Biology 9700 · AS & A Level · Respiration

Respiration — practice question

Fig. 6.1 shows the first three stages of respiration under aerobic conditions.
(a)[1]

State the name of molecule Y in Fig. 6.1.

(b)[1]

Explain how Fig. 6.1 demonstrates that glycolysis is an oxidation process.

(c(i))[2]

At one time, it was believed that the oxidative phosphorylation of one molecule of reduced NAD produces $3$ ATP molecules and one molecule of reduced FAD produces $2$ ATP molecules. Using Fig. 6.1, work out the theoretical total number of ATP molecules synthesised for each molecule of glucose respired in all phosphorylation reactions. Show your working.

(c(ii))[2]

Suggest two reasons why the actual net number of ATP molecules synthesised is lower than the theoretical figure.

(d)[3]

Outline the functions of NAD and FAD in aerobic respiration.

(e)[3]

Rotenone is used as an insecticide. It kills insects by blocking electron transfer in the electron transport chain of the mitochondrion. Explain how rotenone affects ATP synthesis in the mitochondrion.

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