The lack of rust in the oldest existing rocks suggested that the primitive atmosphere had little or no ____
a. oxygen
b. nitrogen
c. hydrogen
d. water vapor
e. carbon dioxide
ANSWER: a
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The probable extinction of the ivory-billed woodpecker was mainly driven by
A. direct exploitation. B. introduced species. C. habitat destruction. D. climate change. E. genetic drift.
Which of the following includes other levels of hierarchy?
a. kingdom b. domain c. order d. phylum e. family
What is cartilage composed of?
A. Chondroitin and collagen fibers B. Osteocytes and calcium phosphate C. Chondroitin and calcium phosphate D. Collagen fibers and osteocytes E. Osteocytes and glycoproteins