Transcript Control Systems In Plants

Control Systems In Plants
Plant Hormones
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Five known classes of hormones control
plant growth and development
Auxin – promotes fruit growth
Cytokinins – stimulate cell division
Gibberellins – stimulate growth in leaves
and stems
Abscisic Acid – slows plant growth
Ethylene – inhibits root growth
Tropisms
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Phototropism –bends shoot towards light;
enhances photosynthesis
Gravitropism – uses specialized plastids
(statoliths).
Roots display positive gravitropism
(grows down towards the earth) and the
shoot displays negative gravitropism
(grows up out of the earth)
Tropisms
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Thigmotropism:
Developmental response to
mechanical stimulation
Example: thicker stemmed plants
are found in locations where the
winds are strong
Turgor Movements
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Turgor movements are relatively
rapid, reversible plant responses
Biological Clocks
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Biological clocks control circadian
rhythms in plants and other
eukaryotes
Photoperiodism
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Photoperiodism synchronizes many
plant responses to changes of
season
Phytochrome
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Phytochrome functions as a
photoreceptor in many plant
responses to light and photoperiod
Control Systems
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Control systems enable plants to
cope with environmental stress
Plants
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The study of plants began when
early humans began to distinguish
edible plants from poisonous
ones.
Then began to make things from
wood and other plant products.
Modern Science
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Today scientists aim for
increasing crop productivity, but
the fun of discovery is what
motivates most plant scientists.
Plants
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Plant biology, one of the oldest
branches of science, is driven by
curiosity and need – curiosity about
how plants work and a need to feed,
clothe, and house an increasing human
population. Plant biology is in the midst
of a renaissance, in which new
methods, coupled with clever choices
of experimental organisms, have
catalyzed a research explosion.