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Mitochondria
Mitochondria are membrane-bound cell organelles (mitochondrion, singular) that generate most of the chemical energy needed to power the cell's biochemical reactions. Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP).
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The islands had different environments, and the organisms had adaptations that enabled the organism to live in those environments. The island had been inhabited by its own kind of species found nowhere else in the world. Darwin also noticed that considerable variation exists between members of the same species. Offspring vary from their parents and between themselves.
