plant reponses Flashcards
biotic
living factors
abiotic
non - living factors
what are physical defences
include, thorns barbs, spikes hair and inedible parts of the plant
list the chemical defenses
- tannins
- alkaloids
- terpenoids
- phermones
what is a tropism
a directional growth response, determined by the direction of an external stimulus.
what is a nastic response
- a non directional response.
- e.g. some plants close there leaves when touched
how do hormones move around the plant
- xylem + phloem
- active transport
- diffusion
where does plant growth occur
- at the tips of the roots and shoots
- at the lateral bud meristem
- at the intercalary meristem
what are the 4 types of tropism
- thigmotropism
- chemotropism
- geotropism
- phototropism
what are the main similarities between animal and plant hormones
- produce in one place and act in a different place
- both are chemical messengers
- both are long lasting and act over a long period of time
- both affect the activity of the target cells/ tissue
what are the main differences between animal and plant hormones
- plant hormones, have an effect at low concentrations
- different concentrations of plant hormones, have different effects of different tissues in a plant
- animal hormones ae made by endocrine glands
- different plant hormones, can work together to have a synergistic effect on the growth
what is effect Auxin
- controls cell elongation
- inhibits growth of side shoots
- inhibits leaf abscission
- stimulates the release of ethene
what is the effect of Cytokinin’s
promote cell division
what is the effect of Gibberellins
promote pollen tube growth in fertilisation seed germination and elongation of stems
what is the effect of abscisic acid, i.e. ABA
maintains dormancy of seeds and buds, by inhibiting germination, stimulus = cold, protective response, e.g. antifreeze production or stomatal closure, when water availability is low.
what is the effect of Ethene
promotes fruit ripening and leaf abscission
what is abscission
the fall of leaves
what is cotyledon
the seed leaf of a plant embryo and food storage tissue
what is endosperm
food storage tissue, in monocots
what is aleurone
protein granules, found in a single layer of cells
what is monocot
a plant, whose seeds only contains a single cell during germination
what is dicot
plants, whose seeds produce two cotyledons during germination
why do plants produce tannins
bitter tasting, to prevent insects eating and they also deactivate digestive enzymes
what is the difference between a nastic and tropic response
nastic is non - directional whereas tropic is directional
what do we call the tropism, which causes a pollen tube to grow towards the ovary
chemotropism
what are the three ways, that hormones can move through a plant
diffusion, via the xylem, phloem or active transport
which hormone promotes fruit ripening
Ethene
which hormone can promote elongation of stems and seed germination
Gibberellins
what hormone is antagonistic to the hormone Gibberellin
ABA
which hormone, promotes cell elongation
Auxin
how does Auxin work?
- Auxin molecules, bind to specific receptor sites in the plant plasma membrane
- this causes, an ATPase enzyme in the plasma membrane to actively transport H+ ions form the cytoplasm to the cell wall.
- the resulting low Ph, provides optimum conditions for wall loosening enzymes (expanses) to work increasing the stretchiness of the cell wall.
- these break bonds, within the cellulose. So the walls become less rigid and can expand as the cells takes in water.
