Viruses, bacteria, protists and fungi, how they spread and how spread is reduced, plus the specific diseases named in the specification: measles, HIV, TMV, salmonella, gonorrhoea, rose black spot and malaria.
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1.What is a pathogen?
A microorganism that causes infectious disease. Pathogens can be viruses, bacteria, protists or fungi.
2.What is a communicable disease?
A disease that can be spread from person to person, or between animals and people.
3.How do bacteria make us feel ill?
They reproduce rapidly inside the body and produce toxins that damage tissues.
4.How do viruses make us feel ill?
They live and reproduce inside cells, damaging or destroying the cell when the new viruses burst out.
5.Name four ways pathogens can be spread.
Direct contact, through water, through the air in droplets, and by a vector such as an insect.
6.Give four ways the spread of disease can be reduced.
Better hygiene such as hand washing, destroying vectors, isolating infected people, and vaccination.
7.What type of pathogen causes measles, and what are the symptoms?
A virus. It causes a fever and a red skin rash.
8.How is measles spread?
By inhaling droplets from the sneezes and coughs of an infected person.
9.Why is measles a serious disease?
It can be fatal if complications develop, for example affecting the lungs or the brain.
10.How is measles prevented?
Most young children are vaccinated against it.
11.What type of pathogen is HIV, and what are the early symptoms?
A virus. It initially causes a flu-like illness.
12.How is HIV spread?
By sexual contact, or by the exchange of body fluids such as blood when drug users share needles.
13.What does HIV do if it is not treated?
It attacks the body's immune cells. Eventually the immune system is damaged so badly it cannot deal with other infections or cancers.
14.What is late stage HIV infection called?
AIDS.
15.How is HIV controlled?
With antiretroviral drugs, which stop the virus replicating inside the body.
16.What is tobacco mosaic virus and what does it do?
A widespread plant pathogen affecting many species including tomatoes. It produces a distinctive mosaic pattern of discolouration on the leaves.
17.Why does tobacco mosaic virus reduce the growth of a plant?
The discoloured parts of the leaf cannot photosynthesise properly, so the plant produces less glucose for growth.
18.What type of pathogen is rose black spot, and what are the symptoms?
A fungus. Purple or black spots develop on the leaves, which then turn yellow and drop off early.
19.How does rose black spot affect the plant?
With fewer leaves, photosynthesis is reduced, so growth is poor.
20.How is rose black spot spread and treated?
It spreads in the environment by water and wind. It is treated with fungicides, and by removing and destroying the affected leaves.
21.What type of pathogen causes malaria?
A protist, which spends part of its life cycle inside a mosquito.
22.What is a vector?
An organism that carries a pathogen from one host to another without getting the disease itself. Mosquitoes are the vector for malaria.
23.What are the symptoms of malaria?
Recurrent episodes of fever. It can be fatal.
24.How is the spread of malaria prevented?
By stopping the mosquitoes breeding, and by using mosquito nets to avoid being bitten.
25.What type of pathogen is salmonella, and how do people catch it?
Bacteria. From food prepared in unhygienic conditions, or from poultry that has not been cooked thoroughly.
26.What are the symptoms of salmonella food poisoning?
Fever, abdominal cramps, vomiting and diarrhoea, caused by the toxins the bacteria secrete.
27.How is salmonella controlled in the UK?
Poultry are vaccinated against it.
28.What type of pathogen is gonorrhoea, and what are the symptoms?
A bacterium. It causes a thick yellow or green discharge and pain on urinating.
29.How is gonorrhoea spread and controlled?
It is a sexually transmitted disease. Spread is controlled by using a condom, and it is treated with antibiotics.
30.Why has gonorrhoea become harder to treat?
Many strains have become resistant to penicillin, so it no longer works against them.
31.Why does washing your hands reduce the spread of disease?
It removes pathogens from the skin, so they are not transferred to your mouth or passed to other people.
32.Why does isolating an infected person reduce spread?
It reduces contact with others, so the pathogen has far fewer opportunities to move to a new host.
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