Infection and Response: Exam Practice

This lesson brings together everything you have learned about infection and response, focusing on the key exam skills you need. It also covers the Required Practical: investigating the effect of antiseptics or antibiotics on bacterial growth, which is directly examined in AQA GCSE Biology.

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Required Practical: Effect of Antiseptics or Antibiotics on Bacterial Growth

This is one of the required practicals for AQA GCSE Biology. You need to know the method, how to calculate the area of the zone of inhibition, and how to evaluate the results.

Aim

To investigate the effect of different antiseptics or antibiotics on the growth of bacteria.

Equipment

• Nutrient agar plates (pre-prepared with bacteria such as E. coli)
• Paper discs soaked in different antibiotics or antiseptics
• Forceps (sterilised)
• Bunsen burner
• Incubator (set to a maximum of 25 degrees Celsius in school laboratories)
• Marker pen
• Ruler
• Adhesive tape

Method