# Explain the significance of the G1 and G2 checkpoints in the cell cycle.

> IB DP Biology Standard Level (2023 syllabus) — D2.1 Cell and nuclear division · Explain · 4 marks

## Mark scheme (4 marks)

1. Checkpoints are control points that monitor conditions before the cell cycle can proceed to the next phase.
2. The G1 checkpoint assesses whether the cell is large enough and whether environmental conditions (e.g. nutrients, growth factors) are suitable for DNA replication to proceed.
3. The G2 checkpoint ensures that DNA replication has been completed accurately and that any DNA damage has been repaired before mitosis begins.
4. These checkpoints prevent the transmission of mutations or incomplete/damaged DNA to daughter cells, maintaining genetic integrity.

## Key terms

- [G2 checkpoint](https://www.gradenine.co.uk/glossary/g2-checkpoint)
- [cell cycle](https://www.gradenine.co.uk/glossary/cell-cycle)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-the-significance-of-the-g1-caf594bd) · Published by Druglandscape Ltd.