Include treated and untreated cultures, standardise bacterial growth and compound dose, repeat measurements and identify the lowest concentration meeting the MIC threshold.
The resistance of bacteria to antibiotics can be studied using a mast ring.
A mast ring is made of filter paper.
Each part of the mast ring contains a different type of antibiotic or different mass of the same antibiotic.
The diagram shows a mast ring placed on agar in a Petri dish that has been spread with bacteria.
The table shows the mass of each antibiotic in the mast ring.
Clear zones around the mast ring indicate that the growth of the bacteria has been inhibited.
The greater the diameter of the zone of inhibition, the more effective the antibiotic.
Explain how the results shown in the diagram can help a doctor decide how to prescribe antibiotics to a patient who is infected with this type of bacteria.
(b) How much more antibiotic is in part B3 than in part B2?
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A 0.5 times