plant responses Flashcards
1
Q
why have plants evolved to have a wide range of responses to herbivores and abiotic stress?
A
they cannot run away / migrate to more appropriate conditions like animals can
2
Q
state 4 physical defences that plants have to herbivores
A
- thorns
- stings
- spikes
- inedible leaves
3
Q
state 4 chemical defences that plants have to herbivores
A
- tannins
- alkeloids
- terpenoids
- pheromones
4
Q
what are tannins?
A
- bitter tasting chemical compounds
- toxic to insects
5
Q
what are alkaloids?
A
- nitrogenous, bitter tasting chemicals
- affects metabolism of herbivore
- eg caffeine & cocaine
6
Q
what are terpenoids?
A
- essential oils
- toxic to insects & fungi
7
Q
what are pheromones?
A
- chemicals
- released to affect other members of the species
- used by plants to communicate about danger
8
Q
what does ‘folding in response to touch’ mean?
A
- leaves fold when touched
- scares off predators
9
Q
state 4 examples of abiotic stress
A
- high wind
- excess/lack of water
- temp change
- salinity change
10
Q
state 5 plant responses to abiotic stress
A
- leaf loss
- daylength sensitivity
- abscission
- stomatal control
- preventing freezing
11
Q
describe ‘leaf loss’
A
- as temp drops and daylight decreases, photosynthesis rate decreases
- more energy efficient for plants to lose leaves
12
Q
describe ‘daylength sensitivity’
A
- photoperidism = sensitive to lack of light
- when plants detect shorter periods of darkness, leaves bud and flowers bloom
13
Q
describe ‘abscission’
A
- light levels decrease and ethene switches off gene for enzymes that weaken & digest cell waters at abscission zone
- leaf separates from plant
- leaves a waterproof scar which protects rest of plant
14
Q
what is the abscission zone?
A
separation layer in leaf petiole
15
Q
describe ‘preventing freezing’
A
some plants contain chemicals which act as antifreeze to prevent cytoplasm freezing
