B4 and B5 communicable diseases Flashcards Preview

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Flashcards in B4 and B5 communicable diseases Deck (27):

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


isolating infected

destroying or controlling vectors eg mosquitos



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