A carton of milk contains 150 bacteria of one species. The milk is kept warm for 3 hours, and conditions are suitable for the bacteria to reproduce.
The bacteria have a mean division time of 20 minutes. Assume that no bacteria die.
Calculate the number of complete divisions during the 3 hours.
Use your answer to part (a) to calculate the population at the end of the 3 hours.
Give your answer in standard form.
A test gives a positive result when the population reaches at least 1.0 × 104 bacteria.
Calculate the earliest time at which the test would give a positive result.
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.