The yeast Saccharomyces cerevisiae cannot naturally ferment the sugar xylose. Low value biomass, such as straw and wood fibres, contains up to 20% xylose. S. cerevisiae was modified to enable it to produce ethanol from xylose. Information on the two species involved in making the modified S. cerevisiae is shown in the table.
- Explain why biotechnology was needed to modify S. cerevisiae. (2 marks)
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- Two strains of genetically modified S.cerevisiae were produced. The two strains were compared under the same conditions. The results are shown.
- Justify which of these two strains would be better to use to produce commercial quantities of ethanol using low value biomass. In your answer, refer to information from the graph. (3 marks)
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