Disease transmission and immune response
הוצג| English | משמעות |
|---|---|
| pathogen/ˈpæθədʒn/ | פתוגן |
| antigen/ˈæntɪdʒen/ | אנטיגן |
What would explain this observation?
- An antibiotic may help against a bacterial infection but fail against a viral illness. Treatment depends on the causal organism and the evidence supporting diagnosis.
Build the model
- Pathogens 病原体 cause infectious disease.
- Physical barriers, phagocytosis and specific immune responses reduce infection.
- Antibodies bind particular antigens 抗原.
- Vaccination exposes the immune system to antigen safely enough to develop memory.
- pathogen: An agent that causes disease.
- antigen: A structure recognized by a specific immune response.
What explains the spread of antibiotic resistance?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Resistance spreads because resistant variants survive antibiotic treatment and reproduce, so their proportion rises; this is selection acting on existing variation. Bacteria do not change their genes deliberately, and antibiotics have no effect that turns viruses into bacteria.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- After vaccination, memory cells can support a faster secondary response.
- Antibiotic resistance arises through heritable variation and selection; an individual bacterium does not choose to become resistant because it needs to survive.
In the lab: Use published infection data to compare rates per equal population size. Distinguish prevalence at a time from new cases over a period. In school, use safe simulations or approved cultures rather than collecting unknown pathogens.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: 18 cases occur in 900 people.
- Rate per 1,000 = cases / population × 1,000.
- Rate = 18/900 × 1,000 = 20 cases per 1,000.
- A second group with 10 cases in 250 people has 40 per 1,000, even though it has fewer cases.
Your turn: 12 cases occur among 600 people. Find cases per 1,000 people.
12 cases occur among 600 people. Find cases per 1,000 people.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 20 . Known: 12 cases among 600 people. Use rate per 1,000 = cases / population x 1,000. Rate = 12/600 x 1,000 = 20 cases per 1,000 people. Rates per equal population size allow a fair comparison between groups of different size.
Check the conclusion and its limits
- Antibiotics do not act on viruses in the same way they act on bacteria.
- A vaccine is not an immediate cure for an established infection.
Not true: Every antibiotic is effective against every viral infection. Antibiotics act on bacterial structures and processes that viruses do not have, so they cannot cure a viral infection. Using them against viruses adds selection pressure for resistance without benefit.
- Pathogens cause infectious disease.
- After vaccination, memory cells can support a faster secondary response.
- Watch for: antibiotics do not act on viruses in the same way they act on bacteria.
Write from 16 cases per 1000
- 8 cases occur among 500 people.
- Find the rate per 1000. A smaller case count can still be a higher rate.
Every antibiotic is effective against every viral infection.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Antibiotics act on bacterial structures and processes that viruses do not have, so they cannot cure a viral infection. Using them against viruses adds selection pressure for resistance without benefit.
An agent that causes disease: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
pathogen means An agent that causes disease.
8 cases occur among 500 people. What is the rate per 1000 people, and why is the raw case count not enough for a comparison?
8 over 500 is 0.016, and 0.016 times 1000 is 16 per 1000.
What is the rate?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
8 divided by 500, times 1000, is 16.