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10/2/2014 o Plants take up water and minerals from below ground o Plants take up CO2 and light from above ground THREE BASIC PLANT ORGANS ROOTS o Roots o Stems o Leaves o Anchor plant o Absorb water and minerals o Store carbohydrates LARGE AMOUNT OF ABSORPTION OCCURS THROUGH ROOT HAIRS MODIFIED ROOTS 1 10/2/2014 STEMS APICAL DOMINANCE o Raise and separate leaves o Support plant o Conduct materials from roots to leaves o Inhibition of lateral buds by an apical bud MODIFIED STEMS LEAVES o Main photosynthetic organ Consist of blade and petiole Can be simple or compound MODIFIED LEAVES PLANT TISSUES o Dermal o Vascular o Ground 2 10/2/2014 DERMAL TISSUE SYSTEM o Epidermis with waxy cuticle o Periderm replaces epidermis in woody plants VASCULAR TISSUE o Xylem conducts water and minerals upward o Phloem conducts sugars from where they are produced to where they are needed TRICHOMES o Epidermal cells that can provide protection from herbivores XYLEM o Dead at maturity o Xylem and phloem are bundled in the stele PHLOEM o Partially alive at maturity o Companion cells provide cellular support GROUND TISSUE o All tissue that is neither epidermal nor vascular o Internal vascular tissue is pith o External to vascular tissue is cortex o Ground tissue includes cells specialized for storage, photosynthesis, and support 3 10/2/2014 PARENCHYMA COLLENCHYMA o Thin-walled with large vacuole o Intercellular spaces may be present o Most common type of ground tissue o Flexible support with unevenly thickened cell walls SCLERENCHYMA o Rigid support o Thick secondary walls with lignin PLANTS HAVE INDETERMINATE GROWTH o Growth in plants is not limited to embryonic or juvenile periods o Animals show determinate growth, as do some plant organs such as flowers, thorns and leaves o Cell division and growth occurs in meristems Apical meristems initiate primary growth Lateral meristems initiate secondary growth (wood) 4 10/2/2014 TYPES OF LIFE CYCLES PRIMARY ROOT GROWTH o Annuals complete life cycle in one year o Biennials complete life cycle in two years o Perennials live many years ROOT STRUCTURE LATERAL ROOT GROWTH PRIMARY GROWTH OF SHOOTS STEM STRUCTURE 5 10/2/2014 LEAF STRUCTURE SECONDARY GROWTH o Lateral meristems add thickness to woody plants, a process called secondary growth o There are two lateral meristems: the vascular cambium and the cork cambium The vascular cambium adds layers of vascular tissue called secondary xylem (wood) and secondary phloem The cork cambium replaces the epidermis with periderm, which is thicker and tougher SECONDARY GROWTH INCREASES THE DIAMETER OF STEMS AND ROOTS IN WOODY PLANTS o Secondary growth occurs in stems and roots of woody plants but rarely in leaves o The secondary plant body consists of the tissues produced by the vascular cambium and cork cambium o Secondary growth is characteristic of gymnosperms and many eudicots, but not monocots Secondary xylem Secondary phloem Vascular cambium Late wood Early wood Bark Cork cambium Periderm 0.5 mm Cork Vascular ray 0.5 mm Growth ring (b) Cross section of a three-yearold Tilia (linden) stem (LM) 6 10/2/2014 EXAM 2 AN EXAMPLE OF A LIVING PLANT CELL THAT LACKS A NUCLEUS WOULD BE NEW SHOOTS ON AN ACTIVELY GROWING STEM COME FROM a) b) c) d) e) a) b) c) d) 20% 20% 20% 20% 20% lls . tis su e. ce ty l a ym hy po co nc h 20% 20% . 20% ba rk em ph lo m 18 .5 m 11 .5 m 2. 5 m m 1. 5 1. 0 20% lt is s ue . 20% ica phloem. xylem. pith. cortical tissue. bark. . a) b) c) d) e) co rt 20% th . 20% pi 20% . 20% 1.0 m 1.5 m 2.5 m 11.5 m 18.5 m em 20% A. B. C. D. E. THE INCREASE IN GIRTH OF WOODY PLANTS IS PRIMARILY DUE TO THE INCREASE IN THE PRODUCTION OF xy l YOU CARVE YOUR INITIALS 1.5 M ABOVE THE GROUND IN A 10-M-TALL TREE SAPLING. IF YOU RETURN 20 YEARS LATER AND THE TREE IS 25 M TALL, YOUR INITIALS WILL BE _____ ABOVE THE GROUND. sc le re ep a sie a al id er m ar st ip ul yb ud s. es . fib er m . es op hy ll c ve e ll . tu be el em en t. stipules. axillary buds. epidermal cells. sclerenchyma tissue. e) hypocotyl tissue. a co m a pa n gu a io n rd ce ce ll. ll. 20% 20% 20% 20% 20% ax ill a guard cell. a companion cell. fiber. a mesophyll cell. a sieve tube element. t is su e. USING TREE RINGS TO STUDY HISTORY 7 10/2/2014 THINK ABOUT THE STRUCTURE OF A ROOT TIP. IN WHICH REGION WOULD YOU EXPECT THE MAJORITY OF WATER AND NUTRIENT UPTAKE TO OCCUR? A STEM CROSS SECTION WITH DISPERSED VASCULAR BUNDLES WOULD MOST LIKELY BE SEEN IN A. Root cap B. Apical lens (meristem) C. Zone of cell division D. Zone of cell elongation E. Zone of cell maturation fern plants. moss plants. pine trees. maple trees. corn plants 20% 20% 20% 20% tio es . an ts pl co rn es . tre ap le pi ne tre lan an t pl n os sp m fe r Zo ne m s. lm ts . at ur a ng a lo le el el of c of c 20% n n tio sio ivi ld el of c Zo ne Ap ic a Zo ne l le ns (m er Ro ist ot c em n ) ap 20% 20% 20% 20% 20% WHICH OF THE FOLLOWING TISSUE TYPES ARE UNIQUE TO LEAVES? ist M er M es op hy l m 20% em 20% l 20% Xy le 20% te x 20% Co r Stomata Cortex Xylem Mesophyll Meristem St om at a A. B. C. D. E. 8