Plant Organization & Function

Chapter 9-B2

Plant organization & function

A. Plant evolved adaptations for protection because they cannot move

a. waxy coating on epidermal cells which make it impermeable towater

b. bacteria & viruses have a more difficult time getting into a plant

a. very thick cuticle

3. Hairs on epidermis

a. reduces evaporation of surface by breaking wind flow

c. inhibits being eaten

a. natural insecticides (eg. tobacco/nicotine)

II. Plant Organs p. 144

1. Angiosperms=flowering plants

a. root systems

b. shoot systems

-leaves

a. root

b. stem

c. leaf

a. flowers

b. seeds

c. fruits

1. Depth & distribution of roots depends on-

b. timing & amount of precipitation

d. eg. grassland vs. desert

e. normally 90% of roots are 1 mbelow surface but extend 2-4xthe size

a. anchors plant

c. cylinder shape allows movementthrough the soil & absorbs 360 degrees

e. store water eg. pumpkin

f. produces hormones to make surestem & root grow at the same rate

a. increase surface area to acquire more water & nutrients

b. eg. 1-20” rye plant=13,800,000root hairs

d. transplanting-need to getlateral roots & root hairs

a. end of root

C. Stems

1. main axis of plant

a. goal-most sun exposure for leaf

b. node-

-used in identification andasexual reproduction

c. internode-

3. Increases in diameter

5. Vascular tissue (veins)

-nonliving cells

b. phloem transport nutrients

6. may photosynthesize

8. Tubers=horizontal undergroundstems which store nutrients

1. Function

b. almost never woody

d. attach to objects-tendrils

e. store food-bulbs

2. Needs for photosynthesis

b. CO2-surface area to enter plant(stomata)

c. sunlight-surface area to enterplant

3. Blade-

4. Petiole-attaches blade to stem

a. leaf size, shape, color & texture

b. Petiole size & attachment tostem

a. angle between petiole & stem

b. where axillary (lateral) bud forms which becomes branch or flower

7. Deciduous-

8. Evergreens-retain leaves for 2-7years

III. Cells and Tissues of plants

1. defined-tissue which have cells withthe ability to divide &create more tissue.

2. Apical meristem (increases in length-primary growth)

-root tip

b. intercalary meristem (regrowth at nodes & blades)

-grows back FAST!

-PROTODERM makes epidermaltissue

-GROUND MERISTEM makes ground tissue (interior of plant)

-PROCAMBIUM makes vascular tissue

3. primary growth responsible for herbaceous, or non-woody stems

a. in roots & stems makes WOOD

B. Epidermal Tissue (from protoderm)

1. Entire body of herbaceous & youngwoody plants covered in epidermaltissue

a. waxy layer on epidermal tissue exposed to the air

c. protection against bacteriaentering plant

4. Specialized epidermal tissue

a. TRICHOMES (hairs on stems,leaves, and reproductive organs)

-protects from too much sun & conserves water

b. GUARD CELLS p. 146

-surrounds pore opening(stomata) on leaves to controlgas exchange

5. Older woody plants replace epidermis with PERIDERMA

a. made of cork cells

c. becomes waterproof when lipidsencrust outer cells

e. adds protection

g. some bark cracks/ridges

-LENTICELS-loosely packed cork to allow gas exchange

with the interior of the stem

1. Bulk of plant

2. Fills in between epidermis &vascular tissue

3. Stores carbohydrates made fromphotosynthesis

4. Produces hormones, toxins, pigments & specialized chemicals

a. PARENCHYMA

-found in all organs of plant

-can divide & give rise to morespecialized cells (eg. roots

develop from stem cuttings)

-apple flesh mostly parenchyma

-parenchyma with thicker primary walls

-often form bundles below epidermis

-gives support to immatureregions of plant

c. SCLERENCHYMA

-eg. reinforced concrete

Cement=lignin

Steel rods=cellulose fibers

-primary job is to supportmature parts of plant

-eg.

Flax-linen

Seed coats

Nutshells

Peach pits

Pear texture

1. Primary meristem (procambium)makes VASCULAR TISSUE

a. XYLEM-

b. PHLOEM-

2. Xylem & phloem complex tissues

a.made of 2 or more kinds of cells (hollow, non-living cells)

-VESSEL ELEMENTS

-plates with perforations in end walls to move water

-cells have tapered ends

-has pits and depressionswhere secondary wall doesn’t

form-water moves but lessefficient

c. Phloem

-SIEVE-TUBE MEMBERSforms continuous tube (has cytoplasm but

no nuclei)

-sieve plate-cluster of pores atthe end

-COMPANION CELL-

-connected to each other byPLASMODESSMATA

-communication of cellsthrough the sieve tubemembers of each cell

-nucleus of companion cellcontrols both cells

a. Roots-vascular cylinder

b. Stems-

c. Leaf-Leaf veins

IV.

A. Cotyledons (seed leaves)

1. Monocotyledons=1 cotyledon

B. Vascular tissue (transport) p. 149

1. Monocot

-ring shaped

-scattered bundles

-parallel

a. root

-x-shaped

b. stem

-vascular bundles in a ring

c. leaves

-pinnateveination(feather-like)

C. Structural differences

1. Monocot

-multiples of 3

b. Pollen

-1 aperture

2. Eudicot

-multiples of 4 x 5’s

b. Pollen

D. Examples

1. Monocot-

2. Eudicot-Dandelion to maple trees

A. Root growth

1. Division of tissue

-protected by root cap

-root cap worn away & replaced often

b. Zone of elongation

-cells become specialized (eg. vascular)

-root hairs present

1. Epidermis-single layer for Protection

2. Cortex-parenchyma cells for food & water storage

a. Casparian strip

b. cells impermeable on 4 sides, 2 sides permeable (root hairs)

c. single cell layer between cortex & vascular tissue

a. may become meristematic forbranch roots

b. main cylinder has xylem &phloem

C. Anatomy of Monocot roots

1. Same growth zones as eudicot

a. central location

3. Vascular ring around pith

D. Root Diversity

a. primary roots

-fleshy

-eg. carrot, sweet potatoe

b. lateral roots (side of primary root)

2. Monocot

a. large number of slender roots

3. Root specialization p. 152

-arise from stem

-helps to anchor plant

-horizontal stems (eg. evy)

-roots which need O2 for cellrespiration

c. Epiphytes (air plants)

-grow on other plants

-eg. orchids

d. parasitic plants

-roots tap into vascular system of other plant and stealnutrients

-eg. dodder

-Legumes (beans)bacteria

Plant receives N from N-fixing bacteria in nodules on roots

Bacteria receives place tolive and plentiful carbohydrates

Plant receives increased surface area to absorb

more water and food

Fungus receives sugars and amino acids from plantroots

VI.

A. Anatomy of a woody twig

1. Terminal bud-end of stem

b. bud scale protection(modified leaves)

2. Scars (every year caused by buds growing)

a. leaf

c. can tell age of stem by countingscars

a. flowers or

4. Node-where one or more leavesattach to a stem

5. Internode

b. gets larger as stem grows

6. Lenticels

-openings for gas exchange in twig

1. primary meristems

a. growth

b. protoderm-

2. ground meristem makes parenchyma (pith & cortex)

3. procambium makes immature xylem & phloem & changes to vascularcambium

1. shows only primary growth

2. anatomy (internal)-monocot

b. epidermis

-xylem & phloem

-xylem faces inside

-phloem faces outside

a. vascular bundles in distinct ring

b. cortex can photosynthesize

4. sugar

1. General information

-primary grows every year and occurs in ALL plants

-secondary developssubsequent years from lateralmeristematic

tissue andoccurs only in woody plants

a. cork-dead cells

-grows cork beneath epidermis

-adds wax to cork forwaterproofing but kills the cell

-woody makes stems less edible

3. Woodp. 157

a. secondary xylem

c. dormant in winter(xylem/phloem)

-spring wood

-both spring & summer=annualring

-outer annual ring

-old trees

-clogs with resin/gums etc.

g. Advantages & disadvantages tobeing a woody plant

Advantages-

Disadvantages-

a. modifications to vertical stems - Stolons-horizontal above ground (ex. berries)

~nodes produce new plantwhen it touches theground

b. Rhizomes-

-helps survive the winter

-ex. cattail, iris

c. Corm (bulb)

-thin leaves & thick stem

-eg. onion, daffodils, tulips

VII. Organization of leaves

A. General External Anatomy

2. ______-attaches to stem

3. Veins visible

b. netted-eudicot

a. for protection

b. eg. toxins

6. Stomata

a. openings for gas exchange

c. guard cells photosynthesize & regulate opening by using water pressure

1. Mesophyll-tissue in body of blade

-elongated cells beneath the epidermis

-photosynthesis

-irregular cells

-photosynthesis

C. Leaf diversity

1. Simple-single blade

a. ______-occurs in pairs (eg. Black walnut)

c. Bipinnately compound-eg. mimosa

3. Leaf arrangement on stem

b. opposite

c. whorled-

4. Leaf adaptation

-broad, wide leaves, why?

-needlelike leaves & sunkenstomata, why?

c. leaves surrounded by short stem

-eg.

d. Petiole fleshy

-eg. celery, rhubarb

f. carnivores (trigger trichomes)

-eg. venus fly trap

--swampy areas

VIII. Uptake & transport of nutrients

CO2 + H2O = C6H12O6 + O2

1. Root (root hairs)

3. Active transport needed forminerals

4. ______model of Xylem transport

a. cohesion-water molecules sticktogether making a water column

b. adhesion-water attracted topolarity of walls ofxylem

c. stomata open causingevaporation/transpiration & pullwater column up

through tension

-corn loses 135-200L a growing

season

e. cut flowers under water to keep the water pressure in the xylem.

B. Opening & closing of stomata p. 164

a. regulated by water pressure

b. K+ accumulate..attract waterfor diffusion…stomata open due

to increase of water in theguard cells

-circadian rhythm

C. Organic Nutrient Transport

1. Role of Phloem

b. sample collecting damagesphloem

-scientists use aphids to collect phloem. Aphids bite…needlelike mouth inside the phloem…kill aphid but leave mouth…pump out phloem.

2. Nutrients (sugar) moves from greater concentrations to lesser

concentration (diffusion)