In: Biology
Electrons in the ETC move from:
A. Complex I to Complex II to Complex IIII to Complex IV
B. Complex I to Complex III to Complex IV
C. Complex II to Complex III to Complex IV to the ATP Synthase
D. Complex I, Complex II, Complex III and Complex IV to the ATP Synthase
Electrons in the ETC move from Complex I to Complex III to Complex IV. Hence, the correct answer is B.
Option A is not the correct answer because electrons do not move from Complex I to Complex II. During ETC electrons move from NADH to Complex I, which transfers electrons to Ubiquinone or coenzyme Q. During ETC, electrons from FADH2 move to complex II, which transfers them to Ubiquinone or coenzyme Q. Ubiquinone or coenzyme Q is the electron carrier that transfers electrons from Complex I and Complex II to Complex III. So, there are two pathways of electron movement in the ETC. They depend on the source of electrons. If the source of electrons is NADH, the electrons move from Complex I to Complex III to Complex IV. If the source of electrons is FADH2, electrons move from Complex II to Complex III to complex IV.
Option C is not the correct answer as electrons do not move from Complex IV to the ATP synthase. They are used for oxygen reduction at Complex IV. Option D is not the correct answer as electrons do not move from Complex I to Complex II and from Complex IV to ATP synthase.