6. Select the scenario in which a mutation may become fixed in a population.
A mutation causing light skin shows up in a population of people living near the equator in South America.
A mutation for a stubby tail occurs in a population of Eastern gray squirrels, which normally have long, bushy tails.
Several bacteria in a population resistant to the antibiotic erythromycin show susceptibility to erythromycin because of a recent mutation.
A mutation occurs in a population of brown toads, causing green stripes that allow for better camouflaging in its habitat.
In a population of people whose main food source is the milk of their livestock, a mutation for lactose intolerance appears.

This aquarium exhibits biotic and abiotic factors in an aquatic environment. one of the abiotic factors is

Human genes only differ by less than percent. a. 1 b. 6 c. 11 d. 16

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).