4.1 Communicable diseases, disease prevention, immune system Flashcards
(30 cards)
What is a bacteria?
Bacteria are simple organisms classified as prokaryotes. They divide rapidly and cause diseases.
What diseases do bacteria cause?
Tuberculosis (TB),
Bacterial meningitis,
Ring rot in potatoes and tomatoes.
What are viruses?
Viruses are much smaller than bacteria and not true organisms, as they cannot survive long without a host.
Examples of diseases caused by viruses include AIDS (caused by HIV) and influenza.
What diseases do viruses cause?
AIDS (caused by HIV),
Influenza (in many animals),
Infection with tobacco mosaic virus (in plants)
What is a protoctista?
A protoctista is a unicellular organism that is eukaryotic and often carried by vectors, such as mosquitoes.
An example of a disease caused by protoctista is malaria.
What diseases do protoctista cause?
Protoctista can cause malaria and potato blight/tomato late blight.
What are fungi?
Fungi can be unicellular or multicellular. They are a type of eukaryotic cell with a nucleus, organelles, and a chitin cell wall.
Examples of diseases caused by fungi include black sigatoka in bananas and ringworm in cattle.
What diseases do fungi cause?
Fungi can cause black sigatoka in bananas, ringworm in cattle, and athlete’s foot in humans.
What is direct transmission?
Direct transmission refers to the spread of a disease or infection from one person to another through close contact or physical contact.
What is vertical transmission?
Transmission of a disease or infection from parent to offspring.
What is horizontal transmission?
Transmission of a pathogen passed between people by touching, kissing or sexual intercourse.
What diseases are spread through direct transmission?
HIV, Tuberculosis, Cholera, Anthrax.
Examples: HIV - from mother to child, sexual intercourse or contact with infected blood. Tuberculosis - droplets in the air from coughing and sneezing. Cholera - drinking infected water. Anthrax - travels as spores through the air, spores present in the soil.
What is indirect transmission?
Transmission of a disease through an intermediate source, such as contaminated objects or vectors.
What diseases are spread through indirect transmission?
Malaria, Lyme disease, Sleeping sickness, Dutch elm disease.
Examples: Malaria - bite from an infected female Anopheles mosquito. Lyme disease - bite from a tick, usually Ixodes ricinus. Sleeping sickness - bite from a tsetse fly (Africa). Dutch elm disease - transmitted by a beetle, Scolytus multistriatus.
How do diseases spread?
Warm, cramped, over-populated environments, with poor ventilation and sanitation.
What are plant defences?
Cellulose cell walls, lined with waterproof lignin, act as a physical barrier to pathogens. However, plant tissue also contains chemicals to kill any pathogens that try to cross this barrier.
What are some primary defences against pathogens?
Stomatal closing, production of chemicals, cellulose deposition, tylose formation.
What does stomatal closing do?
Stomata are the small pores on the underside of the leaf. These can close when pathogens are detected.
What does the production of chemicals do?
Plants produce many chemicals, such as terpenes, alkaloids, and phenols.
What is callose deposition?
This is when the sieve plates in the phloem are blocked with a polysaccharide called callose. This prevents pathogens moving through the phloem and limits the spread of the pathogen.
What is tylose formation?
This is when the xylem is blocked from carrying water by a terpene-filled swelling called a tylose. This prevents pathogens moving through the xylem.
What are the differences between callose deposition and tylose formation?
A callose deposition occurs in the phloem and a tylose occurs in the xylem. A callose is a blockage caused by polysaccharides and a tylose is a blockage caused by a terpene-filled swelling.
What are antibiotics?
Antibiotics are a group of medicines used to treat bacterial infections.
What are the benefits of antibiotics?
The first antibiotic was discovered by Alex Fleming, which was Penicillium, in 1928. Since the 1920s, many other antibiotics have been discovered, reaching a peak in the 1980s. Some come from plants and fungi, while others have been made in the laboratory by modifying already known antibiotics. However, fewer new antibiotics have been discovered in the last 2 decades. This is a problem because of the worldwide increase in the antibiotic resistance in bacteria.
