The oxygen in the atmosphere developed approximately ________ billion years ago.

A. 4.5
B. 2.0
C. 3.5
D. 1.5


Answer: B

Biology & Microbiology

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a. narrow; narrow b. narrow; wide c. wide; narrow d. wide; wide e. flat; flat

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HIV is transmitted in ____

a. food b. water c. body fluids d. air e. infected surfaces

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What type of eating disorder involves consuming large amounts of food, followed by self-induced vomiting?

A) anorexia B) bulimia C) osteoporosis D) diabetes

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The mitochondria of a eukaryotic cell is the site of

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