• Unicellular organisms - Single cell
performs all basic functions. e.g. Amoeba
Multi-cellular organisms – Most of the cells
are specialize to carry our a few functions.
e. g. Human beings
In human
• Muscles – movement
• Nerve cells – carry messages
• Blood – transport – food, oxygen,
hormone, waste materials
• In multicellular organism - DIVISION OF
LABOUR
• TISSUE – A group of cells similar in
structure that work together to perform a
particular function.
PLANT TISSUE
• I) Meristematic tissue
• II) Permanent tissue
Meristematic tissue
Cells devide repeatedly
Undifferentiated
Small
Intercellular spaces
generally absent
Vacuole absent
Permanent tissue
Cells are derived from
meristematic tissue &
normally do not devide
Fully differentiate
Variable in shape and
size
Intercellular spaces are
present
Large vacuoles in mature
cells
Name
Apical
meristems
Lateral
meristems
(Cambium)
Intercalary
meristems
Location
Growing tips
(Apex) of roots
and stems
Beneath the
bark, in vascular
bundles of dicot
stems
Base of the
leaves /
internode
Function
Elongation
Increase in
diameter
Increase of
length
Classification of Plant Tissues
Plant
Tissue
Meristmatic
Apical
Tips of
root and
stem
Cells are capable of cell division
and have toipotency
Lateral
Intercalary
Below bark,
Internodes
Cambium, in
dicot roots
and stems
of stem
Permanent
Simple
Mature cells incapable of
cell division
Complex
Parenchyma
Phloem
Collenchyma
Xylem
Sclerenchyma
II) PARMANENT TISSUE
• i) Simple permanent tissue
• ii) Complex permanent tissue
Simple permanent tissue
Parenchyma
Collenchyma
Location
Soft parts of
Below the
plat – Cortex
epidermis
of root,
of dicot
ground
stem and
tissues in
petiole
stem,
(Absent in
mesophyll of
monocot)
leaves
Sclerenchyma
In stem around
vascular bundle,
roots, veins of
leaves, hard
covering of seeds
and nuts
Nature
•
•
•
•



Cells are isodiametric
i.e. equally expanded on
all sides
They may be oval,
round, polygonal or
elongated
Nucleus is present and
hence living
The cell walls are thin
and made of cellulose
Cytoplasm is dense with
a single large vacuole
Intercellular spaces may
be present
May contain
chlorophyll. Parenchyma
which contain
chlorophyll are called
chlorenchyma.
•


•

•
The cells are
elongated and are
circular, oval or
polygonal in
cross-section
Cell wall is
unevenly
thickened with
cellulose at the
corners against
the intercellular
spaces
Nucleus is
present and hence
the tissue is living
Vacuoles are
small
Intercellular
spaces are
generally absent
If they contain
chlorophyll they
are known as
chlorenchyma
•
•


•
The cells are long,
narrow, thick and
lignified, usually pointed
at both ends
The cell wall is evenly
thickened with lignin and
sometimes is so thick that
the cell cavity or lumen
is absent
Nucleus is absent and
hence the tissue is made
up of dead cells
They have simple, often
oblique pits in the walls
The middle lamella i.e.
the wall between
adjacent cells is
conspicuous
Function




Store and
assimilate food
Give mechanical
strength by
maintaining
turgidity
Prepare food if
chlorophyll is
present
Store waste
products like tanin,
gum, crystals and
resins


Provide mechanical
support to the stem
Allows easy bending
in various parts of the
plant without actually
breaking it
Gives mechanical
support to the
plant by giving
rigidity, flexibility
and elasticity to
the plant body.