A technician rinses the inside of a reusable drinks bottle with sterile water. A measured volume of the rinse water is spread onto sterile nutrient agar and incubated. Separate colonies appear on the agar.
Why can each colony be used as evidence that a bacterial cell was present in the measured volume?
Bacteria from different parts of the rinse water joined together to produce the colony.
A bacterium from the rinse water absorbed agar and enlarged to produce the colony.
A bacterium from the rinse water divided many times to produce the colony.
Bacteria already in the agar divided wherever the rinse water was spread.
282 exam-style questions on AQA GCSE Biology 1.1 Cell structure, covering 1.1.1 Eukaryotes and prokaryotes, 1.1.2 Animal and plant cells, 1.1.3 Cell specialisation, 1.1.4 Cell differentiation, 1.1.5 Microscopy, and 1.1.6 Culturing microorganisms. Each one has a worked solution and a mark scheme showing where the marks go.