Communicable Diseases Flashcards
What causes communicable diseases?
pathogens such as bacteria, viruses and fungi.
What is the role of a vector and give examples.
They carry pathogens from one organism to another. Common vectors are water and insects.
How are bacteria classified?
By their shape- can be rod/spherical/comma/spiralled/corkscrew shaped.
By their cell walls- Gram positive bacteria appear blue and Gram negative bacteria appear red (when stained).
What is a virus and what is the basic structure of a virus?
They are non-living infectious agents. Structure is some genetic material surrounded by proteins.
How does a virus act as a pathogen?
How are they successful pathogens?
They invade living cells and the genetic makeup of the virus invades the host cell and takes over to be able to produce more viruses.
Successful because they evolve adaptations to the host cell so they survive longer.
What is a bacteriophage?
A virus that attacks bacteria. Some are used to treat diseases.
What are protoctista?
A group of eukaryotic organisms that acts as parasites, using hosts to cause disease.
Give 2 examples of pathogenic protoctista.
hint: they need a vector to work
Malaria and sleeping sickness
Some fungi are saprophytes. What does this mean?
They feed on dead and decaying matter.
Some fungi are parasitic. What does this mean?
They feed on living plants and animals.
Which type, saprophyte or parasitic fungi, cause disease?
Parasitic fungi
What implications does a fungal disease in plants have on a community?
Whole crops can be destroyed therefore causing starvation and a lot of hardship for many people.
Pathogens have two modes of action. What are they?
1) Damaging the host tissue directly
2) Producing toxins which damage the host tissue
Explain how a pathogen works by damaging host tissue directly.
1) Viruses- take over the DNA of host cell, makes new viruses, these burst out and destroy the cell.
2) Protoctista- digest and use host cell contents to reproduce, then break open the host cell.
3) Fungi- digest living cells and destroy them.
Explain how a pathogen produces toxins to damage tissue of a host cell.
1) Bacteria- produce toxins that poison or damage the host cell in some way.
2) Fungi- produce toxins that damage the host cell.
What is ring rot?
What pathogen is it caused by?
A bacterial disease of potatoes + tomatoes.
Caused by Gram positive bacteria.
Why is ring rot threatening to humans?
Once it infects a field of crops, the field cannot be used to produce any crop for at least 2 years!
What is the tobacco mosaic virus?
What pathogen is it caused by?
A virus that infects tobacco plants.
Viruses cause this.
What is potato blight?
Which pathogen causes it?
Destruction of leaves, tubers and fruit by the fungus-like protoctist oomycete.
Why is potato blight so devastating for humans?
Each year millions of pounds worth of crop is destroyed.
What is black sigatoka and what pathogen causes it?
A banana disease caused by a fungus that attacks and destroys the leaves by digesting the plant cells, turning the leaves black.
What is common about all these plant diseases?
None of them have a cure but resistant strains and chemical treatments are used to reduce the risks of crop loss.
What is tuberculosis?
A bacterial disease of humans, cows, pigs, badgers and deer.
Damages lung tissue and suppresses the immune system.
What can be done to stop TB?
Can be cured by antibiotics and can be prevented by improving living conditions and vaccinations.
What is bacterial meningitis?
Bacterial infection of the meninges of the brain (protective membranes on the brain surface).
Can cause septicaemia and rapid death.
What can be done to prevent meningitis?
Vaccines and antibiotics if given early enough.
What is HIV/AIDS?
A disease where T helper cells are targeted by this virus and destroys the immune system so people are open to other diseases like cancer, TB and pneumonia.
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