14. which of the following best defines homeostasis? (points : 3)
the maintenance of an organism’s internal environment within certain limits
the maintenance of an organism's external environment within broad limits
the ability of an organism to find its own food
the ability of an organism to find a mate

15. biological organization extends beyond the organism to include which of the following? (points : 3)
cells, tissues, and organs
dna, rna, and protein
populations, communities, and ecosystems
family, genus, and species

The many volcanoes located along the edge of the pacific ocean make up the ring of fire. how does subduction play a role in the volcanic activity in the ring of fire?

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).

Crossing over is a method of (blank)?