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GCSE Biology · key term
A substance that kills microorganisms or prevents them from growing.
Used by OCR
Specification PAG 7 · Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Microbiological techniquesOne way to investigate an antimicrobial agent is a disc-diffusion test. Spread a suitable diluted bacterial culture evenly over sterile agar to make a lawn. Place separate sterile paper discs containing the agents on the agar, spaced apart so that their effects can be distinguished.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A substance or treatment that kills microorganisms or prevents them from growing.
When comparing antimicrobial agents, state what was kept the same: bacterial species, amount spread on the plate, disc size, agent concentration and incubation conditions.
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An antimicrobial agent can stop microorganisms growing or kill them. Antibiotics are one type; antiseptics are another. In this investigation, bacteria grow as a lawn across a nutrient agar plate.