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Multiple Choice
In the electron transport chain, which molecule accepts the electron after it passes through the second complex (Complex II)?
A
Ubiquinone (Coenzyme Q)
B
Cytochrome c
C
Oxygen
D
NAD+
Verified step by step guidance
1
Understand the role of Complex II in the electron transport chain: Complex II, also known as succinate dehydrogenase, is involved in the citric acid cycle and the electron transport chain. It oxidizes succinate to fumarate and reduces FAD to FADH2.
Recognize that Complex II transfers electrons from FADH2 to the electron transport chain. Unlike Complex I, Complex II does not pump protons across the mitochondrial membrane.
Identify the electron acceptor from Complex II: After electrons are transferred from FADH2, they need to be passed to the next component in the electron transport chain.
Recall the role of ubiquinone (Coenzyme Q): Ubiquinone is a lipid-soluble molecule that acts as an electron carrier within the inner mitochondrial membrane. It accepts electrons from both Complex I and Complex II.
Conclude that ubiquinone (Coenzyme Q) is the molecule that accepts electrons from Complex II, facilitating their transfer to Complex III in the electron transport chain.