1. AGENDA March 24
Objective: Examine evidence to support the age of the Earth and the history of life.
1. Chapter 17
Study your notes every day
Stop in for extra help if you need it before tests
2. Chapter 15 and 16 Tests
All Grades in Genesis
3. Review and Homework

2. The History of Life
Chapter 17

3. 17-1 The Fossil Record Paleontologists study fossils.
Fossil Record provides evidence of the history life on Earth.
Infer structure of organisms
What they ate
Environments they lived in
Fossils appear in a particular order.
Some only present in older rocks
Some only in newer rocks

4. Fossil Formation Recall that fossils form in sedimentary rock.
Weather breaks down rock into small particles.
Particles carried by water where they settle to the bottom.
Pressure and chemical processes preserve remains into rock.
Why is the fossil record an incomplete record of life on Earth?

5. Fossil Evidence
Identify and compare anatomical structures between fossils and living organisms.
Age of a fossil is determine by two techniques.
1. Relative Dating
2. Radioactive Dating

6. Relative Dating
Determines age of fossil by comparing its placement with other fossils in various layers of rock.
Oldest layers on bottom
Index fossils are easily recognizable for comparison.
Existed for a short period of time
Wide geographic range
Found in specific layers of rock in different locations.

7. Radioactive Dating Use of radioactive decay to assign ages to fossils.
Some elements are radioactive
Decay is measured as HALF-LIFE or the time for half of the radioactive atoms in a sample to decay

8. Radioactive Dating
Age of a fossil based upon amount of remaining radioactive isotope it contains.
Different radioactive elements have different half-lives.
Carbon 12  most common and does not decay
Carbon 14  radioactive and decays into N-14
Has half-life of 5730 Years
More C-12 compared to C-14 = older fossil

9. Carbon-14 Decay

10. Question of the DAY March 25
Which of the following cannot be determined through fossils?
A. the approximate age of the organism
B. other organisms closely related to the fossilized organism
C. anatomical structure of an organism
D. physiological processes of the organism

11. AGENDA March 25
Objectives: Investigate factors that led to the formation of Earth and early forms of life.
1. Question of the Day
2. Continue Chapter 17 Notes
3. Complete the Guided Reading Packet
4. Chapter 16 Tests
5. Review and Homework

12. Geologic Time Scale Precambrian Time  Eras  Periods
Represents evolutionary time.
Precambrian Time 
Eras 
Periods
Cenozoic – Age of
Mammals
65 mya to present

13. Eras and Periods Precambrian Time
Paleozoic, Mesozoic, and Cenozoic Eras
Eras are further subdivided into Periods
Periods range from 10s of millions of years to 2 million years

14. 17-2 Earth’s Early History
Birth of planet took place over 100 million years
Collisions with other large objects
Produced tremendous amount of heat
Most dense elements formed Earth’s core
Decay created a molten rock core
Moderately dense elements cooled into Earth’s crust.
Least dense formed first atmosphere

15. SECTION 17-2 NOTES NOTES are in the Guided Reading Packet.
Answer Key is posted on my webpage.

16. First Organic Molecules
Miller and Urey’s Experiment – 1950s
Atoms do not assemble themselves into complex molecules or living cells today.
Oxygen is very reactive
See FIGURE 17-8 PAGE 424
Suggested how mixtures of organic compounds necessary for life could have been formed from simpler compounds

17. Question of the DAY March 26
Radioactive Uranium-232 has a half-life of approximately 70 years. The Chernobyl Nuclear Power Plant Disaster in released high levels of radiation into nearby surrounding areas including the town of Pripyat.
What year would see a reduction in radiation to 20% of the original level of uranium-232?

18. DO NOW MARCH 26
Briefly describe how Miller and Urey simulated Earth’s early atmosphere.

19. DO NOW ANSWERED March 26
Mixed hydrogen, methane, and ammonia with water vapor.
Charged the mixture with electric sparks.
Cooled the mixture of gases.
Found the formation of amino acids and other organic compounds.

20. AGENDA March 26
Objectives: Investigate factors that led to the formation of Earth and early forms of life.
1. Question of the Day
2. Complete the Guided Reading Packet
3. Discuss 17-2 Guided Reading Questions
Packet DUE TOMORROW – THURSDAY March 27
Answer Key will be posted on my webpage
Any late work will receive a 50% penalty.
4. Review and Homework

21. Puzzle of Life’s Origins
What event was necessary for the first cells to appear on the planet?
What types of organisms did these first cells resemble?

22. Question of the Day March 27
Which of the following statements is true?
A. Anaerobic organisms require oxygen to survive.
B. Aerobic organisms can survive in environments with or without oxygen.
C. Aerobic organisms do not require oxygen for cellular processes.
D. Anaerobic organisms will die in an oxygen-rich environment.

23. DO NOW March 27
What are the three pieces of evidence that support the Endosymbiotic Theory?

24. DO NOW ANSWERED March 27
1. Mitos and Chloros contain DNA similar to bacterial DNA.
2. Have ribosomes whose size and structure closely resemble those found in bacteria.
3. Reproduce by binary fission like bacteria.
How do cells reproduce?

25. AGENDA March 27
Objectives: Investigate factors that led to the formation of Earth and early forms of life.
1. Question of the Day and DO NOW
Homework Check
Evolution of Multicellular Life
Answer Key will be posted on my webpage TOMORROW
Any late work will receive a 50% penalty.
4. Review and Homework

26. Origins of Earth and Early Life
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27. 17-3 Evolution of Multicellular Life
Precambrian Time- 90% of Earth’s history
Life only existed in the seas
Simple anaerobic life  photosynthetic forms  aerobic life
Eukaryotes  Multicellular organisms
Why do very few fossils exist from this time?

28. Paleozoic Era Carboniferous Period – reptiles and giant insects
Cambrian Period – Cambrian Explosion
Invertebrates, brachiopods, arthropods (trilobites)
Devonian Period – Plants adapt to drier areas
Insects
Age of Fishes – jaws, bony skeletons, scaled bodies
SHARKS!!!
First land animals – amphibians
Carboniferous Period – reptiles and giant insects
plant remains  coal
Mass Extinction – 95% of life extinct

29. Mesozoic Era Dominance of dinosaurs and flowering plants
Triassic Period – Age of Reptiles
225 mya  first dinosaurs
First mammals very small
Jurassic Period – Dinosaurs ruled Earth
Archaeopteryx appeared – first birds
Fossils show skulls/teeth of dinos but body and feathers of birds
Cretaceous Period – T. rex and flying reptiles
Flowering plants produced seeds enclosed in fruit
EXTINCTION EVENT

30. Cenozoic Era Quaternary Period – Ice Ages Ocean levels drop 100 meters
Age of Mammals
Mammals evolve to live in different environments
Tertiary Period – Earth warm and mild
Whales and dolphins evolve
Grasses provide food source for grazing mammals
Quaternary Period – Ice Ages
Ocean levels drop 100 meters
20,000 years ago – climate warms
Mammals such as bats, cattle, mammoths common
200,000 years ago – first fossils of Homo sapiens in Africa

31. 17-4 Patterns of Evolution
What is macroevolution?
1. Extinction
Most researchers look for a single massive event – Asteroid striking Earth at Chicxulub Crater, Mexico
Extinction of dinosaurs
Ecosystems collapse due to natural factors (earthquakes, volcanoes)
Organisms still able to compete
Food webs destroyed Disrupts energy flow

32. Adaptive Radiation
adaptive radiation: multiple species evolve from a single species
also known as divergent evolution
Darwin’s Finches

33. Convergent Evolution
convergent evolution: different species evolve to have similar appearances and behaviors
Different groups of mammals or dinosaurs
Different locations
Different times
Similar environments

34. Coevolution
Process in which two species evolve in response to changes in each other over time
An evolutionary change in one organism 
A corresponding change in another organism
Plant defense vs. fedding insect

35. Punctuated Equilibrium vs Gradualism
punctuated equilibrium: involves long periods of stability that are interrupted by episodes of rapid change
gradualism: evolution occurs slow and steady over a long period of time

36. Developmental Genes and Body Plans
Recall the function of HOX Genes.
Changes in genes can produce changes in growth and differentiation during embryonic stages of life.
Turning genes OFF
Changing timing of cell differentiation and gene expression
Long vs short legs
Single winged vs double winged

37. Pace of Evolution
punctuated equilibrium: involves long periods of stability that are interrupted by episodes of rapid change
gradualism: evolution occurs slow and steady over a long period of time