Key ideas1 of 3
Count the divisions first
Suppose one bacterium divides every 20 minutes. In 60 minutes there are 60 ÷ 20 = 3 divisions. Double three times: 1 → 2 → 4 → 8 cells.
Separate Biology · Paper 1 · Foundation + Higher
Bacterial numbers and clear-zone area
No timer. Read the explanation after each answer.
Lesson questions complete
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.