Multiple Choice
Which of the following processes led to the development of new kinds of wheat and barley?
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21. Evolution
Introduction to Evolution and Natural Selection
Multiple Choice
What was the "oxygen revolution," which took place approximately 2.3 billion years ago?
A
A period when photosynthetic organisms began producing significant amounts of oxygen, leading to a dramatic increase in atmospheric O\(_2\) levels.
B
The first appearance of multicellular life forms in the fossil record.
C
A mass extinction event caused by a sudden drop in atmospheric oxygen.
D
The time when oxygen was first used as a fuel source by early animals.
Verified step by step guidance1
Understand the term 'oxygen revolution': This refers to a significant event in Earth's history when photosynthetic organisms, such as cyanobacteria, began producing oxygen as a byproduct of photosynthesis. This process dramatically increased atmospheric O₂ levels.
Recall the process of photosynthesis: Photosynthetic organisms use sunlight, water (H₂O), and carbon dioxide (CO₂) to produce glucose (C₆H₁₂O₆) and oxygen (O₂). The chemical equation is: .
Recognize the impact of increased oxygen levels: The rise in atmospheric O₂, known as the Great Oxidation Event, had profound effects on Earth's environment, including the formation of the ozone layer and the eventual support of aerobic (oxygen-using) life forms.
Differentiate the options provided: The oxygen revolution is not directly related to the first appearance of multicellular life, a mass extinction event caused by oxygen depletion, or the use of oxygen as a fuel source by animals. Instead, it is tied to the production of oxygen by photosynthetic organisms.
Conclude that the correct answer is: 'A period when photosynthetic organisms began producing significant amounts of oxygen, leading to a dramatic increase in atmospheric O₂ levels.' This aligns with the historical and biological significance of the oxygen revolution.
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