Plant Hormones Flashcards
Define plant hormones.
chemical signals that modify/control one mor more physiological processes
are plant hormones produced in high or low concentrations?
low
t/f; each plant hormone only has a single effect
false! each hormone has multiple effects, however many hormones can influence one process.
what are the major plant hormones?
- auxin
- cytokinins
- giberellins
- ethylene
- abscisic acid
- strigolactones
- brassinosteroids
- jasmonates
where is auxin synthesized? what is its purpose?
- synthesized at SAM and young leaves
- promotes apical growth
- plays role in developing fruits and seeds
what is the effect of the polar transport of auxin?
polar transport of auxin plays a role in pattern development in roots and leaf venation pattern
which three plant hormones work together to suppress development of axillary buds
auxin, cytokinins, strigolactone
where is cytokinin synthesized? what is its purpose?
- synthesized in actively growing tissues such as roots, fruits and embryos
- stimulate cytokinesis
- work with auxin to control cell division and differentiation
what is the effect of the removal of a terminal bud?
plant becomes bushier
what is the purpose of giberellin?
cell elongation!
it is the release of gibberellins from embryo that signal seed to germinate.
what is the purpose of abscisic acid?
- slows growth
what are the two effects of abscisic acid? describe them.
seed dormancy; ensures that seeds will only germinate in optimal conditions. however, ABA may be removed prematurely by harsh environmental conditions.
drought tolerance; is the primary internal signal allowing plants to withstand drought by causing stomata to close rapidly to prevent water loss
what can precocious germination be attributed to?
low levels of ABA
what processes is gaseous ethylene involved in?
- fruit ripening
- leaf abscission
- or if there is : drought, flooding, mechanical pressure, injury, or infection
what is the process that occurs in the fall when leaves fall off trees? what is the cause?
leaf abscission!
balance of auxin (inhibiting) and ethylene (promoting) controls this process, in the fall ig more ethylene is produced.
