Which is the best explanation for a convection current in the atmosphere? Hot air expands and rises to the top of the atmosphere, while the cool air stays

Hot air expands and rides becoming cooler and denser, then falling again in a

Cold air expands and rises, becoming warmer and contracting, then falling again

in a continuous cycle.

Cold light air rises in the atmosphere, while the warmer air stays near the

ground

Long term exposure to waves can cause sunburns and skin cancer.

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).

What's the waste product of electrons and pyruvate combining in fermentation?