Plant responses to herbivory

Question 1

What physical defences against herbivory?

Answer 1

• thorns, barbs, spikes, spiny leaves, fibrous and inedible tissue
• hair leavbes
• probably just need to spurt out a few of these
  *

Question 2

What are tannins? (chemical responses)

Answer 2

• a phenols
• produced by many plants
• make upto 50% of the dry weight of the leaves

Question 3

How are tannins effective against herbivory?

Answer 3

• bitter taste
  
  • puts animals off
• toxic to insects
  
  • bind to digestive enzymes in saliva and inactivate them
• tea and red wine are both rich in plant tannins

Question 4

What are alkaloids? (chemical defence)

Answer 4

• very bitter tasting
• nitrogenous compounds found in many plants

Question 5

Hiow are alkaloids effective? What are some examples?

Answer 5

• act as drugs
  
  • affects metabolism
  • sometimes poisonous
• caffeine
  
  • toxic to fungi and insects
  • also spreads through soil, through seedlings, preventing the germination of other plants
    
    • also stops plant rivals
• nicotine
  
  • produced in roots of tobacco plants
  • toxin
  • stored in vacuoles in leaves to be released when the leaf is eaten

Question 6

What are terpenoids? How are they effective?

Answer 6

• large group of compounds produced by plants
• often form essential oils but act as toxins to insects and fungi that might attack the plant
• some act as insect repellants