History  of  Life  on  Earth
It Started with the Sun <ul><li>From a ball of swirling gas  a centre point emerged.  </li></ul><ul><li>This centre mass b...
<ul><li>This reaction began about five billion years ago.  </li></ul><ul><li>We estimate that the Sun is about halfway thr...
<ul><li>Some of the gas at the centre as it was cooling was ejected outwards. </li></ul><ul><li>This gas further cooled an...
<ul><li>Luckily at about 1.5 x10 8  km from the Sun a little speck formed. </li></ul><ul><li>This is just the right distan...
Once Upon a Time on Earth  <ul><li>The history of life on Earth began approx. 3.5 billion years ago. </li></ul><ul><li>How...
<ul><li>Scientific evidence indicates that since life’s beginning, each organism that has inhabited this planet has been t...
Let’s Visualize  <ul><li>Could you physically carry $1 billion dollars? </li></ul>
Let’s Visualize <ul><li>One  million  dollars would be a stack of $1000 bills approx. 1 metre high.  (1000 bills high) </l...
<ul><li>The Earth was over 1 billion years old  before  any kind of life was present. </li></ul><ul><li>We can use Radiome...
<ul><li>Isotopes are different forms of an element that have differing atomic masses.  </li></ul><ul><li>Half-life is asso...
<ul><li>Most scientist believe that life on Earth developed through natural chemical and physical processes. (p.253 text) ...
<ul><li>This process of nothing to something is known as spontaneous origin. </li></ul><ul><li>There are two main models t...
Explain the Primordial Soup Model. <ul><li>This model states that there were many different types of organic molecules pre...
Explain the Bubble Model. <ul><li>This model states that the key process to form chemicals for life took place within tiny...
Bubble cont. <ul><li>Most gases are lighter than liquids so they rose to the surface of the oceans, which then released th...
According to Theory <ul><li>What was the importance of oxygen? </li></ul><ul><ul><li>Oxygen was essentially “tied up” with...
According to Theory  <ul><li>What was the first step that led toward cellular organization? </li></ul><ul><ul><li>Microsph...
According to Theory <ul><li>How did the development of heredity contribute to the successful formation of life? </li></ul>...
<ul><li>Models can change, when might a model change? </li></ul><ul><ul><li>Models may change as our understanding increas...
The Atmosphere <ul><li>Is the Atmosphere an infinite resource?  </li></ul><ul><li>Will it always be present in its current...
<ul><li>So long ago the atmosphere was a hostile place for life as we know it. </li></ul><ul><li>Ammonia, Methane, Carbon ...
Complex Organisms Development <ul><li>See Graphic Organizer on Board </li></ul>
<ul><li>Write down the definitions for the following. </li></ul><ul><ul><li>fossil </li></ul></ul><ul><ul><li>cyanobacteri...
Compare and Contrast <ul><li>Use a Venn Diagram to show similarities between prokaryotes and eukaryotes. </li></ul>
<ul><li>Why might mass extinctions be important? </li></ul>
Project <ul><li>Create an interesting Time Line of life on Earth. </li></ul><ul><li>Start at about 3.5 billion years ago a...
 
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History Of Life On Earth

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Biology PowerPoint on the History of Earth. 4 billion years ago to maybe 3 billion years ago.

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History Of Life On Earth

  1. 1. History of Life on Earth
  2. 2. It Started with the Sun <ul><li>From a ball of swirling gas a centre point emerged. </li></ul><ul><li>This centre mass became the Sun. </li></ul><ul><li>99.8% of the entire mass of our solar system is contained in the Sun. </li></ul><ul><li>Nuclear fusion powers the Sun. </li></ul><ul><ul><li>Essentially 4 H  He + energy +2 neutrinos </li></ul></ul>
  3. 3. <ul><li>This reaction began about five billion years ago. </li></ul><ul><li>We estimate that the Sun is about halfway through its life cycle, so we only have about five billion years to go before the Sun burns out. </li></ul><ul><li>No Sun no life. </li></ul>
  4. 4. <ul><li>Some of the gas at the centre as it was cooling was ejected outwards. </li></ul><ul><li>This gas further cooled and collected to form the planets, and some other debris. </li></ul><ul><li>Remember that all the masses of the planets and debris only account for about 0.2% of the entire mass of our Solar System. </li></ul>
  5. 5. <ul><li>Luckily at about 1.5 x10 8 km from the Sun a little speck formed. </li></ul><ul><li>This is just the right distance from a star for life, as we know it, to form. </li></ul><ul><li>This little speck became known as the Earth. </li></ul>
  6. 6. Once Upon a Time on Earth <ul><li>The history of life on Earth began approx. 3.5 billion years ago. </li></ul><ul><li>How this occurred has been and will continue to be a topic for inquiry. </li></ul><ul><ul><li>Remember people often just thought that life was life and little questioning occurred. </li></ul></ul><ul><ul><li>Until science came along. </li></ul></ul>
  7. 7. <ul><li>Scientific evidence indicates that since life’s beginning, each organism that has inhabited this planet has been the product of evolution. </li></ul><ul><li>Evolution is the change of an organism over time. </li></ul>
  8. 8. Let’s Visualize <ul><li>Could you physically carry $1 billion dollars? </li></ul>
  9. 9. Let’s Visualize <ul><li>One million dollars would be a stack of $1000 bills approx. 1 metre high. (1000 bills high) </li></ul><ul><li>A billion dollars would be 1000 metres high. (1 million bills) </li></ul>
  10. 10. <ul><li>The Earth was over 1 billion years old before any kind of life was present. </li></ul><ul><li>We can use Radiometric dating, looking at the amount of radioactive isotopes present in a sample, to determine the age of something, including the Earth </li></ul>
  11. 11. <ul><li>Isotopes are different forms of an element that have differing atomic masses. </li></ul><ul><li>Half-life is associated with this. </li></ul><ul><ul><li>How long half of a substance will exist as it decays. </li></ul></ul><ul><ul><li>Carbon-14 is a common one isotope used for things up to about 50 000 years old. </li></ul></ul>
  12. 12. <ul><li>Most scientist believe that life on Earth developed through natural chemical and physical processes. (p.253 text) </li></ul><ul><li>Essentially nonliving matter reacted to produce life, due to the presence of the Sun, and volcanoes. </li></ul><ul><li>These molecules combined to form more complex molecules and then eventually life. </li></ul>
  13. 13. <ul><li>This process of nothing to something is known as spontaneous origin. </li></ul><ul><li>There are two main models to help explain this spontaneous origin. </li></ul><ul><ul><ul><li>Primordial Soup Model, and </li></ul></ul></ul><ul><ul><ul><li>the Bubble model </li></ul></ul></ul>
  14. 14. Explain the Primordial Soup Model. <ul><li>This model states that there were many different types of organic molecules present in the ocean, like a soup. </li></ul><ul><li>These organic molecules were formed when energy from the sun, volcanoes and lightning were added to the oceans. </li></ul><ul><li>Due to high levels of energy these molecules could freely interact. (More energy led to electron interactions between molecules.) </li></ul>
  15. 15. Explain the Bubble Model. <ul><li>This model states that the key process to form chemicals for life took place within tiny bubbles on the surface of the oceans. </li></ul><ul><li>Underwater volcanic activity released gases, gases in a liquid form bubbles. </li></ul><ul><li>The bubbles may have protected these gases from harmful UV rays. (Reactions in bubbles would happen quicker, which was a flaw of the primordial soup model”.) </li></ul>
  16. 16. Bubble cont. <ul><li>Most gases are lighter than liquids so they rose to the surface of the oceans, which then released these organic molecules into the air. (Not O 2 rich yet.) </li></ul><ul><li>Still able to rise further chemical reactions were able to occur. </li></ul><ul><li>Some of the more complex molecules returned to the oceans for more reactions to take place. </li></ul>
  17. 17. According to Theory <ul><li>What was the importance of oxygen? </li></ul><ul><ul><li>Oxygen was essentially “tied up” with hydrogen and minerals. This did not allow it to freely be present in our atmosphere. UV radiation helped release some oxygen which eventually formed ozone (O 3 ). Remember that ozone helps filter UV, too much UV is bad, it may lead to mutations. </li></ul></ul>
  18. 18. According to Theory <ul><li>What was the first step that led toward cellular organization? </li></ul><ul><ul><li>Microspheres might have led to cellular organization. </li></ul></ul><ul><ul><li>Microspheres are short chains of amino acids that gather into tiny vesicles. </li></ul></ul><ul><ul><li>Microspheres that survived for a long time may gathered more molecules that led to an organization. </li></ul></ul>
  19. 19. According to Theory <ul><li>How did the development of heredity contribute to the successful formation of life? </li></ul><ul><ul><li>Heredity is a necessary feature of living things. Microspheres that contained replicating RNA might have transferred both their structure and their RNA to offspring. </li></ul></ul>
  20. 20. <ul><li>Models can change, when might a model change? </li></ul><ul><ul><li>Models may change as our understanding increases. </li></ul></ul><ul><ul><li>More information usually changes peoples thinking. </li></ul></ul>
  21. 21. The Atmosphere <ul><li>Is the Atmosphere an infinite resource? </li></ul><ul><li>Will it always be present in its current form? </li></ul>
  22. 22. <ul><li>So long ago the atmosphere was a hostile place for life as we know it. </li></ul><ul><li>Ammonia, Methane, Carbon Dioxide were some of the main constituents of our atmosphere. </li></ul><ul><li>It took an oxygen rich atmosphere for life to really exist. </li></ul><ul><li>Is there a problem now? </li></ul>
  23. 23. Complex Organisms Development <ul><li>See Graphic Organizer on Board </li></ul>
  24. 24. <ul><li>Write down the definitions for the following. </li></ul><ul><ul><li>fossil </li></ul></ul><ul><ul><li>cyanobacteria </li></ul></ul><ul><ul><li>eubacteria </li></ul></ul><ul><ul><li>archaebacteria </li></ul></ul><ul><ul><li>endosymbiosis </li></ul></ul><ul><ul><li>Protists </li></ul></ul><ul><ul><li>mass extinction </li></ul></ul>
  25. 25. Compare and Contrast <ul><li>Use a Venn Diagram to show similarities between prokaryotes and eukaryotes. </li></ul>
  26. 26. <ul><li>Why might mass extinctions be important? </li></ul>
  27. 27. Project <ul><li>Create an interesting Time Line of life on Earth. </li></ul><ul><li>Start at about 3.5 billion years ago and go to present day. </li></ul><ul><li>Show at least 25 biological events that have occurred during this time. </li></ul><ul><li>Due Tuesday 15.01.08 </li></ul>

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