# Explain why the transition from prokaryotic to eukaryotic cells is considered a major step in the history of life on Earth.

> IB DP Biology Standard Level (2023 syllabus) — A2.1 Origins of cells · Explain · 4 marks

## Mark scheme (4 marks)

1. Prokaryotic cells lack a membrane-bound nucleus whereas eukaryotic cells possess one, allowing separation of transcription and translation.
2. Eukaryotic cells contain membrane-bound organelles (e.g. mitochondria, endoplasmic reticulum) that allow compartmentalisation of metabolic processes.
3. The origin of eukaryotes enabled greater complexity, including the development of multicellular organisms.
4. The endosymbiotic origin of mitochondria (and chloroplasts) gave eukaryotes a significant increase in energy efficiency / aerobic respiration capacity, enabling more complex metabolism.

## Key terms

- [prokaryotic](https://www.gradenine.co.uk/glossary/prokaryotic)
- [eukaryotic](https://www.gradenine.co.uk/glossary/eukaryotic)

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-transition-from-prokaryotic-e2c8e68e) · Published by Druglandscape Ltd.