b3

• what’s a communicable disease

  Disease caused by a pathogen which can be passed between animals or plants
• what’s a pathogen

  A disease-causing microorganism
• how do bacteria cause disease

  once inside the body they divide rapidly by binary fission. They kill cells and produce harmful toxins
• how do viruses cause disease

  They invade and reproduce inside living body cells, leading to cell damage
• 3 ways pathogens are spread

  the air

  by water

  direct contact
• 4 ways spread of pathogens can be reduced

  hygiene

  quarantine

  vaccination

  pesticides (removing vector)
• what is measles

  serious viral disease that can cause blindness and brain damage. Main symptoms are fever and red skin.
• how is measles spread

  through air , cough droplets
• what is hiv/ aids

  virus which attacks and damaged immune system until it can no longer function properly. No cure or vaccination.
• how is hiv spread

  direct sexual contact
• what is tobacco mosaic virus

  A plant pathogen which causes leaf discolouration when cells are damaged. Affected areas cannot synthesise reducing crop yield
• what is salmonella

  Type of bacteria found in raw meat. Enter the body via food poisonin.
• what is gonorrhoea

  Sexually transmitted viral infection caused by unprotected sex with an infected individual.
• what’s rose black spot

  A fungal disease which causes purple or black spots to develop on rose leaves. Reduces area of leaf which is available for photosynthesis
• what is malaria

  Disease caused by protist pathogens. Carried from host to host by mosquitoes and enter human bloodstream when they feed
• how does skin prevent pathogens entering the body

  Acts as physical barrier

  Scab formation after skin is cut or wounded
• how does respiratory system prevent pathogens entering body

  Nose has hairs and mucus which trap pathogens

  Trachea and bronchi have mucus that trap pathogens. Ciliates cells move to mucus to the mouth so it can be swallowed
• how does stomach prevent pathogens infecting body

  secrets hydrochloride acid which kills any pathogens
• how do phagocytes protect us against disease

  white blood cells (phagocytes) ingest and destroy pathogens so they can’t infect more cells
• how does antibody production help us against disease

  white blood cells produce antibodies which are complementary to a specific antigen or pathogen. Binding of antibodies to antigens causes pathogens to clump together making them easier to destroy. Correct antibodies can be produced rapidly if they get the disease agin
• how does antitoxin production protect us against disease

  Antitoxin bind to toxins released by pathogens and neutralises them
• What is a vaccination

  Contains a dead or inactivated form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen. In case of second infection memory cells can rapidly produce correct antibodies
• what drugs are used to cure some bacterial diseases

  Antibiotics can kill bacterial pathogens inside body
• how do antibiotics work

  Antibiotics for example penicillin kill pathogens in body but not human cells
• what is antibiotic resistance

  When mutations lead to individual bacteria being resistant to an antibiotic. These bacteria are able to survive, reproduce and pass on their alleles leading to a greater proportion of antibiotic resistant bacteria
• how can we prevent antibiotic resistance

  Avoid overuse and unnecessary use of antibiotics

  Finish antibiotic course
• what plant is the heart drug digitalis extracted from

  Foxgloves
• What painkiller originated from a compound found in willow bark

  Aspirin
• What antibiotic what discovered by Alexander Fleming from a type of mould

  Penicillin
• 3 min factors tested when developing new drugs

  Toxicity

  Efficiency

  Dose
• How is clinical trials tested out

  Using healthy volunteers and patients. One group of random people get the drug the others get placebo in order to assess its efficiency.
• what are monoclonal antibodies

  Antibodies that are clones from one parent cell

  Specific to one type of antigen
• Describe how monoclonal antibodies are produced

  Specific antigen injected into animal

  B-lymphocytes producing complementary antibodies extracted

  B-lymphocytes fuse with tumour cells to for hybridoma cells which can divide and produce antibodies.

  Hybridoma cells cultured

  Moniclonal antibodies collected and purified
• Uses of monoclonal antibodies

  Detect pathogens

  Location of cancer cells and blood clots

  Treatment of cancer
• why can monoclonal antibodies be used to target cancer cells

  Cancer cells have specific antigens called tumour markers on their membranes

  Monoclonal antibodies are specific to one type of antigen so can be targeted to tumour markers without damaging other cells
• physical defence responses used by plants

  Cellulose cell walls

  tough waxy cuticles on leaves

  bark on trees

  leaf fall
• chemical defence responses used by plants

  Poison

  Antibacterial chemicals