Question

How did the success of photosynthetic bacteria change Earth's atmosphere? (1 point)
O decreased oxygen concentration
O Increased oxygen concentration
O Increased hydrogen concentration
O decreased hydrogen concentration

Answer 1

The success of photosynthetic bacteria, particularly cyanobacteria, led to an **increased oxygen concentration** in Earth's atmosphere. This process, known as oxygenic photosynthesis, produces oxygen as a byproduct and significantly transformed the early Earth atmosphere, contributing to the Great Oxygenation Event. Therefore, the correct answer is:

**O Increased oxygen concentration**.