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  • Created by: niki
  • Created on: 03-04-11 17:15

> infectoius diseases are caused by microorganism such as bacteria and viruses

> microorganisms which cause disease are called pathogens

> bacteria and viruses reproduce rapidly inside your body. They may oriduce toxins which make you feel ill

> Viruses use and damae your cells as they reproduce. This can also make you feel ill

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pathogens

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> your body has several methods of defending itself against the entry of pathogens using the skins, the mucus of the breathing system and the clotting of blood

> your white blood cells help to defend you against pathogens by ingesting them, making antibodies and making antitoxins

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defence mechanisms

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> some medicines relieve the symptoms of disease but do not kill the pathogens which cause it

> antibiotics cure bacterial diseases by killing the bacteria inside your body

> antibiotics do not destroy viruses as viruses reproduce inside the cells. It is difficult to develop drugs that can destroy viruses without damaging your body cells

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using drugs to treat diseases

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> many types of bacteria have developed antibiotic resistance as a result of natural selection. To prevent the problem getting worse we must not over use antibiotics

> if bacteria or viruses mutate, new strains of a disease can appear which spread rapidly to cause epidemics and pandemics

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changing pathogens

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> when we develope new medicines they have to be tested and trialled extensively before we can use them

> drugs are tested to see if they work well. We also make sure they are not toxic and have no unnaceptable side effects

> thalidomide was developed as a sleeping pill and was found to prevent morning sickness in early pregnancy. It had not been fully tested and it caused birth defects. Thalidomide is now used to treat leprosy and other diseases

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developing new medicines

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> you can be immunised against a disease by introducing small amounts of dead or inactive pathogens into your body

> your white blood cells produce antibodies to destroy the pathogens. Then your body will respond rapidly to future infections by the same pathogen, by making the correct antibody. You become immune to the disease

> we can use vaccination to protect against both bacterial and viral pathogens

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immunity

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> all living things have adaptations which help them to survive in the conditions where they live

> animals which are adapted for cold environments are often large, with a small suface area: volume (SA/V) ratio. They have thick insulating layers of fat and fur

> Changing coat colour in the different seasons gives animals year round camoflauge

> adaptations for hot, dry environments include a large SA/V ratio. thin fur, little body fat and behaviour patterns that avoid the heat of the day

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adaptaion in animals

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> plants lose water all the time by evaportation from their leaves

> plants which live in dry places have adaptaions which help to reduce water loss. These adaptaions may often include reduced surface area of their leaves and/or water storage tissues

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adaptation in plants

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> animals often compete with each other for food and territories

> animals compete for mates

> animals have adaptations which make them good competitors

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competition in animals

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>plants often compete with each other for light, for water and for nutrients (minerals) from the soil

> plants have many adaptations, which make them good competitiors

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competition in plants

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