Plant Responses To Herbivory Flashcards
what is a herbivore?
an animal that eat plants.
why do plants need responses to protect them?
they are immobile so cannot escape herbivores.
what are some physical defences to herbivory?
- thorns
- barbs
- spikes
- spiny leaves
- fibrous and inedible tissue
what are the chemical defences to herbivory?
- tannins
- alkaloids
- terpenoids
what is the role of tannins?
part of a group of compounds called phenols.bitter taste puts animals off of eating them. they bind to the digestive enzyme in saliva and inactivate them.
what is the role of Alkaloids?
nitrogenous compounds that act as drugs and affect the metabolism of animals.
what are some examples of alkaloids?
- caffeine
- nicotine.
- morphine
- cocaine
what is the role of terpanoids?
they are a large group of compounds which often form essential oils but also act as toxins to insect and fungi.
what is an example of a terpanoid?
pyrethrin - acts as an insect neurotoxin and interfers with the nervous system.
citronella - insect repellent.
what is a pheromone?
a chemical made by an organism which affects the social behaviour of other members of the same species.
why dont plants rely much on pheromones?
plants dont act socially.
what are the instances where a plant might use a pheromone?
- if a maple tree is attacked, it releases a pheromone which is absorbed by leaves on other branches. the leaves will then make callose to protect them.
- some evidence that plants communicate by chemicals produced in root systems; one plant can tell a neighbour if it is under water stress.
what do plants produce instead of pheromones?
Volatine Organic Compounds (VOCs)
what is an example of a VOC being used?
when apple trees are under attack by spider mites, they produce VOCs which attract predatory mites that come and destroy apple tree pests.
how does the mimosa pudica plant respond to herbivores?
when the leaf is touched, there is an electrochemical change in the cells which results in something like an action potential which causes the movement of potassium ions into the cells of the upper, flexor side of the pulvinus. water follows by osmosis so turgor in the top cells increases and decreases in lower cells.
