1. Age of Earth: BIO chapter 12

2. Earth’s Age: 4.6 Billion years Measured age of rocks Radiometric dating-using isotopes and half-life that produce radiation and energy

3. Chemicals: Basic building blocks of life-CHO Is thought by some that organic molecules have formed from non-living molecules

4. Three Life beginning models: 1.Primordial soup model-organic molecules formed spontaneously with added energy- water and sunlight **scientists today still disagree on origin of life

5. Life beginning models: 2. Miller-Urey model-atmospheric material could make organic compounds-no ozone problem-water and electricity

6. Life beginning models: 3. Bubble model-cycle of gases forming in ocean water releasing chemicals into the atmosphere- water and volcanoes

7. Microspheres: A. A. formed in tiny droplets 1 st step toward cellular organization Thought that RNA formed from DNA

8. First Life froms Thought to appear 2.5 billion years ago

9. Sequence of formation: anthropods-vertebrates-fish-amphibians-reptiles-birds-mammals

10. Extinction: 5 periods of extinction on Earth so far Extinction-one species dies out Mass extinction-many species die