Multiple Choice
Why is there more carbon-14 ($^{14}$C) in living bones than in once-living ancient bones of the same mass?
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21. Evolution
Introduction to Evolution and Natural Selection
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Why did Carl Sagan famously say that 'we are star stuff'?
A
Because the elements that make up our bodies were formed in the interiors of stars and distributed throughout the universe by supernovae.
B
Because the energy that sustains life on Earth comes directly from starlight.
C
Because humans are made primarily of hydrogen, the most abundant element in stars.
D
Because the process of evolution began with the formation of stars in the early universe.
Verified step by step guidance1
Understand the context of Carl Sagan's statement: 'We are star stuff' refers to the origin of the elements that make up our bodies.
Recall that heavier elements like carbon, oxygen, and nitrogen, which are essential for life, are formed through nuclear fusion in the cores of stars.
Learn that when massive stars reach the end of their life cycle, they explode in supernovae, dispersing these elements into space.
Recognize that these elements eventually become part of new stars, planets, and living organisms, including humans.
Connect this idea to the correct answer: The elements that make up our bodies were formed in the interiors of stars and distributed throughout the universe by supernovae.
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