PlantsPlants

Plant Evolution and ClassificationPlant Evolution and Classification

Preventing Water LossPreventing Water Loss Reproducing by Spores and SeedsReproducing by Spores and Seeds Transporting materials throughout the plant.Transporting materials throughout the plant.

Classifying PlantsClassifying Plants

2 groups based on the presence of vascular 2 groups based on the presence of vascular tissuetissue Nonvascular PlantsNonvascular Plants Vascular PlantsVascular Plants

Seedless-fern likeSeedless-fern like Seeded- Maples, and PineSeeded- Maples, and Pine

ClassificationClassification

Nonvascular PlantsNonvascular Plants Phylum BryophytaPhylum Bryophyta Phyla Haptophyta and AnthocerophytaPhyla Haptophyta and Anthocerophyta

Seedless Vascular PlantsSeedless Vascular Plants

Phylum PsilotophytaPhylum Psilotophyta Phylum LycophytaPhylum Lycophyta Phylum SphenophytaPhylum Sphenophyta Phylum PterophytaPhylum Pterophyta

Vascular Seed PlantsVascular Seed Plants

GymnospermsGymnosperms Phylum CycadophytaPhylum Cycadophyta Phylum GinkgophytaPhylum Ginkgophyta Phylum GnetophytaPhylum Gnetophyta Phylum ConiferophytaPhylum Coniferophyta

AngiospermsAngiosperms Phylum AnthophytaPhylum Anthophyta

Classes of AngiospermsClasses of Angiosperms

MonocotMonocot On cotyledonOn cotyledon Parallele VenationParallele Venation ScatteredScattered Flower parts in 3’sFlower parts in 3’s FibrousFibrous

DicotDicot 2 cotyledons2 cotyledons Net venationNet venation Radially arranged Radially arranged

vascular bundlesvascular bundles Flower parts in 4 and Flower parts in 4 and

55 TaprootTaproot

Plant Structure and FunctionPlant Structure and Function

Plant CellsPlant Cells 3 types3 types

ParenchymaParenchyma CollenchymaCollenchyma SclerenchymaSclerenchyma

ParenchymaParenchyma

Loosely packed cube-shaped or elongated cells Loosely packed cube-shaped or elongated cells that contain large central vacuole.that contain large central vacuole.

Metabolic functions, photosynthesis and Metabolic functions, photosynthesis and storage of water and nutrients.storage of water and nutrients.

Example~ Fleshy part of an appleExample~ Fleshy part of an apple

Collenchyma CellsCollenchyma Cells

Thicker cell walls, irregular shapeThicker cell walls, irregular shape Usually grouped in strands and are specialized Usually grouped in strands and are specialized

for supporting regions that are still growing.for supporting regions that are still growing. CeleryCelery

Sclerenchyma CellsSclerenchyma Cells

Thick rigid cell walls.Thick rigid cell walls. Support and strengthen the plant in areas Support and strengthen the plant in areas

where growth is no longer occurring. where growth is no longer occurring. Gritty texture of a pear fruit.Gritty texture of a pear fruit.

Tissue SystemsTissue Systems

Dermal TissueDermal Tissue Ground TissueGround Tissue Vascular TissueVascular Tissue

Dermal TissueDermal Tissue

Forms the outer coverings in plantsForms the outer coverings in plants Consists of the epidermis, the outer layer made Consists of the epidermis, the outer layer made

of parenchyma cells.of parenchyma cells. Roots~ absorption, protectionRoots~ absorption, protection Stems~ gas exchange, protectionStems~ gas exchange, protection Leaves, gas exchange, protections.Leaves, gas exchange, protections.

Ground TissueGround Tissue

All 3 cell typesAll 3 cell types Storage, metabolism and support.Storage, metabolism and support.

Vascular TissueVascular Tissue

Functions in transport and supportFunctions in transport and support Xylem-deadXylem-dead Phloem-livingPhloem-living 2 major components for xylem2 major components for xylem

TracheidTracheid Vessel ElementVessel Element

TracheidTracheid

Long thick walled Long thick walled sclerenchyma cell with sclerenchyma cell with tapering ends.tapering ends.

Water moves from on Water moves from on tracheid to another tracheid to another through pithsthrough piths

Vessel ElementVessel Element

A sclerenchyma cell that has either large holes A sclerenchyma cell that has either large holes in the top and bottom or no end wall at all.in the top and bottom or no end wall at all.

Stacked to form long tubes called vessels.Stacked to form long tubes called vessels.

Sieve Tube MemberSieve Tube Member

Conducting parenchyma cells of angiosperm Conducting parenchyma cells of angiosperm phloem.phloem.

Compounds move from one to another through Compounds move from one to another through sieve plats.sieve plats.

Each cell has a companion cells, specialized Each cell has a companion cells, specialized parenchyma cell.parenchyma cell.

Growth in Meristems (Primary Growth in Meristems (Primary Growth)Growth)

Meristem- regions where cells continuously Meristem- regions where cells continuously divide for plant growth.divide for plant growth.

Apical Meristem- located in the tips of stems Apical Meristem- located in the tips of stems and roots.and roots.

Intercalary meristems- growth between the Intercalary meristems- growth between the nodes of plants.nodes of plants.

Root StructuresRoot Structures

Root StructuresRoot Structures

Root CapRoot Cap Covering of cells that protects the apical meristem.Covering of cells that protects the apical meristem. Produces a slimy lubricant.Produces a slimy lubricant.

Root HairsRoot Hairs Extensions of the epidermal cells.Extensions of the epidermal cells. Increase the surface area.Increase the surface area.

Primary Growth in RootsPrimary Growth in Roots

Roots increase in length Roots increase in length cell divisioncell division elongation elongation maturation in the root tip maturation in the root tip

Dermal tissue matures to form the epidermis Dermal tissue matures to form the epidermis Ground tissue matures into 2 regions Ground tissue matures into 2 regions

Cortex and EndodermisCortex and Endodermis

CortexCortex

Located just inside the endodermis.Located just inside the endodermis. Largest region of the primary root.Largest region of the primary root. Parenchyma cellsParenchyma cells

EndodermisEndodermis

Inner cylinder of the cortex.Inner cylinder of the cortex. Vascular tissue in roots matures to form the Vascular tissue in roots matures to form the

innermost cylinder innermost cylinder Dicots and gymnosperms~ xylem makes of the Dicots and gymnosperms~ xylem makes of the

central core of the root. central core of the root.

Monocot Root Cross SectionMonocot Root Cross Section

Dicot StemDicot Stem

StemsStems

Primary Growth in StemsPrimary Growth in Stems

Apical meristems give rise to the dermal, Apical meristems give rise to the dermal, ground and vascular tissue.ground and vascular tissue. Dermal- epidermisDermal- epidermis Ground- cortex and pithGround- cortex and pith

Cortex- just inside the epidermisCortex- just inside the epidermis Pith- located in the center of the stem.Pith- located in the center of the stem.

Vascular- xylem and phloemVascular- xylem and phloem

Monocot StemMonocot Stem

Vascular Bundle of MonocotVascular Bundle of Monocot

Dicot StemDicot Stem

Secondary GrowthSecondary Growth

Conifers and Woody dicotsConifers and Woody dicots Increases in girth or lateral dimensionIncreases in girth or lateral dimension Occurs at lateral meristemsOccurs at lateral meristems

Vascular cambium Vascular cambium Gives rise to secondary xylem and phloemGives rise to secondary xylem and phloem

Cork cambiumCork cambium Gives rise to barkGives rise to bark

Vascular CambiumVascular Cambium

Cells on the outside differentiate into phloemCells on the outside differentiate into phloem Cells on the inside differentiate into xylemCells on the inside differentiate into xylem

Only new xylem transports water.Only new xylem transports water. Older xylem located at the center is only for Older xylem located at the center is only for

support.support.

Annual RingsAnnual Rings

LeavesLeaves

Monocot LeafMonocot LeafUpper Epidermis

Lower EpidermisXylem Phloem

Mesophyll

Dicot LeafDicot LeafUpper Epidermis

Lower Epidermis

Palisade

Mesophyll

Spongy

Mesophyll

Xylem

Phloem

Guard Cells with Somata

Leaf StructuresLeaf Structures

EpidermisEpidermis Palisade MesophyllPalisade Mesophyll Spongy MesophyllSpongy Mesophyll Guard CellsGuard Cells Vascular BundlesVascular Bundles

EpidermisEpidermis

A protective covering of one or more layers of A protective covering of one or more layers of cells.cells.

Covered by the cuticleCovered by the cuticle CutinCutin TranspirationTranspiration

Palisade MesophyllPalisade Mesophyll

Parenchyma cellsParenchyma cells Numerous chloroplastsNumerous chloroplasts

Spongy MesophyllSpongy Mesophyll

Parenchyma cellsParenchyma cells Loosely arranged Loosely arranged

Air spaces allow for gas exchangeAir spaces allow for gas exchange

Guard CellsGuard Cells

Specialized epidermal cells that control the Specialized epidermal cells that control the opening and closing of stomata.opening and closing of stomata.

Controls gas exchanges with the environment.Controls gas exchanges with the environment.

Vascular BundlesVascular Bundles

Consists of xylem and phloem tissuesConsists of xylem and phloem tissues Contains bundle sheath cells that prevent gas from Contains bundle sheath cells that prevent gas from

entering the vascular bundle.entering the vascular bundle.

Transport of WaterTransport of Water

Water and dissolved minerals enter the roots Water and dissolved minerals enter the roots through root hairs by osmosis.through root hairs by osmosis. 2 Possible Pathways2 Possible Pathways

ApoplastApoplast SymplastSymplast

ApoplastApoplast

Water moves through cell walls from one cell Water moves through cell walls from one cell to another without every entering the cells.to another without every entering the cells.

SymplastSymplast

Water moves from one cell to another through Water moves from one cell to another through the symplast.the symplast.

Water moves from the cytoplasm of one cell to Water moves from the cytoplasm of one cell to the cytoplasm of the next through the cytoplasm of the next through plasmodesmata.plasmodesmata. Small tubes that connect the cytoplasm of adjacent Small tubes that connect the cytoplasm of adjacent

cells.cells.

When water reaches the When water reaches the endodermis…endodermis…

Water can continue into the vascular cylinder Water can continue into the vascular cylinder only through the symplast pathway.only through the symplast pathway.

Water that is moving via the apoplast pathway Water that is moving via the apoplast pathway is blocked by the suberin that permeates the is blocked by the suberin that permeates the casparian strip. casparian strip.

Water can enter through the endodermal cells Water can enter through the endodermal cells along with Kalong with K++, but Na, but Na++ is blocked. is blocked.

Water then reaches the vasuclar cylinder where Water then reaches the vasuclar cylinder where xylem tissue (tracheids and vessels) conduct xylem tissue (tracheids and vessels) conduct the water up the plant.the water up the plant.

Water Movement Up the PlantWater Movement Up the Plant

3 Mechanisms3 Mechanisms OsmosisOsmosis Capillary ActionCapillary Action Cohesion-tension theoryCohesion-tension theory

Cohesion-tension TheoryCohesion-tension Theory

3 Major Concepts3 Major Concepts TranspirationTranspiration CohesionCohesion Bulk FlowBulk Flow

TranspirationTranspiration

The evaporation of water from plants.The evaporation of water from plants. Water evaporates through the leaves creating Water evaporates through the leaves creating

negative pressure to develop in the column.negative pressure to develop in the column.

CohesionCohesion

The molecular attraction between like The molecular attraction between like substances.substances.

The water molecules “stick” together creating The water molecules “stick” together creating a single column of water molecules. a single column of water molecules.

Bulk FlowBulk Flow

When a water molecule is lost from a leaf by When a water molecule is lost from a leaf by transpiration it pulls up behind it an entire transpiration it pulls up behind it an entire column of water molecules.column of water molecules.

Transport of SugarsTransport of Sugars

4 Step process4 Step process Sugars enter the sieve-tube members via active Sugars enter the sieve-tube members via active

transport.transport. Water enters the sieve-tube members. Water enters the sieve-tube members. Pressure in sieve-tube members at the source Pressure in sieve-tube members at the source

moves water and sugars to sieve-tube members at moves water and sugars to sieve-tube members at the sink through sieve tubes. As a result pressure the sink through sieve tubes. As a result pressure builds causing the water and sugars to move.builds causing the water and sugars to move.

Pressure is reduced in sieve-tube members at Pressure is reduced in sieve-tube members at

Plant MovementsPlant Movements

TropismsTropisms A plant movement that is determined by the A plant movement that is determined by the

direction of an environmental stimulus.direction of an environmental stimulus. PositivePositive NegativeNegative

Nastic MovementsNastic Movements Plant movements that occur in response to Plant movements that occur in response to

environmental stimuli but are independent of the environmental stimuli but are independent of the direction of the stimuli.direction of the stimuli.

TropismsTropisms

PhototropismPhototropism ThigmostropismThigmostropism GravitropismGravitropism

PhototropismPhototropism

StimulusStimulus LightLight

HormoneHormone AuxinAuxin

FunctionFunction Light causes the production of auxin to move to the shaded Light causes the production of auxin to move to the shaded

side.side. As a result the cells on the shaded side are elongated faster As a result the cells on the shaded side are elongated faster

then the lighted side.then the lighted side. The plant bends towards the light.The plant bends towards the light.

ThigmotropismThigmotropism

StimulusStimulus Contact with an objectContact with an object

FunctionFunction Allows for vines to “climb” walls.Allows for vines to “climb” walls. Tendrils will coil around objects.Tendrils will coil around objects.

GravitropismGravitropism

StimulusStimulus GravityGravity

HormoneHormone Auxins, GibberellinsAuxins, Gibberellins

FunctionFunction Allows for roots to grow down.Allows for roots to grow down. Allows for shoots (stems) to grow up at the apical Allows for shoots (stems) to grow up at the apical

meristem.meristem.

PhotoperiodismPhotoperiodism

Is the response of plants to changes in the Is the response of plants to changes in the photoperiod, or the relative length of daylight photoperiod, or the relative length of daylight and night.and night.

Plants maintain a circadian rhythmPlants maintain a circadian rhythm External clues such as dawn and dusk reset the External clues such as dawn and dusk reset the

clock.clock.

PhytochromePhytochrome

The protein involved used in maintaining the The protein involved used in maintaining the circadian rhythm. circadian rhythm. 2 Forms depending on the wavelength of light that the 2 Forms depending on the wavelength of light that the

phytochrome absorbs.phytochrome absorbs. PPrr: Phytochrome red (wavelength of 660nm): Phytochrome red (wavelength of 660nm)

Accumulates at nightAccumulates at night

PPfrfr: Phytochrome far-red (730nm): Phytochrome far-red (730nm) Resets the circadian-rhythm clockResets the circadian-rhythm clock

Reversible relationship between PReversible relationship between Pr r and Pand Pfrfr

When PWhen Prr is exposed to red light it is converted to P is exposed to red light it is converted to Pfrfr

When PWhen Pfrfr is exposed to far-red light it is converted to P is exposed to far-red light it is converted to Prr

Critical Night LengthCritical Night Length

CNL is responsible for resetting the circadian-CNL is responsible for resetting the circadian-rhythm clock.rhythm clock.

Brief dark periods during the day have no Brief dark periods during the day have no effect on the clock.effect on the clock.

Flashes of red light at night cause the clock to Flashes of red light at night cause the clock to be reset.be reset.

Flowering in PlantsFlowering in Plants

Regulated by the photoperiod.Regulated by the photoperiod. 3 types of plants3 types of plants

Long-dayLong-day Plants flower in the spring and early summer when day light is Plants flower in the spring and early summer when day light is

increasing.increasing.

Short-dayShort-day Plants flower in late summer and early fall when daylight is decreasing.Plants flower in late summer and early fall when daylight is decreasing. Flower when daylight is Flower when daylight is less thanless than a critical length. a critical length.

Day-neutralDay-neutral Do not flower in response to daylight changes.Do not flower in response to daylight changes.