Yeast and glucose solution were mixed to make a suspension. The suspension was divided into three equal volumes and placed at 2 °C, 25 °C and 60 °C for 30 minutes. Fig. 4.1 shows the results: froth formed only at 25 °C.

1. (a) Explain the difference between results at 2 °C and at 25 °C. [4]
2. (b) The suspension kept at 60 °C was then placed at 25 °C for another 30 minutes. Predict what will happen in this suspension. [1]
3. (c) Explain your prediction. [2]

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