A student plans an investigation using mould - AQA - GCSE Biology - Question 4 - 2018 - Paper 1

To test the hypothesis, the student would follow these steps:

1. Cut a specified number of slices of bread to the same size.
2. Place the same number of mould spores on each slice of bread to ensure consistency.
3. Seal each slice in different sealable plastic bags.
4. Place the bags in different controlled environments, such as a refrigerator, room temperature, and an incubator to test various temperatures.
5. Leave each bread sample for a set amount of time to allow mould growth.
6. Measure the amount of mould growth on each slice after the incubation period and compare results to determine how temperature affects mould growth.

The student should control the amount of mould spores used on each slice of bread to ensure that the results are consistent and reliable.

To determine the rate of mould growth at 42 °C, observe the amount of mould on day 2 and on day 7 from Figure 3.
If the amount of mould on day 2 is 10 units and on day 7 is 52 units, the rate of growth can be calculated as follows:
$ext{Rate of growth} = \frac{(52 - 10)}{(7 - 2)} = \frac{42}{5} = 8.4 \text{ units per day}$