Explain what happens during interphase and why it is important for mitosis to occur successfully.

Edexcel GCSE Biology (1BI0) — 2.1 Mitosis and the cell cycle · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

During interphase the cell grows, increasing in size and synthesising new organelles.
DNA replication occurs, producing two identical copies of each chromosome.
This ensures that each daughter cell will receive a complete set of chromosomes.
Without interphase, or if DNA is not replicated, mitosis cannot produce two genetically identical daughter cells.

Examiner tips

Use the phrase "DNA replication" and link it to "complete set of chromosomes".
Show the sequence: growth → DNA replication → preparation for mitosis.
Mention that interphase is necessary for accurate chromosome segregation.

Common mistakes

Confusing interphase with mitosis itself.
Forgetting to state that DNA replication occurs during interphase.
Failing to explain why replication is essential for identical daughter cells.

Mark scheme (4 marks)

During interphase, the cell grows / increases in size / new organelles are synthesised
DNA replication occurs during interphase
DNA replication ensures each daughter cell receives a full set of chromosomes / a complete copy of genetic information
Without interphase / if DNA is not replicated, mitosis cannot produce two genetically identical daughter cells

Key terms in this question

interphase · mitosis