This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Bio-Chemistry), Subject name: Biochemistry
The Second most important intracellular cation is 
Select and explain. 
A. Magnesium, B. Calcium, C. Sodium, D. Iron
A: Magnesium
Answer: A: Magnesium 
Explanation: (A) Magnesium # MAGNESIUM is the second most important intracellular divalent cation and is involved in a variety of metabolic processes including glucose metabolism, ion channel translocation, stimulus-contraction coupling, stimulus secretion coupling, peptide hormone receptor signal transduction.> Normal concentrations of extracellular magnesium and calcium are crucial for normal muscular activity.