Transcript Plant Cells, Tissues, and Structures

Introduction to
Plants
Chapter 22.1
Basic Plant Structure
Plants Are…
1)
2)
3)
4)
Multicellular
Eukaryotic
Autotrophic
Use Chlorophyll a or b
How Did Plants
Originate?
First land plants appeared 500 mya
 Resembled present day mosses
 Released nitric acids on rock surfaces
which created soil
 Likely colonies of protists adapted to
dry environment…but how?

Links Between Algae
and Plants
Both have protective cell walls
 Both contain chlorophyll used in
photosynthesis
 Both store food in the form of starches

Plants Must Adapt To
Live On Land
1.
2.
3.
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Absorb nutrients from surroundings
Prevent desiccation
Reproduce without the aid of water
If plants adapt to these strategies,
they can evolve on land
Why would a plant “want” to move
onto the land?
A. Preventing Water
Loss
Cuticle: waxy coating that prevents
tissues from drying out
 Stomata-openings in the cuticle that
allow gas exchange to take place and
also regulate water loss

Prevent Desiccation?
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Desiccation= Drying Out
As plants evolved further away from water,
they needed to evolve a waterproof
structure/coating (cuticle)
But, this structure needs pores (stomata)
WHY?
Think about what the plant needs for
photosynthesis…
CARBON DIOXIDE!
Stomata
B. Autotrophic

Leaf-organ that enables the plant to
trap and absorb light energy
Leaf Layers via
microscope
C. Stabilization and
Nutrient Absorption
(Accomplished with roots and
mycorrihizea)
 Roots-organ that is used to reach and
transport water and minerals, anchor
plants and store food
 Earliest roots are rhizoids
 Fossils show fungi “helped” plants
before roots evolved
The Root
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Main function = absorb water
Functional Part = root hair
Structure from outside in:
– Epidermis with root hair= protection
– Cortex=support/storage
– Vascular Bundle: Phloem, Vascular Cambium*,
Xylem
*Vascular Cam: growth of new vascular tissue
Root Structure
D. Transportation System
Stem- Transport of water, food, and
minerals
 Support of plant
 Storage of materials

Structures of the Stem
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Epidermis (bark or green)=protection
Cork cambium =new growth of bark/
epidermis
Cortex = thick layer, sometimes contains
chloroplasts, mostly for support
Vascular Bundle = contain transport tissues
towards the middle of the stem
Xylem = transports water and minerals
(generally in the middle)
More Structures
Phloem = transports sugars to all cells,
located outside the xylem
 Vascular cambium = separates the X
and P, contains new cells for vascular
growth
 Pith = central portion of stem of tree,
for storage

E. Reproduce Without
Water
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Spores/Cones/Seed-protective coat which
prevents a developing embryo from drying
out
Advent of pollen and seeds make it possible
to reproduce far away from water
Pollen = plant sperm, light weight and won’t
dry out, carried via wind, water, animal, etc
Pollen Images via SEM