2. Shoot
System
Root
System
Root system
- anchors the plant
- penetrates the soil and
absorbs water and minerals
- stores food
Shoot system
- produces sugars by
photosynthesis
- carries out
reproduction
-transport
Shoot and Root Systems
4. Leaf Functions
Manufacture food through photosynthesis
Gas (Air) Exchange – Respiration
Protect vegetative and floral buds
Water Transport – Transpiration
Store Food During Germination
10. Respiration is the release of the energy
derived from the food created by
photosynthesis.
* It is the opposite of photosynthesis (one
molecule of glucose and six molecules of
oxygen are broken up and reorganized by
enzymes to give six molecules of carbon
dioxide and six molecules of water.
11. Usually, photosynthesis will produce more glucose than is needed by
the plant.
The excess sugars are stored and
transformed into
starch, cellulose, lipids (fats) and
other carbohydrates, proteins and
sucrose.
12. Other Functions of Leaves
While Photosynthesis
is a very important
part of the function
of leaves, they have
other responsibilities
to the plant
13. Leaves protect buds through the
winter
Juniper
Mango
Protect Vegetative and Floral
Buds
Leaves protect floral bracts during
development
Poinsettia
Globe artichoke
14. Important in the Water Cycle
Leaves are a very
important part of
the water
cycle, helping
provide
atmospheric
water.
15. Why are leaves the perfect
place for photosynthesis?
Leaves are thin and broad in order to
have a great amount of surface area for
sun and CO2 absorption
Like mini solar panels
Palisade Mesophyll Layer was right below
the upper epidermis
collected the most sunlight
CO2 diffuses across short distances
Large spaces between cells provide easy
passage for CO2 to diffuse
Many stomata in the lower surface
More chloroplasts in the upper surface
Branching network of veins
16. Lets look at the whole plant…
The three major
organs are:
1. Leaf
2. Stem
3. Root system
17. Organs of the plant: Leaf
Collect sunlight
Exchange oxygen and carbon dioxide
Site of photosynthesis
18. Organs of the plant: Stem
Supports plant body
Spaces out the leaves and helps them
compete for sunlight and carbon
dioxide
Helps pollination and later dispersal of
the seeds (holding the flowers above the
ground)
Transports nutrients and also water and salts
19. Organs of the plant: Root
Absorbs water, dissolved nutrients from soil
Anchors the plants
Holds the plants upright
Prevents plants from getting
knocked over
Stores food
Complex structure
Branching network
25. Stomata are open during
daylight but closed during
the evening
Stomata allow carbon
dioxide into the leaf (for
photosynthesis) and
prevent excessive loss of
water vapour
High potassium
concentrationlow water
potentialwater enters the
guard cells stoma opens
26. Plant Tissues: Vascular Tissue
Transport water and nutrients
Throughout the plant
Xylem
Transports water and salts from roots
Conducting cells are dead and
Hollow at maturity VESSELS
Phloem
Sugar and amino acids are transported
from the leaves to pares of the plants
requiring food SIEVE TUBES
The pressures gradient that moves this is
created via the concentration of sugars
Dissolved food transport is called translocation
27. Xylem
• Conducts water and
dissolved minerals
• Conducting cells are dead
and hollow at maturity long
cells joined end to end
• Cell walls are impregnated
with LIGNIN + FIBRES cell
wall is IMPERMEABLE
cytoplasm dies/ no nuclei
vessel
member
tracheids
28. PITH
PITH is the CENTRAL tissue of the stem
These tissues serve also as supporting tissue and
contribute to the stem’s rigidity.
29. Phloem:
A Complex Vascular Tissue
Transports sugars
Main conducting cells
(alive) are sieve-tube
members NO
NUCLEI
Companion cells
assist in the loading of
sugars
sieve plate
sieve-tube
member
companion
cell
32. Root Structure
Root cap covers tip
Vascular bundle in the
centre
Region of cell division
Region of elongation
root cap
33. Root Hairs and Lateral Roots
Root hairs are tiny extensions of
epidermal cells
Root hairs to take up water
(OSMOSIS) and absorb mineral
salts (ACTIVE TRANSPORT). THEY
INCREASE THE ABSORBING AREA
OF THE ROOT
Different kinds of roots: TAP root
and FIBROUS root
(ADVENTITIOUS is a kind of
FIBROUS)
new
lateral
root
34. Turgor Pressure
Turgor pressure
is when
water(inside the
vacuole)
presses on the
cell wall –
inflating the cell
Soft plants have
lots of soft tissue
that needs a
regular supply
of water
This is what
happens
when plants
don’t have
enough water
35. Air Exchange in Plants
Stomata let oxygen out, carbon dioxide in
During the day CO2 defuses into the cell and H2O and O2 defuse out
During the night and when only respiration is happening CO2 defuses out
and O2 defuses in.
Guard cells regulate the stomata
If they absorb water they become turgid (swollen) and open the stoma.
Exchange takes place
in Spongy mesophyll
kept moist to allow
air exchange
Guard Cells
36. Water exchange
Also takes place in Spongy Mesophyll
The process of water evaporating from plants
to environment is TRANSPIRATION
Water is lost from the leaves
Replaced by water from
Xylem in vascular tissue
37. Minerals
H2O
CO2
O2
CO2 O2
H2O Sugar
Light
A variety of physical processes
are involved in the different types of transport
Sugars are produced by
photosynthesis in the leaves.5
Sugars are transported as
phloem sap to roots and other
parts of the plant.
6
Through stomata, leaves
take in CO2 and expel O2.
The CO2 provides carbon for
photosynthesis. Some O2
produced by photosynthesis
is used in cellular respiration.
4
Transpiration, the loss of water
from leaves (mostly through
stomata), creates a force within
leaves that pulls xylem sap upward.
3
Water and minerals are
transported upward from
roots to shoots as xylem sap.
2
Roots absorb water
and dissolved minerals
from the soil.
1
Figure 36.2
Roots exchange gases
with the air spaces of soil,
taking in O2 and discharging
CO2. In cellular respiration,
O2 supports the breakdown
of sugars.
7
38. Transpiration controlled by…
Guard Cell/Stromata
If water pressure is high (lots of water)
guard cells swell up and open stomata
39.
40. Transport in Plants
Vast amounts of water pass through plants
1% of this water is used by the plant cells for
photosynthesis and turgor
99% evaporates from the leaves and is lost to the
atmosphere
This evaporation from leaves is called transpiration
More than 90% of the water moving up a plant is
lost through transpiration as water vapor through
the stomata.
As the water leaves the the plants the concentration
of solutes increases within the cells, this draws more
water into the cells from the xylem
41. Factors affecting Transpiration
Light Light stimulates the stomata to open
allowing gas exchange for
photosynthesis, and as a side effect this also
increases transpiration. This is a problem for
some plants as they may lose water during
the day and wilt
Temperature High temperature
increases the rate of evaporation of
water from the spongy cells, and
reduces air humidity, so transpiration
increases
42. Humidity High humidity means a higher water
potential in the air, so a lower water potential
gradient between the leaf and the air, so less
evaporation
Air movements Wind blows away saturated air from
around stomata, replacing it with drier air, so
increasing the water potential gradient and
increasing transpiration
