transport in plants. water potential the physical property predicting the direction in which water...
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TransportIn Plants
Water Potential
• The physical property predicting the direction in which water will flow– ____________________– Pressure
• water moves from high water potential to low water potential
Water Potential (a)
• Left Side– Pure Water = 0 Water
Potential
• Right Side– Negative Water
Potential• 0 pressure• - solute (has solutes)
• Water moves to the right
Water Potential (b)• Left Side
– Pure Water = 0 Water Potential
• Right Side– 0 Water Potential
• + pressure equal to solute conc.
• - solute (has solutes)
• Water is at equilibrium
Water Potential (c)• Left Side
– Pure Water = 0 Water Potential
• Right Side– Positive Water
Potential• + pressure more
than solute conc.• - solute (has solutes)
• Water moves to the left
Water Potential (d)
• Left Side– Pure Water and
Negative Tension
• Right Side– Negative Water
Potential• 0 pressure• - solute (has solutes)
• Water moves to the left
Transport of Xylem Sap
• Pushing Xylem– Root Pressure
• caused by active pumping of minerals into xylem
• _____________: accumulation of water
Transport of Xylem Sap
• ______________– Transpiration
• evaporative loss of H2O from a plant through the stomata
Transport of Xylem
Sap
The Control of Transpiration
• ______________– turgid - open– flaccid - closed
• Potassium Ions– active transport of H+ out of
cell causes K+ to move in
Translocation of Phloem
• Phloem Sap– 30% sucrose, minerals, amino acids,
hormones– Transported in sieve-tube members
• ____________– leaves, tuber or bulbs•Sugar sink – growing roots, shoots,
fruits
Pressure Flow and
TranslocationA) Pressure is high
B) Pressure is low
C) Xylem recycles water
D) Allows Phloem sap to flow from source to sink
A
B
C
Plant Nutrition
Uptake of Nutrients
_______________ cultures used to determine which chemical elements are essential.
17 essential elements needed by all plants
Soil• Develops from weathered
rocks– Anchors plants– Provides water– Provides dissolved minerals
Soil Texture
• Pertains to sizes of soil particles– includes the following:
• sands (0.02 - 2 mm)• silt (0.002 - 0.02 mm)• clay (less than 0.002 mm)
Soil Composition• Made up of sand, silt, clay,
rocks, humus, microorganisms (bacteria, fungi, algae, protists, insects, worms, roots)
• Soil contains a mixture of different sized particles– _______ – roughly equal amounts
of sand, silt, and clay – most fertile
The Nation that Destroys Its Soil Destroys Itself – Franklin D. Roosevelt 1937
Loss of Topsoil• 1930’s “_____________”• Due to inappropriate farming in
late 1800’s and early 1900’s• Wheat and cattle farming• Droughts• Steinbeck’s Grapes of Wrath• 30% of world’s farmlands have
reduced production due to poor soil conditions.
Nitrogen Fixation
Unusual Nutritional Adaptations in Plants - Epiphytes
Unusual Nutritional Adaptations in Plants - Mistletoe
Unusual Nutritional Adaptations in Plants – Venus Fly Traps
Unusual Nutritional Adaptations in Plants – Pitcher Plants
Unusual Nutritional Adaptations in Plants - Sundews
Control Systems in Plants
Plant Hormones
• Coordinates growth• Coordinates development• Coordinates responses to
environmental stimuli
Auxins
• Stimulates stem elongation• Stimulates root growth• Stimulates differentiation and
branching• Stimulates development of fruit• Stimulates apical dominance• Stimulates phototropism and
gravitropism
Auxin Control• Auxin stimulates
growth• Auxin block on
right causes cells to elongate and the plant bends left
• Auxin block on left causes cells to elongate the the plant bends right
• Proton pump stimulated by auxin lower pH of wall• H+ activates Enzyme• Enzyme breaks hydrogen bonds in cellulose• Wall takes up water and elongates
Acid Growth
Auxin Others• Promotes secondary growth
by stimulating vascular cambium and secondary xylem
• Promotes adventitious root at the base of a cut stem
• Promotes fruit growth without pollination (seedless tomatoes)
Cytokinins• Works with Auxin:
– more cytokinin - shoot buds develop
– more auxin - roots develop
• Stimulates germination• Delays Senescence
Gibberellins• Promotes seed and bud
germination• Promotes stem elongation• Promotes leaf growth• Stimulates flowering and
fruits– (with auxin)
Ethylene• Promotes fruit ripening• Controls Abscission (causes
leaf loss)
Daily and Seasonal Responses
• Circadian Rhythm• Photoperiodism
– controls flowering (short-day vs. long-day)
– critical night length
Phytochromes
• Function as photoreceptors / red (660nm) to far red (730nm)
• Activates kinases (regulatory proteins)
Red vs. Far Red Response
Responses to Herbivores
• Produce _________ (an amino acid similar to arginine)
• Recruitment of predatory animals
Why plants are important?• Food!
• Humans have domesticated plants for 13,000 years.
• ____ of all the calories consumed by humans come from six crops: Wheat, Rice, Maize, Potatoes, Cassava, and Sweet Potatoes.
• Also, we use plants to feed cattle, 5-7kg to produce 1 kg of beef.
Pyramid of Net Productivity
Plants remove CO2
•_____ of all US Prescription Drugs contain one or more active ingredients from plants.
•____ earth’s species will become extinct within the next 100 years (larger than the Permian or Cretaceous)
•Only 5,000 of 290,000 species have been studied.
•3-4 species per hour,
27,000 per year!
Cinchona tree
• Bark contains __________• Grows in the
Andes in peru• Used since the
early 1600’s to treat malaria
Aspirin• Acetylsalicylic acid or ASA Acetylsalicylic acid or ASA • Dates back to 3000 B.C.Dates back to 3000 B.C.• Greek Physician Hippocrates Greek Physician Hippocrates
prescribed it.prescribed it.• From _____________ and other From _____________ and other
Salicylate-rich plants (leaves Salicylate-rich plants (leaves and bark) and bark)
• Scientists at Bayer began Scientists at Bayer began investigating acetylsalicylic investigating acetylsalicylic acid as a less-irritating acid as a less-irritating replacement for standard replacement for standard common salicylate medicines. common salicylate medicines. By 1899, Bayer named it this By 1899, Bayer named it this Aspirin Aspirin