Question

Ubiquinone is a mobile electron carrier between
I. Complex I and complex III
II. Complex II and complex III
III. Complex III and complex IV
IV. Complex I and complex IV

• A. I & III
• B. II & III
• C. II & IV
• D. I & II

Hint:

Ubiquinone is lipid-soluble and moves freely in the inner mitochondrial membrane. Remember its role: I → III and II → III. Cytochrome c moves electrons III → IV. Visual diagrams help avoid confusion.

Answer 1

The Correct Option is D

Ubiquinone (Coenzyme Q) is a lipid-soluble electron carrier in the mitochondrial electron transport chain. It transfers electrons: - From Complex I (NADH dehydrogenase) to Complex III (cytochrome bc1). - From Complex II (succinate dehydrogenase) to Complex III. It does not interact with Complex IV directly; cytochrome c carries electrons from III to IV. Therefore, the correct pairs are I & II.