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Biology 102 Environmental Biology Plants/Agriculture Unit Page 1 of 15 Based on Mader, Sylvia S. 1996. Biology - 5th Ed. WCB and Cox, G.W. 1997. Conservation Biology - 2nd ed. WCB and Levine, J.S. and K.R. Miller. 1994. Biology: Discovering Life. D.C. Heath and Lewis, Gaffin, Hoefnagels & Parker. 2004. Life - 5th ed. McGraw Hill [Chapters 26 & 27] Plants Reading: Chapters 26 & 27 in Lewis et al. I. Plants A. Basic Needs 1. Sunlight a) Trees grow to it b) Algae may swim to it c) Need for support 2. Water a) Need for roots 3. Reproduction a) Special structures b) Plants can’t move (1) B. Evolution – movement onto land 1. Must solve 3 problems a) Support b) Water to leaves (1) 2. D:\769853838.doc Replacement of water as a means for mixing gametes A lot of work to raise gallons of water to the top of a tall tree c) Replacing water as a medium for sperm to swim in Solutions a) Roots b) Vascular tissue c) Pollen May 4, 2017 Biology 102 Environmental Biology Plants/Agriculture Unit Page 2 of 15 Figure 26.1A p 515 C. Parts of a plant: 1. Three main parts: a) Roots – obtain water, nutrients, anchor plant b) Stems – hold up plant, transfer water, nutrients, sap c) Leaves – photosynthetic center Figure 26.12 p. 525 2. D:\769853838.doc 3 tissues a) dermal tissue - protection b) vascular tissue – moving materials c) ground tissue – support, photosynthesis May 4, 2017 Biology 102 Environmental Biology Plants/Agriculture Unit Page 3 of 15 Figure 26.1b p. 515 3. Meristems a) Apical meristem (1) (2) b) lateral meristem (1) (2) c) D:\769853838.doc at the tips of roots increase in length circles stems and roots increase in girth differentiation – transformation of one of the divided meristem cells into a specialized cell May 4, 2017 Biology 102 Environmental Biology Page 4 of 15 Plants/Agriculture Unit Figure 26.2 page 516 4. Cell types: a) Epidermal cells (1) Covered with extracellular cuticle (2) Guard cells Figure 26.5 p. 519 Ground Tissues D:\769853838.doc May 4, 2017 Biology 102 Environmental Biology b) Parenchyma cells – ground tissue (1) c) Support of growth areas Sclerenchyma cells - ground tissue (1) (2) (3) Vascular tissues e) Storage, photosynthesis Collenchyma cells - ground tissue (1) d) Page 5 of 15 Plants/Agriculture Unit Support of non-growth areas Dead when functional Hard structures, fibers Xylem – transports water, minerals up (1) (2) (3) Comprised of tracheids or vessel elements Transport water Dead when functional Figure 26.6 p. 520 f) Phloem – transports sap – both ways (1) (2) Sieve-tube members – no nucleus Companion cells Figure 26.7 p. 520 D:\769853838.doc May 4, 2017 Biology 102 Environmental Biology 5. Plants/Agriculture Unit Page 6 of 15 Roots a) Primary roots b) Secondary roots Figure 26.14 p. 526 Figure 26.15A & B p. 527 D:\769853838.doc May 4, 2017 Biology 102 Environmental Biology Plants/Agriculture Unit Page 7 of 15 Figure 26.15 C, D & E p. 527 c) epidermis (1) d) e) (1) Figure 26.16 p 528 D:\769853838.doc Root hairs Cortex Endodermis Casparian strip Figure 26.17 p. 528 May 4, 2017 Biology 102 Environmental Biology II. Plants/Agriculture Unit Page 8 of 15 Transport Figure 27.1 p. 537 A. Water movement 1. 3 forces: a) root pressure b) capillary action c) transpiration (1) 2. 3. Ultimately powered by the sun 100 liters/day = 4 liters/hr = 4 kg/hr = 10 pounds / hr up 300 feet. Figure 27.6 p. 543 D:\769853838.doc transpiration is made effective by: (a) tension - “pull” from leaves (b) cohesion – water molecules stick together (c) adhesion – water sticks to walls of xylem Figure 27.7 p. 543 May 4, 2017 Biology 102 Environmental Biology B. Plants/Agriculture Unit Page 9 of 15 Water uptake by roots 1. Active transport of mineral ions into roots 2. Water follows due to osmotic pressure 3. Endodermis and Casparian strip regulate water flow – water must move through cells 4. High salt levels in soil can pull water out of the root hairs a) Halophytes tolerate higher salt concentrations Figure 27.8 p. 544 C. Sap movement 1. Pressure/flow hypothesis a) Sugars produced in leaves b) Sugars pumped into phloem c) Water follows by osmosis d) Roots remove sugar, cause gradient which draws sugar and water to roots e) Water usually moves in the opposite direction of sap Figure 27.9 p. 545 D:\769853838.doc Figure 27.1 p. 546 May 4, 2017 Biology 102 Environmental Biology D. D:\769853838.doc Plants/Agriculture Unit Page 10 of 15 Tree stems 1. Two layers of meristem tissue a) Vascular cambium produces new xylem to inside, phloem to outside b) Cork cambium forms new cork (bark) to outside 2. Annual rings – xylem produced more rapidly in spring May 4, 2017 Biology 102 Environmental Biology Plants/Agriculture Unit Page 11 of 15 Figure 26.19 p. 530 Figure 26.19 p. 530 Figure 26.20A p. 530 Figure 26.20B p. 530 Figure 26.21 p. 532 D:\769853838.doc May 4, 2017 Biology 102 Environmental Biology Figure 26.21 p. 532 III. Page 12 of 15 Plants/Agriculture Unit Figure 26.21 p. 532 Plant Growth A. Seeds 1. Three parts a) Embryo b) Stored food c) Seed coat 2. Monocots: a) One cotyledon b) Food stored in endosperm c) Grasses (corn, rice, wheat, etc) 3. Dicots: a) Two cotyledons b) Food stored in cotyledons c) Woody plants Figure 28.10 p 561 D:\769853838.doc Figure 28.13A p565 May 4, 2017 Biology 102 Environmental Biology Plants/Agriculture Unit Page 13 of 15 Figure 28.13B p565 B. Dormancy 1. Period of inactivity by the seed 2. Allows bad growing seasons to be bypassed 3. May last days to 12,000 years 4. Many seeds need drought, damage to seed coat, or freezing temperatures before germination Plant nutrients – Figure 27.2 p. 538 IV. A. 1. Materials needed for photosynthesis Water - source of hydrogen a) taken in through roots b) aided by mycorrhizae c) transported up trunk via xylem d) lost through stomata - transpiration e) Stomata open due to turgor pressure f) Turgor pressure requires water g) No water - stomata close, reduces water loss D:\769853838.doc May 4, 2017 Biology 102 Environmental Biology 2. a) b) c) CO2 - source of carbon Taken in at stomata Stomata open only when water available Taken in at night by desert plants a) b) c) d) e) Nitrogen - needed for amino acids Taken in as NO3- dissolved in H2O Nitrogen fixed by bacteria in soil Nitrogen present in animal wastes, fertilizers Rhizobium in nodules of legumes also fix N2 In short supply for bog plants --> carnivory 3. 4. Phosphorous - used in ATP, DNA, cell membranes a) Taken in with water as PO4 b) uptake enhanced by mycorrhizae c) "mined" from decaying organisms 5. a) B. Page 14 of 15 Plants/Agriculture Unit Magnesium - used in chlorophyll taken up with water Sources of minerals 1. Fertilizers a) N-P-K ratios --> nitrogen - phosphorous - potassium b) Elements removed from soil most quickly c) = 5% nitrogen, 10% phosphorous, 5% potassium d) Test soil to determine proper ratio 2. Mineral availability - affected by soil Property of pH - acids leach minerals from soils Under acid conditions soil releases aluminum and iron rather than calcium, magnesium and potassium c) Aluminum and iron may be toxic to the plant d) Plants can use energy to concentrate minerals far above levels found in the soil a) b) 3. a) b) c) Epiphytes - getting by without soil Some have roots, get water from atmosphere or rain Bromeliads Some send haustoria into plant for water or sugars or both D:\769853838.doc May 4, 2017 Biology 102 Environmental Biology C. 1. 2. 3. Plants/Agriculture Unit Page 15 of 15 Agriculture Human recreation of natural systems Only cycles if wastes returned to soil Otherwise --> mining soil 1. a) Practices: preparing soil (1) (2) (3) (4) (5) b) slash-and-burn machinery soil erosion use of fossil fuels soil compaction monoculture (1) (2) c) efficiency susceptibility to disease, pests fertilizers (1) (2) (3) d) replace lost nutrients expense eutrophication pesticides (1) D:\769853838.doc attempt to deal with pest problems caused by monoculture May 4, 2017