Let the Water Flow
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Let the Water Flow Recall that vascular tissue transports water and nutrients throughout a plant. Imagine that you and your partner have been asked by a bioengineering firm to design a mechanism that can be used by plants to transport food, water, and essential nutrients to a height of 92 meters. Section 23-1 Interest Grabber 1. What plant characteristics must you consider in your design? 2. What environmental conditions must you take into account for your design to be functional? 3. Outline the major characteristics of your design.
Specialized Tissues in Plants A. Structure of Seed Plants 1. Roots 2. Stems 3. Leaves 4. Tissue Systems B. Meristematic Tissue C. Dermal Tissue D. Vascular Tissue 1. Xylem 2. Phloem E. Ground Tissue Section 23-1 Section Outline
Parenchyma cells are the most common plant cell type. store starch, oils andwater help heal wounds tothe plant have thin flexible walls Plant tissues are made of three basic cell types.
they are strong and flexible. celery strings are strands of collenchyma. they have unevenly thick cell walls. • Collenchyma cells provide support to a growing plant.
second cell wall hardened by lignin die when they reach maturity used by humans to make linen and rope • Sclerenchyma cells are the strongest plant cell type.
Dermal tissue covers the outside of a plant. protects the plant secretes cuticle of leaves forms outer bark of trees Plant organs are made of three tissue systems.
provides support stores materials in roots and stems most commonly made of parenchyma • Ground tissue is found inside a plant.
two networks of hollow tubes xylem transports water and minerals phloem transports photosynthetic products stem leaf root • Vascular tissue transports water, minerals and organic compounds.
Dermaltissue Meristematictissue Vasculartissue Groundtissue Epidermalcells Parenchymacells Collenchymacells Schlerenchymacells Xylem Phloem Companioncells Vesselelements Sieve tubeelements Tracheids Section 23-1 Concept Map Plant Tissues include includes includes includes includes includes
Section 23-1 Figure 23–1 Root, Stem, and Leaf Tissues Leaf Stem Root Dermal tissue Vascular tissue Ground tissue
Stem Study Imagine walking through a botanical garden. You probably would see many different kinds of plants, such as small and large trees, flowering plants, and cacti. Section 23-3 Interest Grabber 1. How do the stems of trees, flowering plants, and cacti differ? 2. How are the stems of these plants similar?
Section 23-3 Section Outline • Stems • A. Stem Structure and Function • B. Monocot and Dicot Stems • 1. Monocot Stems • 2. Dicot Stems • C. Primary Growth of Stems • D. Secondary Growth of Stems • 1. Formation of the Vascular Cambium • 2. Formation of Wood • 3. Formation of Bark
Compare/Contrast Table Section 23-3 Comparing Primary and Secondary Growth of Stems Characteristics Where It Occurs Effect on Plant How It IsProduced Primary Growth Secondary Growth At ends of plants Increases plant length By cell division in the apical meristem In stem Increases stem width By cell division in meristems other thanthe apical meristem
Figure 23–14 Secondary Growth in Stems Primaryphloem Bark Secondaryphloem Cork Epidermis Corkcambium Secondary xylem Cortex Wood Primaryxylem Primaryphloem Secondaryphloem Vascularcambium Secondary xylem Primaryxylem Pith Section 23-3 A. Vascular cambium appears B. Secondary growth continues C. Mature stemdevelops
Figure 23–15 Layers of a Tree Trunk Contains old, nonfunctioning phloem that protects the tree Produces protective layer of cork Contains old, nonfunctioningxylem that helpssupport the tree Transports sugars produced by photosynthesis Produces new xylem and phloem, which increase the width of the stem Contains active xylem that transports water and minerals Section 23-3 Wood Bark Cork Xylem:Heartwood Cork Cambium Phloem Vascular Cambium Xylem: Sapwood
KEY CONCEPTThe vascular system allows for the transport of water, minerals, and sugars.
Xylem contains specialized cells. vessel elements are short and wide tracheid cells are long and narrow xylem cells die at maturity tracheid vessel element Water and dissolved minerals move through xylem.
Plants passively transport water through the xylem. Cohesion is the tendency of water molecules to bond with each other. • The cohesion-tension theory explains water movement. • Adhesion is the tendency of water molecules to bond with other substances.
absorption occurs at roots • Water travels from roots to the top of trees. • cohesion and adhesion in xylem • transpiration at leaves
water vapor exits leaf stomata helps pull water to the top branches • Transpiration is the loss of water vapor through leaves.
Phloem contains specialized cells. sieve tube elements have holes at ends companion cells help sieve tube elements unlike xylem, phloem tissue is alive Phloem carries sugars from photosynthesis throughout the plant.
plants actively transport sugar from the source sugar flows to the sink due to pressure differences phloem xylem sugars Water moves from the xylem into the phloem by osmosis, due to the higher concentration of the sugars in the phloem. The water flow helps move sugars through the phloem. 2 Sugars move from their source, such as photosynthesizing leaves, into the phloem. 1 water The sugars move into the sink, such as root or fruit, where the are stored. 3 • The Pressure-flow model explains sugar movement.