1. Notes #34 I can: Understand how life developed on Earth
Origins of Life
Notes #34
I can:
Understand how life developed on Earth

2. Exit Ticket Review
1. The breakup of Pangaea had which effect on the subsequent history of animal speciation?
A. Animals had to become adapted to distinct climates.
B. Animal diversity declined due to loss of available territory.
C. Separated animal populations evolved independently.
D. A single animal kingdom separated into multiple, distinct phyla.

3. Exit Ticket Review
2. Mosquito fish found on the islands of the Bahamas live in various isolated freshwater ponds that were once a single body of water. When several male and female mosquito fish are taken from two isolated ponds and placed into a single pond, the breeding preference of each mosquito fish is for fish from its own original pond. Which of these most likely resulted in this breeding preference?
A. Availability of food influenced the breeding preferences of the fish.
B. Competition for a suitable mate influenced the breeding preferences.
C. Predators in the pond influence the breeding preferences of the fish.
D. Speciation due to reproductive isolation influenced the breeding preferences.

4. Exit Ticket Review
3. Two species of wood mouse live on opposite sides of a river. Which is a likely reason they have become separate species?
A. They mate at different times.
B. They have different courtship rituals.
C. Their gametes cannot fertilize each other.
D. Geography prevents mating from occurring.

5. Hadean Eon Earth forms no oxygen in atmosphere
constant volcanic activity

6. Archean Eon first anaerobic prokaryotes
first photosynthetic prokaryotes
oxygenation of atmosphere causes mass extinction of anaerobic bacteria

7. Proterozoic Eon first eukaryotes first sexually reproducing organisms
first multicellular organisms
glaciation event

8. Phanerozoic Eon major diversification of life
major mass extinctions eliminate 90% of marine species
modern era

9. The fossil record provides evidence about the history of life on Earth and how different groups of organisms have changed over time.
Fossils are remains of dead organisms.
Paleontologists are scientists who study fossils. They look for anatomical similarities and differences between the fossil and living organisms.

12. The age of a fossil is very important and can be determined in two ways:
1. Relative dating – allows paleontologists to estimate a fossil’s age compared with that of other fossils.
youngest
fossils
The oldest fossils are the furthest down.
The youngest fossils are nearest to the surface.
oldest
fossils

13. The age of a fossil is very important and can be determined in two ways:
2. Absolute dating – scientists determine the exact age of a fossil by using radiometric dating

14. anaerobic – without oxygen aerobic – with oxygen
Vocabulary Review
anaerobic – without oxygen
aerobic – with oxygen
prokaryotes are simple cells with no nucleus or membrane-bound organelles
eukaryotes are larger, have a nucleus and membrane-bound organelles

15. How did life develop on Earth?
The Earth formed 4.6 billion years ago.
anaerobic atmosphere with simple organic compounds
water was present
How did life develop on Earth?

16. The Miller-Urey experiment showed that the mixture of complex organic compounds necessary for life could form from simpler compounds present on primitive Earth.
COMPLEX COMPOUNDS!

17. Important events in the development of life on Earth

18. 3.5 billion years ago – the first anaerobic organism formed.
The first organisms were anaerobic prokaryotes who were able to thrive in the harsh conditions of early Earth.

19. What does photosynthesis produce? Then aerobic prokaryotes developed.
3.4 billion years ago – anaerobic photosynthetic organisms evolve.
What does photosynthesis produce?
After the evolution of photosynthetic bacteria, the Earth’s atmosphere had much more oxygen in it – it became aerobic.
Then aerobic prokaryotes developed.

20. 2 billion years ago – aerobic eukaryotic cells developed.
The endosymbiotic theory explains how the first eukaryotic cells developed.
a symbiotic relationship formed among several different prokaryotic organisms
prokaryotes became permanent organelles

21. both bacteria and mitochondria and chloroplasts have circular DNA
Evidence of endosymbiosis:
mitochondria and chloroplasts contain their own DNA
the ribosomes of these two organelles are similar to those found in bacteria
mitochondria and chloroplasts reproduce by binary fission, just like bacteria
both bacteria and mitochondria and chloroplasts have circular DNA
both bacteria and mitochondria and chloroplasts reproduce by binary fission

22. ??? years ago – sexual reproduction developed
the crossing-over and shuffling of genes that occur during sexual reproduction allowed for tremendous diversity to develop

23. ??? years ago – multicellularity evolves
multicellular organisms consist of more than one cell
this allows for cells in organisms to have specific jobs