orientation Flashcards
what is a tropisim?
a growth response towards or away from an environmental stimulus, from one direction
what do plant hormones do?
regulate their growth and development, produces a growth response
what is auxin?
a growth hormone that effects the roots and shoots of plants, depending on the concentration.
effect of high concentration of auxin on a radical(root)?
inhibits cell growth/elongation
effect of low concentration of auxin on radical (root)
stimulates cell growth and the downwards bending of the root
effect of high concentration of auxin on plumule (shoot)
stimulates cell growth and bending towards the stimulant e.g. sun
effect of low concentration of auxin on plumule (shoot)
inhibits cell growth
gravitropism in plumule
negatively gravitropic
gravitropism in radical
positively gravitrophic
apical dominance
the growth of lateral buds depending if the the apical bud ( top of plant) is removed or not.
if apical bud is removed what stimulates lateral bud growth?
the low concentration of auxin
thigmotropism
cells that touch a surface, produce auxin (climbing plants)
how auxin works
the high concentration of auxin makes cell membrane acidic dissolving the cellulose and stretches. Water (tugor) pressure increases and cell elongates.
nastic responses
non directional responses to changes in temperature, humidity and light surrounding a plant.
photonasty?
response to changes in light intensity
