Describe the effect of pH on the enzyme by comparing the volumes and appearance of the filtered juice in measuring cylinders B and D. State two variables that were controlled in this investigation. Suggest two ways in which you could change this investigation to make the results more accurate.

2. (e) Step 1: Recall the pH values for buffer X and buffer Y from part (a). Buffer X has a pH of 4, and buffer Y has a pH of 8. Step 2: Compare the volumes of filtered juice for cylinders B and D from Table 2.2. Volume for B (with enzyme and buffer X, pH 4) is 19 cm^3. Volume for D (with enzyme and buffer Y, pH 8) is 11 cm^3. Step 3: Describe the difference in volumes and relate it to enzyme activity and pH. The volume of filtered juice in cylinder B (19 cm^3) is greater than in cylinder D (11 cm^3). This indicates that the enzyme was more active at pH 4 (buffer X) than at pH 8 (buffer Y), as more juice was produced. Therefore, the enzyme works better at pH 4, which is closer to its optimum pH* for breaking down the fruit pulp. 2. (f) (i) Step 1: Identify variables that were kept constant throughout the experiment to ensure a fair test. The volume of fruit pulp* was 25 cm^3 in all cups. The volume of buffer* (X or Y) was 5 cm^3 in all cups. The volume of enzyme solution* (or water for control) was 2 cm^3 in all cups. The temperature* was kept constant (implied by the setup, usually experiments are done at room temperature or controlled temperature). The type of fruit* used was the same. The time* allowed for the enzyme reaction was the same for all cups. Step 2: State two of these controlled variables. 1. Volume of fruit pulp (or type of fruit) 2. Volume of enzyme solution (or water) 2. (f) (ii) Step 1: Think about ways to improve the accuracy of experimental results in general. Repeat the experiment* multiple times and calculate an average to reduce the impact of random errors. Use more precise measuring equipment* (e.g., burettes or pipettes instead of measuring cylinders for smaller volumes). Use a wider range of pH values* with smaller intervals to pinpoint the optimum pH more accurately. Maintain a more constant temperature* using a water bath. Ensure thorough mixing* of contents in each cup. Step 2: Suggest two specific ways to change this investigation for more accurate results. 1. Repeat the experiment multiple times and calculate an average. 2. Use a water bath to maintain a constant and precise temperature. Drop the next question.