Answer:
The original water sample contains 830,000 cells per milliliter.
Explanation:
A sample of well water is tested for its bacterial content in a plate count assay. A one-milliliter sample of the water is diluted in a 1:10 dilution series. One milliliter of the fourth dilution tube is plated in a pour plate. After incubation, the plate has 83 colonies, indicating that the original water sample contained 830,000 cells per milliliter.
The right answer is C
This process is called anaerobic respiration. It doesn't need dioxygen to occur (it can happen with or without O2).
Anaerobic respiration is a mechanism in which electrons pass through a chain of transporters whose final acceptor is a mineral substance other than oxygen, unlike aerobic respiration where the final acceptor is dioxygen. The final acceptor may be the nitrate ion (as in the case of Pseudomonas), carbon dioxyde or the sulfate ion.
Some bacteria (Pseudomonas) are able, anaerobically, to reduce nitrates to nitrites and then, depending on the case, to dinitrogen (with the enzyme Nitrate reductase A).
NO3- ==> NO2- ==> N2.
<span>It is going to depend on what you consider stable. A
diverse population would be more resistant to disease because of simple
biology. The more sources for possible resistance the better the
heterogeneous pool will be at resisting disease. You also have to take
in to consideration things like the availability of modern medicine and
the ability to be isolated during illness. </span><span>
Personally I think it has to do with the fact that many of the worlds
more diverse population centers are also many of the worlds largest
population centers which make them less prone to invasion on that basis
alone. </span>
