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Bio 123 lecture notes first three weeks.docx

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BIO 121
Jason Wiles

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Bio 123 lecture notes 01/22/2014 January 22, 14 Woody plants have both primary growth, in which they increase in height/length and secondary growth, in  which they increase in thickness Axilliary bud Parts of a leaf Blade Veins – vascular tissue Petiole – stem part of leaf Axiliraty bud Stipules Stem Leaves Broad, flat blade Stalklike petiole Some also have stipules Small leaf like outgrowths from the base Leaf forms Simple and compound Venation patterns Leaves Epidermis Covers upper, lower surfaces of lead blade Waxy cuticle coats epidermis Helps plants survive dry terrestrial conditions Stomata Small pores in epidermis Permit gas exchange for photosynthesis Surrounded by two guard cells Often associated with special epidermal cells (subsidiary cells) Stoma Inside guard cells Eudicot and Monocot Guard Cells Mesophyll ­ tissue Photosynthetic parenchyma cells Palisade mesophyll Functions primarily for photosynthesis Spongy mesophyll Functions primarily for gas exchange Leaf veins Xylem  Conducts water and essential minerals to leaf Phloem Conducts sugar produced by photosynthesis to rest of plant Monocot leaves Have parallel veins Eudicot leaves Adaptations for Photosynthesis 1 Most leaves have broad, flattened blade Efficient in collecting sun’s radiant energy Stomata open during day For gas exchange needed in photosynthesis Close at night to conserve water when photosynthesis is not occurring EXCEPT for in CAM plants (usually arid environments)! Then, the stomata open at night QUESTION Leaves are important to plants for obtaining water True (x) False () Transpiration Loss of water vapor from aerial parts of plants Occurs primarily through stomata Rate of transpiration Affected by environmental factors Temperature Wind Relative humidity Effects of transpiration Both beneficial and harmful to plant Trade­off between CO2 required for photosynthesis Need for water conservation QUESTION Loss of leaves can prevent water loss True (x) False () Leaf Abscission Loss of leaves As winter approaches in temperate climates At beginning of dry period in tropical climates with wet and dry seasons Complex process Physiological and anatomical changes occur prior to lead fall Spines Tendriles Bud Scales Bulbs Succulent Leaves Carnivorous Plants Key Concepts Some leaves are modified for special functions in addition to photosynthesis Stems Node An area on stem where leaf is attached Internode Region of stem between two nodes Cork Cambium Lateral meristem that produces periderm Cork parenchyma and cork cells Tension – cohesion Model 1 Explains rise of water Even in the tallest plants Transpiration Evaporative pull causes tension at top of plant Result of water potential gradient Ranges from slightly negative in soil and roots to very negative in atmosphere January 27, 2013 QUESTION Sugars conducted via phloem are transported by gravity alone. – FALSE Sugar Translocation – sucrose is the predominate sugar located in plants Dissolved sugar in translocated upward or downward in phloem From area of e
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