Practice IB Biology Topic C3.2 Defense Against Disease with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for C3.2 Defense Against Disease and mirrors Paper 1A, 1B, 2 style where relevant.
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Bacterial and virus-infected human-cell cultures were treated for six hours. Which inference explains why P and Q cannot treat the viral infection?
| Treatment | Target | Bacterial population / % control | Virus yield / % control |
|---|---|---|---|
| none | none | 100 | 100 |
| P | peptidoglycan synthesis | 8 | 98 |
| Q | 70S ribosomes | 12 | 101 |
| R | eukaryotic ribosomes | 96 | 6 |
…
Antibody binding was measured after treating intact pathogens. Which antigen property is supported?
| Treatment | Antibody binding / % of control |
|---|
| Membrane integrity / % |
|---|
| none | 100 | 100 |
| surface protease | 8 | 100 |
| surface lipase | 92 | 100 |
Hosts received live or heat-killed agent X. Which classification is supported?
| Preparation | X replicates | Disease develops | Antibodies to X develop |
|---|---|---|---|
| live X | yes | yes | yes |
| heat-killed X | no | no | yes |
X was injected on days 0 and 28; Y only on day 28. Peak ratio = post-day-28 peak ÷ X's first peak. Which evidence identifies the secondary response?
Which exposures can transmit HIV?
| Exposure | Description |
|---|---|
| P | HIV-containing blood contacts intact skin |
| Q | HIV-containing semen contacts rectal mucosa |
| R | saliva without blood contacts intact skin |
| S | HIV-containing blood enters through a shared needle |
A lipid antigen is exposed on the pathogen surface
A protein-containing antigen is exposed on the pathogen surface
A protein-containing antigen is confined inside the pathogen
A nucleic-acid antigen is released from the pathogen
