Link reaction and Krebs cycleAQA A-Level Biology: Mind map

Exam questions on Link reaction and Krebs cycle

1. Pyruvate produced by glycolysis in the cytoplasm of a liver cell is taken up by the mitochondria when oxygen is available.
   Explain, with reference to carbon atoms and NAD, what happens to pyruvate when it is oxidised to acetate in the link reaction.2 marks
2. The Krebs cycle was studied in isolated mitochondria supplied with acetylcoenzyme A and oxygen.
   Explain why the Krebs cycle would stop if the isolated mitochondria were deprived of oxygen.2 marks
3. Each glucose molecule gives two pyruvate molecules in glycolysis. Each pyruvate goes through the link reaction, which releases one carbon dioxide molecule and forms one reduced NAD, and each acetylcoenzyme A then enters one turn of the Krebs cycle. One turn of the Krebs cycle releases two carbon dioxide molecules and produces three reduced NAD, one reduced FAD and one ATP.
   Calculate the number of carbon dioxide, reduced NAD and ATP molecules produced by the link reaction and Krebs cycle for each glucose molecule.3 marks