A student in a school laboratory is investigating the antimicrobial properties of garlic extract on a culture of Bacillus subtilis. To ensure a safe and valid investigation, aseptic techniques must be strictly followed.
Which of the following options describes an incorrect procedure or explanation for a step in this aseptic protocol?
The inoculating loop is flamed until red-hot to sterilise it, and is then allowed to cool near the Bunsen burner flame to prevent killing the bacteria upon contact.
The Petri dish is sealed completely around its circumference with airtight tape to prevent any potentially pathogenic bacteria from escaping into the laboratory.
The neck of the culture bottle is passed through a flame to heat the air at the opening, creating an outward convection current that prevents airborne contaminants from entering.
The inoculated agar plates are incubated at a maximum temperature of 25 ∘C25\ ^\circ\text{C}25 ∘C rather than 37 ∘C37\ ^\circ\text{C}37 ∘C to avoid promoting the selective growth of human pathogens.
40 exam-style questions on OCR A A Level Biology Communicable diseases, disease prevention and the immune system. Each one has a worked solution and a mark scheme showing where the marks go.