What role does oxygen play in the context of abiotic chemical evolution?

Oxygen plays a pivotal role in the context of abiotic chemical evolution, particularly in shaping the conditions for the development of life on Earth. The statement that oxygen ended abiotic chemical evolution reflects the idea that the introduction of free oxygen into the atmosphere, particularly through photosynthesis by primitive cyanobacteria, drastically altered the prevailing environmental conditions.

Prior to the Great Oxidation Event, which occurred around 2.4 billion years ago, the Earth's atmosphere was anoxic (lacking oxygen). The accumulation of oxygen transformed the planet's atmosphere and led to the extinction of many anaerobic organisms that thrived in the absence of oxygen. This shift marked a significant transition in Earth's chemical evolution, leading to the development of more complex life forms that rely on aerobic respiration.

The other options do not accurately reflect the role of oxygen in this context. For instance, stating that oxygen was the first element to form the atmosphere overlooks the fact that the early atmosphere was primarily composed of gases such as nitrogen, carbon dioxide, and water vapor. Additionally, claiming that oxygen was not significant in the evolution of life neglects its essential role in cellular respiration, a key process for most life forms. Lastly, the assertion that oxygen was only introduced by mammals misrepresents historical biology