Transport Y12

TRANSPORT
• Study the different methods of transport in

plants and animals.
• Recognize the increasing complexity of the

vertebrate heart.
Type of plants
NON VASCULAR PLANTS
• Do not have xylem and phloem.
• Rely on diffusion and osmosis for transport of water and
nutrients.
• Water and food diffuse directly into the their cells.
• lack of true roots and stems.
• Small and closer to the ground (wet habitat)
• Example mosses and algae.
VASCULAR PLANTS
• They have a well developed system of
xylem and phloem.
• Have true roots and stems.
• Can grow larger and taller due to
transport system.
• Example mango trees.
TRANSPORT IN VASCULAR PLANTS
•Xylem cells are specially
adapted for carrying water and
dissolved minerals through
plants (root to shoot).
Parenchyma cells
Tracheid's are elongated, tube-like cells with
Store nutrients, help in the radial transport
thick, lignified walls. They have tapered ends of water and nutrients, also repair and
and are interconnected through pits (areas
maintenance of xylem tissue.
where the cell wall is thin and allows water to

pass).
Function: They facilitate the transport of
water and minerals and provide structural
support. Water moves from one tracheid to
another through the pits. Xylem vessels are long tubes formed by a
series of vessel elements (cells) aligned
end-to-end. They are the primary tubes for
water transport due to their larger diameter
compared to tracheids. They also
They provide mechanical strength and contribute to structural support
support to the plant due to their thick cell
walls
HOW WATER IS
TRANSPORTED FROM
ROOT TO LEAVES
WATER TRANSPORT IN PLANTS
Water is absorbed from the soil by root hairs through osmosis. This process
occurs because the concentration of water in the soil is higher than in the root
cells.
Active Transport: Minerals and nutrients are actively transported into the root
cells, creating a higher solute concentration inside the roots, which further
facilitates water uptake by osmosis.
Movement Through Roots
Apoplastic Pathway: Water moves through the cell walls and intercellular
spaces of the root cortex.
Symplastic Pathway: Water moves from cell to cell through the cytoplasm.
Xylem Loading: Water reaches the endodermis, a selective barrier, and enters
the xylem vessels and tracheids in the vascular cylinder.
Cohesion-Tension Mechanism:
• Cohesion: Water molecules are polar, allowing them
to stick together via hydrogen bonds. This cohesion
creates a continuous column of water within the xylem
vessels and tracheids.
• Adhesion: Water molecules also adhere to the walls of
xylem vessels and tracheids, helping to counteract
gravity.
• Tension (Transpirational Pull): Transpiration, the evaporation of water from
the stomata (small openings) on the leaves, creates a negative pressure (tension)
in the leaf's air spaces. This tension pulls water up from the roots through the
xylem vessels and tracheids.
• Capillary Action: Due to the small diameter of xylem vessels and the adhesive
properties of water, capillary action helps water rise through the xylem.
• Transpiration, Water evaporates from the mesophyll cells in the leaves into the
air spaces and then exits through the stomata. This creates a negative pressure
in the leaf, pulling more water upward from the roots through the xylem.
Water manages to reach the top of every tall tree by being sucked up by the
xylem as water evaporates from the leaves.
THIS IS CALLED THE COHESION THEORY OF WATER TRANSPORT
• The Cohesion Theory of Water - Water manages to reach the top of
every tall tree by being ‘sucked’ up by the xylem by water transpiring
from the leaves and water molecules sticking together (i.e., they are
cohesive).
 Root pressure - The force of water moving into root helps to push water
up the xylem.
• Transpiration pull - plants lose a lot of water by transpiration in order to
pull water up from the roots.
WHY PLANTS NEED WATER?
To remain turgid.

To use in photosynthesis.
PHLOEM
• Phloem cells are adapted for carrying food from leaves to all
the other parts of plants.
• Plant starch (carbohydrate) is produced by photosynthesis
process.
• Therefore starch are large molecules which cannot pass
through cell membranes.
• Starch needs to be hydolysed into sucrose for transport
through phloem.
• The solutions of water, sucrose and other food molecules in
the phloem is called Sap.
•Translocation - The transport of the sap (the solution of
water, sucrose and other food molecules organic
materials).
Sap in the phloem is under very high pressure. (as much
as five types higher than air pressure in a car tyre)
• This pressure will help sap to push through phloem.
Phloem tissue is made up of two
kind of cells.
•Sieve cells
•Companion cells.
Sieve cells
• Are continuous tubes throughout
the plant.
• End wall of this continuous tube
has lot of little holes at the both
sides of cell walls, to allow sap to
pass through more easily.
• There porous ends of sieve cells
are called sieve plates.
Companion cells
• Provide sieve cells with ATP for active
transport.
• Tell them in which direction they should
carry the food.
• Sieve cells can carry sap in either direction.

• The companion cells direct sieve cells to
carry food to stems and roots for storage or
to cells that need it for energy.
CLASS ACTIVITY
1. Why algae and mosses live in wet habitat?
2. What is the primary function of xylem in plants?
3. Explain the cohesion theory of water transport in xylem.
4. What are the two types of conducting cells found in xylem?
5. Phloem is made up of two cells. Name the two cells.

6. Define the following terms:
a. Translocation b. Hydrolysis
7. Explain why sap in phloem is under high pressure?
8. What is sap?
9. State one function for sieve cells and companion cells.
10. The force of water moving into roots is called?
11. Explain why each end of cell wall, sieve cells has holes?

Transport Y12

Uploaded by

Copyright:

Available Formats

Transport Y12

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Transport Y12

Uploaded by

Copyright:

Available Formats

TRANSPORT

• Study the different methods of transport in

• Recognize the increasing complexity of the

where the cell wall is thin and allows water to

To remain turgid.

• Sieve cells can carry sap in either direction.

1. Why algae and mosses live in wet habitat?

2. What is the primary function of xylem in plants?

3. Explain the cohesion theory of water transport in xylem.

4. What are the two types of conducting cells found in xylem?

5. Phloem is made up of two cells. Name the two cells.

7. Explain why sap in phloem is under high pressure?

9. State one function for sieve cells and companion cells.

10. The force of water moving into roots is called?

You might also like