Describe in general terms how the appearance of molecular oxygen in Earth’s atmosphere about 3 billion years ago affected the history of living organisms.
Describe in general terms how the appearance of molecular oxygen in Earth’s atmosphere
about 3 billion years ago affected the history of living organisms.
The earth was created almost 4.5 billion years ago. The evidence suggests that the planet was devoid of oxygen at the beginning of its evolution. Oxygen appeared some 3 billion years ago on earth.
Early organisms on the earth were anaerobic organisms that survived on methane and ammonia as nutritional sources. The earth around 4 billion years ago had almost no oxygen. Oxygen is believed to have come from the photosynthetic activity of bacteria that released oxygen as a byproduct of photosynthesis.
The appearance of oxygen led to the evolution of higher organisms.
- The organisms may have become bigger in size and more active in the presence of oxygen. This might have resulted in cyanobacteria that are believed to have formed the chloroplasts in plants. So oxygen may have shifted the balance from simple organisms to multicellular organisms
- Oxygen is the most potent electron accept. The appearance of molecular oxygen may have resulted in developing processes such as electron transport chain and oxidative phosphorylation. The development of these biochemical processes may have resulted in the evolution of multicellular organisms to aerobic life forms (vertebrates).
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