The appearance of free oxygen in Earth's atmosphere led to the "Great Oxidation Event". Where did all of this oxygen come from? o A. Volcanic eruptions which spewed gases from the Earth's interior.
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B. Cyanobacteria, a mutated unicellular organism, began to release oxygen as it performed photosynthesis.
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C. The reduction of carbon dioxide which caused the Earth to freeze from pole to pole.
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D. Oxygen was released from meteors during the Late Heavy Bombardment about 3.8 billion years ago.

Proteins are made from amino acids. an amino acid has three parts that are joined to a central carbon atom. identify the three parts that create an amino acid.

Name the plastid and pigment likely to be found in the cells of (a) petals of sunflower (b) ripe tomato.

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).