Question

Mobile carrier cytochrome C transfer electrons between

• A. Complex I and II
• B. Complex II and III
• C. Complex III and IV
• D. Complex II and IV

Hint:

Ubiquinone carries electrons from Complex I/II to Complex III, while Cytochrome c carries electrons from Complex III to Complex IV.

Answer 1

The Correct Option is C

Concept: The Electron Transport Chain (ETC) is located on the inner mitochondrial membrane. Electrons move through a series of complexes and mobile carriers before finally reducing oxygen to water. Two important mobile carriers are:
• Coenzyme Q (Ubiquinone)
• Cytochrome c

Step 1: Recall the sequence of electron transport. \[ \text{Complex I} \rightarrow Q \rightarrow \text{Complex III} \rightarrow \text{Cytochrome c} \rightarrow \text{Complex IV} \rightarrow O_2 \]

Step 2: Role of cytochrome c. Cytochrome c is a small soluble protein located in the intermembrane space. Its function is to carry electrons from Complex III to Complex IV.

Step 3: Evaluate options. Complex I and II are not connected by cytochrome c. Complex II and III are linked through ubiquinone. Complex III and IV are linked through cytochrome c. Therefore only option (C) is correct.

Step 4: Final conclusion. Cytochrome c transfers electrons between: \[ \boxed{\text{Complex III and Complex IV}} \] Hence option (C) is correct.