Question

Which of the following ETS complex is inhibited by cyanide?

• A. Complex II
• B. Complex V
• C. Complex IV
• D. Complex III

Answer 1

The correct option is C Complex IV

Some poisons, including cyanide, inhibit the normal activity of the cytochromes. Cyanide binds tightly to the iron in the last cytochrome in the electron transport chain (cytochrome a${}_3$- component of complex IV), making it unable to transport electrons to oxygen. This blocks the further passage of electrons through the chain and ATP production ceases.

So, the correct answer is option C.