Scientists investigated the spread of a fungal disease in two similar nursery plots. The plants surrounding the infected source plants were initially healthy.
The source plants in both plots had been infected for the same length of time and had already released some spores. The scientists then removed the source plants from one plot but left the source plants in the other plot.
Four weeks later, the scientists recorded the percentage of surrounding plants that had become infected.
| Distance from the source plants or their original position (m) | Source plants left in place (%) | Source plants removed (%) |
|---|---|---|
| 2 | 50 | 22 |
| 10 | 34 | 14 |
| 20 | 19 | 7 |
| 40 | 7 | 2 |
Compare the patterns in the results for the two plots.
Suggest why infection was still recorded in the plot where the source plants were removed.
The nursery removes infected material from both plots after the survey. Explain why restricting the movement of plants from other growing areas at the nursery is still necessary.
112 exam-style questions on Edexcel GCSE Biology 5.1 Health and communicable disease, covering 5.1.1 Communicable and non-communicable diseases, 5.1.2 Disease susceptibility interactions, 5.1.3 Pathogens as disease-causing organisms, 5.1.4 Common infections, 5.1.5 Spread and prevention of pathogens, 5.1.6 Lifecycle of a virus, and 5.1.7 Spread and prevention of STIs. Each one has a worked solution and a mark scheme showing where the marks go.