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A-LevelBiologyEnzymesFeb/Mar 2017Paper 3 Q121 Marks

Enzyme E hydrolyses (breaks down) starch to reducing sugar. You are required to investigate the effect of temperature (independent variable) on the activity of E by recording the time taken for the starch to be hydrolysed (dependent variable). (a) You will investigate the hydrolysis of starch: • at room temperature • at other temperatures, starting at 40°C to a maximum of 80 °C. You are provided with: labelled | contents | hazard | volume/cm³ E | 2.0% enzyme E solution | harmful | 20 S | starch solution | none | 50 iodine | iodine solution | none | 15 You are advised to wear suitable eye protection. Iodine solution is a stain. If E or iodine comes into contact with your skin, wash it off immediately under cold water. The enzyme and starch solutions are mixed together and then a sample of the mixture is removed every 15 seconds and tested for starch. The end-point of the hydrolysis of the starch is when a sample does not change the colour of iodine solution, showing that all of the starch has been hydrolysed.

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About This A-Level Biology Question

This structured question appeared in the Cambridge A-Level Biology (9700) Feb/Mar 2017 examination, Paper 3 Variant 3. It tests the topic of Enzymes and is worth 21 marks.

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