b5

• Communicable diseases are diseases that can be spread from one person to another.
• Binary fission - bacteria dividing rapidly
• Viruses take over cells in bodies. They live and reproduce in the cell and destroy the cell
• Pathogens are spread by : By air (droplet infection)

  Direct contact

  By water
• Growing pathogens at high temperature, can risk to pathogens growing too rapidly(37C)
• Ways to stop bacteria : Hand washing

  Disinfectants on surfaces

  Raw meat away from uncooked food

  Coughing/Sneezing into handkerchief

  Isolation

  Vaccination

  Controlling Vectors
• Measles - red rashes , spread by droplet infection
• HIV/AIDS - Spread by sexual contacts, sharing needles , not curable but suppressible
• Tobacco Mosaic Virus - causes yellowing of leaves and stunted growth , No treatment.
• Salmonella - bacteria that causes food poisoning and diarrhoea. Can be found in many guts of animals
• Gonorrhoea - sexually transmitted disease , early symptoms are painful urination and green/yellow discharge
• Rose black disease - Fungal disease that spread via wind and water. Spread is controlled by removing affected leaves and chemical sprays
• Protists cause lots of diseases , usually involve a vector that transfers the protist to a host like melaria
• Malaria - protist which spread via mosquito bites. The protist produce sexually in the mosquito and asexual in humans. The female needs to have two human meals before laying eggs , where the protists transfer.
• Malaria can be prevented by : nets , insecticides , antimarial drugs , preventing vectors from breeding
• Human defense - Skin acts a barrier , antimicrobial secretion to destroy pathogens

  Nose is full of hair and mucus which trap particles

  Trachea and Bronchi have cilia and mucus

  Stomach produces hydrochloric acid

  White blood cells
• Phagoctyosis - White blood cell ingesting the pathogen and killing it

  
• Antibodies - proteins produced by the immune system that bind to specific antigens

  
• Antitoxins - antibodies that neutralize toxins produced by bacteria

  
• Plants can be infested with aphids , to control this you can introduce a predator like ladybirds
• Plants can have mineral disease like magnesium which leads to chlorosis
• Nitrate ions make proteins with glucose
• Deficiency in Magnesium causes chlorosis
• Deficiency in Nitrate ions causes stunted growth
• Symptoms of disease : Stunted Growth

  Spots on leaves

  Areas of decay and rotting

  Growths (Crown galls , bumps)

  Malformed stems and leaves

  Discoloration

  Pests
• Physical barriers of plants: Thick cell wall

  Waxy Cuticle

  Bark on trees

  Leaf fall (Leaves that also contain disease)
• Other barriers of plants : Thorns

  Poison to deter herbivores

  Hair

  Drooping and Mimicry