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

Plant Transport SystemsPlant Transport 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

StomaStoma

WE WILL DISCUSS STOMATA IN LENGTH LATER IN THIS POWERPOINT

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

Vascular Tissue

Xylem and PhloemXylem and Phloem

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

PhloemPhloem

Xylem and PhloemXylem and Phloem

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

Root TypesRoot Types

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!!!!!

MITOSIS COUNTING LABMITOSIS COUNTING LAB

400x

40x

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..

ENDODERMIS

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

Root UptakeRoot Uptake

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.

http://plantandsoil.unl.edu/croptechnology2005/pages/animationOut.cgi?anim_name=root movement.swf

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

STEMSSTEMS

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 

DO YOU FEEL LUCKY? FOUR LEAF CLOVER

DO YOU FEEL REALLY LUCKY?DO YOU FEEL REALLY LUCKY?

21 LEAF CLOVER: OLD RECORD WAS 18 LEAVES!

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

Leaf MarginsLeaf Margins

Leaf ArrangementsLeaf Arrangements

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

SEM of LEAFSEM of LEAF

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

THIS IS WHAT YOU WILL BE LOOKING FOR IN LAB ON WEDNESDAY!

normal epidermal cell

2 guard cells

stoma

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

STOMATA & GUARD CELLSSTOMATA & GUARD CELLS

StomataStomata

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

Capillary ActionCapillary Action

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.