B4 and B5 communicable diseases Flashcards
what are pathogens
microorganisms that cause disease ( bacteria, viruses, protists and fungi)
what are viruses
viruses aren’t living things by themselves- they need a host cell that they can infect and take over in order to reproduce
how do bacteria reproduce
by splitting in 2 called binary fission
how do pathogens spread
by air (droplet infection)
direct contact (sexual, skin, blood)
by water
what are the 5 barriers of bacteria into the body
skin (acidic so nothing grows and a literal barrier)
eyes ( saline solution in tears is antibacterial)
blood (wbc’s produce antibodies that kill virus and platelets that clot
stomach (HCL acid kills bacteria in food)
lungs (ciliates epithelial cells and mucus trap dirt and bacteria
what factors affect growth rate of bacteria
temperature, available nutrients, pH and oxygen levels
what is the mean division time for a type of bacteria
how long it takes for binary fission to occur
what is the equation for the number of bacteria at the end of the growth period
bacteria at start of growth period X2 (to the power of no of dimensions)
what did ignaz semmelweis introduce
the idea of hand washing in hospitals to prevent spread of disease
what did louis pasteur show
that microorganisms cause disease. he also developed vaccines
what did joseph lister introduce
the use of antiseptic chemicals to destroy pathogens before they cause infection in surgery
what are 4 ways of preventing the spread of communicable disease
hygeine
isolating infected
destroying or controlling vectors eg mosquitos
vaccination
what is tobacco mosaic virus
widespread plant pathogen that causes a distinctive mosaic pattern of discolouration on the leaves as the virus destroys the cells, affects growth as can’t photosynthesise
what is salmonella
bacteria that live in the gut. found in raw meat, poultry and egg. disrupts the balance of the natural gut bacteria
what is gonorrhoea
an std that can cause long term pelvic pain, infertility and ectopic pregnancy. bacterial- early symptoms include thick yellow discharge and painful urination
what is agrobacterium tumefacians
a bacterium that causes crown galls (a mass of unspecialised cells that grows in joints between root and shoot)
what is rose black spot
a fungal disease of rose leaves spread by wind and water that damages leaves so they drop off which affects growth as photosynthesis is reduced
what is malaria
caused by parasitic protists and spread by bite of female mosquitos can be fatal, damages blood and liver cells and causes fever and shaking
what does a lack of nitrates cause
lack of growth
what is chlorosis
when leaves turn yellow due to lack of magnesium
why do aphids have sharp mouthparts
so they can penetrate into the phloem vessels and feed on sugar rich phloem sap. they can transfer virus bacteria and fungi
how do cellulose cell walls help defend the plant from disease
they strengthen the plant cells to resist invasion of microorganisms
how does the waxy cuticle prevent the plant from disease
they’re on the surface so they act as a barrier to entry of pathogens
how does bark on trees/ ayer of dead cells on stems act as a barrier from disease
they are hard which makes it difficult for pathogens to penetrate
how does leaf fall prevent disease
when deciduous leaves fall all the pathogens attached to them leave the plant site also
what are chemical plant defence responses
they produce antibacterial chemicals and there are positions to deter herbivores
what are mechanical plant defence responses
thorns and hairs
leaves that droop or curl when touched
mimicry to trick animals
