Ch 9 Transport in plants 2018 - IGCSE

1. Transport in plants

2. Transport systems
 There are two transport
systems in a plant.
 One that transports
water and minerals from
root to all other parts.
These vessels are called
………….
 Another vessels
transport sugars
(sucrose) and amino
acids made in leaves to
all other plant parts.
These are called phloem
vessels.

3. Xylem vessels
 Are long , hollow,
continuous tubes that
carry water and dissolved
minerals from the root
up to all parts of the
plant.
 Contain a tough
substance called lignin
that lines the walls to
provide support.

4. Phloem vessels
 Phloem tubes are living
cells with end tubes with
pores (sieve plate).
 All cell contents have
disappeared except the
cytoplasm
 The phloem cells have
companion cells near
them.
 Phloem cells transport
sucrose and amino acids
from where they are
made to where they are
used or stored.

5. Dicot stem Dicot root
Arrangement of xylem and phloem vessels

6. Stem structure

7. Root structure

8. How water moves into the plant.

9. Experiments
1. measure water
uptake by plant
shoots.
2. Show that
transpiration takes
place in shoots.
3. Show there are
more stomata on the
lower side of a leaf.

10. How does water
move up the
plant?
Water molecules
tend to “stick” to
the walls of their
container. The
narrower the
container the
higher water
travels up. This
helps plants
because they have
no pumps to push
the water up in
xylem vessels.

11. Transpiration
It is the loss
of water
vapour out of
leaves (and
stems)
through
stomata by
diffusion.

12. Potometer
A potometer
measures the rate of
water uptake.
The distance moved
by the air bubble can
be measured every
minute to show the
rate of water uptake.
The air bubble can be
moved back to the
start position
by…………………….
Water is not only lost
by transpiration in
the leaves it is also
used by the leaves
during ………….….

13. Put your thinking caps on!
 Predict what would happen to the rate of water
uptake if the temperature increases.
 When the wind speed increases?
 When light intensity increases?
 When humidity increases?

14. Transpiration is affected by
Weather condition Rate of transpiration Why?
Windy Speeds up transpiration
Moist air around the leaf
is blown away
Humid Slows down transpiration
Air around the leaf is
already full of moisture
Warm Speeds up transpiration Evaporation occurs faster
Light Speeds up transpiration The stomata opens

15. Controlling stomata 10

16. Translocation
 Is moving food (sucrose and amino acids) from the
sources (leaf, root) to sinks (developing
flowers/fruits, storage organs) through the phloem
vessels.
10

17. Xerophytes
Adaptations of xerophytes to live in
dry habitats:
1. Some have their leaves reduced to
needle like structures to reduce their
surface area.
2. The stems are swollen to store water
such as cactus.
3. The stems are green to carry out
photosynthesis.
4. The leaves & stem are covered with a
thick waxy cuticle.
5. The roots grow deep in the soil & branch
on the surface to absorb water when it
rains.
6. The stomata are in deep grooves to
reduce transpiration.
7. Many leaves have tiny hairs to trap
water vapour around the leaf, increasing
humidity.
10

18. Hydrophytes
Adaptations of water plants:
 They have a thin cuticle.
 Stomata are open most of the
time, & may be present on
upper surface.
 They are less rigid, as they are
supported by water & to
prevent their damage by water
currents.
 Large flat leaves to float, which
usually contain many air sacs
for flotation.
 Small roots, water can diffuse
directly through leaves.
10
P. 100 610/31/J/11