Ed is analyzing feedback mechanisms that maintain homeostasis in the human body. He follows the procedure that is listed below. (NOTE: Do not conduct this investigation at this time.) I. Invite a healthy test subject to participate in the investigation.
II. Measure and record the pulse and breathing rate of the subject.
III. Have the test subject exercise vigorously for 1 minute, such as by running in place.
IV. Repeat Step 2.

Why is Step 3 useful for Ed's purpose for the investigation?
a Exercise causes an increase in the pH of blood and other body fluids.
b Exercise increases the body's demand for food and nutrients.
c Exercise has no effect on the body's demand for oxygen, food, and nutrients.
d Exercise increases the body's demand for oxygen.

Select the true statements about eubacteria. most live as decomposers and heterotrophs. most only thrive in a narrow range of environments. certain eubacteria are responsible for food poisoning. eubacteria thrive in extreme environments.

Which would be the most useful source of evidence to support mcneill's contention?

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).