Download The History of Life

17 The History Of Life
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17-1 The Fossil Record
Interpreting Fossil Evidence
Relative dating allows paleontologists to estimate
a fossil's age compared with that of other fossils.
Index fossils are used to compare the relative ages of fossils.
An index fossil is a species that is recognizable and that existed for a
short period but had a wide geographic range.
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17-1 The Fossil Record
Interpreting Fossil Evidence
Radioactive dating is
the use of half-lives to
determine the age of a
sample.
A half-life is the length
of time required for half
of the radioactive atoms
in a sample to decay.
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In radioactive dating,
scientists calculate the
age of a sample based
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on the amount of 3 of 40
remaining radioactive
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isotopes it contains.
17-1 The Fossil Record
The First Organic Molecules
Miller and Urey’s Experiment
Mixture of gases
simulating
atmosphere of
early Earth
Spark simulating
lightning storms
Condensation
chamber
Water
vapor
Cold water cools
chamber, causing
droplets to form.
Liquid containing amino
acids and other organic
compounds
large organic molecules
form tiny bubbles called
proteinoid Slide
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microspheres.
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17-1 The Fossil Record
Origin of Eukaryotic Cells
The rise of oxygen in the atmosphere drove some life forms to
extinction, while other life forms evolved new, more efficient
metabolic pathways that used oxygen for respiration
Endosymbiotic Theory
Ancient Prokaryotes
Chloroplast
Aerobic
bacteria
Nuclear
envelope
evolving
Ancient Anaerobic
Prokaryote
Photosynthetic
bacteria
Plants and
plantlike
protists
Mitochondrion
Primitive Aerobic
Eukaryote
Primitive Photosynthetic
Eukaryote
Animals,
fungi, and
non-plantlike
protists
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