4.3.3.2 Plant Defence Responses

Question 1

What are the physical defences of a plant?

Answer 1

• wavy cuticle which provides a barrier from pathogens
• cell walls made from cellulose which provide physical barrier
• layers of dead cells around stems which act as a barrier

Question 2

What are the chemical defences of a plant?

Answer 2

• some can produce antibacterial chemicals which kill bacteria (mint and witch hazel)
• others produce poisons which can deter herbivores (tobacco plants, foxgloves, deadly nightshade)

Question 3

What are the mechanical defences?

Answer 3

• some have thorns and hair which stop animas touching or eating them
• others droop or curl when something touches them so they can prevent being eaten by knocking off insect
• mimic other organisms (passion flower has bright yellow spots which look like butterfly eggs so stops other butterflies laying eggs there, ice plant family look like stones and pebbles)