Which fact about fossils is most important to scientists who study evolution?
a) fossils are often found in sedimentary rock.
b) footprints, body structures, and even animal droppings can become fossilized.
c) the age of a fossil can be determined by examining the rock strata in which the fossil is found.
d) the formation of a fossil depends on the geologic and chemical conditions present when an organism dies.

What kind of crystalline solid is graphite? o a. molecular solid b. metallic solid o c. network solid d. ionic solid

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).

Give two examples of what would occur if one of the pairs did not match or had an extra chromosomes. explain how this might occur, and if it would be dangerous to the individual. fast.