4.1.3: Plant defences against pathogens

Question 1

what are passive defence mechanisms?

Answer 1

physicals barriers that make it harder for pathogens to gain entry into plants

Question 2

what are somme examples of passive defence mechanisms?

Answer 2

waxy cuticles, cellulose cell wall, closed stomata, bark, casparian strip

Question 3

what are chemical defences?

Answer 3

they prevent pathogens from growing on the surface of the plant by creating acidic conditions

Question 4

what are some examples of chemical defences?

Answer 4

toxic compounds, sticky resin found in the bark, enzyme inhibitors, receptor molecules

Question 5

what are active defence mechanisms?

Answer 5

they are only activated when pathogens have invaded, often limits the spread of pathogens

Question 6

how do plants reduce the spread of a pathogen?

Answer 6

they create physical barriers, these are formed when a pathogen invades releasing callose and lignin, these compounds deposit between cell surface membrane and the cell wall reinforcing it

Question 7

what other kinds of physical barriers are used in plant defences?

Answer 7

narrowing of the plasmodesmata, ingrowths into the xylem vessels and blockage of the phloem

Question 8

what is necrosis?

Answer 8

cells near the site of infection are killed by intracellular enzymes