This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'The enzyme carbamoyl phosphate synthetase requires: \nSelect and explain. \nA. Mg++, B. Ca++, C. K+, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: One molecule of ammonia condenses with CO2 in the presence of two molecules of ATP to form carbamoyl phosphate. The reaction is catalyzed by the mitochondrial enzyme carbamoyl phosphate synthetase-I (CPS-I).\nReference: Vasudevan 7th\xa0 ed, pg 203', 'role': 'assistant'}]