Multiple Choice
Which of the following best explains how bird bones are adapted for flight?
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21. Evolution
Introduction to Evolution and Natural Selection
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Which of the following were the first living organisms on Earth?
A
Vertebrate animals
B
Multicellular plants
C
Fungi
D
Prokaryotic cells (such as bacteria)
Verified step by step guidance1
Understand the timeline of Earth's history: The Earth formed approximately 4.6 billion years ago, and the first living organisms appeared around 3.5 billion years ago. Early conditions on Earth were harsh, with no oxygen in the atmosphere and extreme temperatures.
Recognize the characteristics of the first living organisms: These organisms needed to survive in an anaerobic (oxygen-free) environment and were simple in structure. Prokaryotic cells, such as bacteria, fit this description as they are single-celled and lack a nucleus.
Compare prokaryotic cells to other types of organisms: Multicellular plants, fungi, and vertebrate animals are all more complex and evolved much later in Earth's history. These organisms require oxygen and more stable environmental conditions to thrive.
Understand the role of prokaryotic cells in Earth's history: Prokaryotic cells were the first to perform processes like photosynthesis, which eventually led to the production of oxygen and the development of more complex life forms.
Conclude that prokaryotic cells, such as bacteria, were the first living organisms on Earth due to their simplicity, ability to survive in harsh conditions, and their role in shaping the planet's environment for future life forms.
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