Download Chapter 32 Plant Growth and Development How do seeds

Chapter 32 Plant Growth and Development
How do seeds germinate?
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Germination
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__________________________________ influence germination
Spring rains provide the___________________ amounts necessary to swell and rupture the seed
coat (taking in water is______________________)
______________________ moves in and allows the embryo to switch to aerobic metabolism
Increase__________________________ and number of daylight hours
Repeated cell divisions produce a seedling with a ______________________________.
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Genetic Programs, Environmental Cues
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Patterns of ___________________ and ____________________ have a heritable basis dictated by a
_________________________
Early cell divisions may result in _____________________ of cytoplasm
Cytoplasmic differences trigger variable ______________________, which may results in variations
in hormone synthesis
Even though all cells have the same genes, it is the selective expression of those genes that results in
____________________________________.
Growth and Development
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Growth and development are necessary for plants to _____________________
Growth:
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Development:
Plant Hormones
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_____________________________ have central roles in the selective gene expression underlying
cell differentiation and patterns of development
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Types of Plant Hormones
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Gibberellins:
Help buds and seeds break ___________________and resume growth in the spring.
In some species, they influence the_________________ process.
Cytokinins:
Without
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Grapes (Gibberellins)
WITH
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Auxins:
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May participate in growth responses to _____________________________
_______________________________ (IAA) is applied to fruit trees to promote uniform flowering,
set the fruit, and encourage synchronous development of fruit.
_________________ (such as 2,4-D) are used as herbicides
Abscisic Acid (ABA):
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Ethylene
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Other less well known hormones trigger_______________ and ______________ the growth of
lateral buds (apical dominance)
What are tropisms?
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A plant tropisms is a ___________________________
Evidenced by a turning of a root or shoot toward or away from an _______________________
___________________________ mediate the shifts in rates at which different cells grow and
elongate to cause the overall response
Gravitropisms:
__________________, together with a growth—inhibiting hormone, may play role in promoting, or
inhibiting, growth in strategic regions
_______________________, which are unbound starch grains in the plastids, respond to gravity and
may trigger the redistribution of auxin
Phototropisms:
Bending toward the ____________ is caused by elongation of cells (_____________ stimulation on
the side of the plant not exposed to light).
______________________, a pigment molecule probably plays a role because of its capacity to
absorb blue wavelengths of light
_____________________________ is shift in growth triggered by physical contact with surrounding
objects.
Prevalent in climbing _________________ and in the tendrils that support some plants
___________________ and _________________ may have roles in the response
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Response to Mechanical Stress
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Response to the _______________________ of strong winds explain why plants grown at higher
mountain elevations are more stubby than their counterparts at lower elevations
Human interventions such as ___________________ can inhibit plant growth.
How do plants know when to flower?
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Phytochrome:
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_________________________ are internal time-measuring mechanisms that adjust daily and
seasonal patterns of growth, development, and reproduction
Phytochrome–
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___________________________- can absorb both read and far-red wavelengths with different
results.
When is the pigment activated?
When is the pigment inactive?
Some plants activities occur regularly in cycles of 24 hours (__________________________) even
when environmental conditions remain constant
Flowering – Photoperiodism
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_____________________________ is a biological response to a change in relative length of daylight
and darkness in a 24-hour cycle; this resetting of the biological clocks is necessary to make seasonal
adjustments
The flowering process is keyed to changes in daylength throughout the year.
Short-day plants:
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Example:
Long-day plants:
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Example:
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Day-Neutral Plants:
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Example:
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Senescence
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The dropping of leaves, flowers, fruits is called _______________________
Senescence:
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Decrease of daylight hours trigger the reduction of __________________
Cells in ________________________ produce ethylene which causes cells to deposit suberin in their
walls
Entering and Breaking Dormancy
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___________________ occurs in autumn when daylight shortens and growth stops in many trees
and nonwoody perennials– it will not resume until spring
Strong cues for dormancy include in
______________________has great adaptive value in preventing plant growth on occasional warm
autumn days only to be killed by later frost.
Vernalization
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Vernalization
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Deliberately exposing seeds to _______________________________ to stimulate flowering the next
season is common agricultural practice.
Breaking Dormancy
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_____________________ is broken by milder temperatures, rains, and nutrients.
It probably involves_________________ and ________________________, and require exposure to
specific periods of low temperatures.