A-LevelBiologyEnergy and respiration9700/43 · May/June 2019 · Q89 Marks
(a) Table 8.1 shows some of the stages of glycolysis and respiration in anaerobic conditions in yeast. The stages are not listed in the correct order. [Table 8.1]
- (a)Complete Table 8.2 to show the correct order of the stages. One stage has been completed for you. [Table 8.2][4]
- (b)Yeast respires glucose in aerobic and anaerobic conditions. Explain why less ATP is produced when yeast respires in anaerobic conditions compared to when yeast respires in aerobic conditions.[5]
Mark scheme
Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.
- [4] (a) E and H in correct position; A and I in correct position ; B and C in correct position; G and D in correct position ;
- [5] (b) any five from: in yeast 1 only glycolysis occurs ; 2 (net) 2 ATP produced ; 3 no oxygen as (final) electron acceptor; 4 (so) pyruvate does not enter mitochondria ; 5 ETC / chemiosmosis / oxidative phosphorylation / Krebs cycle / link reaction, does not occur; 6 (ETC / chemiosmosis / oxidative phosphorylation) produce most ATP ; 7 pyruvate / ethanal, converted to ethanol ; 8 ethanol still energy-rich / AW ;
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