3.1.1: Communicable (infectious) diseases
Not started yet — this one needs some love.
Pathogens: microorganisms that cause infectious disease — can be viruses, bacteria, protists or fungi.
Spread: direct contact, contaminated water, air (droplets from coughs/sneezes).
Bacteria: reproduce rapidly; produce toxins (poisons) that damage tissues and cause symptoms.
Viruses: reproduce inside host cells; cause cell damage when they burst out; cannot replicate outside cells.
Ways to reduce spread: good hygiene, isolation of infected individuals, vaccination, destroying vectors.
Common exam mistakes
Symptoms of bacterial disease are caused by the toxins the bacteria produce — must say 'toxins released/produced/secreted'.
Just saying 'toxins' without stating they are 'released' or 'produced' will lose marks.
Different pathogens spread differently — do not say all pathogens spread by droplets (only respiratory ones do).