B2

• communicable disease - caused by pathogens that can be spread from one person to another
• pathogens are micro-organisms that cause disease
• 4 types of pathogens - virus, bacteria, fungi, protist
• incubation period - time it takes for pathogens to multiply and cause symptoms
• non communicable disease - caused by genetic inheritance or lifestyle/environmental factors
• Pathogens and plant disease -

  Virus: tobacco mosaic virus

  Fungi: ash die back

  Bacteria: crown gall disease
• Human non-specific defences -

  Physical: skin, mucus in airways

  Chemical: stomach acid, saliva, tears

  Bacterial: good bacteria in the gut that compete with pathogens
• Platelets - the human blood contains platelets, they clot up the blood and seal the wound to prevent infection by reducing the chance of pathogens entering the blood
• Plant defences - plants do not have an immune system

  Chemical: antimicrobial substances

  Physical: waxy leaf cuticle, cell wall
• Human immune system - white blood cells make specific antibodies to match the antigens on the surface of the pathogens. They then engulf and digest the pathogen
• Immunity - once the body has made the specific antibodies for a pathogen and it has been killed, some antibodies remain in the blood. Memory cells also stay in the blood to make antibodies very quickly if reinfected, they will destroy all the pathogens before they make you ill
• Vaccination - dead or weakened form of pathogen is introduced to the body, white blood cells respond by making specific antibodies and memory cells for longer lasting protection. You may need vaccination boosters because memory cells can die or pathogens can mutate
• Vaccination in mammals -

  95% vaccination: Heard Immunity

  Contraception

  Good hygiene/sanitisation
• Vaccination in plants -

  Crop rotation

  regulating plant movement

  pest control
• Risk of development of non-communicable disease -

  Cardiovascular disease: high fat diet, alcohol

  Cancers: genetics, smoking, pollution

  Diabetes: genetics, high sugar diet, obesity
• Antibiotics - used to treat bacterial infections only, however they are becoming less effective due to bacteria evolving to become resistant to them
• Treating cardiovascular disease -

  Lifestyle change

  Medicines: statins(reduces cholesterol in blood), anticoagulants(stops blood clotting)

  Surgery: Stents(opens up blood vessel), bypass surgery, heart transplant
• Testing treatments -

  Pre-clinical: Human cells are tested with disease, then animals

  Clinical trials: Healthy volunteers, then humans with disease
• 𝜋 x r² - to find the effectiveness area of the antibiotic
• Active Transport:

  • occurs when nitrate ions move from the soil into the plant roots
  • happens across a partially permeable membrane and moves nutrients from a lower concentration in the soil to a higher concentration in the plant
  • the process goes against the concentration gradient therefore energy (ATP) is needed for it to occur
• Transpiration:

  • movement of water from the roots to the leaves in the xylem
• Translocation:

  • movement of sugars around a plant
  • sugars move by active transport into the phloem from the leaves
  • water from the xylem moves in osmosis
  • high pressure of water and sugar molecules push substances down the tube
  • sugar moves by active transport into the roots where it can be stored until needed
• Biomass - the living material of organisms
• Interdependence - all populations rely on each other for their survival in a community
• Individual - a single organism within a population of species
• Population - all the organisms of the same species living in a habitat
• Community - all the populations of different organisms living in a habitat
• Ecosystem - a community of organisms with all the non-living conditions
• Biotic - living things within a habitat
• Abiotic - non-living conditions in a habitat (light,wind,water)
• Testing for Biological Molecules:

  • Starch - use iodine, black/blue if present
  • Glucose - use benedicts solution heated up, red/orange observed
  • Lipids/fats - use ethanol and water, white layer on top is observed
  • Protein - biuret test (potassium hydroxide, copper sulphate), purple observed