Sore throat is a symptom, not a disease. In each case, there was a different cause that dictated a different treatment. The scratchy throat probably was a mechanical problem caused by dry, heated winter air and aggravated by my friend's tendency to breathe through her mouth when she sleeps.
Biogeochemistry includes the history of the great carbon reservoirs in the crust of the Earth, like limestone rocks and the coal deposits, as well as the distribution of nitrate and phosphate in the ocean.
Diagram of the carbon cycle. The black numbers indicate how much carbon is stored in various reservoirs, in billions tonnes (GtC stands for gigatonnes of carbon; figures are circa 2004). The purple numbers indicate how much carbon moves between reservoirs each year.