1. Aim # 61: How do scientists explain the development of life on earth?
Date: March 27th, 2017
Aim # 61: How do scientists explain the development of life on earth?
HW:
Daily Review of class notes.
Castle Learning due Thursday
Human Reproduction Labs due Tuesday
Quarterly Exam next Wednesday 4/5
Do Now:
How would you define the term evolution?
What comes to mind when you hear the term “evolution”?
Do you have any questions about evolution that you hope to have answered by the end of the unit?

3. Aim #61: How do scientists explain the development of life on earth?

4. 1) What were the conditions on earth 4.5 billion years ago?
Hot
Little Oxygen
Abundant Lightning
4) Volcanic Activity
Harsh Early Earth

5. 2) Primitive Earth’s Energy Source
As earth cooled, thunderstorms drenched the earth with water and the oceans formed. Lightning provided an energy source for life to begin.

6. How did life begin on earth? Formation of Organic Compounds
Inorganic compounds formed organic compounds.
Amino Acids,
Nitrogenous Bases,
Monsaccharides,
Fatty Acids
Experiment by Stanley Miller & Harold Urey

7. Formation of Organic Polymers:
Scientists have proven that polymers of organic compounds
like polysaccharides, polypeptides, lipids and nucleic acids
could have formed during the conditions of early earth.
“RNA World”
Scientists hypothesize that the first genes were RNA. RNA
served as the both the molecule that stored the genetic info.
& the molecule that directed protein synthesis.

8. Formation of Pre-Cells:
Experiments show that membranes can form around
organic polymers in a solution if certain kinds of lipids
are present.
**The simplest living organisms are far more complex
than these “pre-cells”

9. 3) Where did life begin? Today’s deep sea vents are
populated with simple unicellular
organisms that may resemble
some of the earliest living cells.

10. 4) First organism on Earth
prokaryote cells
heterotrophs
Anaerobic
The first organisms on earth were simple unicellular organisms.

11. 5) Where did the oxygen come from?
Some of these early forms of life developed into unicellular autotrophs (they got their energy from the sun and produced oxygen)
The first cells were heterotrophs, anerobic prokaryotes. They had to compete for food so what adaptation would help them survive? By what process do autotrophs make their food?
What is given off by the process of photosynthesis?
So, now what gas do we have in our environment

12. 6) Aerobic Organisms
Now, that the new atmosphere had OXYGEN, organisms that could use oxygen to do cell respiration slowly developed.

13. 7) How do scientists explain this change from simple to more complex organisms?
Theory of Evolution
The process by which
species change over time
(simple to complex).
Present day species are
related to ancient species.

14. 8) What is a theory? Theory of Evolution
Is an explanation, supported by observations and/or
experiments, that can be used to explain related
occurrences.

15. 9) What is the evidence that supports the Theory of Evolution?
Fossil Record- collection of fossils that provides clues
to the history of Earth’s organisms. The fossil record spans
much of geologic time (billions of years of Earth’s history).
Similarities in Structure
Similarities in Development (Embryology)
Molecular Biology (DNA & Proteins)

16. Hint: How do we know dinosaurs existed?
10) How do we know that we have evolved from ancestors distinctly different from us?
FOSSILS
The fossil record (remains of dead organisms) have given scientists the clues they needed to determine an organisms ancestry by comparing them to present day species.
Hint: How do we know dinosaurs existed?

17. 11) The fossil record shows…
Life has evolved from simple to more complex
Newer Organisms:
more complex
Older Organisms: more simplistic

18. 12) What do we learn from fossils?
How did behaviors evolve?
How long did individuals live?
How do features evolve over time?

19. Aim # 61: How do scientists explain the development of life on earth?
Date: March 28th, 2017
Aim # 61: How do scientists explain the development of life on earth?
HW:
Daily Review of class notes.
Castle Learning due Thursday
Quarterly Exam next Tuesday 4/4
Do Now:
Place all labs in bin.
Answer the following questions on your “Do Now Log”
What is a theory?
What is the theory of evolution?
What evidence supports the theory of evolution?

20. Brain Pop: Fossils

21. 13 & 14) Speciation
Evolution has lead to the formation of new species from different ancient organisms
Species- a group of organisms that
share certain characteristics & can
mate with one another, producing
fertile offspring.

22. Similar to a family tree
Descendents
Descendents
Common
Ancestor

23. Species living at present time (top) Ancestral common species (bottom)
15) Evolutionary Tree
Species living at present time (top)
Ancestral common species (bottom)

24. 100’s of Millions of year ago
Our Common Ancestor
Unicellular
Common
Ancestor
100’s of Millions of year ago

25. How closely related are they?
Which organisms are closely related?
Those who have a recent common ancestor (a close point of intersection in a tree diagram)
Which are distant relatives?
Those who have a distant common ancestor (a far point of intersection in a tree diagram)

26. 16) What organisms are our closest relatives? Why?

27. Summary of early evolution
Present day