Figure 17-2 pg. Figure 8-13 1920's Oparin and Haldane independently hypothesized that conditions on primitive earth favored chemical reactions that synthesized organic compounds from inorganic precursors present in the early atmosphere, seas, and soils. These important properties are a direct result of the chemical interactions between these complex molecules. Thus, the cell is the unit on which all life on earth has been built. Photosynthesis changed the earth environment and changed the course of evolution.
Aerobic respiration is much more rapid and efficient than anaerobic metabolism.
Thus, aerobic organisms have dominated since their evolution. Eukaryotes are more complex and organized with specialized compartments called organelles such as the nucleus which contains multiple chromosomes. Sex changed the course of evolution. Reproduction with variation, the basis of adaptation to environmental change, is major characteristic of life. Thus, organisms with eukaryotic sexual reproduction have dominated since their evolution.