Bio1151b Chapter 26 The Tree of Life
  1. The 4.6 billion years of earth's history is divided into three geologic       , which are further divided into       ,          , and         .
  2. There have been several episodes of mass              , but they were replaced by forms that evolved from the survivors; the trend has been an           of diversity over time.
  3. The          (PT) extinction was the most severe, and claimed over 90% of marine species. The             (KT) extinction is famous for the disappearance of            .
  4.              were Earth’s sole inhabitants from 3.5 to about      billion years ago. The oldest known fossils are               
  5. Cyanobacteria were photosynthetic              which released oxygen, allowing the evolution of          organisms to obtain energy through cellular              .
  6. The first eukaryotes probably evolved from the                of small prokaryotes living within larger host cells and developing into organelles such as mitochondria and chloroplasts.
  7. Multicellular eukaryotes diversified in the late Proterozoic eon, after           Earth started to thaw.
  8. The first multicellular organisms were           , collections of autonomously              cells.
  9. Most of the major animal phyla, including the first            , appeared during the early           period in what is known as the           Explosion.
  10. Plants first colonized land during the             period in the company of        , followed by          .
  11. Humans evolved from tetrapods during the              epoch. If the clock of Earth’s history were scaled to represent an hour, humans appeared about one         ago.
  12. The movement of the Earth's             due to continental        has great impact on the habitats in which organisms live, and shaped the diversity of life on Earth.