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Chapter 1 Hierarchy of Life

Chapter 1 Hierarchy of Life. Atoms Molecules Cells Tissue Organs (systems) Organism Population Communities Bioshpere. What is Life. Definition: An organized genetic unit capable of metabolism, reproduction and evolution.

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Chapter 1 Hierarchy of Life

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  1. Chapter 1Hierarchy of Life • Atoms • Molecules • Cells • Tissue • Organs (systems) • Organism • Population • Communities • Bioshpere

  2. What is Life • Definition: An organized genetic unit capable of metabolism, reproduction and evolution. • What is evolution: Any genetic and resulting phenotypic change in organisms from generation to generation.

  3. What is the smallest Unit of Life • The Cell • Cell Theory- All organisms consist of cells and that all cells come from preexisting cells. • So, then, where did life begin?

  4. Evolution • Start with a “soup” of chemicals that eventually interacted into enclosed compartments and became cells (3.8 billion years ago). • For 2 billion years, cells were unicellular and prokaryotic and many were photosynthetic • Photosynthesis deposited oxygen into the atmoshpere, helping to dampen the suns damaging rays (how????) and life could move onto land.

  5. Evolution (cont.) • Some cells became eukaryotic (how?) • Multicellularity (1 billion years ago) arose, and cells could now specialize. • Sexual reproduction changed everything! And speeded up evolution. • Darwin explained it all with his Theory of Natural Selection.

  6. Tree of Life • Three Domains • Bacteria • Archaea • Eukarya • Bacteria split from the other two very early and while Archaea are also prokaryotes, they share a common ancestor with Eukarya.

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