Download - February 28 th QUIZ – Chapter 23 Notes – chapter 23 February 28 th QUIZ – Chapter 23 Notes – chapter 23 Roots, Stems, and Leaves HW: Plant book.

February 28February 28thth

QUIZ – Chapter 23QUIZ – Chapter 23

Notes – chapter 23 Notes – chapter 23 Roots, Stems, and Leaves

HW: Plant book

March 2nd

• Weekend HW • Finish notes – Chapter 23 Roots,

Stems and Leaves• Grade Plant book • **BRING YOUR LEAF TOMORROW!!

****No microscopes today**

23-1 Specialized Tissues in Plants

• Plants are as successful if not more successful than animals

• Seed plants have three main structures:– Roots– Stems– Leaves

• Linked together by various means


• Roots– Absorbs water and

nutrients– Anchor plant to the

ground– Hold soil in place

and prevent erosion– Protect from soil

bacteria– Transport water and

nutrients– Provide upright

support


• Stems– Support for the

plant body– Carries nutrients

throughout plant– Defense system to

protect against predators and infection

– Few millimeters to 100 meters


• Leaves– Main photosynthetic

systems– Susceptible to

extreme drying– Sight of

oxygen/carbon dioxide intake and release


• Plant tissue systems– Exist within the

root, stems, and leaves•Dermal tissue•Vascular tissue•Ground tissue


• Dermal Tissue– Outer covering – Single layer of cells– Cuticle – waxy

coating • Trichomes – Spiny

projections on the leaf

– Roots have dermal tissue

• Root hairs

– Guard Cells


• Vascular Tissue– Transport System– Subsystems

• Xylem• Phloem

– Subsystems are used to carry fluids throughout plant


• Xylem– Two types

• Seed plants• Angiosperms

– Tracheid – long narrow cells

– Walls are connected to neighboring cells

– Will eventually die– Vessel Element –

wider that trachieds


• Phloem– Sieve Tube

Elements• Cells arranged

end to end• Pump sugars

and other foods– Companion

Cells• Surround sieve

tube elements• Support phloem

cells

23-1 Specialized Tissues in Plants• Ground Tissue

– Cells between dermal and vascular tissue

– Parenchyma• Thin cell walls, large

vacuoles• Site of photosynthesis

– Collenchyma• Strong, flexible cell walls• Support large plants

– Sclerenchyma• Extremely thick, rigid

cell walls


• Plant Growth– Meristems – tissues

responsible for growth • Undifferentiated cells

– Apical Meristem• Produce growth

increased length

– Differentiation• Cells will assume roles

in the plant

• Flower Development– Starts in the meristem

23-2 Roots

• Types of Roots– Taproots

• Found in dicots• Long, thick root• Hickory and oak trees

– Fibrous roots• Found in monocots• No single root larger than any other• Many thin roots

23-2 Roots

• Root Structure– Outside layer– Epidermis

• Root hairs - absorption• Cortex - spongy

– Central cylinder – vascular system

– Root Cap – cellular production

• Key role in water/mineral transport

23-2 Roots

• Root Functions– Anchor plant– Absorb water– Absorb nutrients

23-2 Roots

• Plant Nutrient Uptake– Soil type determines

plant type

• Plant requirements– Oxygen, CO2

– Nitrogen– Phosphorus– Postassium– Magnesium– Calcium– Trace elements

23-2 Roots

• Active Transport in Plants– Root hairs use ATP

• Pump minerals from soil

• Causes water molecules to follow by osmosis

• Vascular Cylinder– Casparian Strip –

water retention

• Root Pressure– Forces water up

into the plant

23-3 Stems

• Stem Structure– Produce leaves,

branches, and flowers– Hold leaves up– Transport substance

between roots and leaves

• Essential part of transport system

• Function in storage and photosynthesis

23-3 Stems

• Xylem and phloem – major tubule systems– Transport water and

nutrients

• Composed of three tissue layers

• Contain nodes – attachment for leaves

• Internodes – regions between the nodes

• Buds – undeveloped tissue

23-3 Stems

• Stem Types– Monocot – vascular

bundles are scattered throughout

• Distinct epidermis

– Dicot – vascular tissue arranged in a cylinder

• Pith – parenchyma cells inside the ring

23-3 Stems

• Stem Growth– Primary growth – new

cells produced at the root tips and shoots

• Increases the length

– Secondary growth – increase in stem width

• Vascular cambium – produces tissue and increases thickness

• Cork cambium – produces outer covering of stems

23-3 Stems

• Formation of Vascular Cambium– Xylem and phloem

bundles present intially

– Secondary growth initiates production of a thin layer

– The vascular cambium divides

• Produces new xylem and phloem

23-3 Stems

• Formation of wood– Wood – layers of xylem– Produced year after year– Results from the older xylem not conducting water

– heartwood– Becomes darker with age– Sapwood – surrounds heartwood

23-3 Roots

• Formation of Bark– All the tissues

outside the vascular cambium

– Consists of outermost layers of dead cork

– Water proof

23-4 Leaves

• Main sight of photosynthesis

• Consist of:– Blade – thin flattened

section– Petiole – stalk that

attaches stem to blade

• Covered by epidermis and cuticle– Create water proof

barrier

23-4 Leaves

• Leaf Functions– Photosynthesis –

occurs in the mesophyll

• Palisade mesophyll – absorb light

• Spongy mesophyll – beneath palisede level

• Stomata – pores in the underside of the leaf

• Guard Cells – Surround the stomata

23-4 Leaves

• Transpiration– Loss of water

through its leaves

– Replaced by water drawn into the leaf

23-4 Leaves

• Gas Exchange– Take in CO2 and

release O2

– Can also do the opposite – How?

– Gas exchange takes place at the stomata

• Not open all the time

– Stomata is controlled by water pressure in guard cells

23-5 Transport in Plants

• Water Transport– Active transport

and root pressure• Cause water to

move from soil to roots

– Capillary action• Combined with

active transport and root pressure, moves materials throughout the plant


• Capillary Transport– Capillary transport

results from both cohesive and adhesive forces

– Water molecules attracted to one another

– Water is also attracted to the xylem tubes in the plant

– Causes water to move from roots to the stem and upward


• Transpiration– Evaporation is the

major moving force– As water is lost,

osmotic pressure moves water out of vascular tissue

– This pulls water up from the stem to the leaves

– Affected by heat, humidity, and wind


• Controlling Transpiration– Open the stomata –

increase water loss– Close the stomata –

decrease water loss


• Transpiration and Wilting– Osmotic pressure –

keeps plants semi-rigid– Wilting is a result of

high transpiration rates

– Loss of water causes a drop in osmotic pressure

– Loss of rigidity– Conserves water


• Nutrient Transport– Most nutrients are pushed through plant

– Nutrient movement takes place in phloem

• Source to Sink– Source – any cell that

produces sugars– Sink – any cell where

sugars are used– Pressure-flow

Hypothesis