Edexcel GCSE Biology 1BI0
Key Concepts in Biology
Cells and Control
Genetics
Natural Selection and Genetic Modification
Health, Disease and the Development of Medicines
Plant Structures and Their Functions
Animal Coordination, Control and Homeostasis
Exchange and Transport in Animals
Ecosystems and Material Cycles
Health, Disease and the Development of Medicines
Aseptic technique in culturing microorganisms
- 3 things to know
- Paper 1
Overview
Aseptic technique, sterilising growth medium and Petri dishes in an autoclave, flaming and cooling the inoculating loop, keeping cultures covered and taping lids, and why school cultures are incubated at 25 °C.
What you need to know
Answer each one before you reveal it.
What is an autoclave used for?
Explain why growth medium must be sterilised before it is used.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by aseptic technique?
Model answer
Working in a way that prevents unwanted microorganisms contaminating a culture or escaping into the surroundings.
- 2
What is an autoclave used for?
Model answer
An autoclave uses steam at high temperature and pressure to sterilise growth medium and Petri dishes.
- 3
Explain why growth medium must be sterilised before it is used.
Model answer
Any microorganisms already present would grow on the medium and make the results invalid.
- 4
Describe how an inoculating loop is sterilised.
Model answer
It is held in a Bunsen flame until it glows red hot, then allowed to cool.
- 5
Explain why an inoculating loop must be cooled before it touches a culture.
Model answer
A hot loop would kill the microorganisms it is meant to transfer.
- 6
Explain why Petri dishes and culture vials are kept covered.
Model answer
The lid stops microorganisms in the air landing on the medium, and stops the cultured microorganisms escaping.
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