B5 - disease



Health - a state of physical and mental well being

Causes of ill health -

  • Smoking
  • Lack of exercise
  • Poor diet
  • Exposure to carcinogens

If you are depressed, you are more likely to get a disease.

If your immmune system is damaged, you are more likely to get an infectious disease.

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Pathogens - Microorganisms that cause disease, eg. bacteria

Bacteria = release toxins, damage cells and tissue

Viruses = reproduce rapidly inside cells, replicate copies made, the cells burst, cell damage makes you feel ill

Protists = eukaryotes, live in or on other organisms and damage them, transferred by a vector

Fungi = Hyphae (thread like) or single celled, penetrate skin or plants, produce spores which spread.

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Spread by -

  • Air - droplets from cough or sneeze (influenza virus)
  • Water - drinking or bathing in dirty water (cholera)
  • Direct contact - touch contaminated surface (athletes foot, shower floor)

Bacteria reproduce through binary fission, single cell-->2 identical daughter cells, every 20mins

Bacteria at begining of growth X 2^(num of divisions)

Antibiotics kill bacteria in bodies.

Disenfectants kill bacteria in environment around us.

Zone of inhabition = a place wherr bacteria killed and can't grow.

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Uncontaminated culture:         Inoculate = introduce

1. Boil agar, petri dish,inoculated loop, surfaces and agar sterilised.

2. Turn on bunsen burner for convection current.

3. Flame neck of sample bottle, inoculate agar using inoculating loop.(dip in bacteria then zig zagonto gel)

4. Replace lid of petri dish, secure with tape, upside down, stops condensation

5. Incubate 25C, few days, then observe growth

Used for seeing what effects chemicals have (eg antibiotics)

Low temp so it doesn't produce harmful pathogens, only ones that don't reproduce in the body.

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Prevent spread:

  • handwashing
  • disenfect surfaces
  • raw meat away from uncooked food
  • isolate infected people
  • destroy/control vectors (eg.mosquitoes, vaccination)

Stop pathogens:

  • Immune system
  • White blood cells = engulf and digest(phagocytosis) produce antibodies, lock onto antigens then phagocytosis, produce antitoxins, counteract toxins
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Virus - measles, HIV, tobacco mosaic virus

Bacteria - Salmonella, Gonhorrhea/STD, bacteria leaf spot

Fungi - Rose black spot, ringworm

Protists - Malaria

A plant will show - stunted growth (Nitrate, phosphate), spots on leaves, rot/decay, malformation, abnormal growth, discolouration (magnesium)

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Farmers can: go to the lab, gardening manual, look online, testing kit

To defend against pathogens:

  • cell wall
  • waxy cuticle
  • dead cells on stem
  • fallen dead leaves
  • antibacterial chemicals

To defend against herbivores:

  • Poisons
  • Thorns
  • Drooping/curling
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