A-LevelBiologyEnergy and respiration9700/41 · Oct/Nov 2018 · Q66 Marks

[Fig. 6.1] outlines some of the steps of glycolysis. [Fig. 6.1: (diagram showing glucose -> glucose 6-phosphate -> fructose 6-phosphate -> fructose 1,6-bisphosphate -> 2 triose phosphates -> 2 pyruvates, with steps 1, 2, 3, 4, 5 indicated between stages)]

(a)(i)State the precise location of glycolysis in the cell.[1]
(a)(ii)With reference to Fig. 6.1: state the steps where phosphorylation occurs ... state the step where oxidation occurs ... name the type of reaction by which ATP is made during step 5.[3]
(b)Some cancer cells have different metabolic requirements from normal cells. These cancer cells obtain most of their ATP from glycolysis, even if oxygen is available. State how the glucose and oxygen requirements of these cancer cells differ from normal cells.[2]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.

[1] cytoplasm;
[3] phosphorylation: 1 (and) 3; oxidation: 5; reaction in step 5: substrate-linked phosphorylation ;
[2] any two from cancer cells 1 need / use, more glucose ; 2 need / use, less oxygen; 3 get, little energy / 2 ATP / small amount of ATP, per glucose (molecule) / from glycolysis ;

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