Biology 5090/61 — October/November 2012
Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme
Topics Experimental Contexts · Observations and Measurements · Microscopy and Biological Drawing · Analysis, Conclusions and Evaluation · Planning Experiments and Investigations · Use of Techniques, Apparatus and Materials
Enzymes are used commercially to extract juice from apples.
Fig. 1.1 shows two containers of apple juice. One contains juice extracted using an enzyme and the other without an enzyme.
With reference to Fig. 1.1, compare the volume and appearance of the two juices extracted.
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Some students investigated the effect of pH on the production of apple juice using the same enzyme.
- The apples were chopped up and formed into a smooth pulp.
- The pulp was divided into samples. Each sample was adjusted to a different pH.
- Enzyme was stirred into each sample of pulp and left to stand for 10 minutes for the enzyme to react.
- The mixtures of pulp and enzyme were then filtered for 20 minutes to collect the juice. The volumes of apple juice collected, are shown in Table 1.1.
Table 1.1
| pH | volume of apple juice collected / |
|---|---|
| 3 | 40 |
| 4 | 56 |
| 5 | 95 |
| 6 | 60 |
| 7 | 30 |
Construct a graph to show the effect of pH on the production of apple juice using this enzyme.
State the optimum pH for the action of this enzyme.
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Describe and explain the effect of pH on the production of apple juice, using this enzyme.
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Suggest the factors that need to be controlled in this investigation.
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