Edexcel IGCSEBiologyGeneral Applications7 Marks
A student investigated the effect of different antibiotic concentrations on bacterial growth.
- (a)Suggest two aseptic techniques the student should use to prevent contamination of their bacterial cultures.[2]
- (b)Describe how the student could measure the effect of the antibiotic on bacterial growth.[3]
- (c)Explain why it is important for a patient to complete the full course of antibiotics, even if they feel better.[2]
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- 19(a) B1: sterilise petri dishes / agar / equipment / work surface (1)
- B1: flaming the inoculating loop / working near a Bunsen flame / wash hands (1)
- 19(b) M1: place antibiotic discs (of different concentrations) on agar plate (1)
- M1: inoculated with bacteria (1)
- A1: measure diameter of zone of inhibition (after incubation) (1)
- 19(c) M1: (not completing course) may leave some bacteria alive (1)
- A1: these bacteria are likely to be resistant / leads to development of antibiotic resistance (1)
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