BIOL 1030 Lecture Notes - Gibberellin, Xylem, Plasmodesma
7 May 2018
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BIOLOGY 1030 - KEVIN SCOTT and CARLA ZELMER - WINTER 2018 - Lectures 33-34!
Lecture 33: Plant Nutrition
"Carbon dioxide and oxygen from the atmosphere, and water and minerals (active
transport) from the soil are required for a plant to produce its organic compounds.!
Vascular Plant Nutrition: Water and minerals are taken in from the soil by the root hairs
(unicellular outgrowths of the root epidermis). High surface area is needed to maximize
absorption and as root hairs have a short lifespan of 2 to 7 days, are continuously produced.
"Cations : K+, Ca2+, Mg2+, NH3!
"Anions : P, N, S, H2O, O2!
" " Symbiotic relationships with fungi and N-fixing bacteria may arise in the soil.!
-**Lateral Transport: of water and minerals by root; entering the root from the soil by the root
epidermis (root hair zone), crosses the cortex of root (through transmembrane, symplast,
apoplast), and enters the vascular cylinder to the root xylem and up the stem.
•Transmembrane: cell to cell; repeated crossings of plasma membrane!
•Symplast: solutes and water more from cell to cell via plasmodesmata, in vacuoles!
•Apoplast: extracellular (intercellular) pathway (cell walls and extracellular spaces); the
plant does not control movement of water and solutes (which is controlled by Casparian
strip from the endodermis to the stele. !
"Endodermis is the boundary between the cortex (root) and the vascular cylinder;
controlling movement of solutes in/out of the root vascular cylinder. At the endodermis, water
and minerals flowing in through the apoplast pathway are blocked by the waxy casparian strip
of the endodermis between cells. Water and minerals are faced into living endodermis cells
which can control what will happen to them, exerting control on amino acids and sugars.!
Essential Plant Minerals:
•Nitrogen: for nucleic acids, amino acids, chlorophyll (dark green)!
•Phosphorous: nucleic acids, ATP!
•Sulphur: cysteine, methionine (nucleic acids)!
•Magnesium: chlorophyll !
•Calcium: cell wall, cytoplasmic control!
•Iron: chlorophyll synthesis!
•Potassium: opening and closing of stomates. !
Mineral uptake from soil (active transport):
-Root respiration (ATP)!
-O2 acceptor of electrons!
-Specific membrane proteins (co-transport of nitrates and phosphates)!
Symbiosis with fungi
Mycorrhizae: fungus root ( root and fungi, mycelia)!
-Fungus receives sugar produced by the plant, offering increased surface area for absorption
and enzymatic capabilities and foraging for nutrients for the plant. !
Ectomycorrhizae: fungus is extracellular and links plants in a forest.!
-Fungus penetrates the tree’s mantle, root cell wall but does not pass the plasma membrane!
"Nitrogen fixation !
Symbiosis: the conversion of N2 (nitrogen gas) to ammonia or nitrate!
-In legume nodules, with limited O2, bacteroids are provided with sugar in exchange for fixing
nitrogen to be absorbed. !
Carnivory: a result of nitrogen needs of the plant!
-Sticky traps: insects, daphnia, protists are lured by nectar produced by the plant and are
unable to escape!
-Digestive enzymes: mutualism or symbiosis with an insect to eat give faces to the plant!
-Pitfall traps: bacteria or enzymes digest drowned insects!
-Snap traps: actively trap by perturbation of hair, enzymes are secreted to digest the insect. !
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BIOL 1030 Full Course Notes
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Biology 1030 - kevin scott and carla zelmer - winter 2018 - lectures 33-34. Lecture 33: plant nutrition transport) from the soil are required for a plant to produce its organic compounds. Carbon dioxide and oxygen from the atmosphere, and water and minerals (active. Vascular plant nutrition: water and minerals are taken in from the soil by the root hairs (unicellular outgrowths of the root epidermis). High surface area is needed to maximize absorption and as root hairs have a short lifespan of 2 to 7 days, are continuously produced. **lateral transport: of water and minerals by root; entering the root from the soil by the root. Endodermis is the boundary between the cortex (root) and the vascular cylinder; controlling movement of solutes in/out of the root vascular cylinder. At the endodermis, water and minerals owing in through the apoplast pathway are blocked by the waxy casparian strip of the endodermis between cells.
