Disease transmission and immune response
Введено| English | Значение |
|---|---|
| pathogen/ˈpæθədʒn/ | патоген |
| antigen/ˈæntɪdʒen/ | антиген |
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?
Сложность 1/5 · 100 монет + небольшой бонус за первое выполнение сегодня
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.
Сложность 2/5 · 140 монет + небольшой бонус за первое выполнение сегодня
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?
Сложность 2/5 · 140 монет + небольшой бонус за первое выполнение сегодня
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.
Сложность 2/5 · 140 монет + небольшой бонус за первое выполнение сегодня
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 45 cases per 1,000 people
- 18 cases occur among 400 people.
- Find cases per 1,000 people. Antibiotics do not treat viral infections.
Every antibiotic is effective against every viral infection.
Сложность 1/5 · 100 монет + небольшой бонус за первое выполнение сегодня
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.
Сложность 1/5 · 100 монет + небольшой бонус за первое выполнение сегодня
pathogen means An agent that causes disease.
18 cases occur among 400 people. How many cases is that per 1,000 people, and why is an antibiotic not a treatment for a viral infection?
Scale the count to 1,000 people by dividing by the population and multiplying by 1,000. The drug has to match the kind of pathogen.
How many cases is that per 1,000 people?
Сложность 1/5 · 100 монет + небольшой бонус за первое выполнение сегодня
18 divided by 400 is 0.045, and 0.045 times 1000 is 45. Other options — 20 (the lesson example's result for 12 cases among 600 people); 18 (the number of cases).