A) one
B) two
C) three
D) four
E) eight

A) Both Q and QH₂ are substrates for Complex III.
B) Four protons are released on the P side of the membrane for every two electrons transferred to cytochrome c.
C) This protein contains both iron-sulfur clusters and heme as prosthetic groups.
D) Two protons from the matrix side are used to generate QH₂ from the semiquinone radical.
E) Overall, in each cycle one cytochrome c is reduced for every QH₂ oxidized (net).

A) P_i-H⁺ symporter
B) ATP synthase
C) pyruvate translocase
D) All of the answers are correct.
E) None of the answers is correct.