Control System in Plants Flashcards
Abscisic Acid (ABA)
slows growth; closes stomata during dry spells; helps maintain seed dormancy; promotes leaf aging
Abscission
the separation of fruits, flowers or even leaves from plants at specialized separation layers.
Acid Growth Hypothesis
when exposed to auxin, susceptible cells excrete protons into the wall (apoplast) at an enhanced rate, resulting in a decrease in apoplastic pH.
Adventitious Roots
roots that form from nonroot tissues
Amyloplast
a colorless plant plastid that forms and stores starch.
Apical Dominance
the hormonal inhibition of axillary buds by a terminal bud.
Auxin
stimulate stem elongation; affect root growth, differentiation, branching; development of fruit; apical dominance; photo and gravitropism; prevent leaf abscission
Biological clocks
internal timekeepers that control circadian rhythms
Circadian Rhythm
An innate biological cycle of about 24 hours that is not controlled by any known environmental variable
Coleoptile
cylindrical organs that ensheath the first leaf and shoot apex in grass seedlings.
Cytokinins
hormones produced in actively growing tissues—particularly in roots, embryos, and fruits—that promote cytokinesis, or cell division, and cell differentiation. They also prevent the aging of leaves and flowers by inhibiting protein breakdown
Day neutral plants
plants form flowers regardless of day length
Ethylene
promotes fruit ripening and leaf abscission; opposes some auxin effects; promotes root formation and flowers
Foolish seedlings
disease is characterized by increased internodal length and low seed production in rice plants.
Gibberellins
promote bud development; stem elongation, and leaf growth; stimulate flowering, fruit development and seed germination
Gavitropism
he directional growth of a plant in response to gravity—explains why, no matter how a seed lands on the ground, shoots grow upward (negative) and roots grow downward (positive)
Herbivores
plant-eaters
Hormone
a chemical signal produced in one part of the body and transported to other parts, where it acts on target cells to change their functioning
Long-day plants
such as spinach, lettuce, radishes, and many cereal grains, usually flower in late spring or early summer, when light periods lengthen
Nastic Movement
The non-directional movement of plants in response to a stimulus (e.g. humidity, temperature)
Photomorphogenesis
a developmental process in plants in which the incident light determines the growth of the plant.
Photoperiod
The environmental stimulus plants most often use to detect the time of year
Phototropism
The growth of an organ in response to light
Phytochrome
proteins with a light-absorbing component.
precocious germination
involves the germination of seeds while still on the parent plant
Short-day plants
generally flower in late summer, fall, or winter, when light periods shorten.
Signal Transduction
the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events,
Solar tracking
when a plant follows the movement of the sun during the day.
Statolith
sediments at the bottom of the gravisensing cells, the statocytes
Systemic acquired resistance
Upon infection with necrotizing pathogens many plants develop an enhanced resistance to further pathogen attack
thigmomorphogenesis
the response by plants to mechanical sensation (touch) by altering their growth patterns.
Thigmotropism
directional growth in response to touch, is illustrated when the tendril of a pea plant contacts a wire and coils around it for support
Triple response
The application of low levels of ethylene to etiolated seedlings results in seedlings with an exaggerated curvature of the apical hook.
Tropism
Any growth response that results in plant organs curving toward or away from stimuli
