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
Complex I of ETC is inhibited by 
Select and explain. 
A. Amobarbital, B. Cyanide, C. CO, D. H2S
A: Amobarbital
Answer: A: Amobarbital 
Explanation: Inhibitors of ETC Site-I (Complex-I) Rotenone: A fish poison and also insecticide. Inhibits transfer of electrons through complex-I-NADH-Q-reductase.Amobarbital (Amytal) and Secobarbital: Inhibits electron transfer through NADH-Q reductase.Piericidin A: An antibiotic. Blocks electron transfer by competing with CoQ.Drugs: Chlorpromazine and hypotensive drug like guanethidine.Ref: MN Chatterjea Textbook of Medical Biochemistry, 6th edition, page no: 143