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2. (a) The rates of enzyme-catalysed reactions can be influenced by the pH at which they occur.
Table 1 shows the relative reaction rates for salivary amylase and arginase at different pH
values.
(i) On the graph grid provided, plot a graph of the relative rates for BOTH salivary
amylase and arginase.
[6 marks] DO NOT WRITE IN THIS AREA
TABLE 1: REACTION RATES FOR TWO ENZYMES
Relative reaction rates
pH Values Salivary amylase Arginase (units)
(units)
4.5 2.2 0
5.0 5.0 0
5.5 8.0 0.2
6.0 13.0 1.0
6.5 17.0 4.0
7.0 18.0 7.0
7.5 16.0 9.0
8.0 11.0 11.8 DO NOT WRITE IN THIS AREA
8.5 6.0 13.5
9.0 2.0 16.0
9.5 18.0
10.0 17.8
10.5 15.0
11.0 14.0
(ii) Using the graph, determine the optimal pH for
(a) arginase activity ...............................................................................................
[1 mark]
(b) salivary amylase activity .................................................................................
[1 mark] DO NOT WRITE IN THIS AREA
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