module 4 - 12.1 plant and animal pathogens Flashcards
what are communicable diseases caused by?
infective organisms called pathogens
what are the 4 types of pathogens?
- bacteria
- viruses
- fungi
- protoctista
what is a communicable disease?
can be passed from one organism to another
what are vectors?
carry pathogens from one organism to another
- common vectors are water/insects
what are bacteria?
prokaryotes - so have different cell structure to eukaryotic organisms they infect
what 2 ways are bacteria classified?
- by their basic shape
- by their cell walls
how are bacteria classified by their basic shape?
- may be rod shaped (bacilli)
- spherical (cocci)
- comma shaped (vibrios)
- spiralled (spirilla)
- corkscrew (spirochaetes)
what are the two main types of bacterial cell walls?
- gram positive cell walls (look purple-blue under light microscope)
- gram negative cell walls (look red under light micorscope)
useful as type of cell wall affects how bacteria reacts to antibiotics
what are viruses?
non-living infectious agents
what is the basic structure of a virus?
genetic material (DNA/RNA) surrounded by protein
what type of viruses are pathogenic?
all naturally occurring viruses
what are protoctista?
- eukaryotic organisms
- some are pathogens
- they use people/animals as their host
- may need a vector to transfer to hosts
what are fungi?
- eukaryotic organisms - usually multicellular
- example - yeast (unicellular)
- parasitic fungi affect living plants and animals
- cant photosynthesise so digest food extracellularly
- many are saprophytes - feed on dead and decaying matter
- pathogenic fungi cause diseases
how can fungi kill a plant?
fungal infections affect leaves on plants - cant photosynthesise so die
what happens when fungi reproduce?
produce millions of tiny spores that can spread huge distances - rapidly
