CAIE A-Level Biology A2 12.2.3 Pyruvate and the Link Reaction Questions
Explain pyruvate formation and the link reaction using evidence from each question and mark scheme.
- Syllabus
- 2028–2030
- Course
- Biology 9700
- Level
- A2
Exam points
- Explain pyruvate formation and the link reaction connecting glycolysis to the Krebs cycle.
CAIE A-Level Biology A2 12.2.3 Pyruvate and the Link Reaction Questions question 1
[Maximum number: 4]
Aerobic respiration occurs when oxygen is available. A much greater energy yield is obtained from aerobic respiration than from respiration in anaerobic conditions.
Explain why the link reaction only occurs when oxygen is available.
any four from:
Marking guidance:
accept ora
1 pyruvate converted to, acetyl group / 2C group / acetyl CoA (in link reaction) ;
2 NAD needed (in link reaction) ;
3 (where) NAD becomes reduced ;
4 reduced NAD goes to ETC ;
5 ETC / oxidative phosphorylation, works if oxygen is present or oxygen is the final electron acceptor ;
6 (so) reduced NAD is oxidised / NAD is regenerated ;
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