Download Plants IGCSE

Plants
Do Plants Breathe?
How do they Breathe?
An Organism is made up of:
organs  tissues cells.
What part of this
plant is involved
in breathing?
In Multicellular Organisms, Cells
are Specialized
Tissues: Group of Specilized
Cells
 Blood
 Bone
 Nervous
 Fat
3 Types of Tissues: What are
they specialized to do?
 Stem
Tissues: Vascular: Support and
Transport
 Leaf
Tissues: Photosynthetic
 Root
Tissues: Storage and Transport
A leaf is an organ. How is it adapted for
photosynthesis?
Functions of a leaf:

1.
 2.
 3.
 5.
absorption of light
gas exchange
water conservation
transport products of photosynthesis.
Structure of a Leaf
Leaf Cross-section
Transpiration
 Transpiration
is the evaporation of water
from the leaves and stem of a plant.
 Plants
reduce transpiration by:
1. Closing of stomata by guard cells
2. Waxy cuticle to protect top layer of
leaf.
Transpiration is affected by:
 Virtual
Lab for Transpiration rates
Transpiration (water loss) is
affected by:
 1. Temperature: Increase, causes more transpiration.

2. Humidity: Less humid (drier) air
causes more transpiration

3. Wind: Increases evaporation

4. Light: Increases transpiration
How does water moves upwards against the
force of gravity to bring water from the roots
to the leaves?
 The
tallest trees in the world are the
Redwoods (Sequoia semervirens) and are
115 meters tall.
Xylem: Carries water from roots to leaves
 Transpiration
Stream: the continuous flow of
water from roots through stem to the leaves. This
is created by:
1.
2.
3.
Evaporation of water from the leaves creates
an area of low pressure.
Transpiration Pull – Low pressure in the
leaves creates a pressure gradient and
water moves from a high pressure area (in
the roots) towards the low pressure area in
the leaves.
Water molecules stick together by cohesion
(water molecules bond to each other)
 Transpiration
 Virtual
Lab for Transpiration rates
 Potometer
(how it works)
Function of Stems
 1.
Support and give leaves access to
sunlight (cellulose, lignin and turgor
pressure provide support)
 2.
Transportation of water, minerals and
products of photosynthesis
 3.
Some photosynthesis and storage
Structure of a Stem
Phloem
Translocation:
Movement of sugar and amino acids
Sugar produced in photosynthesis moves from:
Source to Sink
source: (the leaf or place it is produced)
sink:
(the roots or place it is put into storage)
 https://www.youtube.com/watch?v=MxwI6
3rQubU
Structure and Function of Roots
 Roots
absorb minerals and water from soil
 Roots
anchor and support plants
 Roots
sometimes store food
Root Hair Cell
 Roots
have a large surface area due to
branching and root hairs
 Plants
absorb minerals (potassium,
phosphate, nitrate ) by active transport
(usually less concentrated inside the cells
compared to outside)
 When
minerals move inside root cells by
active transport, water follows by osmosis
and this creates a pushing force.