Module 2: Plant Responses to the Environment Flashcards
cells found near the vascular tissue in shoots, and in the root cap columella in roots
statocytes
starch-filled organelles in statocytes; settle at the bottom of statocyte in direction of gravity
statoliths
auxin levels are higher on the lower sides of roots and shoots
lateral auxin gradient
directional growth in response to touch or physical contact with a solid object
thigmotropism
response towards the touch stimulus
positive thigmotropism
response away from the touch stimulus
negative thigmotropism
changes in the form of the plant body due to mechanical stress
thigmomorphogenesis
makahiya leaves; no matter where the leaf or leaflet is touched, the stimulus is propagated through neighboring leaflets
thigmonastism
specialized motor organs located at the joints of the leaf
pulvini
Folding in makahiya results from ___
rapid loss of turgor in cells within pulvini
environmental dynamics fall out of the optimal limit, changes in metabolism and functioning occur
stress
under this condition, plants will increase the saturated fatty acid proportion in their cell membranes
high temperature
under this condition, plants will increase the unsaturated fatty acid proportion in their cell membranes
low temperature
molecular chaperones; prevent aggregation of denatured proteins; promote renaturation of aggregated protein molecules
heat-shock proteins
under this condition, plants will close their stomata to reduce stomatal conductance and water-loss due to transpiration
high temperature
under this condition, plants will accumulate solutes like sugars – sucrose, glucose, and fructose, within their cells.
low temperature
plants respond to moderate salt stress by increasing internal levels of solutes like _____ & _____ that are well-tolerated at high concentrations
proline and glycine
can ameliorate some effects of salt stress by facilitating potassium uptake through the regulation of ion transporters
calcium
salt-resilient
halophytes
not salt-resilient
glycophytes
have salt glands in their stems and leaves
recretohalophytes
specialized epidermal glands that take up excess salt from neighboring tissues and excrete it onto the plant surface
salt glands
general plant response to drought stress
synthesis of abscisic acid
soil bacterium that is reported to induce drought tolerance in Arabidopsis; increased nitrogen fixation by rhizobium and increased growth of the bean plant
Paenibacillus polymyx
appears as swelling of tissues at the stem base during flooding; aid in the downward diffusion of oxygen and potential venting of toxic compounds
hypertrophic growth
defense against both herbivores and pathogens; toxic and lethal to other organisms; can repel predators with noxious odors, repellant tastes, or allergenic characteristics
secondary metabolites
mechanism that enables plants to sense the presence of pathogens and activate defense responses to pathogen attacks
systemic acquired resistance (SAR)
unique set of light-sensitive proteins
photoreceptors
non-protein, light-absorbing pigment
chromophore
class of photoreceptors that sense red and far-red light
phytochromes
growth and development of plants in response to light
photomorphogenesis
Exposure to ____ triggers the elongation of stems and petioles in search of light.
far-red light
Exposure to ____ enhances lateral growth and branching.
red light
intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles
circadian (or biological) clock
collective term for the biological responses of plants to variations in the relative lengths of dark and light periods
photoperiodism
period of light-exposure (night length)
photoperiod
plants that flower after a minimum number of consecutive long nights
short-day plants
plants that flower after a minimum number of consecutive short nights
long-day plants
(night length, plant type)
high Pfr : low Pr
short night, long-day plant
(night length, plant type)
low Pfr : high Pr
long night, short-day plant
detect presence of pathogen; result in cascade of responses
membrane-bound receptors
detect effector molecules; lead to expression of pathogen-related genes and rapid-programmed cell death
resistance proteins
released to attract parasite that kills herbivore
volatiles
