O-LevelBiologyRespiration5090/22 · Oct/Nov 2014 · Q411 Marks
Fig. 4.1 is an incomplete flow chart of the process of anaerobic respiration in yeast and in muscles. [Figure 4.1]
- (a)Complete Fig. 4.1 to show the substrate and products for anaerobic respiration in yeast and in muscles.[4]
- (b)(i)Yeast cells may be killed by their use in food biotechnology. Explain what causes the death of the yeast in each of the following. brewing[2]
- (b)(ii)Yeast cells may be killed by their use in food biotechnology. Explain what causes the death of the yeast in each of the following. making bread[1]
- (c)Explain why muscle cells are not killed by anaerobic respiration in a healthy person.[2]
- (d)Suggest why anaerobic respiration does not release as much energy as aerobic respiration for each molecule of the same substrate.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.
- [4] glucose / C6H12O6 (substrate);
- (yeast) alcohol / ethanol / C2H5OH ;
- (yeast) carbon dioxide / CO2;
- (muscles) lactic acid / lactate / C3H6O3 ;
- [max. 2] food/glucose deficiency / AW ;
- (killed) by alcohol ;
- poisoned by competing organisms (e.g. bacteria) ;
- [1] (killed) by heat / baking / high temperature ;
- [max. 2] lactic acid removed/broken down/converted ;
- by circulation / blood / AW ;
- lactic acid not toxic (at concentrations experienced);
- [max. 2] substrate/glucose not completely broken down ;
- chemical energy ;
- still contained within product/lactic acid/alcohol;
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