plant defences against pathogens

Question 1

state 3 examples of barriers to pathogens in plants

Answer 1

• waxy cuticles on leaves
• bark on trees
• cellulose cell wall

Question 2

describe the difference between plants response to pathogens and explain why this is a possible successful strategy for plants.

Answer 2

• plants do not heal diseased tissue, they seal it off and sacrifice it
• plants are continually growing at meristems so they can replace damaged parts unlike animals

Question 3

describe 2 ways in which a plant cell can detect the presence of a pathogen.

Answer 3

• receptors respond to mols from pathogens
• receptors respond to chemicals produced when cell wall is being broken down/attacked

Question 4

name 2 molecules produced by plants to limit the spread of a pathogen

Answer 4

callose and lignin

Question 5

describe the structure of callose

Answer 5

• polysaccharide
• ß-1,3 linkages and ß-1,6 linkages

Question 6

state 6 different types of plant chemical defences.

Answer 6

• insect repellent
• insecticide
• antibacterials
• antifungals
• anti-oomycetes
• toxins

Question 7

what is an example of insect repellents?

Answer 7

pine resin

Question 8

what is an example of inseticides?

Answer 8

pyrethrins - made by chrysanthemums (act as insect neurotoxins)

Question 9

what is an example of antibacterials

Answer 9

phenols - antiseptics made in many plants

Question 10

what is an example of antifungals

Answer 10

chitinases - break down chitin fungal cell wall

Question 11

what is an example of anti-oomycetes

Answer 11

glucanases - break down glucans (polymers found in cell walls of oomycetes)

Question 12

what is an example of toxins

Answer 12

chemicals that can be broken down to form cyanide compounds when plant cell is attacked