M7: Plant reponses to Pathogens

Question 1

what are passive defences in plants?

Answer 1

physical and chemical barriers

Question 2

what are active defences in plants?

Answer 2

pathogen recognition, rapid active response, and delayed active response

Question 3

What is the physical barrier in plants?

Answer 3

waxy cuticle, hairs, small stomata, bark, vertical hanging leaves, cell wall

Question 4

how do pathogens enter physical barriers?

Answer 4

enter via stomata or wounds in plant tissue, infecting the area between cells and using enzymes to break the cell wall.

Question 5

what are chemical barriers in plants?

Answer 5

• toxic chemicals such as glucosides and saponins
• closing of stomata via chemical signalling
• enzyme production that breaks down pathogen toxins
• chemical receptors that detect pathogens

Question 6

What do active defences do in plants?

Answer 6

take over when passive barriers are breached

Question 7

what are the two types of active defences?

Answer 7

• rapid active response
• delayed active response

Question 8

what do rapid active responses do?

Answer 8

• changes cell membrane permeability
• oxidative bursts (hydrogen that kills pathogens)
• thickening of the cell wall (cell wall apposition)
• apoptosis

Question 9

what is apoptosis?

Answer 9

suicide of certain plant cells which causes dead cells to accumulate around the pathogen to isolate and prevent the spread

Question 10

what do delayed active responses do?

Answer 10

• wound repair of bark through cork cell production and gum secretion
• a lysosome-like chemical release that has antimicrobial action
• release of salicylic acid