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Figure 35.10 Review of General Plant Cell Structure
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Shoot and Root Systems Shoot system produces sugars by photosynthesis
carries out reproduction Shoot System Root system anchors the plant penetrates the soil and absorbs water and minerals stores food Root System
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Shoot and root systems are interdependent
water & minerals sugar SHOOT SYSTEM ROOT SYSTEM
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Plant Tissue Systems Ground tissue system Vascular tissue system
EPIDERMIS Ground tissue system Vascular tissue system Dermal tissue system VASCULAR TISSUES GROUND TISSUES SHOOT SYSTEM ROOT SYSTEM
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Meristems – Where Cells For New Organs Originate
Regions where cell divisions produce plant growth Apical meristems Lengthen stems and roots Responsible for primary growth Lateral meristems Increase width of stems Responsible for secondary growth
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Apical Meristems Lengthen shoots and roots protoderm epidermis
activity at meristems Cells that form at apical meristems: new cells elongate and start to differentiate into primary tissues protoderm epidermis ground meristem ground tissues procambium primary vascular tissues
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Lateral Meristems Increases girth of older roots and stems
Cylindrical arrays of cells vascular cambium secondary vascular tissues periderm cork cambium thickening
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Figure 35.7 The three tissue systems
in Plants
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Made up of only one type of cell
Simple Tissues Made up of only one type of cell Parenchyma Collenchyma Sclerenchyma
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Morphology of Three Simple Tissue Types
parenchyma collenchyma sclerenchyma
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Figure 35.11 The three major categories of plant cells
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Parenchyma: A Simple Tissue
Comprises most of a plant’s soft primary growth Cells are pliable, thin walled, many sided Cells remain alive at maturity and retain capacity to divide Mesophyll is a type of parenchyma that contains chloroplasts
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Collenchyma: A Simple Tissue
Specialized for support for primary tissues Cells are elongated, with walls (especially corners) thickened with pectin Makes stems strong but pliable Cells are alive at maturity
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Sclerenchyma: A Simple Tissue
Supports mature plant parts Protects many seeds Cells have thick, lignified walls and are dead at maturity Two types: Fibers: Long, tapered cells Sclereids: Stubbier cells
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Composed of a mix of cell types
Complex Tissues Composed of a mix of cell types Xylem Phloem Epidermis
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Xylem Conducts water and dissolved minerals
Conducting cells are dead and hollow at maturity vessel member tracheids
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Figure 35.8 Water-conducting cells of xylem
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Phloem: A Complex Vascular Tissue
sieve plate Transports sugars Main conducting cells are sieve-tube members Companion cells assist in the loading of sugars sieve-tube member companion cell
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Figure 35.9 Food-conducting cells of the phloem
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Figure 36.17 Pressure flow in a sieve tube
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Epidermis: A Complex Plant Tissue
- Covers and protects plant surfaces - Secretes a waxy, waterproof cuticle In plants with secondary growth, periderm replaces epidermis
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Monocots and Dicots – same tissues, different features
1 cotyledon 2 cotyledons 4 or 5 floral parts 3 floral parts Netlike veins Parallel veins 3 pores 1 pore Vascular bundles dispersed Vascular bundles in ring
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organs consisting of an alternating
Stems – organs consisting of an alternating system of nodes, the points at which leaves are attached, and internodes, the stem segments between nodes. the main functions of the stems include conducting sugars and water and holding leaves up into the sunlight
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Monocot and Dicot Stems (Two Divisions of Angiosperms)
Monocot Stem
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Bud = undeveloped shoot of meristematic tissue
Leaves Internode spaces between leaf attachments Axillary bud at node (can form lateral shoots) Longitudinal section of terminal bud
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Shoot Development shoot apical meristem procambrium ground meristem
protoderm cortex procambrium pith primary xylem primary phloem
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Internal Structure of a Dicot Stem
- Outermost layer is epidermis - Cortex lies beneath epidermis - Ring of vascular bundles separates the cortex from the pith - The pith lies in the center of the stem
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Internal Structure of a Monocot Stem
The vascular bundles are scattered throughout the ground tissue No division of ground tissue into cortex and pith Internal Structure of a Monocot Stem
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Secondary Growth Occurs in perennials
A ring of vascular cambium produces secondary xylem and phloem Wood is the accumulation of these secondary tissues, especially xylem
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Woody Stem periderm (consists of secondary phloem cork, cork cambium,
and secondary cortex) secondary phloem SAPWOOD HEARTWOOD BARK vascular cambium
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Figure 35.23 Anatomy of a tree trunk
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Annual Rings Concentric rings of secondary xylem
Alternating bands of early and late wood Early wood Xylem cells with large diameter, thin walls Late wood Xylem cells with smaller diameter, thicker walls
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Types of Wood Hardwood (oak, hickory) Dicot wood
Xylem composed of vessels, tracheids, and fibers Softwood (pine, redwood) Gymnosperm wood Xylem composed mostly of tracheids Grows more quickly
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Adapted for Photosynthesis
Leaves are usually thin High surface area-to-volume ratio Promotes diffusion of carbon dioxide in, oxygen out Leaves are arranged to capture sunlight Are held perpendicular to rays of sun Arrange so they don’t shade one another
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Leaf Structure Stoma with guard cells cuticle xylem phloem UPPER
EPIDERMIS cuticle PALISADE MESOPHYLL xylem SPONGY MESOPHYLL phloem LOWER EPIDERMIS Stoma with guard cells CO2 one stoma O2
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Figure Leaf anatomy
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Mesophyll: Photosynthetic Tissue
A type of parenchyma tissue Cells have chloroplasts Two layers in dicots Palisade mesophyll Spongy mesophyll
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Collenchyma Parenchyma
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Leaf Veins: Vascular Bundles
Xylem and phloem – often strengthened with fibers In dicots, veins are netlike In monocots, they are parallel
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Root Structure Root cap covers tip Apical meristem produces the cap
Cell divisions at the apical meristem cause the root to lengthen Farther up, cells differentiate and mature root apical meristem root cap
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Fibrous Tap Root Systems Lateral Roots grow from the Tap Root
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Primary Growth of a Root
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epidermis endodermis cortex pericycle root hair phloem xylem
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Cross Section of a Root cortex epidermis endodermis pericycle xylem
phloem Cross Section of a Root
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Internal Structure of a Root
Outermost layer is epidermis Root cortex is beneath the epidermis Endodermis, then pericycle surround the vascular cylinder In some plants, there is a central pith
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Root Hairs and Lateral Roots
Both increase the surface area of a root system Root hairs are tiny extensions of epidermal cells Lateral roots arise from the pericycle and must push through the cortex and epidermis to reach the soil new lateral root
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Figure 35.16 The formation of lateral roots
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Figure 36.7 Lateral transport of minerals and water in roots
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Transport Proteins in the plasma membrane regulate traffic between the
Figure Compartments of plant cells and tissues and routes for lateral transport Transport Proteins in the plasma membrane regulate traffic between the cytosol and the cell wall The symplast is the continuum of cytosol connected by plasmodesmata. The apoplast is the continuum of cell walls and extracellular spaces.
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Figure 35.15 Organization of primary tissues in young roots
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Prop Roots
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Pandanus Tree With Prop Roots
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Prop Roots
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Buttress Roots
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Banyan Tree With Aerial Roots
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