plant responses Flashcards
why have plants evolved to have a wide range of responses to herbivores and abiotic stress?
they cannot run away / migrate to more appropriate conditions like animals can
state 4 physical defences that plants have to herbivores
- thorns
- stings
- spikes
- inedible leaves
state 4 chemical defences that plants have to herbivores
- tannins
- alkeloids
- terpenoids
- pheromones
what are tannins
- bitter tasting chemical compounds
- toxic to insects
what are alkaloids?
- nitrogenous, bitter tasting chemicals
- affects metabolism of herbivore
- eg. caffeine and cocaine
what are terpenoids
- essential oils
- toxic to insects and fungi
what are pheromones
- chemicals
- released to affect other members of the species
- used by plants to communicate about danger
what does ‘folding in response to touch’ mean?
- leads fold when touched
- scares of predators
what plants fold when touched?
Mimosa pudica
state 4 examples of abiotic stress
- high wind
- excess/lack of water
- temp change
- salinity change
state 5 plant responses to abiotic stress
- leaf loss
- daylight sensitivity
- abscission
- stomatal control
- preventing freezing
describe leaf loss
- as temp drops and daylight decreases, photosynthesis rate decreases
- more energy efficient for plants to lose leaves
describe daylength sensitivity
- photoperidism = sensitive to lack of light
- when plants detect shorter periods of darkness, leaves bud and flowers bloom
describe abscission
- light levels decrease and ethene switches off gene for enzymes that weaken & digest cell waters at abscission zone
- leaf separates from plant
- leaves waterproof scar which protects rest of plant
what is the abscission zone?
separation layer in leaf petiole
describe preventing freezing
some plants contain chemicals which act as antifreeze to prevent cytoplasm freezing
describe stomatal control
- evaporation of water out of plant provides cooling effect
- opening/closing controlled by hormone ABA in response to temp stress