Pathogens: distinguish spread from damage
הוצג| English | משמעות |
|---|---|
| pathogen/ˈpæθədʒn/ | מחווה |
| toxin/ˈtɒksɪn/ | רעל |
What would explain this observation?
- Two diseases can spread through the same route but damage a host in different ways. Identify both the pathogen 病原体 and its route before proposing a control.
Build the model
- A pathogen causes infectious disease.
- The specification includes viruses, bacteria, fungi and protists.
- Bacteria can multiply rapidly in suitable host conditions and may release toxins 毒素 that damage tissues.
- Viruses reproduce inside host cells, causing cell damage.
- Pathogens can pass by direct contact, contaminated water or air; a vector can carry a pathogen between hosts.
- pathogen: An agent that causes infectious disease.
- toxin: A poison produced by an organism that can damage tissues.
Which explanation matches a viral infection?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Viruses replicate only inside host cells, often damaging or bursting them - that is how viral disease develops. A virus is not a toxin, and most microorganisms are harmless or beneficial.
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
- A prevention must interrupt the stated transmission route.
- Safe food and clean water reduce ingestion of pathogens; hygiene can reduce contact transmission.
- Ventilation and limiting exposure can reduce some airborne transmission.
- Controlling a vector interrupts a different route.
- These measures reduce risk rather than prove that every infection has been prevented.
In the lab: Use fictional outbreak records without collecting classmates’ medical information. Sort evidence into pathogen type, transmission route, host damage and proposed control. Explain each control using the route given, then identify evidence needed to test the explanation. Never culture unknown samples from bodies or an outbreak.
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: a fictional school model records 18 cases among 300 people exposed to a stated source.
- The observed proportion is 18/300×100 = 6%.
- A second group has 8 among 200, or 4%.
- Counts alone would hide the different denominators.
- These observations do not establish causation or diagnose an individual.
Your turn: A fictional record has 12 affected individuals among 240. Calculate the percentage.
A fictional record has 12 affected individuals among 240. Calculate the percentage.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 5 %. Known: 12 affected among 240. Use percentage = affected / total x 100. Percentage = 12/240 x 100 = 5%. Observed proportions do not by themselves establish causation.
Check the conclusion and its limits
- A toxin is not the same thing as a virus.
- An infectious disease can affect a plant as well as an animal.
- Not all microorganisms cause disease, and a high observed disease rate does not by itself identify the transmission route.
Not true: Every microorganism is a pathogen. Pathogens are the minority of microorganisms that cause disease. Decomposers, nitrogen-fixers and gut bacteria are essential and harmless members of the microbial world.
- A pathogen causes infectious disease.
- A prevention must interrupt the stated transmission route.
- Watch for: A toxin is not the same thing as a virus.
Pathogens are the minority of microorganisms that cause disease.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
True. Pathogens are the minority of microorganisms that cause disease. Decomposers, nitrogen-fixers and gut bacteria are essential and harmless members of the microbial world.
An agent that causes infectious disease: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
pathogen means An agent that causes infectious disease.