(a) During a sporting event, an athlete carries out respiration in aerobic conditions.

Mark scheme

Marking points from the official mark scheme (Feb/Mar 2017). The mark or mark type is shown in brackets.

1. [2] (a)(i) 4 correct = 2 marks 2/3 correct = 1 mark glycolysis: 1 cytoplasm/cytosol/sarcoplasm ; link reaction: 2 mitochondrial matrix ; Krebs cycle: 3 mitochondrial matrix; oxidative phosphorylation: 4 inner (mitochondrial) membrane/ cristae ;
2. [1] (a)(ii) 1 too big to pass through (membrane/glucose's protein channel) ;
3. [1] (a)(ii) 2 polar/AW;
4. [1] (a)(ii) 3 no specific, transport/carrier/channel, protein (for phosphorylated glucose);
5. [1] (b) five from: in anaerobic conditions: 1 only, glycolysis/conversion of glucose into pyruvate, occurs ;
6. [1] (b) 2 (only) produces 2 molecules of ATP (net) ;
7. [1] (b) 3 (only) substrate-linked phosphorylation (occurs) ;
8. [1] (b) 4 pyruvate converted to lactate ;
9. [1] (b) 5 lactate is energy-rich/AW ;
10. [1] (b) 6 oxygen not available as final electron acceptor ;
11. [1] (b) 7 electron transport chain/chemiosmosis/oxidative phosphorylation, does not occur;
12. [1] (b) 8 most ATP is produced (in aerobic conditions) in, electron transport chain/chemiosmosis/oxidative phosphorylation ;
13. [1] (c) three from: 1 reference oxygen debt;
14. [1] (c) 2 converts lactate to, pyruvate/glucose;
15. [1] (c) 3 in liver (cells);
16. [1] (c) 4 re-oxygenate, haemoglobin/myoglobin ;
17. [1] (c) 5 meet demands of continued increased metabolic rate/AW;