Slides transpiration pull

broadrick_Math_n_Science_Trail

1. Transport in Plants
-Transpiration

2. Objective
Briefly explain
the movement of water
through the stem
in terms of transpiration pull

3. What is transpiration?
It is the loss of water from the aerial
parts of the plant, especially through
the stomata of the leaves.
9.4
Moving Water
against Gravity

4. Activity (Roles)
Volunteer for one of these roles
1.Sticker
2.Fixer
3.Suck-er
4.Recorder
9.4
Moving Water
against Gravity

5. Activity (Materials)
Collect the following materials from the front
•1 bottle of juice drink
•10 straws
•1 scotch tape
•1 pair of scissors
•1 metre rule
•1 damp cloth
(for wiping spills on surfaces)
9.4
Moving Water
against Gravity

6. Activity (Instructions)
1.Draw the juice from one straw
2.Tape the first straw to another straw and
draw juice from the straw
3.Continue this process till juice is no longer
able to reach the mouth
4.Measure the total length of the straws in cm
5.Complete the worksheet
9.4
Moving Water
against Gravity

7. Activity (Precautions)
1.Wash your hands before and after the
experiment.
2.Start by placing the cup on the table,
move it to the stool, then to the floor.
3.Ensure fans are switched off.
4.You may climb on the stool and then the
table to complete your experiment.
5.Slowly climb down from the tables or
stools.
9.4
Moving Water
against Gravity

8. How does transpiration occur?
Processes that pull water molecules
up the xylem vessels are
–Transpiration pull
•Suction force
–Capillary Action
•Cohesion
•Adhesion
9.4
Moving Water
against Gravity

9. What causes transpiration pull?
Evaporation of water from the leaves
results in a suction force that pulls
water up the xylem vessels.
9.4
Moving Water
against Gravity

10. What is capillary action?
•Tendency of water to
move up inside very
narrow tubes (e,g, xylem)
•Depends on the
cohesion and adhesion
of water molecules
9.4
Moving Water
against Gravity

11. •Cohesion force
•The tendency for similar
substances to stick to each
other
–Water molecules stick to each
other
•Adhesion force
–The tendency for dissimilar
substances to stick to each other
–Water molecules stick to xylem
vessel wall
9.4
Moving Water
against Gravity