This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory chain, Subject name: Biochemistry
[{'content': 'Barbiturates act on which step of mitochondrial respiratory chain? \nSelect and explain. \nA. Compelx 1 to co-enzyme Q, B. Compelx 2 to co-enzyme Q, C. Co-enzyme Q to compelx 3, D. Cytochrome C to compelx 4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 1. Complex I to Co-Q specific inhibitorsAlkylguanides (guanethidine), hypotensive drugRotenone, insecticide and fish poisonBarbiturates (amobarbital), sedativeChlorpromazine, tranquilizerPiericidin, antibioticRef: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 234', 'role': 'assistant'}]