b3

Cards (37)

  • Explain why plants infected with tobacco mosaic virus grow slowly.
    discolouration in leaves so less chlorophyll
    reduced photosynthesis
    less glucose produced so less amino acids / proteins / cellulose made
  • Explain how the pregnancy test strip works to show a positive result.
    -urine passes through reaction zone
    -HCG hormone binds to the mobile HCG antibody in the reaction zone -passes up the stick
    -HCG hormone binds to the immobilised HCG antibodies in the results zone
    -the other antibodies which do not attach to HCG
    -bind to antibodies in control zone
    -blue dye appears in both control and results zones to show positive result
  • How to prevent malaria spread via mosquitoes? 3 ways?
    Method: mosquito net
    Reason: Prevents being bitten
    Method: Vaccination
    Reason: Provides immunity
    Method: Insecticides
    Reason: Kills the mosquitoes
  • how is HIV reduced?
    better education into prevention of spread
    condoms more widely available
    better drugs
    more testing
  • How do vaccinations prevent viruses?
    • Inactive virus injected into bloodstream
    • white blood cells produce antibodies
    • if infected, white blood cells produce antibodies more quickly
    • These antibodies destroy the virus before it causes major harm
  • Monoclonal antibodies
    • inject mouse with antigens
    • collect mouse lymphocytes that make a specific antibody to the antigen
    • lymphocytes are combined with a tumour cell to create a hybridoma
    • hybridoma is cloned to create many cells that produce the antibody
  • How does a monoclonal antibody prevent virus infection?
    Monoclonal antibody is specific to the virus antigen
    Monoclonal antibodies attach/ bind to all the virus antigens
    Virus cannot bind to the human cell to enter it's genetic material
  • what does the skin do?
    secretes oils and antimicrobial substances that kill pathogens
    covers the body, physically preventing pathogens from entering
  • Viruses live and reproduce inside cells, causing cell damage.
  • How do bacteria make us ill?
    Produce toxins that damage tissues
  • Pathogens are
    microorganisms that cause infectious disease.
  • Measles symptoms
    fever
    red-skin rash
  • The measles virus is spread by inhalation of droplets from sneezes and coughs.
  • HIV is spread by sexual contact or exchange of body fluids
    • HIV initially causes a flu-like illness.
    • Unless successfully controlled with antiretroviral drugs
    • the virus attacks the body’s immune cells.
    • AIDS occurs when the body’s immune system becomes so badly damaged
    • it can no longer deal with other infections or cancers.
  • How is salmonella spread

    bacteria ingested in food, or on food prepared in unhygienic conditions.
  • Symptoms of salmonella
    Fever
    abdominal cramps
    vomiting
    diarrhoea
  • How to control gonorrhoea spread

    treatment with antibiotics
    barrier method of contraception such as a condom.
  • What could be treated with penicillin before resistant strains?
    Gonorrhoea
  • Gonorrhoea symptoms
    thick yellow / green discharge from the vagina / penis
    pain on urinating
  • How is rose black spot spread
    water or wind
  • how is rose black spot treated
    fungicides or removing and destroying the affected leaves
  • White blood cells help to defend against pathogens by:
    phagocytosis
    antibody production
    antitoxin production.
  • nose
    hairs inside it that are coated with mucus, preventing pathogen entry
  • trachea and bronchi

    goblet cells secrete mucus trapping pathogens
    cilia hairs sweep the mucus out
  • It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
    • Pre-clinical testing is done in a laboratory using cells, tissues and live animals.
    • Clinical trials use healthy volunteers and patients.
    • Very low doses of the drug are given at the start
    • If safe, further clinical trials to find the optimum dose
    • In double blind trials, some patients are given a placebo.
  • uses of monoclonal antibodies
    • for diagnosis such as in pregnancy tests
    • measure the levels of hormones and other chemicals in blood, or to detect pathogens
    • locate / identify specific molecules in a cell / tissue by binding to them with a fluorescent dye
    • to treat some diseases:
    cancer - monoclonal antibody bound to radioactive substance / toxic drug / chemical which stops cells growing and dividing. delivers the substance to the cancer cells without harming other cells in the body.
  • Plant diseases can be detected by

    stunted growth
    spots on leaves
    • areas of decay
    growths
    malformed stems or leaves
    discolouration
    • the presence of pests.
  • how to identify plant diseases

    • reference to a gardening manual or website
    • taking infected plants to a laboratory to identify the pathogen
    • using testing kits that contain monoclonal antibodies.
  • stunted growth caused by nitrate deficiency (needed for proteinsynthesis)
  • chlorosis caused by a magnesium deficiency
  • Physical plant defences

    Cellulose cell walls.
    Tough waxy cuticle on leaves.
    • Layers of dead cells around stems (bark on trees) which fall off.
  • Chemical plant defences

    Antibacterial chemicals.
    Poisons to deter herbivores.
  • Mechanical adaptations
    Thorns and hairs deter animals.
    • Leaves which droop or curl when touched.
    Mimicry to trick animals.
    1. phagocyte track downs a pathogen, and then binds to it. 
    2. phagocyte's membrane will then surround the pathogen and engulf it.
    3. enzymes inside the phagocyte break down the pathogen to destroy it
  • What do antitoxins do?

    Bind and neutralise the toxins produced by bacteria