Invertase is an enzyme found in honey. Invertase breaks down sucrose into reducing sugars, as shown in Fig. 1.1. sucrose invertase reducing sugars [Figure 1.1] You will carry out an investigation to determine the concentration of invertase in a sample of honey. The presence of the reducing sugars can be detected by using Benedict's solution. The time taken for the Benedict's solution to first show a colour change can be used to estimate the concentration of invertase in the honey extract, H. You will need to prepare a serial dilution of 1.0% invertase solution, E. You are provided with the materials shown in Table 1.1. Table 1.1 labelled contents hazard volume/cm³ H honey extract none 10 E 1.0% invertase solution harmful irritant 10 B Benedict's solution harmful irritant 30 S 5% sucrose solution none 25 W distilled water none 150 If any solution comes into contact with your skin, wash off immediately under cold water. It is recommended that you wear suitable eye protection.

1. (a)(i)Think about the hazards of using the invertase solution, E, as shown in Table 1.1. State whether the risk of using the invertase solution, E, is low, medium or high. Give a reason for your answer. risk reason[1]
2. (a)(ii)You need to carry out a serial dilution of the invertase solution, E, to reduce the concentration of invertase by a factor of 10 between each successive dilution. Fig. 1.2 shows how to prepare the 1.0% and 0.1% concentrations of invertase solution. Complete Fig. 1.2 by drawing as many extra beakers as you need for your serial dilution of invertase solution. For each beaker: • state, under the beaker, the volume and concentration of invertase solution available for use in the investigation • use one arrow with a label, above the beaker, to show the volume and concentration of invertase solution added to prepare the concentration • use another arrow with a label, above the beaker, to show the volume of W added to prepare the concentration. [Figure 1.2][3]
3. (a)(iii)State the result for H. seconds[1]
4. (a)(iv)Record your results in an appropriate table for the concentrations of invertase solution you prepared in step 1.[5]
5. (a)(v)Use your results from (a)(iii) and (a)(iv) to estimate the concentration of invertase in H. concentration of invertase in H =[1]
6. (a)(vi)Suggest how you would make improvements to this investigation in order to obtain a more accurate estimate of the invertase concentration in H.[3]
7. (b)(i)Plot a graph of the data in Table 1.2 on the grid in Fig. 1.3. Use a sharp pencil for drawing graphs. [Figure 1.3][4]
8. (b)(ii)Describe the change in percentage concentration of sucrose shown by your graph in Fig. 1.3.[2]
9. (b)(iii)State which sugars, other than sucrose, will be present in the honey after 25 weeks. Explain your answer. sugars present explanation[2]

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