Each hemoglobin molecule is made of four subunits, each containing a heme group that can bind one molecule of oxygen. Therefore, one molecule of hemoglobin can bind four molecules of oxygen. Oxyhemoglobin is hemoglobin bound by oxygen, and it gives oxygen-rich blood a red color.ach hemoglobin molecule is made of four subunits, each containing a heme group that can bind one molecule of oxygen. Therefore, one molecule of hemoglobin can bind four molecules of oxygen. Oxyhemoglobin is hemoglobin bound by oxygen, and it gives oxygen-rich blood a red color.
The First Reich was the Holy Roman Empire. There is little agreement as to when it was founded. Most German historians date the foundation from the coronation of Otto I in 962. That 'empire' had a continuous existence till 1806. The Second Reich was created by Bismarck in 1871 and lasted till 1918.
The First World War redrew the map of Europe and the Middle East. Four great empires, the Romanov, the Hohenzollern, the Habsburg, and the Ottoman, were defeated and collapsed. They were replaced by a number of weak and sometimes avaricious successor states.