[Campbell Biology P.223] Based on Figure 9.12 and the associated text, which statement accur... | Practice Question

Based on Figure 9.12 and the associated text, which statement accurately describes the flow of electrons and the concept of electron affinity in the electron transport chain?

  • A: Electrons travel from carriers with higher affinity to those with lower affinity, releasing energy.
  • B: NADH has the lowest affinity for electrons, and O2 has the highest affinity, driving electron flow down the chain.
  • C: Complexes I-IV solely consist of coenzymes, without any protein components.
  • D: The overall energy drop for electrons traveling from NADH to oxygen is approximately 40 kcal/mol.

Explanation

Figure 9.12 and the accompanying text clearly state that NADH has the lowest affinity for electrons and O2 has the highest affinity being very electronegative , which drives the 'downhill' flow of electrons. The overall energy drop is 53 kcal/mol, and complexes I-IV consist of multiple proteins with electron carriers, including prosthetic groups like coenzymes, not solely coenzymes.