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: Pharmacology
Penicillin is the metabolic product of ? 
Select and explain. 
A. Aminoadipic acid, B. Aminocaproic acid, C. Levulinic acid, D. Arachidonic acid
A: Aminoadipic acid
Answer: A: Aminoadipic acid 
Explanation: Ans. is 'a' i.e., Aminoadipic acid Penicillin is a product of secondary metabolic pathway of Penicillium chrysogenum. a-aminoadipic acid is the precursor of penicillin. This compound is normally conveed to lysine primary metabolic pathway. However, when the growth of fungus is inhibited, a-aminoadipic acid is conveed to penicillin secondary metabolic pathway.