Infection & ResponseDeep Dive
Required Practical: Growing Bacterial Cultures
Part of Pathogens and Disease Transmission — GCSE Biology
This deep dive covers Required Practical: Growing Bacterial Cultures within Pathogens and Disease Transmission for GCSE Biology. Types of pathogens, how diseases spread, transmission methods, and prevention strategies It is section 9 of 18 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 9 of 18
Practice
18 questions
Recall
20 flashcards
Required Practical: Growing Bacterial Cultures
Safety Considerations
- Temperature: Grow cultures at 25°C (not 37°C) to reduce risk of growing harmful pathogens
- Sterilisation: All equipment must be sterilised to prevent contamination
- Personal protection: Wear goggles, gloves, and work near a Bunsen burner flame
- Disposal: Autoclave cultures before disposal
- Sealed plates: Tape petri dishes shut but don't completely seal (allows gas exchange)
Investigating Antibacterial Substances
- Preparation: Sterilise petri dishes and nutrient agar
- Inoculation: Spread bacteria evenly across agar surface (bacterial lawn)
- Treatment: Place paper discs soaked in different antibacterial substances
- Control: Include disc soaked in water (negative control)
- Incubation: Leave at 25°C for 24-48 hours
- Measurement: Measure diameter of clear zones around each disc
Results Interpretation
- Clear zones: Areas where bacteria have been killed or inhibited
- Larger zones: More effective antibacterial substance
- No zone: Substance has no antibacterial effect
- Control importance: Shows that the disc itself doesn't kill bacteria