figure 35.10 review of general plant cell structure
TRANSCRIPT
Figure 35.10 Review of General Plant Cell Structure
Shoot System
Root System
Root system
- anchors the plant
- penetrates the soil and absorbs water and minerals
- stores food
Shoot system
- produces sugars by photosynthesis
- carries out reproduction
Shoot and Root Systems
water & minerals
sugar
SHOOT SYSTEM
ROOT SYSTEM
Shoot and root systems are interdependent
Plant Tissue Systems
VASCULAR TISSUES
GROUND TISSUES
SHOOT SYSTEM
ROOT SYSTEM
EPIDERMIS
• Ground tissue system
• Vascular tissue system
• Dermal tissue system
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
Apical Meristems
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
procambium primary vascular tissues
protoderm epidermis
Cells that form at apical meristems:
ground meristem ground tissues
Lengthen shoots and roots
Lateral Meristems
vascular cambium secondary vascular tissues
periderm cork cambium
thickening
Increases girth of older roots and stems
Cylindrical arrays of cells
Figure 35.7 The three tissue systems
The Three Tissue Systems in Plants
Simple Tissues
Made up of only one type of cell
Parenchyma
Collenchyma
Sclerenchyma
collenchymaparenchyma sclerenchyma
Morphology of Three Simple Tissue Types
Figure 35.11 The three major categories of plant cells
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
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
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
Complex Tissues
Composed of a mix of cell types
Xylem
Phloem
Epidermis
Xylem
• Conducts water and dissolved minerals
• Conducting cells are dead and hollow at maturity vessel
membertracheids
Figure 35.8 Water-conducting cells of xylem
Phloem: A Complex Vascular Tissue
• Transports sugars
• Main conducting cells are sieve-tube members
• Companion cells assist in the loading of sugars
sieve plate
sieve-tubemember
companioncell
Figure 35.9 Food-conducting cells of the phloem
Figure 36.17 Pressure flow in a sieve tube
Epidermis: A Complex Plant Tissue
- Covers and protects plant
surfaces
- Secretes a waxy,
waterproof cuticle
-In plants with
secondary growth, periderm
replaces epidermis
Monocots and Dicots – same tissues, different
features
Parallel veinsNetlike veins
3 pores1 pore
4 or 5 floral parts
3 floral parts
1 cotyledon 2 cotyledons
Vascular bundles dispersed
Vascular bundles in ring
Stems –
organs consisting of an alternatingsystem of nodes, the points at which leaves are attached, and internodes, the stem segments between nodes.
• the main functions of the stems includeconducting sugars and water and holdingleaves up into the sunlight
Monocot and Dicot Stems (Two Divisions of Angiosperms)
Dicot StemMonocot Stem
Bud = undeveloped shoot of meristematic tissue
Internodespaces betweenleaf attachments
Leaves
Axillary bud at node(can form lateral shoots)
Longitudinal section of terminal bud
Shoot Development
ground meristem
primary xylempithprocambriumcortex
procambrium
protoderm
shoot apicalmeristem
primary phloem
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
Internal Structure
of a Monocot
Stem
• The vascular
bundles are
scattered
throughout the
ground tissue
• No division of
ground tissue into
cortex and pith
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
Woody Stemperiderm (consists ofcork, cork cambium,and secondary cortex)
secondaryphloem
BARK
HEARTWOOD
SAPWOOD
vascular cambium
Figure 35.23 Anatomy of a tree trunk
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
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
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
Leaf StructureUPPER
EPIDERMIS
PALISADEMESOPHYLL
SPONGYMESOPHYLL
LOWEREPIDERMIS
one stoma
cuticle
O2CO2
xylem
phloem
Stoma with guard cells
Figure 35.19 Leaf anatomy
Mesophyll:Photosynthetic Tissue
• A type of parenchyma
tissue
• Cells have chloroplasts
• Two layers in dicots
–Palisade mesophyll
–Spongy mesophyll
Parenchyma
Collenchyma
Leaf Veins: Vascular Bundles
• Xylem and phloem –
often strengthened with fibers
• In dicots, veins are netlike
• In monocots, they are parallel
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
Root SystemsTap
Fibrous
Lateral Rootsgrow from the Tap Root
Primary Growth of a Root
pericycle
phloem
xylem
root hair
endodermis
epidermis
cortex
xylem
phloem
endodermis
pericycle
cortex epidermis
Cross Section of a Root
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
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
newlateralroot
Figure 35.16 The formation of lateral roots
Lateral Root
Figure 36.7 Lateral transport of minerals and water in roots
Figure 36.6 Compartments of plant cells and tissues and routes for lateral transport
Transport Proteinsin the plasma membrane regulatetraffic between the cytosol and the cellwall
The symplast is the continuum of cytosolconnected by
plasmodesmata.The apoplast is the continuumof cell walls and extracellular
spaces.
Figure 35.15 Organization of primary tissues in young roots
PropRoots
Pandanus Tree WithProp Roots
Prop Roots
Buttress Roots
BanyanTree WithAerial Roots