How did an oxygen-rich atmosphere develop from a carbon dioxide-rich atmosphere?
A) Through photosynthesis by cyanobacteria
B) Through volcanic eruptions
C) Through asteroid impacts

Question

Quizplus · Accepted Answer

Photosynthesis by cyanobacteria played a crucial role in transforming Earth's early carbon dioxide-rich atmosphere into an oxygen-rich one. These organisms began to produce oxygen through photosynthesis over 2.4 billion years ago, leading to the Great Oxygenation Event.

How Did an Oxygen-Rich Atmosphere Develop from a Carbon Dioxide-Rich