THE HINDU SENIOR SECONDARY SCHOOL, INDIRA NAGAR,
CHENNAI-20
Class: 9
Sub: Biology
I.
Chapter: 6. Tissues (Classwork)
ANSWER THE FOLLOWING:
1. Define a) Tissues b) the process of differentiation.
Ans: a) Tissues: A group of cells that are similar in structure and origin and
perform similar function.
b) Differentiation is defined as the process in which the ability to divide is
lost at the stage of maturity by obtaining permanent shape and function.
2. Differentiate between:
a) meristematic and permanent tissues in Plants.
Ans:
Meristematic tissues
1. These tissues have the
capacity to divide.
2. They have thin cell wall made
up of cellulose.
3. They have dense cytoplasm
with prominent nucleus,
small vacuoles and do not
have intercellular spaces.
4. They produce permanent
tissues.
5. These are immature,
undifferentiated cells.
6. These are composed of living
cells.
7. It provides growth to the
Plant.
Permanent tissues
1. These tissues have lost the
capacity of division.
2. They have thick cell wall made
up of cellulose which may be
lignified or it may have Suberin.
3. They have thin cytoplasm with
nucleus, large vacuole and have
large intercellular spaces.
4. They are produced by
meristematic tissues.
5. These are mature, differentiated
cells.
6. These are group of live and dead
cells.
7.It provides, protection, support,
and involve in conduction,
photosynthesis, storage etc.
b) Types of Meristematic tissues in Plants.
Apical meristem
 It is present at
the growing tips
of stems and
roots.
 Cell division in
this tissue leads
to the elongation
of stem & root.
 It is involved in
primary growth of
the plant
Intercalary meristem
 These are present at
the base of leaf &
internode region.
 These lead to the
increase in the length
of leaf in monocots
like grass and mint
and also increases the
internodes.
 It is the part of apical
meristem which is left
behind during growth
period.
Lateral meristem
 It occurs along
the sides of
longitudinal axis
of the plant.
 It gives rise to the
vascular tissues
and causes
growth in girth of
stem & root.
 They are
responsible for
secondary
growth.
c) Parenchyma, Collenchyma and Sclerenchyma.
1.
2.
3.
4.
5.
Parenchyma
Parenchyma cells
are found in
every soft part of
the plant.
Composed of
unspecialized
living cells.
Cell wall is thin
and made up of
cellulose.
Intercellular
space is present
between cells.
Photosynthesis,
storage of food,
gas exchange and
Collenchyma
Sclerenchyma
1. Collenchyma cells
1. Sclerenchyma is
are found in
found in the
petiole, leaves
mature parts of
and young stems.
the plant.
2. Composed of
2. Composed of
specialized living cells.
specialized dead cells.
3. Cell wall is unequally
thin and made up of
cellulose and pectin.
4. No or little
intercellular space is
present.
5. Providing mechanical
support to the plant,
resisting bending and
3. Cell wall is thick and
rigid and made up of
water proofing lignin.
4. No intercellular space
is present.
5. Providing mechanical
support, protection and
transportation of water
floating of
aqueous plants
are the major
functions.
stretching by the wind
and nutrients are the
are the major functions. major functions.
d) Xylem and Phloem
Xylem
It transports water and
minerals from the roots to
the aerial parts of the plant.
It consists of tracheid,
vessels, xylem fibres and
xylem parenchyma.
i)
ii)
i)
ii)
iii)
Only xylem parenchyma is
living and other three
elements are dead tissues.
iii)
iv)
Conduction in xylem is
unidirectional. i.e., from
roots to aerial parts of the
plant.
It gives mechanical strength
to the plant.
iv)
v)
v)
Phloem
It transports food material
from the leaves to all
growing parts of the plant.
It consists of sieve tubes,
sieve cells, companion cells,
phloem fibres and phloem
parenchyma.
Sieve tubes, companion
cells and phloem
parenchyma are living and
phloem fibres are dead
tissues.
Conduction in phloem is
bidirectional. i.e., from
leaves to storage organs
and growing parts.
It does not provide
mechanical strength.
3. Write a short note on Epidermis.
Ans: • Epidermis tissue covers the entire body of plant. They protect
plant from injury, germs and water loss.
 Cells of epidermal tissue form a continuous layer without intercellular
spaces.
 Stomata are small openings on epidermal layer of leaf and soft part of
stem to facilitate the gaseous exchange and transpiration in plants. Each
stomata is composed of two guard cells which regulate the opening and
closing of stomata.
 In desert plants, epidermis and cutin (a water proof waxy
substance secreted by epidermis) are thicker to reduce loss of
water due to transpiration.
4. Write a note on the protective tissue – Cork or Phellem.
Ans:
 These types of tissue consist dead cells with no intercellular spaces. They
form the outer layer of old tree trunks.
 Cork cells have a chemical called suberin in their walls that makes them
impervious to gases and water.
 Cork tissue protects plants from injuries, germs and water loss.
 Cork being light in weight is used for making several products like bottle
stoppers and shuttle cork.
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