ch16 - plant responses to herbivory

what is herbivory

when herbivores (e.g. insects) eat plants

what does it mean by plant responses to herbivory

mechanisms & structures which plants have to stop herbivores from attacking

name 3 physical defences

thorns

spikes

hairy leaves

how do thorns and spikes act deter herbivores

prevents animal from eating plant

how do hairy leaves deter herbivores

creates a physical barrier which is difficult to overcome

name 2 chemical defences

alkaloids

pheromones

how do alkaloids deter herbivores

chemicals with a bitter taste - interferes with digestion and other biological processes of animals

name 4 examples of alkaloids and how they affect herbivores

caffeine, nicotine = toxic and poisonous

morphine, cocaine = act as a drug which affects metabolic rates

how do pheromones deter herbivores

chemicals which affect the social behaviour of other members in the same species

explain how pheromones act

if a plant is being attacked it will release pheromones which induces nearby leaves on the same plant & on other nearby plants to produce callose which strengthens cell wall

what are VOC

volatile organic compound

-same as pheromones BUT can also affect members of different species

why are VOC so useful

when plants release VOC it attracts predators to prey onto the insect/pest before it attacks the plant - prevents plant from being attacked

what is the folding response

when the leaves of a plant fold up in response to being touched

name the plant which uses folding response

mimosa pudica

how does the folding response work in mimosa pudica & why is it beneficial for the plant

when touched = leaves fold up and the plant droops

- deters insects since it appears less appetising

- causes any insects which were on the plant to slide/ fall off