february 28 th quiz – chapter 23 notes – chapter 23 february 28 th quiz – chapter 23 notes –...
TRANSCRIPT
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
23-1 Specialized Tissues in Plants
• 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
23-1 Specialized Tissues in Plants
• Stems– Support for the
plant body– Carries nutrients
throughout plant– Defense system to
protect against predators and infection
– Few millimeters to 100 meters
23-1 Specialized Tissues in Plants
• Leaves– Main photosynthetic
systems– Susceptible to
extreme drying– Sight of
oxygen/carbon dioxide intake and release
23-1 Specialized Tissues in Plants
• Plant tissue systems– Exist within the
root, stems, and leaves•Dermal tissue•Vascular tissue•Ground tissue
23-1 Specialized Tissues in Plants
• 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
23-1 Specialized Tissues in Plants
• Vascular Tissue– Transport System– Subsystems
• Xylem• Phloem
– Subsystems are used to carry fluids throughout plant
23-1 Specialized Tissues in Plants
• Xylem– Two types
• Seed plants• Angiosperms
– Tracheid – long narrow cells
– Walls are connected to neighboring cells
– Will eventually die– Vessel Element –
wider that trachieds
23-1 Specialized Tissues in Plants
• 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
23-1 Specialized Tissues in Plants
• 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
23-5 Transport in Plants
• 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
23-5 Transport in Plants
• 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
23-5 Transport in Plants
• Controlling Transpiration– Open the stomata –
increase water loss– Close the stomata –
decrease water loss
23-5 Transport in Plants
• 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
23-5 Transport in Plants
• 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