Download Resource Acquisition and Transport in Vascular Plants

Resource Acquisition and
Transport in Vascular Plants
Resource acquisition and transport
Transport review
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Passive transport – no energy required,
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Active transport – energy required
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ex. diffusion
Transport proteins required, ex – proton pump
Uses energy from ATP to pump H+ across
membrane
Cotransport – coupling of the steep gradient
of one solute(H+) with a solute like sucrose
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Drop in potential energy by H+ pays for transport
of sucrose.
Water potential (potential grid problems)
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Osmosis – movement of water across cell
membrane via aquaporins
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Water moves from area of high water potential to
low potential
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Water potential includes the effects of solute
concentration and physical pressure.
Transpiration
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Loss of water vapor from the leaves
Water and minerals are transported to rest of
plant via bulk flow
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Bulk flow is the movement of liquids in response
to a pressure gradient
Rate of transpiration is regulated by stomata
Stomata
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Pore in leaf epidermis with guard cells on
each side.
Water enters guard cells, following K+, turgor
pressure increases, stoma opens and vise
versa
Stomata open and close in respond to
environmental signals
Cohesion-tension hypothesis
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Transpiration provides the pull for the ascent
of water.
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Water is lost due to lower water potential of the air
Cohesion of water molecules via hydrogen
bonds plus adhesion of water to plant cell
walls form a water column.
Organic nutrient transport
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Girdling – removing bark form tree,
accumulation of sugar
Pressure flow model – 29.22
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Sugar enters the sieve tubes (active transport)
and creates positive pressure, phloem begins to
flow
Roots are a sink – provide place for sugar to be
used for cellular activities (respiration)
Source to sink – leaves to roots or any place that
needs sugar (new leaves…)
Soil and Plant Nutrition
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95% of plant’s dry weight (biomass) is
carbon, hydrogen, and oxygen
(carbohydrates, CO2 and water)
Minerals – provide proteins and nucleic acids
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Essential nutrients – has role, no substitute, and a
deficiency results in death.
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Macro and micronutrients according to concentration
Beneficial nutrients – required or enhances growth
Mutualistic relationships
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Nitrogen-fixing bacteria – root nodules of
legume plants
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Fix atmospheric nitrogen into a form that plants
can use, plants provide food to bacteria
Mycorrhizae – plant roots and fungi, plants
give fungus food, fungus increases surface
area for water uptake and minerals
Symbiotic relationships that are
not mutualistic
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Parasitic plants (dodder), does not undergo
photosynthesis, needs other plants for
nutrients
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Epiphytes – grown on surface of other plants
instead of soil, not parasitic, ex. orchids
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Carnivorous – photosynthetic but get some
nitrogen and minerals from small animals