In the classification of organisms by kingdom, all prokaryotes are grouped together in the kingdom Monera. Genetic research, however, led to the separation of prokaryotes into two domains, Archaea and Eubacteria. Which of the following best describes similarities between Archaea and Eubacteria?

Both can undergo binary fission and are autotrophs.
Both are able to withstand extreme temperatures and lack of oxygen.
Both have single-stranded, helical DNA and cell walls.
Both lack membrane-bound organelles and are single-celled.

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).