A citrate is a derivative of citric acid; that is, the salts , esters , and the polyatomic anion found in solution. An example of the former, a salt is trisodium citrate ; an ester is triethyl citrate .
If a bacterium cannot use citrate agar will not change its color (stays green). On the other hand, if bacteria have the ability to use citrate, the medium will change its color from green to blue.
This happens because citrate agar contains pH indicator such as bromothymol blue which transforms from green to blue in alkaline conditions.
<span>The wings on
the beetles are examples of vestigiality. Vestigiality is a structure with
attributes that have apparently loss its ancestral function but stil present
during evolution. It is a normal evolutionary process in the changing
environment that does not pressure them to evolve.</span>
