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67 Cards in this Set
- Front
- Back
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Movement to land: plants |
490 mya |
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Movement to land: animals |
418 mya |
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Challenges to new terrestrial environment and adpatiation
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Easier to dry out, less water availability - waxy cuticle, water scavenging systems, stomata - harder reproduction - pollen, seeds - gravity difference - vassculature, lignification, rhizoids and roots (Xylem and lignin, collenchyma came later) |
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-Oxygen Revolution |
- 2.7 bya - 2.3 bya caused the extinction of many prokaryotic groups - 500 mya another huge increase in O2 |
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What is the closest relatives of land plants |
Green Algae called charophytes |
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Advantages to moving to land |
- unfiltered sun -more plentiful CO2 and O2 - nutrient rich soil |
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-Five key traits of land plants (absent in embryophytes) |
- alternation of generations - walled spores produced in sporangia --> spores by meiosis inside sporangia - multi cellular gametangia -multi cellular dependent embryos -apical meristems |
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-What kind of plant has the sporophyte dependent on the gametophyte |
-Mosses |
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Do gymnosperms make pollen? |
Yes, just not fruits Pollen lands on cones "naked seeds" |
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Cotyledons |
"seed leaves" |
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difference between monocot and dicot |
monocot has one cotyledon and dicot have two cotyledons |
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-Meristems |
-sites of undifferentiated cells undergoing permanent cell division |
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- Root functions |
-anchoring the plant -absorbing minerals and water -storing carbohydrates |
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Taproot versus Fibrous root system |
Taproot --> giant root, anchorage, water Fibrous root --> very branched, mine surface layers very efficiently, erosion control |
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Stems |
an organ consisting of - and alternating system of nodes, the points at which leaves are attached -internodes (stem segments between nodes) |
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Intercalary meristems |
meristems at internodes (stem segments between nodes) |
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Axillary bud |
has the potential to form a lateral branch, thorn or flower |
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Ground Tissue |
- everything else other than dermal and vascular tissue -a lot of specialized function pith and cortex - storage, photosynthesis, support, and transport - Parenchyma, Collenchyma, Sclerenchyma |
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Parenchyma cells
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-have thin and flexible walls -are the least specialized - retain the ability to divide and differentiate Ground Tissue |
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Collenchyma Cells |
-grouped in strands and help support young parts of the plant shoot - thicker and uneven cell walls - cells provide flexible support without restraining growth ex: celery Ground Tissue |
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Sclerenchyma Cells |
Rigid because of thick walls strengthened with lignin -dead at functional maturity ex: Peach skin grittiness or nuts Ground Tissue |
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Vascular Tissue System |
-facilitates the transport of materials through the plant and provide mechanical support -two vascular tissues are xylem and phloem |
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Xylem |
Conducts water and dissolved minerals upward from roots into shoots -Vessels - plumbing system made out of cells, but really well interconnected; highly lignified - very strong - Tracheids: similar to vessels; dead when functional (hollow) make wood |
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Vessels
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plumbing system made out of cells, but really well interconnected; highly lignified - very strong |
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Tracheids |
Similar to vessels dead at maturity so they're hollow and easier for water to flow through make wood |
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Phloem |
Transports sugars from where they are made to where they are needed
- Sieve tube elements -Sieve plates |
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Sieve-Tube elements
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alive at functional maturity, though they lack organelles- to help stuff pass through |
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Sieve plates |
porous end walls that allow fluid to flow between cells along the sieve tube |
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Companion cells
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Each Sieve-tube element has a companion cell whose nucleus and ribosomes serve both cells |
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Stele |
the vascular tissue of a root or stem collectively |
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Apical meristems versus lateral meristems |
Apical meristems - located at the tips of roots and shoots, elongate shoots and roots, a process called primary growth Lateral meristems - secondary growth, vascular and cork cambrium |
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Root structure |
Root cap, apical meristem, zone of cell division, zone of elongation, zone of differentiation Quiescent center cells in the middle Pericycle - give rise to lateral roots |
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Pericycle |
lateral roots arise from within the pericycle, the outermost cell layer in the vascular cylinder -able to generate meristematic cells - not always in constant division |
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Leaf primordia |
basically just a meristem along the sides of the apical meristem that develops leaves |
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Vascular Cambrium |
secondary xylem and phloem |
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Cork Cambrium |
repairs and replaces the epidermis with periderm during secondary growth |
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Ψp - positive and negative |
Positive if pumped and negative if sucked |
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Flaccid guard cells |
stomata closed |
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Turgid guard cells |
stomata opened more K+ makes solute potential more negative making guard cells turgid |
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Plasmodesmata |
cytoplasmic junctions that helps move ions through the cytoplasm in the symplastic route |
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How do you pump sugar into the phloem? |
Done by a proton symporter (co transporter) ATP fuels pump and moves H+ across the membrane (inside sieve tube to outside), sucrose then moves from the outside of the phloem to the inside of the phloem with H+ ions going Chemiosmosis
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Endophytes |
nonpathogenic bacteria that live between the cells of host plants tissues |
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Epiphytes |
plants that grow on the surface of other plants |
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A standard leaf |
upper waxy cuticle palisade mesophyll - chloroplast Spongy mesophyll - air spaces so CO2 can get through Lower waxy cuticle |
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Leaf hairs |
called Trichomes - trap humid air -act as physical deterrents -contain chemical defenses |
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To make a flower |
apical meristems of a plant gets developmental cues to switch from vegetative to floral |
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The four whorls of the flower |
Sepals Petal Stamen Carpel |
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Inflorescences |
clusters of flowers |
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Overview of angiosperm life cycle |
Gametophyte development Pollination Double Fertilization Seed Development |
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Imbibition |
the uptake of water due to low water potential of the dry seed - germination depends on this |
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Radicle |
embryonic root |
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Etiolated |
grow plants in the darkness so the plant thinks it's still underground and will grow really tall to try and reach sunlight |
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Plant senses |
"smell", touch, temperature, light |
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Cytokinins |
plant hormone that promotes cell division and meristem activity |
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Gibberellins |
triggers seed germination and stem elongation |
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Abscisic acid |
plant stress (drought) hormone |
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Ethylene |
plant hormone that regulates flower senescence and leaf fall as well as seed germination |
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All plant hormones tend to be |
-small organic molecules -work at very low concentrations -regulate many different processes |
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Auxin |
plant hormone which regulates cell elongation at the tip of the platns |
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Control of apical dominance |
cytokinins, auxin, and strigolactone interact to control this |
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what is apical dominance |
a terminal buds ability to suppress development of the axillary buds |
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Auxin and cell elongation |
auxin stimulates proton pumps in plasma membrane which lower the pH in the cell wall which then activates expansins (enzymes) which loosen the walls fabric |
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What wave lengths of light trigger phototropism |
blue light and red light |
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phytochromes |
red light photoreceptors - seed germination and shade avoidance |
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Pfr |
seed germination -shade avoidance (growth) internal clocks control of flowering |
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Pr |
inactivates phytochrome |
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Cryptochrome |
are a class of flavoproteins that are sensitive to blue light |
