Decay of Bread

What can speed up the decay of bread?

Aims
In this activity you are going to think about the conditions that would affect the speed at which bread decays and then design a fair test to investigate one of the. This will help you to understand all the points you need to consider when planning an experiment.

Safety
If you perform this activity: * Do not taste any food. * Wear gloves when handling food. * Wash your hands when you have finished setting up your experiment. * Your teacher my ask you to wear safety glasses. * Dispose of the bread as your teacher asks. * Do not open containers once the bread has gone mouldy.

Equipments
If you perform this activity your teacher will tell you what is available.

Method
1 Read the following introduction and then answer the questions that follow:

Materials decay because they are digested (broken down) by microorganisms.
Microorganisms digest materials at different rates depending on the conditions.

In this activity, you are going to plan an experiment to investigate the conditions that speed up the decay of bread. You will be given cubes of bread that have been left in the air for one hour and are then ready to be put into Petri dishes, which you will seal. You can choose the conditions for each Petri dish.

Questions

1 What conditions are needed for bread to decay?

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2 Why do you think the bread has been exposed to the air for an hour? ............................................................................................................................

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