The pH scale is used to quantitatively assess how acidic or basic a solution is. The pH scale ranges from 0 – 10, with lower
pH being more acidic and higher pH being more basic. A pH of 7 is considered neutral (neither acidic nor basic). The pH of the
surrounding environment can have a great effect on what microbes are able to grow. Examine the data in Table 4, which shows
the pH of culture media and the number of microbial colonies observed growing in each culture. Then, answer the questions
below.
Table 4: pH Versus Number of Microbial Colonies
pH 0 1 2 3 4 5 6 7 8 9 10
Number of Colonies Observed 0 2 6 24 36 124 268 296 213 98 34
- What patterns do you observe based on the information in Table 4?
- Develop a hypothesis relating the pH level of the culture media to the number of microbial colonies observed in each
culture. - What would your experimental approach be to test this hypothesis?
- What would be the independent and dependent variables?
- What would be your control?
- What type of graph would be appropriate for this data set? Why?
- Graph the data from Table 4.
- Interpret the data from the graph you made in Question 7.
Sample Solution
