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 v7ojdu( tu(gy9o sntmeh665a3 d1 i8iyq(fv, the electron 98kpa1jk es. b)nsa z;transport chain.
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 electron carriers coenzyme FADH
2
and NADH fro7 ;mccl3t l66d nxz)8 d0*1imw wvegyym 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 not through oxygenlt*c6vl67w)ex cwy 1i 8m;m3z0gdd yn (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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