🦠microbiology review

Oxygen Revolution

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

The Oxygen Revolution, also known as the Great Oxidation Event, marks the period in Earth's history when oxygen levels significantly increased due to photosynthetic microorganisms. This led to drastic changes in the biosphere and the evolution of aerobic life.

5 Must Know Facts For Your Next Test

  1. Occurred approximately 2.4 billion years ago.
  2. Triggered by cyanobacteria performing oxygenic photosynthesis.
  3. Led to the formation of an ozone layer, which protected life from harmful UV radiation.
  4. Caused a mass extinction of anaerobic organisms that were unable to survive in high-oxygen environments.
  5. Enabled the development and diversification of aerobic (oxygen-dependent) organisms.

Review Questions