Victor has been studying the vascular systems of plants. He wanted to find out if food coloring would travel up the stalk of celery faster if the temperature of the water increased. Victor set up his experiment with three cups of colored water at different temperatures, three equal sized celery stalks, and a stopwatch. Cup A was filled with colored water at 21 C. Cup B was filled with cold colored water at 4 C, and Cup C was filled with warm colored water at 30 C. One celery stalk was placed in each cup at the same time. Victor timed how long it took the colored water to travel to the leaves at the top of the celery stalk. He measured the time in minutes. What is the independent variable

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).