sheryl searcy ninth grade center 2012 roots, leaves & stems specialized tissue in plants...
TRANSCRIPT
Sheryl Searcy Ninth Grade Center 2012
ROOTS, LEAVES &
STEMSSpecialized Tissue in Plants
Chapter 23
Sheryl Searcy Ninth Grade Center 2012
Basic Parts of a Plant Roots Stem Leaves Flower
Sheryl Searcy Ninth Grade Center 2012
ROOTSSection 23-2
Sheryl Searcy Ninth Grade Center 2012Sheryl Searcy Ninth Grade Center 2012
Types of Root Systems Taproot System
– Primary roots grow down from the stem with some secondary roots forming.
Fibrous Root System– Small lateral roots that
spread out just below the soil surface.
Sheryl Searcy Ninth Grade Center 2012
Four Root Functions1. Absorption of water and nutrients.2. Transportation of water and nutrients to
stem.3. Anchor plant to maintain stability.4. Store food and wate.r
Sheryl Searcy Ninth Grade Center 2012
Parts of a Root
Sheryl Searcy Ninth Grade Center 2012
Parts of a Root Epidermis
– Outermost layer of cells, like the skin of the root.
Cortex– Tissue inside epidermis that stores starch and
other substances for the growth of the root.
Sheryl Searcy Ninth Grade Center 2012
Parts of a Root Root Cap
– Provides protection for the root tip.
Root Hairs– Site of absorption.
Vascular Tissue– Within cortex, contains cells that transport water,
nutrients, and minerals to all parts of the plant.
Image found at: www.bio.psu.edu
Sheryl Searcy Ninth Grade Center 2012
Parts of a Root
Sheryl Searcy Ninth Grade Center 2012
STEMSSection 23.3
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Function of Stems Transport water and nutrients from roots
to leaves. Supports/produces
leaves, branches, and fruit/flowers.
Food storage.
Image found at: www.karencarr.com
Sheryl Searcy Ninth Grade Center 2012
Types of Stems Woody:
– Thick cell walls that support the plant.– Trees, shrubs, and vines.
Herbaceous:– Stems are smooth, supported by hydrostatic
pressure (turgor).– Dandelions, zinnias, petunias.
Sheryl Searcy Ninth Grade Center 2012
Types of StemsWoody Stem Herbaceous Stem
Sheryl Searcy Ninth Grade Center 2012
Parts of a Stem Node
– Areas where side branches and leaves develop.
Internode– Area between nodes.
Xylem– Carries water up.
Phloem– Carries nutrients throughout plant.
Sheryl Searcy Ninth Grade Center 2012
Monocot & Dicot Stems
Monocot: vascular bundles scattered throughout the stem.
Dicot (and most gymnosperms): vascular bundles are arranged in a cylinder.
Sheryl Searcy Ninth Grade Center 2012
Cross-Section of Stems
Woody Stem Dicot Stem Monocot Stem
Sheryl Searcy Ninth Grade Center 2012
Growth of Stems Primary growth of stems is
produced by cell divisions in the apical meristem.– It takes place in all seed plants.
In conifers and dicots, secondary growth takes place in the lateral meristematic tissues called the vascular cambium and cork cambium.
Sheryl Searcy Ninth Grade Center 2012
Woody Stems Actual wood part of the stem is xylem
tissue. Heartwood (pith): stores food. Sapwood: active in fluid transport; xylem
and phloem. Cambium:
producing new tissue, vascular.
Cork: bark
Sheryl Searcy Ninth Grade Center 2012
Formation of Bark
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LEAVESSection 23.4
Sheryl Searcy Ninth Grade Center 2012
Function of Leaves The structure of a leaf is optimized for absorbing
light and carrying out photosynthesis. Photosynthesis
– Process that plants use to produce their food.– 6CO2 + 6H2O C6H12O6 + 6O2
Transpiration– Loss of water and
exchange of carbon dioxide.
Sheryl Searcy Ninth Grade Center 2012
Parts of a Leaf Cuticle
– Waxy outer surface; retains moisture.
Mesophyll – Middle layer of leaf
where photosynthesis occurs.
– Palisade layer (upper)– Spongy layer
(underside)
Sheryl Searcy Ninth Grade Center 2012
Parts of a Leaf Epidermis
– “Skin” of leaf - responsible for gas exchange– Upper and lower
Stomata– Outside layer of leaf opening
in epidermis where gas and water exchange (controlled by guard cells)
Sheryl Searcy Ninth Grade Center 2012
Leaves
Sheryl Searcy Ninth Grade Center 2012
LeavesLetter Structure Color Function
A Cuticle Yellow Waxy outer surface; retains moisture.
B Epidermis Orange “Skin” of leaf - responsible for gas exchange.
C Vein (Xylem) Blue Pumps water up from soil through roots.
D Vein (Phloem) Red Moves nutrients and carbohydrates throughout the plant.
E Mesophyll Green Middle layer of leaf where photosynthesis occurs.
F Stomata Pink Outside layer of leaf opening in epidermis where gas and water exchange.
G Guard Cells Brown Control stomata; trigger when water is scarce causing stomata to become flaccid and pores close.
Sheryl Searcy Ninth Grade Center 2012
LeavesDicot Leaf
Sheryl Searcy Ninth Grade Center 2012
Turgor Pressure Turgor pressure (water pressure)
– Stomata close automatically when supplies of water from roots start to dry up
– Guard cells trigger when water is scarce causing stomata to become flaccid and pores close
Sheryl Searcy Ninth Grade Center 2012
Leaf Venation
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Leaf Adaptations
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TRANSPORT IN PLANTS
Section 23.5
Sheryl Searcy Ninth Grade Center 2012
Capillary Action The tendency of water
to rise in a thin tube.– The result of the water
molecules’ ability to stick to one another (cohesion) and to the walls of the tube (adhesion); contributes to the movement of water up the cells of the xylem tissue.