A virus infects cells of a single-celled organism grown in culture. Immediately after the 4-hour sample, an environmental stress is applied to the culture.
| Time in hours | Number of host cells in the sample | Number of host cells with viral DNA incorporated into their chromosomes | Number of complete virus particles detected | Host cell lysis detected |
|---|---|---|---|---|
| 0 | 100 | 100 | 0 | no |
| 2 | 200 | 200 | 0 | no |
| 4 | 400 | 400 | 0 | no |
| 6 | 120 | 120 | 28 000 | yes |
Explain what the results show about the viral pathway operating from 0 to 4 hours and how the environmental stress affected the viral pathway by 6 hours.
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.