2 Draw a labelled diagram to show how this investigation was carried out. 3 How would David and Ben make sure that they carried out a fair test?
pH Trial 1 (volume of foam cm3)
3 5 7 9
11 4
16 20 19 4
Trial 2 (volume of foam cm3)
6
17 29 20 4
Trial 3 (volume of foam cm3)
5
18 17 21 4
4 Why do you think they repeated each investigation three times?
It is important to analyse data to see if any repeated measurements do not match. These are called outliers. To make sure that results are reliable, the investigation should be repeated until at least two points are close in value.
5 Which data set do you think needed to be repeated again? Explain your choice.
Effect of pH on the effectiveness of the enzyme catalase David and Ben constructed the following graphs of their findings.
10 15 20 25
0 5
Effect of pH on the effectiveness of the enzyme catalase
10 15 20 25
0
0 5
0
10 15 20 25
0 5
Effect of pH on the effectiveness of the enzyme catalase 3 7 pH z Effect of pH on the effectiveness of the enzyme catalase
10 15 20 25
0
6 Discuss the advantages and disadvantages of each graph. 0
0 5
3 5 7 pH 9 11
7 David and Ben drew conclusions from their observations about what the pH of blood must be for enzymes to work at their best. What conclusions do you think they came up with?
8 Do some research to find out if these conclusions agree with what is known about the pH of blood. Write a short paragraph to explain why the pH of blood is important for normal body functions.
