INTRODUCTION
•All living organismsare made of cells.
•In unicellular organisms (like Amoeba),
one cell performs all functions – movement,
food intake, breathing, and waste removal.
•Multicellular organisms have many cells
that perform different, specialized functions.
•Specialized cells do their work efficiently
because they focus on one function.
3.
INTRODUCTION
•In humans:
•Muscle cellshelp in movement.
•Nerve cells carry messages.
•Blood transports oxygen, food, hormones, and waste.
•In plants, vascular tissues carry food and water to
all parts of the plant.
•This is called division of labour in multicellular
organisms.
•Similar cells that perform one function group
together in one place in the body.
•This group of similar cells is called a tissue.
•Examples of tissues: Blood, phloem (in plants),
muscles.
4.
Are Plants andAnimals Made
of Same Types of Tissues?
Movement:
Plants: Do not move; they are fixed in one place.
Animals: Move to find food, shelter, and mates.
Support:
Plants: Need more support to stay upright, so they
have more supportive tissue, usually made of dead
cells.
Animals: Have living tissues as they need more
energy and movement.
Energy Use:
Plants: Use less energy.
Animals: Use more energy due to active movement.
5.
Are Plants andAnimals Made
of Same Types of Tissues?
Growth Pattern:
Plants: Grow only in certain regions (called
meristematic regions).
Animals: Grow uniformly throughout the body.
Plant Tissue Types:
Meristematic Tissue: Keeps dividing for growth.
Permanent Tissue: Does not divide, has a fixed role.
Dividing Regions:
Plants: Have clear dividing and non-dividing
regions.
Animals: No such clear division; cells divide more
evenly.
6.
Are Plants andAnimals Made
of Same Types of Tissues?
Organ Systems:
Plants: Less specialised even if complex.
Animals: Have more specialised and localised
organs and organ systems.
Mode of Life:
Plants are suited for a still (sedentary) life.
Animals are suited for active movement
(locomotion).
7.
Questions
1. What isa tissue?
Answer: A group of cells that are similar in structure
and work together to do a peculiar function is called
tissue.
2. What is the utility of tissues in multicellular
organisms?
Answer: Tissues provide structural strength,
mechanical strength, show division of labour.
9.
Plant Tissues
Fig. 6.1:Growth of roots
in onion bulbs
•Place onion bulbs on two water-
filled jars and observe root
growth daily for 3 days.
•On day 4, cut 1 cm from the
root tips of the bulb in jar 2, but
leave the bulb in jar 1 as it is.
•Continue observing and
measuring root growth in both
jars for 5 more days and record
the results in a table.
Growth of rootsin onion bulbs
1. Which of the two onions has longer roots? Why?
The onion in jar 1 has longer roots, as the growth of roots
continues in it due to intact root tips.
2. Do the roots continue growing even after we have
removed their tips?
The roots did not continue to grow in jar 2 after cutting
down their tips.
3. Why would tips stop growing in jar 2 after we cut
them?
The tips of root stopped growing in jar 2 because the tips of
these roots were cut down and the tissues which helps in
the growth of roots i.e., meristematic tissues are removed
from it.
12.
Types of MeristematicTissue
• Plant growth happens only
in specific regions where
meristematic tissue
(dividing tissue) is present.
(a) Apical meristem—(at tips of
roots and shoots) Function:
growth in length.
(b) Lateral meristem— (at the
sides for thickness) Function:
growth in thickness.
(c) Intercalary meristem—(at the
base of leaves or internodes)
Function: growth in
intemodes.
• New cells from meristem
are similar at first but later
change (differentiate) to
become parts of other tissues.
13.
Meristematic Tissue
• Cellsof meristematic tissue are very active.
• Small
• They have dense cytoplasm, thin cellulose cell
walls and prominent nucleus.
• Compactly arranged without intercellular spaces.
• Continuously dividing cells.
• They lack vacuoles.
• Meristematic cells lack vacuoles because their
main function is cell division and growth, not
storage.
14.
Meristematic Tissue -Why
they would lack vacuoles?
•Vacuoles store water, waste, and other materials,
but meristematic cells are focused on rapid cell
division, not storage.
•Having no vacuole leaves more space for organelles
like the nucleus and cytoplasm, which are needed for
active growth.
•Vacuoles maintain cell rigidity, which is not needed
in meristematic cells as they are constantly dividing
and changing.
Differentiation
•Cells formed bymeristematic tissue stop
dividing after some time.
•These cells take up specific roles in the plant.
•They become permanent tissue.
•This process is called differentiation.
•Differentiation gives the cells a fixed shape,
size, and function.
•It leads to the formation of different types of
permanent tissues.
17.
Activity 6.2 Sectionof a stem
•Take a plant stem and cut very thin slices.
•Stain the slices using safranin.
•Place one slice on a slide, add a drop of
glycerine.
•Cover it with a cover-slip and observe under a
microscope.
•Observe the types and arrangement of cells.
•Compare what you see with Fig. 6.3 in the
textbook.
•https://www.youtube.com/watch?v=-1vw-BjUDb
4
Activity 6.2 Sectionof a stem
Now answer these:
•Are all the cells the same in structure?
•No, all cells are not similar in structure, we see variety
of cells with different shape and size.
•How many types of cells do you see?
•We can see at least ten different types of cells in the
slide.
•Why do you think there are so many different types of
cells?
•– Yes, because different cells perform different
functions, like transport, support, or storage.
– So, the plant needs different types of cells to carry
out all its activities properly for growth of plant.
20.
Simple Permanent Tissue-
PARENCHYMA
•A few layers of cells under the epidermis are simple
permanent tissue.
•Parenchyma is the most common simple permanent tissue.
•It has unspecialised, living cells with thin cell walls.
•The cells are loosely arranged with large spaces between
them (intercellular spaces).
•Parenchyma usually stores food.
•If it has chlorophyll and does
photosynthesis, it is called chlorenchyma.
•In aquatic plants, parenchyma has
large air cavities to help the plant float.
•This type is called aerenchyma.
21.
Simple Permanent Tissue-
COLLENCHYMA
•Collenchyma is a permanent tissue that gives flexibility
to plants.
•It helps plant parts like tendrils and climber stems to
bend without breaking.
•It also gives mechanical support to the plant.
•It is found in leaf stalks, just below
•the epidermis.
•The cells are living, elongated, and
have irregularly thickened corners.
•There is very little intercellular space
between the cells.
22.
Simple Permanent Tissue-
SCLERENCHYMA
•Sclerenchyma is another type of permanent tissue.
•It makes the plant parts hard and stiff.
•The husk of a coconut is made of sclerenchyma.
•Its cells are dead, long, and narrow.
•The cell walls are thick due to a substance called lignin.
•The walls are so thick that there is
no space inside the cells.
•It is found in stems,
around vascular bundles, leaf veins,
and seed/nut coverings.
•It gives strength and support to
the plant.
23.
Activity 6.3 -Rhoeo Leaf to
observe Epidermis
•Take a freshly plucked Rhoeo leaf.
•Stretch and break it gently to make the skin (peel)
come out.
•Carefully remove the peel and place it in a petri dish
with water.
•Add a few drops of safranin to stain the cells.
•Wait for a few minutes, then place the peel on a slide.
•Gently place a cover slip over it.
•Observe the peel under a microscope to see the cells.
https://www.youtube.com/watch?v=iOjJUHmBgmU
24.
Activity 6.3 -Rhoeo Leaf to
observe Epidermis
(a) The slide shows epidermal cells
with stomatal pores as shown in
Fig. (a).
(b) On focusing stomata pores
under microscope. We can see
guard cells and stomata pore as
shown in Fig. (b).
25.
Dermal tissues
•Tissues thatform outer coverings are called as
Dermal tissues
•Mainly consists of the epidermis, which is made up
of only one type of cell – epidermal cells.
•Simple permanent tissues are those made of similar
types of cells that perform common functions.
•Since the epidermis is a single layer of similar, flat
cells that protect the plant, it fits the definition of
simple permanent tissue.
•In some cases, it may have specialized structures
like guard cells or trichomes, but the basic tissue is
still simple.
EPIDERMIS
•The outermost layerof cells in a plant is called the epidermis.
•It is usually made of a single layer of cells.
•In dry-area plants, the epidermis may be thicker to prevent
water loss.
•The entire plant surface is covered by the epidermis.
•It protects all parts of the plant.
•Epidermal cells in aerial parts secrete a waxy, water-resistant
layer.
•This layer helps protect against water loss, injury, and fungal
infection.
•Epidermal cells form a continuous layer with no spaces
between them.
•These cells are mostly flat, with thicker outer and side walls
than the inner wall.
28.
EPIDERMIS
•Small pores areseen in the epidermis of leaves.
•These pores are called stomata.
•Each stoma is surrounded by two kidney-shaped guard
cells.
•Stomata help in gas exchange with the atmosphere.
•Transpiration (loss of water as water vapour) also
happens through stomata.
29.
EPIDERMIS
•Root epidermal cellshave long hair-like parts to
absorb more water.
•These root hairs increase the surface area for
absorption.
•In desert plants, the epidermis has a thick waxy layer
of cutin.
•Cutin is a waterproof substance that helps reduce water
loss.
•As plants grow older, their outer protective layer
changes.
•In old stems and branches, a secondary meristem forms
cork in the cortex.
•Cork cells are dead, tightly packed, and have no
intercellular spaces.
•Cork cells contain suberin, which makes them
COMPLEX PERMANENT TISSUE
•Simplepermanent tissues are made of one type of
similar cells.
•Complex permanent tissues are made of more than
one type of cells.
•These different cells work together to do a common
function.
•Xylem and phloem are examples of complex tissues.
•They are conducting tissues and form the vascular
bundle.
•Vascular tissue is one tissue that helps plants survive in
land (terrestrial) environments.
•In stem sections, we can see different types of cells in
the vascular bundle.
32.
Xylem
•Xylem is madeup of tracheids, vessels,
xylem parenchyma, and xylem fibres.
•Tracheids and vessels have thick walls
and are mostly dead when mature.
•They are tubular structures that help in
vertical transport of water and minerals.
•Xylem parenchyma helps in storing food.
•Xylem fibres provide support to the plant.
Phloem
•Phloem is madeof five types of
cells: sieve cells, sieve tubes,
companion cells, phloem
fibres, and phloem
parenchyma.
•Sieve tubes are tubular cells
with perforated walls.
•Phloem helps in transporting
food from leaves to other parts
of the plant.
•All phloem cells are living,
except phloem fibres, which are
dead.
35.
QUESTIONS
1. Name thetypes of simple tissues.
Parenchyma (b) Collenchyma (c) Sclerenchyma
2. Where is apical meristem found?
It is present at the growing tips of stem and root,
it increases the length of the stem and roots.
3. Which tissue makes up the husk of coconut?
Sclerenchyma
4. What are the constituents of phloem?
Phloem constitutes the sieve tubes, companion
cell, phloem parenchyma and phloem
fibres.
