1. Do First
1. Grab a notes paper, a scantron, and a pre-test

2. Agenda
1. Pre-test
No talking to students
2. Notes

3. Origins of
Life

4. Earth was very different Billions of Years Ago
The Earth is thought to be 4.6 Billion Years Old
Early Earth was lifeless
Intensely hot molten lava
No Oxygen
Eventually, rain fell and cooled the surface a little, resulting in a rocky crust and ocean formation

5. How did life emerge from “non-life”?
Life developed when molecules of non-living matter reacted chemically during first billion years of Earth’s history (Spontaneous Origin)
Simple Molecules  Complex Molecules by means of energy

6. Life’s Building Blocks
Hydrothermal Vents
Crack in Earth’s surface under water from which very hot water escapes
Scientists think that heat from hydrothermal vents could have provided energy for chemical reactions to change molecules into organic molecules

7. Life’s Building Blocks
Space
Some scientists think that organic molecules could have arrived on Earth on meteorites
Meteorites are natural objects originating in outer space that survives impact with the Earth's surface

8. Early Prokaryotes
By 3.8 bya, the early seas were filled with organic molecules
The jump from free-floating molecules to the first cells is unclear
First prokaryotes were anaerobic – they got their E from organic molecules
Photosynthetic life evolved about 3.5 bya
Cyanobacteria are photosynthetic and released oxygen into atmosphere
This allowed for the evolution of aerobic prokaryotes

9. Eukaryotes Evolved about 1.5 bya
Hypothesis of eukaryote evolution was proposed by Lynn Margulis
Theory of Endosymbiosis
When one organism lives within the body of another, and both benefit from the relationship.

10. Eukaryotes
The theory suggests that mitochondria and chloroplasts once lived independently
About 1.5 bya, they were engulfed by larger prokaryotic cells
Instead of being consumed, bacteria began to live inside host cell where they performed photosynthesis or cellular respiration

11. Do First
1. You have 30 seconds from the bell to hand over your reading from Friday, if you put it in the back on Friday then I have it
2. Grab a worksheet
3. In your head try to put the below in order of earliest to latest event and then compare with the person sitting next to you
First prokaryotic cell - First amphibians
First Reptiles - First mammals
Oceans formed - First eukaryotic cell

12. Agenda 1. Fossils worksheet 2. If we have time, then fossil notes
No talking to students, this is an independent activity
Sheet needs to get signed by the end of class
2. If we have time, then fossil notes
No talking to students

13. The Fossil Record
As said earlier, scientists hypothesize that the Earth is 4.6 billion years old
Fossil evidence indicates that for much of that long history, Earth has been the home of living things
The fossil record includes all the remains of living things on Earth
Although the examination of the fossil record will never be complete, it presents strong evidence that evolution has taken place

14. How Fossils Form
Most are found in sedimentary rock (rock that is formed by the settling of layers of sediment)
This layering allows dead organisms to be preserved and fossilized

15. Where are Fossils Formed?
Environments that often cause fossil formation are
wet lowlands
slow-moving streams
lakes
shallow seas
areas near volcanoes
Why?

16. Fossils Aren’t Always Formed
If an organism dies in an area where fossils can’t be formed, they are not formed
Fossils of soft-bodied or delicate organisms are rare because they are often destroyed by the heavy sediment
Even if an organism that fossilizes well dies in an area where fossils are formed, it might be eaten before it can become fossilized

17. Analyzing Fossil Evidence
In order to analyze fossil evidence, paleontologists use both relative and absolute dating methods to date a fossil

18. Relative Age of Fossils
Relative dating is used to estimate ages of fossils found within layers of sedimentary rock (strata)
Relative Dating cannot reveal a fossil’s age in years, but it can reveal the order in which organisms lived on Earth

19. Absolute Age of Fossils
Radiometric dating estimates the age in years of an object by measuring how much of a certain radioactive element is found in the rock surrounding the fossil
Video

20. Do First 1. Grab the worksheet 2. Pull out your notes
3. Try to remember, was the first living organism a prokaryote or a eukaryote?

21. Agenda Video from yesterday - No talking.
2. Brief notes on Geological Time
- No talking to students
3. Worksheet on Geological Time
- Yes talking to table mate

24. Describing Geologic Time
The geologic time scale is based on evidence in the fossil record and has been shaped by mass extinctions (when large numbers of species become extinct)
Evidence indicates that world-wide climate changes are common factors that contribute to mass extinctions

25. Age of Invertebrates, Land Plants, and Amphibians
Present
CENOZOIC ERA
Age of Mammals
Mass Extinction
MESOZOIC ERA
Age of Reptiles
PALEOZOIC ERA
Age of Invertebrates, Land Plants, and Amphibians
Past