Transcript transport_in_plants_compressed

Transport in Plant
What you would learn?
•The transport structures of plants.
•How substances move in plants.
•How water enters the plants.
•How water move against gravity.
Vascular Tissues
• A system of transport vessels in plants.
• Composed of xylem and phloem.
Transverse section of a typical
Dicotyledonous plant stem.
• Vascular tissues
extends from the
roots
• through the stem
• to the leaves.
Xylem tissues
• Long, hollow cylindrical tubes.
• Dead -> little resistance to water flow.
• Conducts water and dissolved mineral
salts from roots to stem and leaves.
Xylem tissues
• Wall are lined with lignin.
• Lignin -> tough and hard
substance.
• Deposited in spiral, ring, pit.
• Provides mechanical support for
the plants.
Phloem tissue
• Transport manufactured food
(amino acid and sucrose) from the
green parts to other parts of the
plant.
 Translocation
• Sieve tubes and companion cells.
Sieve tube
– Columns of elongated
thin-walled living cells.
– Degenerated protoplasm.
– Cells separated by cross
wall known as sieve
plates.
• Holes rapid flow of sugars
through the tubes.
Sieve plates
Companion cells
– Provides nutrients and help sieve tubes
cells to transport food.
– Numerous mitochondria to provide energy
to load sugars from the mesophyll tissue
into the sieve tubes.
Energy needed -> Active transport
Arrangement of vascular tissues
in stems
What do you notice about the arrangement of
vascular tissues in the stem?
Vascular Tissues in Stems.
• Xylem and phloem grouped together to give
vascular bundles.
• Arranged in a ring around the pith.
Epidermis (covered with cuticle)
Cortex
Phloem (near to the ‘outside’)
Xylem
Pith
Vascular bundles
Cambium divides and differentiates to form new xylem
and phloem tissue
Xylem
Cambium
Phloem
Arrangement of vascular tissues in
roots
What do you notice about the arrangement of
vascular tissues in the stem?
vascular tissues in roots
• Xylem and phloem
alternate to each other.
• Not grouped in bundles.
Phloem
Xylem
Structure of roots
Root hair
Cuticle?
Epidermis /
piliferous layer
Cortex
Is this from root, stem or leaf?
Is this from root, stem or leaf?
• A–
• B-
Identify X & Y
x
y
Studying the movement of water
through a plant
Studying of movement of sugars
from leaves to other parts
• Using aphids
• Using carbon-14 isotopes.
• Using ring experiment
Ringing experiment
Why is there swelling above the cut
region?
•Removing of
bark would
remove phloem.
•Accumulation of
food substances
would cause
swelling above
the cut region.
Pg 179
• Test Yourself