The processes that use the mechanisms are: Cellular respiration â ATP is generated by oxidation of organic molecules, the passage of electrons down an electron transport chain, and chemiosmosis. The final electron acceptor is almost always inorganic. Aerobic â the final electron acceptor is O 2.
The Sumerians lived in Mesopotamia around 4000 BC. Mesopotamia or the Fertile Crescent was a region in the Middle East between the Tigris and Euphrates rivers, in the territory of modern Iraq, Iran and Syria.
A real system of cities began to develop from 4000 BCE, and they developed better tools, metals, more advanced art and weapons, and the first empires. Sumerian towns may have housed a million of the world's 27 million people by 3000 BCE, and the traded with Elam, in Iran, and Egypt, in the south--both just being born.