algae were faced with challenge of life with little light
TRANSCRIPT
Algae were faced with challenge of life with little light.
zygote
SPOROPHYTE (2n)
GAMETOPHYTE (n)
GREEN ALGA BRYOPHYTE FERN GYMNOSPERM ANGIOSPERM
Evolutionary trend of plants started in the sea and moved slowly to wet lands and then to dry lands.
700 million years
Every plant around us today is a descendant of ancient species of green algae that lived in or near water and made it onto the land
Darwin’s theory: Evolution by Natural Selection
Peppered moth experiment of H.B.D.Kettelwell :
more of light-colored moths survived in unpolluted area. In soot-blackened areas, more dark-colored moths survived.
Overview of Plant BodyOverview of Plant Body
ShootShoot
RootRoot
Stem: Support leaves
Leaves: Photosynthesis
Flowers: Reproduction
Root: * Anchors plant
* Absorbs H2O
* Stores food
Three Types of Plant Tissues:
3) Ground Tissue - makes up bulk of plant body
2) Vascular Tissue - distribute H2O and solutes
1) Dermal Tissue - covers and protects
Where do these tissues originate from?
Meristem Tissues - Cells dividing constantly (mitosis)
- Two locations: * Apical
* Lateral
Shoot Apical Meristem divide to make new cells
Apical MeristemApical Meristem - - located in tip of stem and root- cells undergo mitosis and produce new cells
Root apical meristem divide to make new cells
As the new cells move away from tip, they elongate and form different tissues (maturation)
- increase plant length (primary growth)
Lateral MeristemLateral Meristem - located in vascular cambium and rings of cork cambium
- make new vascular tissue and new epidermis (cork)
- increases plant girth
Vascular cambium
Cork cambium
thickening
Three Types of Ground Tissue:- parenchyma - for storage
- sclerenchyma - for support
- collenchyma - for flexible support
SCLERENCHYMA
parenchyma cells• Thin cell walls
• Functions: photosynthesis, storage, secretion.
• Large central vacuoles filled with product of photosynthesis
• In plant roots that we eat: potatoes, radishes.
Sclerenchyma TissueSclerenchyma Tissue• Though, thick cell wall. Lignin makes cell water proof and strengthen cell wall ( this is what made plants stand on land) • Strengthen and support other plant tissues
• Two types: Fibers- next to vascular tissues. Ex. Cloth, rope, paper. Sclerid- star-shaped. Ex. Pear gritty texture, peach
pit.
PARENCHYMA COLLENCHYMA SCLERENCHYMA
Collenchyma Tissue• Uneven thickened cell wall with pectin ( this polysaccharide glues cellulose fibrils together & makes tissue pliable.
• Provides flexible support to stems and leaves.
SCLERENCHYMA
SCLERENCHYMACOLLENCHYMA
• Thin cell wall
• Storage & photosynthesis
• Uneven cell wall
• Flexible support
• Thick cell wall
• Strength and support
PARENCHYMA
Plant Ground Tissues
Two Kinds of Plant Vascular Tissue• Xylem
• Phloem
- Upward movement.- Dead at maturity.
- Carries H2O, dissolved nutrients.
- Carries products of photosynthsis.- Up and downward movement.- Alive at maturity
- Vessel Elements- pitted cell wall. Absence of end walls make water pipeline.
- Tracheids - pitted cell wall
- Sieve tube - perforated end walls - transport sugar
- Companion Cells- assist loading of sugars to various regions of plants
Vessels Tracheids
Sie
ve-t
ube
Companion cells
Two Kinds of Dermal Tissue• Epidermis - Single layered.
• Periderm - Multilayered cork replaces epidermis.
- For protection. - cuticle- a wax layer reduces water loss. - Epidermis/ from apical meristem
- For protection and reduction of water loss. - Bark/ from cork cambium
periderm
cork cambium
Plants are classified into 2 groups Plants are classified into 2 groups based on their seed based on their seed cotyledoncotyledon
Cotyledon is the leaf-like structure in seeds that store and absorb food for plant embryo.
• Monocotyledons (monocots) - one cotyledon
• Dicotyledons (dicots) - two cotyledons
Numbercotyledons
Numberflower parts
Vascular bundlearrangement in
stem
Leaf veinarrangement
DICOTSMONOCOTS
leaflike structure inseed; nourishes embryo
2
4s/5s ormultiplesof these
netlike
form ring
1
3s or multiple of 3
parallel
scattered
1
3s ormultiplesof 3
parallel
Numbercotyledons
Numberflower parts
Examples
2
lily, iris, tulip,corn, grass,orchids
netlikeLeaf vein
arrangement
DICOTSMONOCOTS
leaflike structure inseed; nourishes embryo
common trees,shrubs & flowers(oak, holly, rose)
4s/5s ormultiplesof these
Internal Structure of StemsInternal Structure of Stems
Monocot Dicot
Vascular bundle
Vascular bundle Epidermis
Cortex
Pith
Epidermis
Ground tissue
Arrangement of Vascular Bundles (VB) inMonocots and Dicots
vessels in xylem
vascular cambium
sieve tube companion cells
air space
sclerenchymafibers
Vessels
in xylem
sieve tube
companion cells Sclerenchyma
fibers
Monocot VB
Dicot VB
Structure of Vascular Bundle in Stem Structure of Vascular Bundle in Stem
epidermis
collenchyma
sclerenchyma
parenchyma
xylem
pholem
epidermis
collenchyma
sclerenchyma
paranchyma
phloem
xylem
External Structure of Roots:External Structure of Roots:Primary root - The first part to emerge from seedLateral root - perpendicular to primary root
Tap Root Fibrous Root