Biology 11–12 · Year 12
Pasteur's swan-neck flask experiment with sterile nutrient broth
Module 7: Infectious Disease (Causes of Infectious Disease)
Teacher-led demonstration
A teacher carries out this activity as a demonstration. Its materials, steps, variables, misconceptions and sources are not published on the open web, and neither is any result, control or note that states a number or an amount: tutors and administrators read them on the learning platform, with the safety card first. The idea, the hazards and the curriculum references are below.
Open the procedure on the learning platform (tutor or administrator sign-in)
School laboratory, not for home
In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
The idea
Sterile broth stays clear when air can reach it but dust cannot, and clouds only once airborne microbes get in, so microbes come from other microbes rather than arising from the broth itself.
Safety card
Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
Hazards
- Unknown airborne microbes grow in the broth and must be treated as potentially pathogenic
- Pressure cooker or autoclave: steam and scalds
- Bent glass tubing can snap
Controls
- Flasks are never opened after sterilisation; they are sterilised again, unopened, before disposal
- Only trained staff operate the pressure cooker or autoclave
- Glass bending is done by the technician; handle the necks by the flask, never by the tube
Note
It states a number or an amount, which may be part of the method, so it is shown with the method to tutors and administrators on the learning platform.
What you should see
It states a number or an amount, which may be part of the method, so it is shown with the method to tutors and administrators on the learning platform.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Biology Stage 6 Syllabus (2017), current: Year 11 taught to the end of 2026 and Year 12 to Term 3 2027BIO12-14BIO11/12-1BIO11/12-2BIO11/12-3
- Biology 11–12 Syllabus (2025), Year 12 focus area Diseases; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12-02
- Biology 11–12 Syllabus (2025), Year 12 Working scientifically; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12WS-01BI-12WS-02BI-12WS-03
- Australian Curriculum v9No Australian Curriculum v9 code is listed.