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Biology, Chapter 14
The History of Life
14.1 The Record of Life
Early History of Earth
1. What evidence indicates a common origin for the entire solar system?
a. Rotating disk shape: solar nebula was rotating
b. Common age dating from the age of the Sun
c. Terrestrial planets inner, Jovian outer
i. Metals and their oxides condense at a higher temperature nearer the
Sun
ii. Jovian planets are still hot because of their large heat of formation
d. Asteroids, comets, and meteors may be leftovers from formation
History in Rocks
Intro
Fossils - Clues to the past
2. Summarize the story told in the fossil record.
a. Deeper fossils are older and less complex
b. Shallower fossils are younger and more complex
Paleontologists - Detectives to the past
3. How is paleontology related to forensic science?
a. Identification of remains
b. Age/how long where found
c. Personal characteristics/lifestyle environment
Fossil formation
Relative dating
4. Differentiate relative and radiometric dating.
a. Relative: deeper is older, shallower is younger (= superposition)
Radiometric dating
b. Radiometric gives absolute date in years
i. Measure radioactive isotope and its decay product
ii. Use half-life to calculate when the sample began to decay
c. Examples
i. Potassium-40  argon-40; half-life = 1.3 billion years
ii. Carbon-14  nitrogen-14; half-life = 5730 years
A Trip Through Geologic Time
Intro
The geologic time scale
5. Summarize the timeline of the universe and life on Earth.
a. Universe began expanding 13.7 bya
b. Sun ignited 5 bya
c. Earth formed 4.6 bya
d. Oldest fossils 3.5 bya
e. Photosynthesis + oxygen atmosphere 2.6 bya
f. Fossil eukaryotes 2.1 bya
g. Fossil multicellular organisms 1.4 bya
Life during the Precambrian
Diversity during the Paleozoic
Life in the Mesozoic
A mass extinction
Changes during the Mesozoic
The Cenozoic Era
14.2 The Origin of Life
Origins: The Early Ideas
Intro
Spontaneous generation is disproved
Pasteur's experiments
6. How did Pasteur disprove the existence of a vital force in the air?
a. Spontaneous generation = living things from non-living
i. Like meat  maggots
ii. Life force of the maggots thought to be present in meat
iii. Life force of microorganisms thought to be in air
b. Pasteur's experiment
i. Sterilized broth in straight-necked flasks prutified
ii. Sterilized broth in S-shaped neck flasks stayed sterile
iii. Both were open to the air
iv. If there was a life force it could have gotten in
Origins: The Modern Ideas
Intro
Simple organic molecules formed
7. Describe the Miller-Urey experiment.
a. Simulated conditions on the early Earth
b. Parts
i. H2, CH4, NH3, H20 = atmosphere
ii. Liquid water = ocean
iii. Sparks = lightning
c. Results: made amino acids and sugars
8. Define the physical and functional minimum for sustainable reproduction.
a. A molecule that can catalyze its own copying
9. Describe the missing link between a self-copying molecule and the central
dogma of molecular biology (DNA ==> RNA ==> Protein.)
a. Ribozymes = RNA molecules which catalyze their own maintenance
b. Discovered in the 1980s, included in the newest Biology texts
The formation of protocells
The Evolution of Cells
Intro
The first true cells
10. What is the evidence that the first organisms were anaerobic, heterotrophic
prokaryotes?
a. Anaerobic: no oxygen in the atmosphere at first
b. Heterotrophic
i. Autotrophy is complex, evolved later
ii. Plenty of energy-rich molecules in the puddles
c. Prokaryote: simplest cells
Photosynthesizing prokaryotes
The endosymbiont theory
11. Describe evidence for the endosymbiont theory for the origin of mitochondria
and chloroplasts.
a. Theory: eukaryotes evolved by close symbiosis with prokaryotes
b. Process
i. Mutualistic associations in mixed communities
ii. One prokaryotes engulfs another for closer cooperation
iii. Engulfed member simplifies
iv. First endosymbionts became mitochondria
v. Next endosymbionts became chloroplasts
c. Evidence
i. Mitochondria and chloroplasts have circular chromosomes like
prokaryotes
ii. They have prokaryote type ribosomes
iii. They reproduce independently of the cell