Pathogens: distinguish spread from damage
| English | 中文 | Pinyin |
|---|---|---|
| pathogen/ˈpæθədʒn/ | 病原体 | bìng yuán tǐ |
| toxin/ˈtɒksɪn/ | 毒素 | dú sù |
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.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
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?
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.
Match each technical term to its precise meaning.
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.
- 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?
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.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- 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.
A fictional record has 12 affected individuals among 240. Calculate the percentage. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A fictional record has 12 affected individuals among 240. Calculate the percentage.
The result is 5 %. 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.
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.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Every microorganism is a pathogen. This claim is false: 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.
Pathogens: distinguish spread from damage: 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.
Every microorganism is a pathogen.
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.
An agent that causes infectious disease: write the technical term.
pathogen means An agent that causes infectious disease.