During the cell cycle, a cell undergoes interphase before entering mitosis. Describe what happens during interphase and then outline the stages of mitosis, in order, that follow it.

Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 2.2 Cell cycle and mitosis · Describe · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A skin cell in the human body divides repeatedly throughout a person's lifetime to replace worn-out cells at the surface.

Model answer (5 marks)

During interphase the cell grows, increasing in size and mass, and synthesises new organelles. DNA replication occurs, so each chromosome is copied.

Mitosis follows in the order:
1. Prophase – chromosomes condense and become visible; spindle fibres begin to form.
2. Metaphase – chromosomes align at the cell equator.
3. Anaphase – sister chromatids are pulled to opposite poles by spindle fibres.
4. Cytokinesis – the cell divides, producing two genetically identical daughter cells.

Examiner tips

  • Use the word ‘grows’ and ‘synthesises’ for interphase growth; mention DNA replication. State the mitotic stages in the correct order and give one key feature for each. Keep the answer concise – 5 marks only.
  • common_mistakes
  • :
  • Confusing interphase with mitosis or omitting DNA replication. Listing mitotic stages out of order or forgetting cytokinesis.

Mark scheme (5 marks)

  1. During interphase the cell grows (increases in size/mass) and new organelles are synthesised
  2. During interphase DNA replication occurs so that each chromosome is copied
  3. During prophase the chromosomes condense / become visible and the spindle fibres begin to form
  4. During metaphase the chromosomes align / line up at the cell equator (middle of the cell)
  5. During anaphase the chromatids are pulled to opposite poles of the cell by spindle fibres, followed by cytokinesis producing two genetically identical daughter cells

Key terms in this question

interphase · mitosis · cell cycle

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