Answer:
sometimes.
Explanation:
external gills are most typically found in amphibians however fishes have internal gills.
The answer isnt yes or no, different species have different gills. Some of them internal others external. Hopefully this answers your question :)
Answer: Option B.
Explanation:
Peak oil is a process whereby the world oil supplies get at the peak but decrease with increases in extraction cost. Today's peak oil is use to fuel farm machineries, produce pesticides, transporting food system. These all depend on peak oil to strive. But livestock agriculture do not depend on peak oil to strive compare to construction, telecommunication, manufacturing, transportation that requires peak oil to fuel their machines.
Not sure if this answered your question fully but hope it helps :)
Biologists do not fully understand DNA because there are constant changes and new discoveries developing.
No, pearl is often considered a gem stone, however it is not a mineral. Hope this helps! =)