plant defences against pathogens

Question 1

what is callose

Answer 1

a large polysaccharide deposit that blocks old phloem sieve tubes

Question 2

examples of passive defences

Answer 2

physical barriers and chemicals

Question 3

examples physical defences

Answer 3

cellulose cell wall
lignin thickening of cell wall
waxy cuticles
bark
stomatal closure
callose
tylose formation

Question 4

how does cellulose cell wall defend

Answer 4

-acts as a physical barrier
-most plant cell walls contain chemical defences that activate when a pathogen is detected

Question 5

how does lignin of cells walls defend

Answer 5

lignin is waterproof and almost indigestible

Question 6

how does waxy cuticles defend

Answer 6

prevent water collecting on the cell surfaces. and since pathogens collect in water and need water to survive, absence of water is a passive defence

Question 7

how does bark defend

Answer 7

most bark contains a verity of chemical defences that work against pathogens

Question 8

how does stomata closure defend

Answer 8

Passagens can enter the stomata, stomatal aperture is controlled by the guard cells. When pathogens are detected, the Guard cells will close the stomata in that part of the plant.

Question 9

how does tylose formation defend

Answer 9

When tylose is fully formed it plugs vessels and the vessel can no longer carry water. blocking the xylem vessels prevent spread of pathogens through the heart wood. Tylose contains a high concentration of chemicals, such as Terpenes that are toxic to pathogens.

Question 10

what do chemicals in plant tissues contain

Answer 10

anti pathogenic properties

Question 13

what chemicals are found in plant tissues

Answer 13

terpenoids, phenols, alkaloids and hydrolysis enzymes