Biology 9700 · AS & A Level · Respiration

Respiration — practice question

Oxygen is required for aerobic respiration in cells. In eukaryotic cells, aerobic respiration takes place in the mitochondrion.
(a)[3]

Fig. 1.1 shows a transmission electron micrograph of a mitochondrion. With reference to Fig. 1.1, complete Table 1.1 by using the letters A-D to indicate where each stage of aerobic respiration takes place. Any letter may be used once, more than once or not at all.

(b)[4]

In anaerobic conditions, oxidative phosphorylation cannot make any ATP because it stops. Explain why ATP synthesis by oxidative phosphorylation stops in anaerobic conditions.

(c)[3]

As much as $60\%$ of the ATP made in cancer cells is generated by lactate fermentation of glucose, despite oxygen being present. Scientists are developing cancer treatments that inhibit the enzyme responsible for the final step of lactate fermentation. Explain how blocking this enzyme lowers ATP production in cancer cells.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: glycolysis is shown by letter B

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