communicable diseases (B5)

• Viruses:

  • Live and reproduce rapidly inside an organism's cells, damaging or destroying them
• • Spread by direct contact of plants with infected plant material, animal and plant vectors, and soil
  • Symptoms include a mosaic pattern of discolouration on leaves and reduced ability to photosynthesize
• Bacteria:

  • Reproduce rapidly inside organisms and may produce toxins that damage tissues and cause illness
  • Spread by bacteria in or on food that is being ingested
  • Symptoms of Salmonella include fever, abdominal cramps, vomiting, and diarrhea
  • Poultry are vaccinated against Salmonella bacteria
  • Gonorrhoea:
  • Spread through direct sexual contact
  • Symptoms include thick yellow or green discharge from the vagina or penis, and pain when urinating
  • Treatment with antibiotics, but many antibiotic-resistant strains have appeared
• Communicable diseases:

  • Can be spread from one organism to another
• Protists:

  • Plant diseases can be directly caused by insects like aphids
  • Aphids:
  • Insects that suck sap from plant stems, resulting in reduced growth, wilting, and discolouration of leaves
  • Ladybirds can be used to control aphid infestations
• • Some plants mimic the appearance of unhealthy or poisonous plants to deter insects or herbivores
• Plant diseases and insects:

  • Signs of plant diseases include stunted growth, spots on leaves, areas of rot or decay, growths, malformed stems or leaves, and discolouration
  • Ways of identifying plant diseases include gardening manuals, websites, laboratory testing, and testing kits with monoclonal antibodies
• Prevention and treatment of communicable diseases:

  • Hygiene: hand washing, disinfecting surfaces, keeping raw meat separate, covering mouth when coughing/sneezing
  • Isolation of infected individuals to stop the spread of disease
  • Controlling vectors by destroying or controlling their population
  • Vaccination to protect against diseases
• Measles:

  • Symptoms of measles include fever, red skin rash, and can be fatal
  • Young children are vaccinated against measles to immunize them
  • Spread by inhalation of droplets produced by infected people when sneezing and coughing
• HIV (human immunodeficiency virus):

  • Spread through sexual contact, exchange of body fluids, and initially presents flu-like symptoms
  • Virus attacks the body's immune cells, leading to AIDS
• Plant defenses:

  • Physical barriers like cellulose cell walls, tough waxy cuticles, and bark on trees
  • Chemical barriers with antibacterial chemicals and poison production
  • Mechanical adaptations like thorns, hairs, and leaves that droop or curl
• • Bacteria:
  • Spread by water and wind
  • Symptoms of rose black spot include purple or black spots on leaves, reduced ability to photosynthesize
  • Fungicides and affected leaves removed and destroyed
• Fungi:

  • Spread by mosquitos feeding on infected people and spreading the protist pathogen
  • Symptoms of malaria include recurrent episodes of fever and can be fatal
  • Prevent mosquito vectors breeding and use mosquito nets and anti-malarial medicine