Equal numbers of bacteria are added to three solutions. The table shows the percentage surviving after the same time.
Table
| Solution | pH | Active lysozyme present | Bacteria surviving |
|---|---|---|---|
| P | 2 | no | 5% |
| Q | 7 | no | 95% |
| R | 7 | yes | 20% |
Which comparisons separately support an effect of acidity and an effect of lysozyme?
P with R for acidity; P with Q for lysozyme
P with Q for acidity; Q with R for lysozyme
Q with R for acidity; P with Q for lysozyme
P with Q for acidity; P with R for lysozyme
45 exam-style questions on Edexcel GCSE Biology 5.2 Plant and body defences, covering 5.2.1 Physical plant defences, 5.2.2 Chemical plant defences, 5.2.3 Detecting plant diseases, and 5.2.4 Human physical and chemical defences. Each one has a worked solution and a mark scheme showing where the marks go.