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The approximate age of Earth is:



6,000 years


150,000 years


4.5 billion years


13.5 billion years


On Aristotle's Scala Naturae, humans were:



on the bottom rung


on the top rung


on the same rung as animals


lower than plants


Which of these ideas is not a central theory for modern biology?



evolution


creationism


cell theory


gene theory