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Transcript
PLANT FORM AND FUNCTION Chapter 27 A. Plant Tissues Gymnosperms (겉씨식물) & Angiosperms(속씨식물) consist of 4 basic tissue types. 1. Meristems Regions of active cell division; contain undifferentiated cells. • Apical meristems • located near tips of shoots & roots in all plants • allow shoots & roots to lengthen • give rise to: (primary growth) protoderm (원표피) dermal tissue procambium(전형성층) vascular tissue ground meristem (기본분열조직) ground tissue • Lateral meristems (측생분열조직: cambia) • located in older roots & shoots of woody dicots (수목 쌍자엽) & gymnosperms (겉씨식물) • allow shoots & roots to increase in diameter (secondary growth) • Intercalary meristems(절간분열조직) • located in bases of grass leaves • allow rapid regrowth 2. Ground(기본) Tissue(조직) • Makes up(구성) the bulk of plant’s interior; consists of 3 cell types. Parenchyma (유조직) cells • • • relatively unspecialized thin primary cell walls function in cellular respiration, photosynthesis & storage of metabolic products • Collenchyma cells(후각조직) • unevenly thickened primary cell walls (can stretch) • function to support growing regions of shoots • Sclerenchyma cells (후벽 조직) • thick secondary cell walls • usually dead at maturity • function to support non-growing regions of plant Sclereids (보강세포) Fibers (밧줄로 사용되는 마닐라삼) 3. Dermal Tissue Single layer of tightly packed cells (epidermis) covering plant. Dermal Specializations: • Cuticle - waxy coating produced by epidermis of stems & leaves Functions to protect plant & conserve water. • Stomata - pores extending through epidermis Regulate gas & water exchange with environment. • Trichomes - epidermal outgrowths Root hairs increase surface area for absorption. Leaf hairs slow air movement over leaf, reducing water loss. Some trichomes deter predators. (공변세포) 4. Vascular Tissue Specialized conducting tissue in plants; xylem & phloem. • Xylem • transports water & dissolved minerals from roots to shoots • • • consists of tracheids (헛물관:물의이동느림) & vessel elements (물의 이동 빠름 why: 직경크고, 직접적인 물의 흐름) dead at maturity but do its function thick secondary cell walls Tracheids - long, narrow cells. Water moves from one cell to the next through thin areas (pits). Vessel elements - short, barrel-shaped cells; more specialized than tracheids. Water moves directly from one cell to the next because the end walls usually disintegrate. Water moves faster through vessel elements because of their larger diameter & direct water movement. • Phloem • transports organic compounds throughout plant • • • • consists of sieve cells (체세포) or sieve tube members (체관요소) & companion cells (동반세포) alive at maturity (체판) B. Plant Anatomy Basic parts of a flowering plant include stems, leaves, roots, flowers & fruits. 1. Stems - central axes of shoots Function to: • support plant • transport nutrients/water • produce/store nutrients Consist of nodes, internodes & axillary buds. Vascular bundle: scattered throughout ground tissue each vascular bundle somewhat resembles a “monkey” face” Modified Stems: stolons fleshy stems thorns tubers tendrils rhizomes 2. Leaves - primary photosynthetic organs of most plants. Most consist of: • flattened blade • stalk-like petiole • central midrib • numerous veins Leaves are shed from an abscission zone (탈리층) at base of petiole. Leaves are classified based on form & type of venation. Leaf Forms simpleleaflets all attach to one point at the top of the petiole palmate compound Leaf Venation netted(호박) parallel pinnate compound leaflets are paired along a central line surrounds outer portion of leaf. It typically secretes a cuticle & contains numerous stomata epidermal layers Vein xylem phloem epidermal layers Modified Leaves: • Cotyledons • Tendrils Spines (Cacti) Bracts (Poinsettia “flower”) Storage leaves(Onion bulbs) • Insect-trapping leaves • • • 3. Roots underground part of a plant Function to: • anchor plant • absorb, transport, & store water and minerals • absorb oxygen Two main types: • taproots • fibrous roots Cortex (피층) Pericycle(내초) (원 표피) (뿌리골무) Monocot root Dicot root (stele) Enlargement of dicot stele(관다발) Modified Roots: • • • • Storage roots Pneumatophores (통기근) Aerial roots(기근) • • Buttress roots Prop roots (부정근) C. Secondary Plant Growth (growth in diameter) Lateral meristems (vascular & cork cambia) increase diameter of stems & roots in woody dicots & gymnosperms. 1. Vascular Cambium Ring of meristematic tissue that produces secondary xylem & phloem. Woody stem secondary growth 2. Cork Cambium Ring of meristematic tissue that produces phelloderm & cork. • phelloderm - parenchyma cells; alive at maturity • cork - waxy, densely packed cells; insulates, waterproofs, & protects underlying tissues; dead at maturity Periderm(주피) = cork + cork cambium + phelloderm(코르크피층) Woody stem secondary growth periderm Bark = periderm + phloem Woody stem secondary growth