Axonal guidance is the process through which axons reach their proper targets in the brain. Researchers hypothesize that the wild-type PTP gene product mediates proper axonal guidance by inactivating the Abl gene product. Which experimental observation would best support this hypothesis?

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).

Knowing the importance of the essential elements, why would someone chose a diet that does not address all of them?

The function of the excretory system is to control homeostasis and