Biology B6 (13)

how disease spreads

communicable diseases are caused by pathogens

bacteria- ver small cells,which can reproduce rapidly, they make you feel ill by producing toxins that damage your cells and tissues

viruses- these are not cells, they are really tiny, they replicate themselves inside the infected organisms cells, these cells then burst, releasing the virus 

protists- these are eukaryotic usually isngle celled and vary in size, protist that cause disease are often paarsites 

fungi- some fungi are single celled while others have a body, which is made up of a thread- like structures called hyphae,these can grow and pentrate on human skin and the surface of plants, causing diseases they can also produce spores which can spread onto other plants and animals 

commuincable diseases are transmitted in dif ways 

water- some pathogens can be pciked up by drinking or bathing in dirty water e.g. chlorea is a bacterial infectionthat causes dirrhoea and dehydration, its spread via drinking water containing diarrhoea of other sufferreres 

air- some pathogens are carried by air, e.g. erysiphe graminis is a fngus that causes barley powdery mildrew. it makes white fluffy patches appaer on the leaves of barley plants, this afects the plants ability to photosyntheisise which can decrese yields its spread by spores that are blown betwen plnats by the wind 

air borne pathogens can be carried by dropelts produced when you cough or sneeze so other people can breathe them in e.g. fluenza virus that caues flu is spread this way

contact- some pathogens can…