A student poured a solution of bromothymol blue indicator into three test tubes. Then he placed an aquatic plant in tubes 2 and 3, and a snail in tube 3 only, as shown below. He placed a stopper on each test tube and placed them all in the dark for 24 hours. Bromothymol blue turns from blue to yellow in the presence of CO2. In which test tube or test tubes would you expect cellular respiration to occur? Explain your answer. Please, hurry!

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).