[BIO] 04 - Plant Tissues (Calsado)

8/14/2019 [BIO] 04 - Plant Tissues (Calsado)

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Plant

tissues


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PLANTS

Photosynthetic autotrophs

Obtain inorganic materials from the external

environment and process them into theorganic compounds needed for life

Cells secrete a cell wall exterior to the plasmamembrane


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Plant PropagationAsexual/vegetative reproduction

Clone

MeristemsSpecial types found at the growing tips, other

parts

Similar to proembryo, all cells can differentiate

AdventitiousPlant parts produced by dedifferentiation


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ComplexityDispersal means

Most primitive: spores

More complex: seedConducting/vascular tissue

Simpler plants: no conducting tissuesComplex plants: with vascular tissues


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Plant OrganizationRoot systemgrowth toward gravity; generally

below ground; consists of rootsRoot epidermis; cortex; stele (vascular tissue);

pith


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Shoot systemGrowth away from gravity along the axisGenerally above the groundConsists of the stem and the leaves

Flowers are modified shoot system


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Plant TissuesMeristems

Surface or dermal tissues

Vascular tissuesGround or fundamental tissues


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MeristemsResponsible for increase in number of cells

Meristems do not specialize

Plant tissues are derived from the meristemsThree types:

Apical

Lateral

Intercalary


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MeristemsIntercalary Meristem- plants without vascular

cambium (grasses)

Growth regions that occur at thebase of nodes


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GrowthPrimary growth

Inc in length of plants (apical meristem)

Secondary growthInc in plant girth (lateral meristem)

Select plants only (woody plants such as dicotand gymnosperms)

Product: wood and cork


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Plant growth patterns and

regionsPrimary growth- growth in length; primary

meristems

Secondary growth- growth which increasesthe girth or circumference of the plant

Vascular cambium- bet wood and bark

Cork cambium-found in the outer bark


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Primary meristemsAt tips

Shoot tip meristems (shoot system)

Stem meristem; leaf primordia; bud primordiaRoot tip meristems

Primary meristems are permanent and selfperpetuating


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Derivative meristemsProduced when meristem cells divide; forms

the tissue systems of the plant Protoderm- develops into surface or dermal tissues

Procambium- develops into vascular tissue

Ground meristem- fundamental /ground tissues

Secondary meristems

Vascular cambium- produces wood (strength);

produces part of bark (protection)Cork cambium- produces protective layer of bark

called cork


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Plant GrowthPrimary Growth

(roots andshoots)

Secondary

Growth (rootsand shoots)


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Meristems from Cell

DedifferentiationDedifferentiate-any plant cell has the ability

to dedifferentiate

Lateral root formation

Adventitious growth

Wound healing

Secondary cork cambium


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Primary Growth of RootsRoot cap

protects the delicate meristems as the rootelongates through the abrasive soil

secretes mucous that lubricates the soil

3 Zones of cells at successive station Zone of cell division

Zone of cell elongation

Zone of cell differentiation


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Simple Tissues


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Ground or fundamental

tissuesFibers- for support

Photosynthetic cells

Storage cellsFill in the spaces cells


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Ground or Fundamental

TissuesParenchyma

basic tissue type

Collenchymasupports young plants

Sclerenchyma

supports for mature plants


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ParenchymaDefinition: a simple tissue composed of spherical-

shaped cells; most common type of tissue

Have thin primary walls

Living, metabolizing tissue

E.g. Chlorenchyma, Aerenchyma

Functions:

Photosynthesis & Respiration

Storage (starch, oil droplets, air, water, and salts)

Wound healing & regeneration


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CollenchymaDefinition: a simple tissue found beneath

the epidermis in young stems and in largeveins of leaves (strings in celery).

Provides a flexible support system (like ourskeletal system).

Found uniformly throughout the plant.

Elongated cells that have unevenlythickened cell walls (especially in thecorners)

Alive at maturity


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SclerenchymaDefinition: a simple tissue

specialized for structuralsupport; occurs in many

areasTwo types:

Fibers

Sclereids

Have both primary andsecondary cell walls.

At functional maturity cellsare often dead


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FibersLong, tapered cells that

often occur in groups orclumps (abundant in the

wood and bark offlowering plants)

Found in leaves & stems.

Primary function is

support


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SclereidsShort, cuboidal cells

common in shells ofnuts and pits of fruits

(peaches, cherries)Found in all plant parts,

usually clustered.

Primary function is for

protection


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Complex tissuesVascular Tissue System


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Vascular tissuesFunctions: conduct water and solutes

support and strength of theplant

Types of vascular tissues

Xylem- conducts water and minerals

Phloem- conducts solutes/food

Continues throughout the plant


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XylemConduction of H2O from roots to leaves

Made up the wood

Composed of: Vessel Elements- elongated cells with secondary

wallsDead at functional maturity; perforatedLarge diameter

Tracheids elongated, narrow cells with secondarywalls; dead at functional maturity; pittedXylem fibersXylem parenchymaXylem rays

Parenchyma cells and Fibers


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TracheidsTracheids are typically found in

gymnosperms and seedless vascular plantsand aid in transporting water.


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Vessel ElementsVessel elements

are typically foundin angiospermsand aid intransporting water.


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PhloemMoves solutes (especially carbs)

Composed of:Sieve tube cells

Elongated cells forming tubesEnd walls have pores forming sieve platesAlive at functional maturityCarry food

Companion cellsParenchyma cells adjoining the sieve tube cellsPhloem fibersPhloem parenchyma

(Sclerenchyma fibers and parenchyma cells)


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Sieve tube membersSieve tube members

can secrete a proteincalled callose to plug

sieve plates to stopthe flow of food ifthe phloem isdamaged


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Complex tissuesDermal Tissues


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Surface or dermal

tissuesProtection

Prevents dessication


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Dermal (surface) tissueEpidermis (herbaceous plants)

Cuticle (protective waxy layer)- prevents dessication(cuticle) and invasion of pathogens , absorption of

water, control of gas exchange

Periderm or cork layer (woody plants) Produced from cork cambium

Secondary epidermis or periderm of woody plants


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DermisEpidermis: Two types

Parenchyma cells

Guard cells

NO Chloroplasts


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CuticleA waxy layersecreted byepidermal cells of

stems and leavesPrevents water loss

and diffusion ofgases

Cuticle Parenchyma cells


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Guard cellsGuard cells form the tiny opening called thestomata


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PeridermisWoody plants initially produce an epidermis thatsplits as the plant grows.

These plants also have periderm, which is

several cells thick and forms under theepidermis.

Periderm composes the outer bark

Composed of two types of cellsCork cells- secrete suberin

Cork parenchyma


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Dermal (surface) tissueEpidermal modifications

Hairs of trichomes Root hairs: absorption of water

Guard cells: form stomata for gas exchange

Glands: modified cells containing oils or other

substances for secretion


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Transport in PlantsCellular level transport

Lateral transport

Long-distance transport


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Plant NutritionChemical composition of plants

80%-85% of herbaceous plants is H2O

Plants grow mainly by accumulating water inthe central vacuoles of their cells

Carbon, hydrogen, oxygen are the mostabundant elements in the dry weight of a plant


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Essential NutrientsHydroponic structure- used to determine

which of the mineral elements are actuallyessential nutrients

Macronutrients- elements required by plantsin relatively large amounts

Micronutrients- elements needed by plants in

small amounts

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[BIO] 04 - Plant Tissues (Calsado)