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
Last electron acceptor in electron transpo chain is 
Select and explain. 
A. FADH2, B. NADH2, C. Cytochrome C, D. O2
D: O2
Answer: D: O2 
Explanation: Complex IV: Cyt-c Oxidase The system functions: * As proton pump * Catalyses transfer of electrons to molecular O2 to form H2O. This is the terminal component of ETC. It catalyzes the transfer of electrons from Cyt-c to molecular O2 Cyt-a, Cu++ ions and Cyt-a3.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 142