In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

When it interacts with ryanodine receptors, this element upregulates its own release, and this compound forms the cell plates of coccolithophores. Stimulation of Gq ("g-sub-q") opens a channel that allows for this ion's movement, and proteins that bind this ion have an EF hand motif. Cellular concentrations of this ion are regulated by IP3. Parafollicular cells of the (*) thyroid produce a compound that reduces the concentration of this ion in blood, and its intestinal absorption requires vitamin D. This ion interacts with Troponin to stimulate muscle contraction, and the lumens of sarcoplasmic reticula have high concentrations of this ion. For 10 points, name this divalent cation that is stored in bones.
Science

This event may have inspired the subsequent Cadet Revolution in Poland, also known as the November Insurrection, and this event was preceded by a string of arsons known as The Norman Fires. Those charged with stopping this event included Colonel Komierowski, while supporters of this event included the Count of Lobau, Georges Mouton, who was the leader of the National Guard, as well as the banker Jacques Laffitte. The Address of the 221 was delivered a few months before this event, which was opposed by the security chief August de Marmont, and whose primary cause was discontent with the Prince de Polignac and the Saint-Cloud Ordinances. Also known as the three glorious days and resulting in the adoption of the tricolor, for ten points name this revolt that overthrew Charles X and led to the accession of Louis-Philippe as King of the French, named for the summer month in which it took place.
History

Sodium phenylburate is often used to treat suffers of disorders of this pathway. Defects in transporters found in this pathway can lead to HHH syndrome and Lysinuric Protein Intolerance. N-acetylglutamate is an allosteric activator of a key enzyme in this pathway. Aspartate and Citrullyl-AMP are used in one step of this reaction to form arginosuccinate. Like a connected pathway, fumarate is a byproduct of this reaction. In the mitochondria, citrulline is formed using a transcarbamoylase. Two amino acids that are part of this pathway are arginine and ornithine, and this cycle is sometimes named for the later. This cycle allows the body to deal with overconsumption of protein. For 10 points, name this cycle which generates a namesake compound allows the body to remove excess nitrogen.
Science