Invertase is an enzyme that catalyses the breakdown of sucrose into glucose and fructose. Invertase can be extracted from yeast cells. You will investigate the effect of an invertase extract on a sucrose solution and estimate the concentration of reducing sugars produced. You are provided with the materials shown in Table 1.1. Table 1.1 labelled contents hazard volume/cm³ E invertase extract irritant 20 R 0.5% reducing sugar solution none 40 W distilled water none 100 S 0.2% sucrose solution none 20 Benedict's Benedict's solution harmful irritant 20 If any solution comes into contact with your skin, wash off immediately under cold water. It is recommended that you wear suitable eye protection. You will need to make the different concentrations of reducing sugar solution using the 0.5% reducing sugar solution, R. You will need to prepare 20 cm³ of each concentration, using R and W. Table 1.2 shows the concentrations of reducing sugar you will use. Decide which volumes of R and W you will use.

1. (a)(i)Complete Table 1.2 to show how you will prepare the concentrations of reducing sugar using R and W. Table 1.2 percentage concentration of reducing sugar volume of R /cm³ volume of W /cm³ 0.5 20.0 0.0 0.1 0.05 0.01 0.4 0 0.0 20.0[2]
2. (a)(ii)Record your results in an appropriate table.[5]
3. (a)(iii)Record the time taken to the first appearance of a colour change in test-tube W and test-tube E. result for W ...................................................... s result for E ...................................................... s[1]
4. (a)(iv)Use your results in (a)(ii) and (a)(iii) to estimate the concentration of reducing sugar in test-tube W and test-tube E. concentration in test-tube W = .......................................................... % concentration in test-tube E = .......................................................... %[1]
5. (a)(v)With reference to the invertase extract, distilled water and sucrose solution, explain the results in (iv). test-tube W test-tube E[3]
6. (a)(vi)Suggest two improvements to the procedure that would give you a more accurate value for your estimated concentration of reducing sugar in test-tube E. 1 2[2]
7. (b)(i)Plot a graph of the data shown in Table 1.3 on the grid in [Figure 1.1]. Use a sharp pencil.[4]
8. (b)(ii)State the percentage concentration of catalase that gave an anomalous result. percentage concentration ........................................................[1]
9. (b)(iii)Describe the trend shown by the results.[1]
10. (b)(iv)Suggest an explanation for the result at 0% concentration of catalase.[1]
11. (b)(v)The student observed that the size of the bubbles varied. Suggest a more accurate method of measuring the oxygen produced.[1]

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