Plant and Animals: Orientation (Plants) Flashcards
Tropism
Are responses to stimuli that results in the long term growth of the plant toward or away from a stimulus (Directional)
Growth results from cell elogation occuring at different rates on different sides of the plant so that it bends in one direction
Photoperiodism
The amount & intensity of sunlight, temperature, levels of precipitation and availability of pollinators vary between the seasons (tell the time of year)
Short-day (SDP)
These plants flower when the days are shorter
Long-day (LDP)
These plants flower when the days are longer
Day-neutral plants
A plant that flowers regardless of the length of the period of light it is exposed to.
Nastic Response
A response of plant parts that is independent of the direction of the external stimulus(Non-directional)
(phyto) Hormones
Control most aspects of a plants life cycle, from germination to formation of flowers, stem, leaves, shedding of leaves etc.
Hormones are signalling molecules that produced ini very small amounts in one part of the plant & transported to toher parts, they then bind to a specific receptor & triggers responses in the target cells/ tissues
Abiscisic Acid (ABA)
Promote see domancy
Ethylene
Stimulates the ripening of fruit & initiates abiscission (fall) of frutis and leaves
Gibberellin (GA)
Breaks dormancy & initate germination
Cytokinins
Stimulate cell division, produces in actively growing regions, especially roots.
Auxins (IAA)
Composed of indoleacetic acid (IAA). Produced in cells in the tip of shoorts & roots and tranported to growth regions
Tugor Pressure
Pressure exerted by fluid in a cell that presses the cell membrane against the cell wal
Phytochrome
The ability of plants to activate the photoperiod response is controlled by a pigment.
Pr (P red)
Pfr (P far red)
The pigment phytochrome absrobs red light during the day and converts Pr into Pfr.
At night Pfr is slowly converted back into Pr.
