromosome number change during S phase?
No, it remains unchanged.
What is the chromosome number of a diploid cell during S phase?
It remains 2n.
What is the quiescent stage (G0) in the cell cycle?
An inactive stage where cells do not proliferate but stay metabolically active.
What are the stages of mitosis for chromosome segregation?
Prophase, metaphase, anaphase, and telophase.
What happens to chromatin during prophase?
It condenses into chromosomes composed of two sister chromatids.
Where do centrosomes move during prophase?
Toward opposite poles of the cell.
What forms during prophase to assist chromosome movement?
The mitotic spindle.
What do spindle fibres attach to during metaphase?
Kinetochores on chromosomes.
Where are chromosomes aligned during metaphase?
At the equator on the metaphase plate.
What occurs to sister chromatids during anaphase?
They separate and migrate to opposite poles as daughter chromosomes.
What nuclear changes occur during telophase?
Chromosomes decondense and nuclear envelopes form around chromosome groups.
What is karyokinesis in cell division?
The division of the nucleus.
What does cytokinesis divide during cell division?
The cytoplasm.
How does animal cytokinesis occur?
By an inward-cleaving plasma-membrane furrow.
How does plant cytokinesis begin?
With a central cell plate that grows outward to lateral walls.
What organelles are distributed during cytokinesis?
Mitochondria and plastids.
What chromosome number do daughter cells usually have after mitosis?
Diploid chromosome number.
What is the genetic relationship of daughter cells to the parent after mitosis?
Genetically identical to the parent cell.
Name one biological role of mitosis in multicellular organisms.
Supports growth of multicellular organisms.
Which cells are replaced by mitosis in animals?
Epidermal, gut-lining, and blood cells.
Where does lifelong plant growth occur via mitosis?
In apical and lateral cambium meristems.
Why is mitosis called equational division?
Because chromosome number is conserved in daughter cells.
What is meiosis?
A specialised division reducing diploid cells to haploid for sexual reproduction.
How many nuclear divisions occur in meiosis?
Two successive nuclear divisions occur in meiosis.
What follows the single DNA replication cycle in meiosis?
Meiosis I and meiosis II follow the single DNA replication cycle.
What happens to homologous chromosomes during prophase I?
They pair by synapsis and form bivalents.
How is genetic material exchanged during prophase I?
By crossing over between non-sister chromatids.
What links homologous chromosomes after crossing over?
They become linked at chiasmata.
What are the stages of prophase I in order?
Leptotene, zygotene, pachytene, diplotene, and diakinesis.
What separates during anaphase I?
Homologous chromosomes separate and move to opposite poles.
How does meiosis II resemble mitosis in chromosome behavior?
Chromosomes align at the equator and sister chromatids separate after centromere splitting.
What happens during telophase II in meiosis II?
Nuclei reform during telophase II.
What does cytokinesis produce at the end of meiosis II?
A tetrad of four haploid daughter cells.
What is Interkinesis in meiosis?
A short stage between meiosis I and II when DNA is not replicated.
Why does meiosis preserve species-specific chromosome number?
Because fertilisation restores the diploid phase after haploid gametes form.
How does meiosis contribute to evolution?
By increasing genetic variability between generations.
Test your knowledge with 20 questions on Cell Cycle and Cell Division.
1. Which sequence best describes the overall purpose of the cell cycle?
2. Which statement correctly distinguishes interphase from M phase?
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