Transcript Diversity of Plants

Specialized Cells in Plants
Student Expectation B.5.B
Examine specialized cells,
including roots, stems, and
leaves of plants.
(EOC) and (Supporting Standard)
Plants
Nonvascular: have no
vessels, no roots, no stems
or leaves. Examples:
Mosses & Liverworts

Vascular: have vessels
to transport food and water.
They have roots, stems
and leaves. Example: Grass,
corn, trees, flowers, bushes

Three Types of Roots
Types of Roots

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Taproots (dicots) – the primary
root grows long and thick
while the secondary roots
remain small. Example: Oak
and hickory trees, carrots,
dandelions, radishes
Fibrous (monocots) – branch
out so that no single root
grows larger than the rest.
Example: grasses
Adventitious – helps to
develop modified underground
stems or to aid in climbing.
Example: ivy
Cross Section of a Root
Cross Section of a Root
Epidermis – outer layer of the root.
 Cortex – spongy layer of ground
tissue.
 Endodermis – encloses the roots
vascular system.
 Vascular System
Xylem – transports water.
Phloem – transports nutrients

Cross Section of a Root
Root Hairs – increase the surface
area for the root to take in water.
 Apical Meristem – Where roots
grow in length, production of new
cells.
 Root Cap – Protects the root as it
forces its way through the soil.

Root Function
Purpose of the Root
-Anchor the plant to the ground.
- Extract water and minerals from the
soil (needs the sun to do this).
How does this occur?
Root Function
1. Uptake of plant Nutrients.
Along with carbon dioxide and water,
flowering plants need inorganic nutrients:
Nitrogen, phosphorus, potassium,
magnesium
2. Active Transport of Minerals – water and
minerals move from the epidermis through
the cortex into the vascular cylinder
(osmosis)
Root Function
3. Movement into the Vascular Cylinder –
water and minerals enter the vascular
cylinder and move up the plant by way of the
xylem. Once in the plant, the waxy
Casparian strip keeps the water and minerals
inside the plant.
4. Root Pressure – the starting point for the
movement of water through the vascular
system of the entire plant.
Stems
Function:
1. Produce leaves,
branches, and
flowers.
2. Hold leaves up to
the sunlight.
3. Transport
substances
between roots and
leaves.
Stems - Vocabulary
Internodes Regions between the nodes
Buds – undeveloped tissue for new stems
or leaves.
Nodes – where leaves are attached.
Leaf Functions

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1. Photosynthesis – uses the sun to
make food.
2. Transpiration – loss of water
3. Gas Exchange – take in CO2 and
give off O2 during photosynthesis.
Leaves
Leaves

Mesophyl – the site where photosynthesis takes
place. There are two types of cells in the
mesophyl.
1)
Palisade Mesophyl – elongated cells, tightly
packed, contain numerous chloroplasts,
absorbs most of the light.
2)
Spongy Mesophyl – rounded and loosly
packed, creates pockets of air space between
the cells to allow CO2 and O2 to diffuse into
cells and into and out of the leaf through
openings in the lower epidermis called the
stomata.
Leaves

Guard Cells – regulate movement
into and out of the leaf tissue.
Internal Feedback Loop

When water pressure is
abundant, the guard
cells will open the
stomata. When water is
scarce, the opposite
occurs. Water pressure
in leaves drops and the
guard cells respond by
closing the stomata.