5. As earth cooled, carbon dioxide dissolved in the early ocean. Cyanobacteria consumes carbon dioxide and converted it to oxygen. Methane was removed from the atmosphere as oxygen was produced, eventually leading to the Cambrian explosion.
6. Metabolic processes that use oxygen produce more energy than anaerobic metabolism. Simple diffusion of oxygen would limit the size of a multicellular eukaryote, but animals evolved ways to transport oxygen to their tissues, which permitted an increase to their size.
(6. As earth cooled, carbon dioxide dissolved in the early ocean. Cyanobacteria consumes carbon dioxide and converted it to oxygen. Methane was removed from the atmosphere as oxygen was produced, eventually leading to the Cambrian explosion.
(7. Metabolic processes that use oxygen produce more energy than anaerobic metabolism. Simple diffusion of oxygen would limit the size of a multicellular eukaryote, but animals evolved ways to transport oxygen to their tissues, which permitted an increase to their size.
It was Narmer who was the first true king of Egypt, and managed to united both the North and South regions into a single unit, which lasted for quite some time.
