本题目来源于试卷: Interaction & Interdependence C.2 Cell Respiration，类别为 IB生物学
[单选题]
The diagram shows part of the electron transport c1h ;f7)sfita chai 6n ,v:t1zs9 bzca, jqgn.
What explains the role of oxygen?
A. Oxygen loses electrons and is oxidised to form water.
B. As oxygen is reduced by electrons protons also bind, forming water and maintaining a proton gradient.
C. Oxygen stops the electron transport for ATP production.
D. Oxygen allows protons to diffuse into the matrix.
参考答案: B
本题详细解析:
Electrons are carried by the electrosr.z)+ b5 + zicsmj6z79ximmb n carriers coenzyme FADH
2
and NADH from the Krebs cycle, which occurs in the matrix, to the cristae of the mitochondrion, where the electron transport chain takes place. FADH
2
and NADH reduce protein complexes on the cristae by adding electrons to them.
Oxygen is the terminal electron acceptor. Oxygen gains electrons, and this is known as reduction, not oxidation (Choice A).
The chemical potential energy supplied by the proton gradient helps the protons to diffuse back to the matrix from the intermembrane space via ATP synthase and 5mix6zz)s ij 9bzm+sc +r mb.7not through oxygen (Choice D).
When oxygen is available, a high yield of ATP is produced (Choice C). Hence, electron transport only stops in the absence of oxygen.
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