In aerobic respiration, most ATP is produced by oxidative phosphorylation.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

1. [1] 1 breaks down / hydrolyses to / converted to, ADP / AMP, and Pi ;
2. [1] 2 releases energy / energy donor ;
3. [1] 3 reversible reaction / high turnover / can be regenerated ;
4. [1] 4 small / soluble, so can, diffuse / move (freely), in cell ;
5. [1] 5 AVP ;
6. [1] 1 ETC / electron flow, less / stops ;
7. [1] 2 no / less, energy, available / released / supplied (from electron flow) ;
8. [1] 3 no / fewer, H+ ions / protons, pumped to intermembrane space ;
9. [1] 4 no / smaller, H+ / proton, gradient ;
10. [1] 5 no / fewer, protons diffuse through ATP synthase ;
11. [1] 6 no / fewer, electrons reach, last carrier / end of chain;
12. [1] 7 no / fewer, electrons can react with oxygen to form water ;
13. [1] 8 (oxidised) NAD not regenerated / lack of NAD ;
14. [1] 9 no / less, glycolysis / link reaction / Krebs cycle ;
15. [1] 10 AVP ;