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Plants
BI102 Exam 3
| Term | Definition |
|---|---|
| Roots | Anchors vascular Absorbs minerals & water near root tip Stores carbs Vast numbers of tiny root hairs incr SA of root May have mutualistic relationship with/ mycorrhiza |
| Taproot system | Most eudicots and gymnosperms One large vertical root with small lateral (branch) roots Often store food (support flowering / fruit prod) |
| Fibrous root system | Seedless vascular plants and most monocots Mat of thin roots spread below soil surface Prevents erosion |
| Stems | Consist of alternating system of nodes and internodes Axillary bud Terminal bud Apical dominance |
| Nodes | attachment points for leaves |
| Internodes | stem segments between nodes |
| Axillary bud | structure that has the potential to form a lateral shoot (branch) |
| Terminal bud | located near the shoot tip and causes elongation of a young shoot |
| Apical dominance | Presence of terminal bud inhibits growth of axillary buds Taller growth increases exposure to light |
| Leaves | Main photosynthetic organ of most vascular plants Consist of a flattened blade and a stalk & petiole (joins the leaf to a node of the stem) Possess veins: vascular tissue of leaves Monocots: parallel veins Eudicots: branching veins |
| Simple leaf | Single, undivided blade Some leaves are deeply lobed as in an oak leaf |
| Compound leaf | Blade consists of multiple leaflets No axillary bud at its base |
| Doubly compound leaf | Each leaflet is divided into smaller leaflets |
| Tissue systems | Each plant organ possesses dermal, vascular, and ground tissues |
| Dermal tissue | -Nonwoody plants: epidermis Single layer of tightly-packed cells Cover / protection Secretes waxy cuticle: prevent water loss -Woody plants: periderm Replaces epidermis in older regions of stems/roots |
| Vascular tissue | carries out long-distance transport of materials b/w roots and shoots Xylem - conveys water and dissolved minerals upward from roots into the shoots Phloem - transports organic nutrients from where they are made to where they are needed |
| Ground tissue | Tissue that is neither dermal nor vascular Includes various cells specialized for functions such as storage, photosyn, and support Eudicot stems –pith: ground tissue internal to vascular tissue –cortex: ground tissue external to vascular tissue |
| Parenchyma cells | Perform most metabolic functions of plant Leaf parenchyma cells: photosyn Stem/root: starch storage Fleshy tissue of most fruit Retain ability to divide/differentiate into other cell types –repair / replacement after injury |
| Collenchyma cells | Grouped into strands / cylinders Help support young parts of plant shoot Strong & bendy, but not woody (think, strands inside celery) |
| Sclerenchyma cells | -Supporting elements of plant -More rigid than collenchyma cells -Occur in non-lengthening regions Don't elongate Most dead at maturity Produce rigid cell walls -Types: fibers (long/slender), sclerieds (hard & irregular) |
| Water conducting cells of Xylem | Tracheids and vessel elements Dead at functional maturity Cell walls remain: channels for H2O flow |
| Sugar-conducting cells of Phloem | -Sieve-tube members Movement of sucrose / other organic compounds Alive at maturity (but lacks a nucleus & ribosomes) -Companion cell Helps load surge Performs cell maintenance for the sieve tube cell |
| Meristem | Generate cells for new organs -Apical meristems Located @ tips of roots & in buds of shoots Elongate shoots & roots thru prim growth -Lateral meristems - add thickness to woody plants thru secondary growth |
| Plant growth terminology | Indeterminate growth: growth throughout life (most plants) Annual plants: complete life cycle in ≤1 yr (reproduce by seed) Biennial plants: complete life cycle in 2 yrs (Must reproduce by seed by the end of 2nd year) Perennial plants: live many years |
| Root cap | Covers root tip Protects the delicate apical meristem as the root pushes through soil during primary growth Secretes lubricating slime |
| Primary growth of roots | Epidermis, ground, and vascular tissue Root cap Lateral roots - arise from w/in pericycle (outermost cell later in vascular cylinder) |
| Primary growth of shoots | Shoot apical meristem Dome-shaped mass of diving cells at tip of terminal bud Gives rise to repetition of internodes and leaf-bearing nodes |
| Tissue organization of stems | In gymnosperms and most edicts vascular tissue consists of vascular bundles arranged in a ring (unlike roots) In monocots vascular bundles are scattered thru out ground tissue |
| Tissue organization of leaves | Epidermal barrier: defense, waxy cuticle, interrupted by stomata (exchange CO2 b/w air & photosyn c) Mesophyll (ground tissue): b/w upper & lower epidermis, parenchyma cells Vascular tissue: Con't w/ vascular tissue of the stem, supports shape of leaf |
| Secondary growth | Add girth to stems & roots in woody plants Occurs simultaneously with primary growth Secondary plant body consists of the tissues prod by the vascular and cork cambium |
| Vascular cambium | Cylinder of meristematic c that form secondary vasc t Develops from parenchyma c Forms layers of secondary xylem (interior) / phloem (exterior) Increase in diameter of woody plant Appears as ring w/ regions of diving c called fusiform & ray initials |
| Cork cambium | Gives rise to the secondary plant body’s protective covering (periderm) Periderm– consists of the cork cambium plus the layers of cork cells it prod Bark- consists of all t external to vasc cambium including secondary phloem & periderm |
| Transport at cellular level | 1. Selective permeability of membranes 2. Role of proton pumps 3. Role of water potential 4. Role of aquaporins |
| Selective permeability of membranes | Ctrl movement of solutes in & out of cell Enables plant cells to maintain diff internal environment than surroundings Active transport Transport proteins Selective channels (e.g. ion channels) |
| Proton pumps | Expend ATP to create H+ gradient that contributes to membr potential; both perform c work Cations (K+) driven into c by membr potential Transport protein - nrg coupled Cotransport |
| Water potential | Direction of osmotic movement of water into & out of plant c Combines the effects of solute concentration and pressure flow: high water potential -> low water potential Affects uptake & loss of water |
| Plasmolyzed | Lose water, water goes to higher solute concentration outside |
| Turgid | Gaining water, as outside has a lower solution concentration Causes wilting |
| Aquaporins | Membr transport proteins that allow transmembr water passage Passive movement Inc flow rate of water (down potential gradient), not altering water potential Regulates rate of H2O uptake & loss |
| Transport at cellular level | Role of symplast / apoplast Most plant tissues: continuous c walls / cytoplasm from cell to cell Plasmodesmata connect cytoplasmic compartments Lateral transport: movement of water and mins thru plant; via transmembrane, symplastic, or apoplastic route |
| Long distance transport at the whole-plant level | Bulk flow: movement of fluid driven by pressure Movement of fl in xylem & phloem Pressure differences @ opposite ends of the xylem vessels & sieve tubes Sieve-tube (phloem): few organelles Vessel elements/Tracheids (xylem): dead |
| Root absorption | Root hairs & Mycorrhizae Endodermis: innermost layer of root cortex c, surround vascular cylinder, last checkpt for selective passage of mins from cortex to vasc tissue Casparian strip - blocks apoplastic transfer of mins from cortex to vasc cylinder |
| Apoplastic movement | Transport of water, minerals, and solutes thru non-living parts of plants—specifically c walls and intercellular spaces w/o crossing plasma membr |
| Xylem transport root pressure | Night: transpiration low Root cells pump mins into xylem Water flows in from the root cortex -> root pressure generated Guttation Exudation of H2O droplets on tips of grass blades / leaf margins of some small eudicots due to root pressure |
| Xylem transport: transpirational pull | Water is pulled upward by negative pressure in xylem Water vapor exits leaf via stomata Transpiration: negative pressure (tension) in the leaf Exerts a pulling force on H2O in xylem Pulls H2O into leaf |
| Xylem transport: cohesion and adhesion | Cohesion: sticking of H2O together due to H-bonds Adhesion: “sticking” of H2O to xylem cell walls due to hydrophilicity of walls Facilitate transmission of transpirational pull on xylem sap; from the leaves to root tips and mechanism of bulk flow |
| Stomata | Help regulate rate of transpiration Located on leaves Flanked by guard c that ctrl stoma opening via shape change Stoma open and close due to changes in turgor pressure Uptake / loss of K+ ions by guard c |
| Xerophytes | Plants adapted to arid climates with modified stomata and other leaf modifications to reduce transpiration rate Xerophyte stomata Concentrated on lower leaf Located in depressions |
| Transpiration rate | evaporation of water from plants (primarily through stomata), is generally incr by higher temperatures, increased wind, higher light intensity, and lower humidity |
| Phloem transport | Sugar loading into sieve-tube members before exposed to sinks; req active transport Many plants suger move via symplastic & apoplastic pathways Proton pumping and cotransport of sucrose and H+ Enable cells to accumulate sucrose Chemiosmotic mechanism |
| Angiosperm transloccation: pressure flow | Sap moves thru a sieve tube by bulk flow driven by positive pressure Pressure flow hypothesis: why phloem sap flows from source to sink Testing pressure flow as the mechanism of translocation in angiosperm |
| Rhizome | The edible base of this ginger plant is an example of a rhizome, a horizontal stem that grows just below the surface or emerges and grows along the surface |
| Stolons | Shown here on a strawberry plant, stolons are horizontal stems that grow along the surface. These “runners” enable a plant to reproduce asexually, as plantlets form at nodes along each runner |
Created by:
phillipchristopherr
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