Transport In 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 H 2 O 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
Stomata Open during the day / Closed at night first light (blue light receptor) depletion of Carbon Dioxide internal clock (circadian rhythms)
Reducing Transpiration Small, thick leaves Thick cuticle Stomata are recessed Lose their leaves C 4 or CAM plants
Translocation of Phloem Sap
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
A Pressure Flow and Translocation A) Pressure is high B) Pressure is low C) Xylem recycles water D) Allows Phloem sap to flow from source to sink C B
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 availability of soil water and minerals
The availability of soil water and minerals Plant takes up water not tied to hydrophilic soil particles Positively charged ions attach to soil H+ help displace minerals attached to soil Roots add H+ to the soil directly and through the release of (reacts with water to form carbonic acid)
The availability of soil water and minerals
Soil Conservation Fertilizers (Nitrogen, Phosphorus, Potassium)
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
Nitrogen Fixation Plants absorb nitrogen in the form of nitrate and ammonifying bacteria produce ammonium Ammonium is shifted to nitrate by nitrifying bacteria Plants shift nitrate back to ammonium for use
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
Plant Hormones Auxin (IAA) Cytokinins Gibberllins Abscisic Acid Ethylene Oligogaccharins Brassinosteroids
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
Acid Growth Proton pump stimulated by auxin lower ph of wall H+ activates Enzyme Enzyme breaks hydrogen bonds in cellulose Wall takes up water and elongates
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 Stimulates root growth Stimulates cell division and differentiation (with auxins) 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)
Abscisic Acid Slows growth Closes stomata under water stress Permits seed dormancy
Ethylene Promotes fruit ripening Controls Abscission (causes leaf loss)
Plant Movements Phototropism Gravitropism
Plant Movement Rapid Leaf Movement (39.27) drop in turgor pressure within pulvini sent by action potentials
Plant Movement Sleep Movements (39.21) cells on opposite sides of pulvinus control the movement
Daily and Seasonal Responses Circadian Rhythm Photoperiodism controls flowering (short-day vs. long-day) critical night length
Photoperiodic Control
Flowering Hormones Experiment indicates the presence of some type of flowering hormone
Phytochromes Function as photoreceptors / red (660nm) to far red (730nm) Activates kinases (regulatory proteins)
Red vs. Far Red Response
Plant Responses to Environmental Stress Water Deficit Oxygen Deprivation Salt Stress Heat Stress Cold Stress Herbivores
Responses to Herbivores Produce (an amino acid similar to arginine) Recruitment of predatory animals
Food! Why plants are important? 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 Dates back to 3000 B.C. Greek Physician Hippocrates prescribed it. From and other Salicylate-rich plants (leaves and bark) Scientists at Bayer began investigating acetylsalicylic acid as a less-irritating replacement for standard common salicylate medicines. By 1899, Bayer named it this Aspirin