Communicable Disease, Prevention and Immunity - Plant Defences Flashcards
what are the two types of plant defences
- physical
- chemical
how does cellulose cell wall act as a physical defence
acts as a physical barrier
how does lignin act as a physical defence
thickens cell wall and is waterproof
almost completely indigestible
how does bark act as a physical defence
contains chemical defences that work against pathogens
how does waxy cuticle act as a physical defence
prevents water collecting on cell surface in which pathogens could survive
how does stomatal closure act as a physical defence
guard cells will close stomata to prevent entry of pathogens
what is tylose
outgrowths of xylem parenchyma cells into the lumens of xylem vessels via pits
how does tylose act as a physical defence
- prevents passage of water and spread of pathogens
- also contains chemicals that are toxic to pathogens
what is callose
a large polysaccharide synthesised by the plant that blocks sieve tubes
how does callose act as a physical defence
blocks sieve tubes, acting as a barrier to limit the spread of pathogens
where is callose deposited
- in between cell walls and membranes in cells next to infected cells
- in plasmodesmata between infected cells and neighbours
- in sieve plates
how does leaf drop (abscission) act as a physical defence
limits spread of pathogens
how do toxins act as a chemical defence
some plants make chemical that can kill pathogens
give an example of an insect repellent produced by a plant
citronella from lemon grass
how do insecticides act as a chemical defence
can reduce insect vectors, preventing the entry of pathogens
give examples of antibacterial defences
aromatic compounds and antibiotics that will kill bacteria
give an example of an antifungal defence
hydrolytic chitinase enzymes that can break down chitin in fungal cell walls
