First Autotrophs
• Probably similar to modern anaerobic
bacteria
– Survive without oxygen
• Chemosynthesis from chemicals at deep
hydrothermal vents
• Supports idea of life’s origins on deep ocean
floor in absence of light
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Photosynthesis and Respiration
• Complex autotrophs developed chlorophyll.
• This allowed the use of the Sun for
photosynthesis.
• Cellular respiration
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Photosynthesis and Respiration
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Great Oxidation Event
• 2.45 billion years ago
• Increased oxygen and ozone eliminated the
anaerobe food supply.
• Light and oxygen kill anaerobes.
• Cyanobacteria adapted and thrived.
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Changes to Earth’s Atmosphere
• Photosynthetic
organisms are
responsible for life as
we know it today.
• Reduce CO2,
increase O2 to 21%
• High oxygen =
biodiversity increase
• Low oxygen
associated with
extinction events
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Plants and Earth’s Environment
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Age of Earth
• Radiometric age dating
– Spontaneous change/decay
– Half-life
• Earth is about 4.6 billion years old.
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Radioactive Decay
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Geologic Time Scale
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End of CHAPTER 1
Introduction to Planet “Earth”
© 2014 Pearson Education, Inc.
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Introduction to Planet “Earth” Chapter 1 Clickers Essentials of Oceanography Eleventh Edition Alan P. Trujillo Harold V. Thurman © 2014 Pearson Education, Inc.
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