TISSUES
Tissues are groups of similar cells that perform a common
function. For example, blood, muscle, and Phloem are all tissues that are
specialized for particular tasks.
Meristematic tissue
- These
are living tissues which are capable of division throughout life. These
tissues are found in growing regions of plants.
- Cells
of meristematic tissues are highly compact with no space between them, no
vacuole and large nucleus.
- Classification
of meristematic tissues
- (i)
Apical meristem - It is present at the growing tips of shoot and roots.
They are responsible for increase in the length of shoot and root.
- (ii)
Intercalary meristem - These are present at the base of leaf or internode
(on either side of the node).They are responsible for the growth in length
of plant organs.
- (iii)
Lateral meristem (cambium) - It lies on the lateral sides of stem and root
or occurs along the sides of the longitudinal axis of the plant. It helps
in increasing the diameter (girth) of the plant, hence helps in secondary
growth.
DIFFERENCE BETWEEN PARENCHYMA
COLLENCHYMA AND SCLERENCHYMA
|
Basis
of Difference |
Parenchyma |
Collenchyma |
Sclerenchyma |
|
Nature of
cells |
Living
cells |
Living
cells |
Dead cells |
|
Shape of
cells |
Usually
round or oval |
Elongated
cells |
Long,
narrow cells |
|
Cell wall |
Thin cell
wall |
Unevenly
thickened at corners |
Very thick,
lignified cell wall |
|
Intercellular
spaces |
Present |
Little or
absent |
Absent |
|
Function |
Storage of
food, photosynthesis |
Provides
support and flexibility |
Provides
strength and rigidity |
|
Found in |
Cortex,
pith, leaves, fruits |
Below
epidermis of stem and leaf |
Seed coat,
nut shell, veins of leaves |
|
Flexibility |
Soft and
flexible |
Flexible |
Rigid, not
flexible |
|
Example |
Potato,
leaf mesophyll |
Celery stem |
Coconut
husk, jute fibre |
ARENCHYMA is
a parenchyma tissues that has air between them .these makes the aquatic plants
to float on the water.
DIFFERENCE BETWEEN XYLEM AND PHLOEM
DIFFERENCE
BETWEEN MUSCLE TISSUES
STRUCTURE
OF NEURON
DIFFERENCE
BETWEEN BONES AND CARTILAGE
What are the functions of stomata?
Ans.
Functions of stomata. (i) Gaseous exchange: Stomata are sites where exchange of
gases (carbon dioxide and oxygen) occurs between the plant internal and
external environment. (ii) Transpiration: Major part of transpiration occurs
through stomata. Transpiration removes excess water and keeps plant surfaces
cool.
9. Name the following : (a) Tissue that forms the inner lining of our mouth. (b) Tissue
that connects muscle to bone in humans. (c) Tissue that transports food in
plants. (d) Tissue that stores fat in our body. (e) Connective tissue with a
fluid matrix. (f) Tissue presents in the brain. Ans. (a) Epithelial tissue (b) Tendon (c) Phloem (d) Adipose (e)
Blood (f) Nervous tissue
10. Identify the types of
tissue in the following: skin, bark of tree, bone, lining of kidney tubule,
vascular bundle. Ans. Skin: Epithelial tissue, connective tissue. Bark of Tree:
Cork (Protective tissue). Bone: Connective tissue with solid matrix. Lining of
Kidney tubule: Epithelial tissue. Vascular Bundle: Complex or vascular tissues,
xylem and phloem.
How does the cork act as a protective tissue?
Ans.
Cork acts as a protective layer because its cells are dead, filled with
tannins, resin and air, impermeable due to deposition of suberin in the cell
walls and absence of intercellular spaces. It is insulating (heat proof),
fire-proof, shock proof, waterproof and repellent to microbes and animals.
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