Download Botany Part IV Plant Signaling fill in the blank

Botany: Part IV
Plant Signaling
Plant Responses
Plant _____________ trigger a signal
transduction pathway
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Tropisms
A _______________
is the turning or
bending movement
of an organism or a
part toward or away
from an external
______________,
such as light, heat, or
gravity.
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Tropisms
What are
these plants
responding
to?
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Plant Hormones
• _____________- stimulate cell elongation,
responsible for tropisms
• _____________-stimulate cytokinesis or cell
division, and cell differentiation
• _______________- stimulate cell elongation in
stems
• _______________-promotes seed dormancy,
slows growth
• _______________- gas, promotes ripening of
fruit and cell death
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Plant Response to Light
Plants can detect light’s direction, intensity, and
wavelength. Light receptors are called
__________________________.
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Photoperiodism
• _______________________ is the physiological
reaction of organisms to the length of day or night.
• It occurs in plants and animals.
• In the 1940s researchers learned photoperiodism is
____________________________.
• Photoperiodism can also be defined as the
developmental responses of plants to the relative
lengths of the light and dark periods.
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Short-Day Plants
• ________________ (long-night) plants flower when
night exceeds a critical dark period.
• A flash of light interrupting the dark period
________________flowering.
• Examples: Chrysanthemums, poinsettias and some
soybean plants generally flower in late summer, fall or
winter.
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Long-Day Plants
• ___________________ (short-night) plants flower only if
the night is shorter than a critical dark period.
• A brief flash of light artificially interrupts a long dark period,
thereby _______________________ flowering.
• Examples: spinach, radishes, lettuce, irises and many cereal
varieties are long-day plants.
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Photoperiodism
• To flower or
not to
flower?
That is the
question.
(Apologies to
Shakespeare)
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Geotropism (or Gravitropism)
• ___________________ or
gravitropism turning or growth
movement by a plant or fungus
in response to gravity.
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Response to Other Stimuli
• ________________________ is a movement in
which a plant moves or grows in response to
touch or contact stimuli.
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