1.
Monocots and Dicots
• Monocots and dicots are named for
the number of seed leaves, or
cotyledons, in the plant embryo.
• Monocots have one seed leaf, and
dicots have two seed leaves
Monocotyledonous plants: grass,grass,
lilies, orchids, and palm treeslilies, orchids, and palm trees
Dicotyledonous plants: Roses,Roses,
oaks, sunflowersoaks, sunflowers

2.
http://www.youtube.com/watch?
v=4uq5ybc4vts&feature=related
Watch the video clip!

3.
– single seed leaf
(cotyledon)
– flowers/petals grow in
groups of three
– leaves have parallel veins
Monocots

4.
• Flowers often small
• Usually grow for only one year
• Examples: corn, grasses, onions, lilies
and many grains

5.
Dicots
–two seed leaves (cotyledons)
–flowers/petals grow in groups of
four or five
–leaves have network veins that
branch out

6.
Examples: trees, sunflower,Examples: trees, sunflower,
beans, pumpkins and cloverbeans, pumpkins and clover..
Greatest number of plants are
dicots
Tend to live a long time – one
season or many
Produce food, clothing, housing

7.
Monocots vs. Dicots
Parallel leaf veinsParallel leaf veins Net-like leaf veinsNet-like leaf veins

8.
Monocots vs. Dicots
Floral Parts in 3’sFloral Parts in 3’s Floral Parts in 4’s or 5’sFloral Parts in 4’s or 5’s

9.
Monocots vs. Dicots
Vascular TissueVascular Tissue
ScatteredScattered
Vascular tissue in ringsVascular tissue in rings

10.
Monocots vs. Dicots
Fibrous root systemFibrous root system Taproot SystemTaproot System

11.
Monocots Verses Dicots
Floral Parts in 3’sFloral Parts in 3’s Floral Parts in 4’s or 5’sFloral Parts in 4’s or 5’s
Parallel leaf veinsParallel leaf veins Net-like leaf veinsNet-like leaf veins
Fibrous root systemFibrous root system Taproot SystemTaproot System
Vascular TissueVascular Tissue
ScatteredScattered
Vascular tissue in ringsVascular tissue in rings
Includes: grass, lilies,Includes: grass, lilies,
orchids, and palm trees.orchids, and palm trees.
Includes: Roses, oaks,Includes: Roses, oaks,
sunflowers and most non-sunflowers and most non-
conifer trees.conifer trees.

12.
Vascular bundles
Leaf Stem Root
Xylem
Xylem
Phloem
Xylem
Phloem
Phloem

13.
Vascular bundle
• A strand of tissue that carry water and
nutrients through the body of the plant
Xylem
Phloem

14.
Xylem on the inside and phloem on the outside,
separated by cambium

15.
Xylem
• Carry water and dissolved mineral
salts upwards from the roots to every
part of the plant
• Provide mechanical support for the
plant

16.
Hollow vessels (cells
without cross-walls)
Walls are thickened and
strengthened with lignin
Water and
mineral
transport
Mechanical
support
Xyle
m
Structures
At maturity, dead tissue → wood

17.
Different patterns of lignification

18.
Adaptations
•Having a continuous lumen without any
protoplasm within to prevent the flow of
water and mineral salts
•Having lignified walls which prevent
collapse of the vessels
Xyle
m

19.
Phloem
• Transports
nutrients (sugars
and amino acids)
from the leaves
to other parts of
the plant

20.
Phloem
Structures
• Consists of a column of sieve
tubes (elongated, thin-walled
living cells) and companion
cells
• Sieve tubes are separated by
sieve plates (cross-walls
separating the cells
perforated by minute pores
Phloem

21.
• The sieve tube cells are perforated to
enable food substances to pass through
them to be transported to various parts
of the plant
• Companion cells have many mitochondria
to load sugars from mesophyll cells into
sieve tubes by active transport
Phloem
Adaptations

22.
Xylem Phloem
Consists of dead cells Consists of living cells
-Transports water and
mineral salts
-Provide mechanical
support to the plant
Transports sugar and
amino acids
Transport is unidirectional Transport – directional,
upwards and downwards
Substances are transported
by passive transport -
osmosis, root pressure,
capillary action,
transpiration pull
Substances are
transported by active
transport, diffusion

23.
Organization of vascular tissue in Stem
1. Vascular Bundle
The xylem and phloem
are grouped together to
form the vascular bundles

24.
Organization of vascular tissue in Stem
1. Vascular Bundle
2. Cambium
Cambium cells can divide
to give rise to new xylem
and phloem tissues, hence
thickening of the stem
Phloem
Cambium
Xylem

25.
Organization of vascular tissue in Stem
1. Vascular Bundle
2. Cambium
The vascular bundles are
arranged in a ring
surrounding a central region
called pith which serves as a
storage tissue for food
substances
3. Pith

26.
Organization of vascular tissue in Stem
1. Vascular Bundle
2. Cambium
The region between the
vascular bundles and
epidermis is the cortex,
which also serves as a
storage tissue for food
substances
3. Pith
3. Cortex

27.
Organization of vascular tissue in Stem
1. Vascular Bundle
2. Cambium
The epidermal cells are
covered with a layer of wax
called cuticle which prevents
excessive loss of water from
the stem
3. Pith
4. Cortex
5. Epidermis

28.
Organization of vascular tissue in Stem
1. Vascular Bundle
2. Cambium
3. Pith
4. Cortex
5. Epidermis
Phloem
Cambium
Xylem

29.
Root
Functions
•Anchor the plant
•Specialized in absorption
of water & dissolved
minerals

30.
Vascular Bundles in Roots
Cross-section of a dicotyledonous root

31.
Organization of vascular tissue in Root
1.Vascular Tissue xylem
phloem
The xylem and phloem
are NOT bundle
together. They alternate
with each other

32.
1. Vascular Tissue
The region between
the epidermis and the
endodermis lies the
Cortex, which serves
as storage tissue
2.Cortex
Endodermis
Organization of vascular tissue in Root

33.
1. Vascular Tissue
The epidermis of the
root bearing the root
hairs are called the
piliferous layer.
NO cuticle is present!
2. Cortex
3.Piliferous layer
Organization of vascular tissue in Root

34.
1. Vascular Tissue
Each root hair is a
tubular outgrowth of
an epidermal cell.
2. Cortex
3. Piliferous layer
4.Root hair
Organization of vascular tissue in Root

35.
1. Vascular Tissue
2. Cortex
3. Piliferous layer
4. Root hair
xylem
phloem
Organization of vascular tissue in Root

36.
What are the
adaptations of
Root?
* Long and narrow
 Increase surface area to volume ratio
* Cells are alive
 Provide energy for active transport
* Root hairs have cell sap of higher concentration than
surrounding soil solution
 Cell sap contains sugar, mineral salts which
helps to prevent water leaking out of cell. Assist
in osmosis

37.
Root
Stem
Leaves
Transpor
t of water

38.
How does water move
through the transport
system of a plant if it
does not have a heart
to act as a pump?
Think Like a Scientist
How is water lifted
against gravity from
the ground to the leaves
through this transport
system?

39.
cytoplasm
vacuole
nucleus
cell wall
cell surface
membrane of
root hair cell
film of liquid
(dilute solution of
mineral salts)
soil particles
Entry of Water through the roots

40.
Entry of Water through the roots
The sap in the root hair cell is a relatively concentrated solution of sugars and
various salts. Thus, the sap has a lower water potential than the soil solution. These
two solutions are separated by the partially permeable cell surface membrane of
the root hair cell. Water enters the root hair by osmosis.
AB
C
xylem
phloem
cortex
root hair
piliferous layer
water entering
the root hair

41.
Entry of water through the roots
• Water enters the roots through the root
hairs.
• Sap of root hair cells has a higher
concentration of sugars and salts. Its is
very concentrated.
• Since the surrounding soil particles has
a high water potential, water enters
the root hair from the soil through
osmosis.

42.
Entry of mineral salts through the roots
* Diffusion –when the concentration of
minerals salts in the soil solution is higher
than that in the root hair cell.
* Active transport –when the concentration
of ions in the soil solution is lower than
that in the root hair cell sap.
* The energy comes from cellular respiration
in the root hair cells

43.
Moving water up the stem
• Root pressure
• Capillary action
• Transpiration pull

44.
• By using active transport, ions in the living
cells around the xylem vessels in the root
are pumped into the vessels.
• Water potential in the xylem vessels is
lowered.
• Water passes from the living cells into the
xylem vessels by osmosis and flows
upwards.
Root pressure

45.
Capillary action

46.
• Water molecules
attract other water
molecules by the
force of cohesion.
• Water sticks to the
inner surface of the
xylem vessels by
adhesion.
• The water moves up
the plant into the
leaves.
Capillary action

47.
• Transpiration is the loss of water
vapour from the leaves, especially
through the stomata.
• The suction force caused by
transpiration is called transpiration pull.
• The stream take the water moves up the
plant is called transpiration stream.
Transpiration pull

48.
Question 1
The root of a flowering plant absorbs water and mineral ions mainly
through …
(d) the xylem
(c) the phloem
(b) the root hairs
(a) the epidermis
Question 2

49.
The epidermis is largely impermeable except in the region where
root hairs develop
No

50.
Transverse section
through a root
root hair
epidermis
phloem
xylem
0.05
mm
Root hair cell
root hair
Yes
The root hairs are extensions
from some of the epidermal
cells. They have very thin cell
walls and absorb water and
mineral ions.

51.
No
The phloem conducts sugars and amino acids to the root but is
not involved in the uptake of water

52.
No
The xylem carries water from the root to the rest of the plant but it
is not the structure involved in the entry of water

53.
Question 2
The force responsible for water travelling up a tree is generated
mainly by …
(d) osmosis
(c) active transport
(b) root pressure
(a) evaporation from the leaves

54.
Yes
Evaporation of water from the leaves
creates a tension which draws water up
the trunk
evaporation

55.
No
Root pressure can force water some distance up the trunk but
is insufficient to take it all the way

56.
No
Active transport enables the roots to take up dissolved substances
against a diffusion gradient. It is not responsible for the flow of
water up the trunk

57.
No
Osmosis generates root pressure but this is insufficient to force
water all the way up the trunk

58.
Transpiration is the loss of water vapour
from the leaves, especially through the
stomata
The suction force caused by transpiration is called
transpiration pull
The stream take the water moves up the plant is
called transpiration stream

59.
Stomata
• When stomata are open, evaporation draws
water out of the leaf. Gas exchange can also
occur to keep photosynthesis and respiration
running.

60.
Transpiration pull draws water and mineral salts
from the roots to the stems and leaves.
 Evaporation of water from the cells in the leaves
removes latent heat of vaporisation. This cools the
plant, preventing it from being scorched by the hot
sun.
 Water transported to the leaves can be used in the
photosynthesis;
- to keep cells turgid
- to replace water lost by the cell
Turgid cells keep the leaves spread out widely to
trap sunlight for photosynthesis.
Importance of TRANSPIRATION

61.
1.1. TemperatureTemperature
Increases  Increases transpiration rate
1.1. Air humidityAir humidity
Increases  Decreases transpiration rate
1.1. Light intensityLight intensity
Increases  Increases transpiration rate
1.1. WindWind
Increases  Increases transpiration rate
1.1. Water supplyWater supply
Decreases  Decreases transpiration rate
5 Factors that affect Transpiration

62.
Temperature
The higher the temperature, the higher the air
water capacity to hold moisture
At 30ºC, a leaf
may transpire 3
times as fast as it
does at 20ºC

63.
Light intensity
During the day, stomata of
the leaves open. Why?
Photosynthesis!!
Gases exchange (CO2 & O2)
Water vapor also evaporates
(Transpiration)