In a cell, the selective permeability of the cell membrane is most closely associated with the maintenance

(a) phagocytosis
(b) hydrolysis
(c) pinocytosis
(d) homeostasis

Which of the following was a characteristic of a dromaeosaur? modified front claw grasping with their forelimbs both a and b none of the above

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).

If the dimensions of a cube-shaped cell with a length,height, and width of 1 micrometer were to double, what would be the cell's new ratio of surface area to volume? a.3 to 1 b.4 to 3 c.1 to 2 d1 to 6