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Separate Biology · Paper 1 · Foundation + Higher

Testing antiseptics and antibiotics

Key ideas1 of 4

Look for a clear zone

An antimicrobial can prevent bacterial growth. On a plate covered in bacteria, a clear zone of inhibition around a disc shows where growth has been inhibited. Compare the zones for A and B.

Three agar plates. A has a small clear circle around its disc; B a larger clear circle; C, the water control, has no clear zone beyond the disc.

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Practice, downloads and sources

Daily 5 · Exam practice · Revision sheet ↓

Foundation + Higher. Use alongside the shared B1–B4 lessons.

AQA GCSE Biology 8461 · 4.1.1.6. Original teaching notes, questions and diagrams.