Scientists investigated a virus that infects insect cells grown in a laboratory. After viral genetic material had entered the cells, all virus particles outside the cells were removed.
Immediately after the measurements at 24 hours, the cells were exposed to environmental stress.
| Time in hours | Number of intact host cells | Number of host cells with viral DNA incorporated into host DNA | Number of free virus particles |
|---|---|---|---|
| 0 | 200 | 0 | 0 |
| 12 | 390 | 360 | 0 |
| 24 | 760 | 720 | 0 |
| 36 | 70 | 5 | 68 000 |
Explain how the results provide evidence that the virus followed two different reproductive pathways during the investigation.
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.