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ROOTS: p. 579ROOTS: p. 579
Absorbs water and dissolved Absorbs water and dissolved mineralsminerals
Anchors plants & prevents Anchors plants & prevents erosionerosion
Protects plant from harmful Protects plant from harmful bacteria and fungusbacteria and fungus
Transport water and minerals to Transport water and minerals to rest of plantrest of plant
Hold plants upright against Hold plants upright against natural forcesnatural forces
STEMSSTEMS
Support system for the Support system for the plant bodyplant body
Transport system to carry Transport system to carry nutrients (sucrose)nutrients (sucrose)
Protects against predator Protects against predator and diseaseand disease
LEAVESLEAVES
Main photosynthetic Main photosynthetic systemsystem
Broad, flat surface helps Broad, flat surface helps to increase the amount to increase the amount of sunlight the plant of sunlight the plant absorbsabsorbs
Plant Tissue SystemsPlant Tissue Systems Tissues are groups of cells with similar Tissues are groups of cells with similar
structures & functionsstructures & functions Plants have 3 tissue systems:Plants have 3 tissue systems:
1. DERMAL1. DERMAL
2. VASCULAR2. VASCULAR
3. GROUND3. GROUND
1.Dermal tissue - consists of the epidermis
2. Vascular tissue - carries out long-distance transport of
materials between roots and shoots: XYLEM & PHLOEM
3. Ground tissue - includes various cells specialized for functions such as storage, photosynthesis,and
support
The Three Tissue SystemsThe Three Tissue Systems
DERMAL TISSUEDERMAL TISSUE Skin of plantSkin of plant Single layer of tightly packed epidermal Single layer of tightly packed epidermal
cells that covers and protects the plantcells that covers and protects the plant Epidermis on stem and leaves prevents Epidermis on stem and leaves prevents
water loss by transpiration water loss by transpiration
& produces a waxy material called & produces a waxy material called CUTICLECUTICLE
Root HairsRoot Hairsare actually epidermal cells are actually epidermal cells adapted to absorb wateradapted to absorb water
* Water enters the cells by Osmosis
* Minerals enter by Active Transport
Root Hairs
DERMAL TISSUEDERMAL TISSUE
Openings in the Openings in the epidermis on the epidermis on the underside of a leaf underside of a leaf where gases are where gases are exchanged are called exchanged are called STOMATA STOMATA
(stoma, singular)(stoma, singular) Sausage-shaped Sausage-shaped
guard cells are found guard cells are found on each side of the on each side of the stoma to help open stoma to help open and close the pore to and close the pore to prevent water lossprevent water loss
Vascular TissueVascular Tissue Vascular tissues transport water and dissolved Vascular tissues transport water and dissolved
substances inside the plant and helps support the substances inside the plant and helps support the stemstem
The 2 types of vascular tissue: The 2 types of vascular tissue: 1. 1. XYLEM XYLEM carries water and dissolved ions carries water and dissolved ions from the roots to stems and leavesfrom the roots to stems and leaves 2.2. PHLOEMPHLOEM carries dissolved sugars from carries dissolved sugars from the leaves to all other parts of the plantthe leaves to all other parts of the plant
XylemXylem Tracheids are long, Tracheids are long,
narrow cells with walls narrow cells with walls and pits for water to and pits for water to move between them move between them
Vessel elements are Vessel elements are short, wide short, wide cells without end walls cells without end walls stacked on top of each stacked on top of each otherother
Angiosperms Angiosperms (flowering plants) have (flowering plants) have tracheids & vessel tracheids & vessel elements, while elements, while gymnosperms (cone gymnosperms (cone bearers) only have bearers) only have tracheidstracheids
PhloemPhloem
Phloem is made of cells called sieve tube members and companion cells Sieve tube members are stacked to form tubes called sieve tubes with porous sieve plates between the cells for movement of sugars and other foods Companion cells are along each sieve tube member & help in loading sugar into the sieve tube
GROUND TISSUEGROUND TISSUE
Lie between dermal and vascular tissueLie between dermal and vascular tissue Three types of cells:Three types of cells:
1. Parenchyma1. Parenchyma
2. Collenchyma2. Collenchyma
3. Sclerenchyma3. Sclerenchyma
Collenchyma CellsCollenchyma Cells(kuh-LENG-kih-muh)(kuh-LENG-kih-muh)
irregular in shape with thicker cell walls & support the growing parts of plants
cell walls are also flexible to support new growth regions of the plant
example: tough strings on a celery stalk
WORKSHEET PACKET PAGE 287# 7
DO IT NOW!!!!
Sclerenchyma CellsSclerenchyma Cells(sklih-RENG-kih-muh)(sklih-RENG-kih-muh)
cells support non-growing parts of plants because they have thick, rigid, non-stretchable cell walls often die at maturity leaving empty, box-like structures
WORKSHEET PACKET PAGE 287# 8
DO IT NOW!!!!
Parenchyma cellsParenchyma cells(puh-RENG-kih-muh)(puh-RENG-kih-muh)
most abundant & least specialized
loosely-packed, cube shaped or elongate cells with a large central vacuole & thin cell walls
In leaves, these cells are packed with chloroplasts
WORKSHEET PACKET PAGE 287# 9
DO IT NOW!!!!
Plant Growth and Plant Growth and Meristematic TissueMeristematic Tissue
Apical Meristem occurs at the tips of roots and shoots and are responsible for the length-wise extension of the plant body known as PRIMARY GROWTH
Cells in apical meristems are produced by mitosis & then differentiate into specialized cells & tissues
23-2: ROOTS23-2: ROOTS
Roots grow underground Roots grow underground (subterranean part of the plant)(subterranean part of the plant)
Roots have 3 main functions --- Roots have 3 main functions ---
1. Anchor plants1. Anchor plants
2. Absorb and conduct water minerals 2. Absorb and conduct water minerals 3. Store food3. Store food
DERMAL TISSUEDERMAL TISSUE Epidermal cells on roots form extensions
called root hairs to absorb H20 & nutrients
REMEMBER: MORE SURFACE AREA: MORE ABSORBPTION
TaprootsTaproots
found mainly in dicots such found mainly in dicots such as carrots, dandelions, beets, as carrots, dandelions, beets, radishes, oak and hickory radishes, oak and hickory treestrees
Can grow very deep to reach Can grow very deep to reach waterwater
Can store sugars or starchesCan store sugars or starches
FIBROUS ROOTSFIBROUS ROOTS
Monocots have highly branched, roots called fibrous roots that grow near the surface & spread out to collect water
Fibrous roots such as in grasses often help prevent erosion
ADVENTITIOUSADVENTITIOUS roots grow
from a stem or leaf above ground in some plants and serve to prop up or support the plant (corn)
PROP ROOTS
AERIAL ROOTSAERIAL ROOTS
obtain water & obtain water & minerals from minerals from the air & the air & enable the enable the plant to climbplant to climb
Aerial RootsAerial Rootsmodified to absorb water modified to absorb water from the airfrom the air
Aerial roots of an Orchid Orchids in bloom
PneumatophoresPneumatophores
are spongy aerating roots which are are spongy aerating roots which are found in some plants found growing in found in some plants found growing in water-logged, badly aerated soils. water-logged, badly aerated soils.
They arise above the surface of the water They arise above the surface of the water and are perforated by many lenticels. and are perforated by many lenticels.
facilitate gaseous exchange between the facilitate gaseous exchange between the air and the subsurface roots to which air and the subsurface roots to which they are attached. they are attached.
Root Growth & StructureRoot Growth & Structure
Root cap covers the Root cap covers the apical meristem apical meristem (growth tissue) at the (growth tissue) at the tip of the root & tip of the root & produces a slimy produces a slimy substance so roots substance so roots can more easily grow can more easily grow through the groundthrough the ground
Apical meristem Apical meristem replaces cells of the replaces cells of the root cap as they are root cap as they are damageddamaged
#6
#8CORTEX
Ground tissue#7
#9
Vascular cylinder#10
epidermisWORKSHEET PAGE 292
ROOT DIAGRAMDO IT NOW!!!!!
Regions of the root tipRegions of the root tip Region of MaturationRegion of Maturation - Most - Most
cells differentiate into various cells differentiate into various distinctive cell types. distinctive cell types. Root hairs form.Root hairs form.
Region of ElongationRegion of Elongation - Cells - Cells become several times their become several times their original length. original length. Vacuoles merge Vacuoles merge
Region of Cell DivisionRegion of Cell Division - - Composed of apical meristem Composed of apical meristem in the center of the root tip. in the center of the root tip. Most cell division occurs at the Most cell division occurs at the
edge of the inverted cup-edge of the inverted cup-shaped zone.shaped zone.
Root CapRoot Cap - Thimble-shaped - Thimble-shaped mass of parenchyma cells mass of parenchyma cells covering each root tip. covering each root tip. Protects tissue from damage. Protects tissue from damage. Function in gravity perceptionFunction in gravity perception..
Root StructureRoot Structure
A single cell layer called endodermis A single cell layer called endodermis separates the cortex & vascular tissueseparates the cortex & vascular tissue
Endodermal cells are coated with a Endodermal cells are coated with a
waxy layer called the waxy layer called the Casparian stripCasparian strip so water is channeled into the so water is channeled into the vascular tissuevascular tissue
Soil water enters the root through its epidermis. It appears that water then travels in both the cytoplasm of root cells — called the symplast — that is, it crosses the plasma membrane and then passes from cell to cell through plasmodesmata. in the nonliving parts of the root — called the apoplast — that is, in the spaces between the cells and in the cells walls themselves. This water has not crossed a plasma membrane.
23-3: STEMS23-3: STEMS
Adapted to support leavesAdapted to support leaves Transport water & minerals Transport water & minerals Transport sugars (usually sucrose) from Transport sugars (usually sucrose) from
Source (where they're made) to Sink (where Source (where they're made) to Sink (where they're stored)they're stored)
Movement of sugars is called translocationMovement of sugars is called translocation Store food and/or waterStore food and/or water Tubers (potatoes) underground food Tubers (potatoes) underground food
storage stemsstorage stems
StemsStems
Stems grow from the tip or apical meristemStems grow from the tip or apical meristem Stems increase in circumference by lateral Stems increase in circumference by lateral
meristemsmeristems Leaves are attached to stems at nodes & Leaves are attached to stems at nodes &
have lateral buds that can develop into new have lateral buds that can develop into new stems or branchesstems or branches
Internode is space between nodes on a Internode is space between nodes on a stemstem
The tip of each stem usually has a Terminal The tip of each stem usually has a Terminal Bud enclosed by specialized leaves called Bud enclosed by specialized leaves called Bud ScalesBud Scales
Monocot & Dicot StemsMonocot & Dicot Stems
Vascular Tissue is Vascular Tissue is arranged in bundles arranged in bundles with xylem toward the with xylem toward the inside & phloem inside & phloem toward the outsidetoward the outside
Vascular bundles are Vascular bundles are scattered throughout scattered throughout monocot stems monocot stems
Vascular bundles are Vascular bundles are arranged in rings in arranged in rings in dicot stems dicot stems
LeavesLeaves
Flat surfaces helps leaves capture sunlight Flat surfaces helps leaves capture sunlight for photosynthesisfor photosynthesis
Convert carbon dioxide and water into Convert carbon dioxide and water into simple sugars (glucose)simple sugars (glucose)
Some leaves store food (onion) and waterSome leaves store food (onion) and water Protect (cactus spines)Protect (cactus spines) Used Dyes, Fibers, Fuels, Drugs, Wax, Used Dyes, Fibers, Fuels, Drugs, Wax,
Soap, Spices and FoodSoap, Spices and Food
Types of LeavesTypes of Leaves
Simple Simple leaves have leaves have one blade, one blade, while while compound compound leaves have leaves have several several leafletsleaflets
Venation in LeavesVenation in Leaves VENATION is the VENATION is the
arrangement of arrangement of veins in a leafveins in a leaf
Monocot leaves Monocot leaves (such as Grasses (such as Grasses or Corn Plants) or Corn Plants) have Parallel have Parallel VenationVenation
Dicot leaves form Dicot leaves form a branched a branched network called Net network called Net VenationVenation
MONOCOT (left) DICOT (right)
Leaf FunctionsLeaf Functions Covered with Covered with
a single layer a single layer of cells of cells called called epidermis epidermis (upper & (upper & lower)lower)
A waxy A waxy cuticle cuticle prevents prevents water losswater loss
Leaf FunctionsLeaf Functions PALISADE mesophyll cells are PALISADE mesophyll cells are
closely packed columnar cells closely packed columnar cells (most photosynthesis occurs (most photosynthesis occurs here)here)
SPONGY mesophyll cells are SPONGY mesophyll cells are loosely packed with air spaces loosely packed with air spaces containing CO2 & O2containing CO2 & O2
VASCULAR BUNDLES (xylem VASCULAR BUNDLES (xylem & Phloem) in the spongy & Phloem) in the spongy mesophyll appear as VEINS on mesophyll appear as VEINS on the surface of the leafthe surface of the leaf
This is a cross-section of a “typical” leaf: Syringa vulgaris (lilac)
upper epidermis
lower epidermis
palisade mesophyll
spongy mesophyll gas space
vein
stoma guard cell
Leaf Anatomy
gas space
Cuticle-:reduce evaporation
Upper Epidermis:protection
Palisade Mesophyll:photosynthesis
Bundle Sheath:load phloem
Xylem:conduct water up from soil
Phloem:conduct sugar away from leaf
Spongy Mesophyll:evaporative cooling
Lower Epidermis:reduce evaporation
Guard Cell:regulate gas exchange
Stoma
TranspirationTranspiration
The surfaces of spongy mesophyll cells The surfaces of spongy mesophyll cells are kept moist so gases can be are kept moist so gases can be exchangedexchanged
Transpiration is the loss of water through Transpiration is the loss of water through its leavesits leaves
Lost water is replaced by water drawn Lost water is replaced by water drawn into the leaf through xylem vesselsinto the leaf through xylem vessels
Gas ExchangeGas Exchange Openings called stomata on the underside of leaves for gas Openings called stomata on the underside of leaves for gas
exchange (CO2 & O2)exchange (CO2 & O2) Two guard cells on either side of the stomata open & close the Two guard cells on either side of the stomata open & close the
openingsopenings When guard cells LOSE water, the stoma CLOSE, while the stoma When guard cells LOSE water, the stoma CLOSE, while the stoma
OPEN when guard cells gain water & swellOPEN when guard cells gain water & swell
Stomata are CLOSED during the HOTTEST parts of the day to Stomata are CLOSED during the HOTTEST parts of the day to
prevent water loss from leavesprevent water loss from leaves
guard cell
guard cell
stoma
When guard cells are pumped up with water, they push each other apart as they elongate, and this opens the stoma!
This photo is from a SEM: scanning electron microscope.
WHEN THE STOMAIS OPEN
WHAT HAPPENS?
GAS EXCHANGE: CARBON DIOXIDE AND OXYGEN
1
1
2
23-5: Water Transport23-5: Water Transport
Transport of Water and mineral Nutrients Transport of Water and mineral Nutrients occurs in the Xylemoccurs in the Xylem
Water movement in plants is driven by root Water movement in plants is driven by root pressure, transpiration, and capillary action pressure, transpiration, and capillary action
As water evaporates, more water is pulled As water evaporates, more water is pulled into the rootsinto the roots
Transpiration produces a NEGATIVE Transpiration produces a NEGATIVE pressure in the xylem pulling water pressure in the xylem pulling water UPWARDUPWARD
Water molecules are cohesive which also Water molecules are cohesive which also pulls water upwardpulls water upward
Water also adheres to the walls of the xylemWater also adheres to the walls of the xylem The tendency of water to rise in a thin tube The tendency of water to rise in a thin tube
is called is called
CAPILLARY ACTIONCAPILLARY ACTION The thinner the tube, the higher the water The thinner the tube, the higher the water
will rise inside itwill rise inside it
Transpiration & WiltingTranspiration & Wilting
Osmotic pressure keeps a plant’s leaves and Osmotic pressure keeps a plant’s leaves and stems rigidstems rigid
High transpiration rates can lead to wilting or High transpiration rates can lead to wilting or water losswater loss
Without internal pressure the plant’s cell walls Without internal pressure the plant’s cell walls bend inward and the plant wiltsbend inward and the plant wilts
When a leaf wilts, its stomata are closedWhen a leaf wilts, its stomata are closed Wilting can help a plant to conserve waterWilting can help a plant to conserve water
Nutrient TransportNutrient Transport
Phloem cells move sugars through a plantPhloem cells move sugars through a plant Sugars made in photosynthetic cells are Sugars made in photosynthetic cells are
PUMPED into Sieve Tubes by ACTIVE PUMPED into Sieve Tubes by ACTIVE TRANSPORT at the SourceTRANSPORT at the Source
Turgor Pressure Increases as Water enters Turgor Pressure Increases as Water enters the Sieve Tube by Osmosisthe Sieve Tube by Osmosis
TURGOR moves the SAP toward the SINKSTURGOR moves the SAP toward the SINKS Known as the PRESSURE-FLOW Known as the PRESSURE-FLOW
HYPOTHESISHYPOTHESIS
Movement From Source Movement From Source to Sinkto Sink
When nutrient are When nutrient are pumped into or removed pumped into or removed from the phloem system, from the phloem system, the change in the change in concentration causes a concentration causes a movement of fluid in the movement of fluid in the same direction. same direction.
As a result, phloem is As a result, phloem is able to move nutrients in able to move nutrients in either direction to meet either direction to meet the nutritional needs of the nutritional needs of the plant.the plant.
1.Sucrose actively loadedInto sieve tube members
Requires ATP
Water diffuses from Xylem to phloem
3.Sucrose actively
unloadedInto sink cell
Water diffuses from Phloem back to xylem
In Most PlantsIn Most Plants GlucoseGlucose is produced in the leaves through is produced in the leaves through
photosynthesis.photosynthesis.
The glucose is converted to The glucose is converted to sucrosesucrose
(by dehydration synthesis) for transportation.(by dehydration synthesis) for transportation.
The sucrose is converted to The sucrose is converted to StarchStarch and stored. and stored.