Bio 131 Chapter 34 Plants

2 basic systems to help plants get resources

root and shoot system

root+ shoot systems=

plant body

vascular tissue

connects the root and shoot system

h20 and nutrients are transported from roots to shoots

sugars go in both directions

importance of a large sa/vol ratio

more absorption area allows for more photosynthesis and uptake of nutrients

taproot

large vertical main root of plant’s root system

axis of a plant (from bottom to top)

basal to apical

3 leaf axis

proximal-distal (stem to the tip of the leaf)

mediolateral axis (margin is on the other side)

adaxial-abaxial axis (adaxial-upper side abaxial- bottom side)

lateral roots

plant root that extends horizontally from another root

herbaceous plants

seed plants that lack woody tissue

perennial

live for many years

phenotypic plasticity

form changeable due to environmental conditions

adventitious

roots that develop from the shoot system instead of the root system

pneumatophores

allow gas exchange between roots and atmosphere, lateral roots grow upward due to gravity

stem

vertical aboveground structure made up of nodes

nodes

where leaves attached

internodes

spaces between the nodes

leaf

appendage that projects from a stem laterally and functions as a photosynthetic organ

axillary or lateral bud

nodes where leaves attach to the stem

site of leaf attachment

have dormant meristematic stems

branch

a lateral extension of a shoot system

if conditions right grow from axillary bud

apical bud

tip of each stem and branch contains this where growth occurs that extends the length of the stem or branch

flowers

reproductive structures that form at the apical or axillary buds if conditions are right

the leaf 2 parts

the stalk- petiole

expanded portion-blade

the leaf function

absorb photons and supports photosynthesis

leaf type

leaf arrangement

compound leaves

blades divided into a series of leaflets

transpiration

loss of h2o vapor from above ground plants parts primarily through the stomata

sun leaves vs shade leaves in oak trees

sun leaves- thicker relatively smaller sa which reduces h2o loss in areas with lots of light

shade leaves- thin board high sa to get photons h20 loss less of a problem

features common in all plants

primary cell wall some have a secondary cell wall

plasmodesmata

chloroplasts or plastids

vacuoles

plasmodesmata

physical connections between 2 plant cells consisting of membrane lined gaps in the cell walls in which the cells plasma membrane’s cytoplasm and smooth er can directly connect

plastids

in almost all plants

precursor/related to chloroplasts

tissue

group of cells that function as a unit

simple tissue

plant tissues that consist of a single cell type

complex tissues

tissues that contain several types of cells

tissue system

grouped based on structural features and location in the plant

the dermal tissue system

consists of dermal tissue also called the epidermis outermost layer of cells represents the interface between the organism and the external environment

function in shoots- protect the plant from h2o loss, disease causing agents, herbivores

function in roots- absorb h20 nutrients

epidermis made of several diff cell types complex tissue

how exactly do epidermal cells protect the surface and functions of this thing

secrete cuticle

cuticle-waxy layer that forms a continuous sheet on surface of stems and leaves

reduces h2o lose by evaporation

forms a barrier to protect plants from viruses bacteria spores and fungi

problem with the cuticle

waxes in cuticles can be bad by reducing gas exchange needed for photosynthesis solved by stomata

stomata

typically found on leaves pores that allow co2 to enter o2 to exit

guard cells

change shape to open or close the stomata

dermal tissue

trichomes

hairlike appendages made up of specialized epidermal cells

found in shoot systems and come in a wide range of shapes size abundance

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trichomes function

1 keep the leaf surface cool by reflecting sunlight

2 reduce h20 loss by forming a dense mat that limits transcription

3 provide barbs or store toxic compounds that thwart herbivores

4 trap or digest insects

the ground tissue system

responsible for most of the synthesis and storage of specialized products such as colorful pigments hormones and toxins required for defense

play a large role in structural support of the shoot system

3 diff. types parenchyma collenchyma sclerenchyma

parenchyma tissue

composed of parenchyma cells have relatively thin primary cell walls most common and versatile

alive and totipotent (can divide

has to do most of the work so it has chloroplasts

important in healing wounds and reproducing asexually

callus

mass of undifferentiated cells

collenchyma

characterized by an unevenly thickened primary cell wall longer and thinner than parenchyma cells

simple tissue

resilient support alive thickened primary cell wall totipotent

not rigid allows it to flex in the wind

provide flexible structural support for shoots

sclerenchyma

tissue characterized by the presence of the thick rigid secondary cell wall in addition to relatively thin primary cell wall

stiff support

dead at maturity

rigid support and secondary cell wall

once they are functional they are dead

what does sclerenchyma secondary cell wall contain

lignin and cellulose

2 types of sclerenchyma cells

fibers and sclereids

fibers

extremely elongated important for paper and fabric production

sclereids

relatively short have variable shapes and often function in protection why pears are gritty

the vascular tissue system

vascular tissue system functions in support and in long distance transport of h20 and dissolved nutrients in vascular plants moves the products of photosynthesis that are made and stored in ground tissue

vascular system made of 2 types of complex tissues

xylem and phloem

xylem

conducts h20 and dissolved nutrients in 1 direction from the root system to the shoot system

phloem

conducts sugar amino acids hormones and other substances in 2 directions

roots to shoots and shoots to roots

vascular bundle

in a plant stem a cluster of xylem and phloem strands that run the length of the stem

xylem structure

includes h20 conducting cells as well as parenchyma cells and fibers

2 types of h20 conducting cells in xylem

2 types of h20 conducting cells in xylem

tracheid and vessel elements

tracheid

in a vascular plant a long thin h20 conducting cell that has pits where its lignin (containing secondary cell wall) is absent allowing h20 movement between adjacent

sides and ends have pits- gaps in secondary cell wall where only the primary cell wall in present moves from cell to cell both vertically and laterally through pits bc resistance flow lowest

long slender cells w/tapered ends

vessel elements

in vascular plants a short wide h20 conducting cell that has gaps through both the primary and secondary cell walls allowing unimpeded passage of h20 between adjacent cells

shorter and wider

has pits and perforations openings in the end walls that lack both primary and secondary cell walls

conduct h20 more effiecntly than tracheids bc their width preformation offer less resistance to flow

are vessel elements and tracheids both alive or dead at maturity

dead

phloem structure

2 specialized types of cells

both are alive at maturity and lacks secondary cell walls

sieve and companion cells

sieve tube elements

long thin cells that have perforated ends

lack nuclei and most other organelles and connected to adjacent companion cells by plasmodesmata

sieve plates

responsible for transporting sugars and other nutrients

companion cells

not conducting cells but instead provide materials to maintain the cytoplasm and plasma membrane of sieve tube elements

contain most of the organelles normally found in plant cells and support the metabolic activity of sieve tube elements

meristems

populations of undifferentiated cells that retain the ability to undergo mitosis

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apical meristem

located at each root and shoot where growth occurs from

primary plant body

all cells and tissues that are derived directly from apical meristems

apical meristems give rise to 3 meristems which are

protoderm ground meristem and procambium

protoderm

gives rise to the dermal tissue system which includes the epidermis

ground meristem

gives rise to the ground tissue system makes up the bulk of the primary plant body

includes the parenchyma collenchyma and sclerenchyma

procambium

gives rise to the vascular tissue system which includes the xylem and phloem

components of primary growth chart

root cap

protects the root apical meristem

necessary to protect and allow for outward growth

synthesizes and secretes a polysaccharide which lubricates it and reduces friction and protects the apical meristem

3 zones behind the root cap

zone of cellular division

zone of elongation

zone of cellular matuartion

root hairs

increase sa of dermal tissue and allows for increased absorption

shoot system includes vascular tissue that runs through it and it’s divided into 2 major regions

pith and cortex

pith

ground tissue towards the center of the stem

cortex

the ground tissue that is between the vascular bundles and the epidermis

what does primary growth do

increases the length of the roots and shoots and increases the plants ability to absorb h20 co2 and nutrients

secondary growth

in trees and other woody plants increases the width of roots and shoots

wood

xylem resulting from secondary growth forms strong supporting material

cambium

special type of meristem (lateral meristem) that differs from an apical meristem in 2 ways


1. made up of a single layer of meristematic cells apical meristem are clusters of cells localized at root and shoot tips


1. cambium cells divide in a way that increases the width of root trunks and branches apical meristems increase the length

2 types of cambium

vascular cambium and cork cambium

vascular cambium

a cylinder of meristematic cells located between the secondary xylem and phloem in roots and trunks and branches

generates new layers of cells toward both the interior and exterior (more toward the inside tho) new cells formed to the inside push all of the other cells outside increase girth

cork cambium

cylinder of meristematic cells located near the outer perimeter of roots trunks and branches

produces new cells primarily toward the exterior

cork cambium mature tissue direction of growth mature cell comp and mature tissue function

cork

produced to the outside

cork cells

protection

vascular cambium (2 types) mature tissue direction of growth mature cell comp and mature tissue function

secondary phloem

produced to the outside

sieve tube elements companion cells sclerenchyma cells (fibers)

transport of sugars amino acids hormones etc

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secondary xylem

produced to the inside

tracheid’s vessels parenchyma cells (arranged in rays) sclerenchyma cells (fiber)

transport of h20 and ions structural support

structurally primary and secondary xylem and phloem are

complex tissues

functionally primary and secondary phloem function in

sugar transport

functionally primary and secondary xylem function in

h20 transport and structural support

secondary xylem makes up

wood

secondary phloem makes up

inner part of tree’s bark

rays

rows of cells and form a living conduit through which h20 and nutrients are transported laterally across the trunk

results of cell division in vascular cambium are

highly asymmetrical

cork cells

a cell in the protective outermost layer of a woody stem and roots that produces and accumulates waxes that make cells less permeable to gases

bark=

and function

cork cambium+ cork cells

provides a particularly tough barrier in species whose cork cells secrete a strong secondary cell wall containing lignin

helps prevent h20 loss bc cork cells make a layer of wax

protects from damage from pathogens

some can protect from fire damage

how can gas exchange still occur through the bark

by way of lenticels

lenticels

small spongy openings in the bark allow for gas exchange

perennial

plants that live for many years