[Figure 6.1] is a diagram of part of a mitochondrion.

Mark scheme

Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.

1. [1] (a) an arrow through phospholipid layer in outer membrane and an arrow through phospholipid layer in inner membrane ; R arrows through proteins or A, B, C or D
2. [7] (b) 1 D = ATP synthase / ATP synthetase ; R ATPase
3. [7] (b) 2 A, B and C = ETC / electron transport chain / electron carriers / electron acceptors ;
4. [7] (b) plus any five from:
5. [7] (b) role of, ETC proteins / A, B and C
6. [7] (b) 3 electrons travel along ETC ;
7. [7] (b) 4 energy released ;
8. [7] (b) 5 (use energy released) to pump / actively transport, H+ / protons, into intermembrane space ;
9. [7] (b) 6 increases concentration of H+ / protons (in intermembrane space) / creates proton gradient ;
10. [7] (b) role of D
11. [7] (b) 7 H+ / protons, diffuse through, ATP synthase / D ;
12. [7] (b) 8 (from intermembrane space) to matrix ;
13. [7] (b) 9 synthesis of ATP from ADP and Pi ;
14. [7] (b) 10 chemiosmosis ;
15. [3] (c) any three from:
16. [3] (c) 1 (named) enzyme for, Krebs cycle / link reaction ;
17. [3] (c) 2 ETC proteins / cytochromes / electron carriers / electron acceptors / A / B / C ;
18. [3] (c) 3 ATP synthase / D / described ;
19. [3] (c) 4 membrane / channel / transport / carrier / structural, proteins ;
20. [3] (c) 5 (make) tRNA / rRNA / ribosomes ;